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Evaluation of the capacity of three halophytes to desalinize their rhizosphere as grown on saline soils under nonleaching conditions

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In the sabkha of Soliman (N-E Tunisia), soil samples of the upper 20 cm were taken during the driest period of the year (July–August) from inside and outside tufts of two perennial halophytes: Arthrocnemum indicum (Willd.) Moq. and Suaeda fruticosa Forssk., both from family Chenopodiaceae. Samples were analysed for electrical conductivity of the saturation paste extract (ECe) and soluble sodium (Na⁺) content. Then, tufts were divided into three size categories and their shoot biomass production and Na⁺ content were determined. Our results showed a considerable contribution of shoot Na⁺ accumulation to rhizosphere desalination. The capacity of the two native halophytes A. indicum. and S. fruticosa to desalinize saline soils was compared with that of an introduced halophyte, Sesuvium portulacastrum L. (Aizoaceae). Seedlings were grown under greenhouse conditions in pots containing 8 kg of saline soil each. Pots were irrigated with tap water during 170 days without leaching. Our results confirmed the contribution of shoot Na⁺ accumulation to soil desalination. They showed also that among the three studied species, Sesuvium portulacastrum L. seems to be the most convenient to be used for this purpose in arid and semi-arid regions where precipitation is too low to leach salts from rhizosphere.

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... In addition to the factors affecting the performance of halophytes mentioned above, the possible mechanisms of halophytes desalinization need clarifying (Shabala, 2013;Jesus et al., 2015;Jesus et al., 2018;Litalien and Zeeb, 2020). Debate on the main mechanism contributing to soil remediation has yet to be settled, including aboveground salt accumulation and rootmicrobe-soil interactions which improve soil properties leading to salt leaching (Qadir et al., 2000;Rabhi et al., 2009;Rasouli et al., 2013). The mechanisms are crucial to improve the phytoremediation-beneficial traits to enlarge the applicability and effectiveness of halophytes desalinization. ...
... Aboveground accumulation and root-soil interaction are two main parts of soil desalinization. Studies proved the potential of halophytes for salt uptake (Ravindran et al., 2007;Rabhi et al., 2009;Rabhi et al., 2010a), while Gharaibeh et al. (2011) suggested that salt uptake in aboveground biomass is a small percentage comparing with original salt content or salt input by irrigation in saline soils and, in consequence, root rhizosphere processes would be the main mechanism of desalinization. This analysis showed that harvest significantly increased desalinization, and desalinization was detected to be greater with larger shoot biomass, indicating the important contribution of aboveground salt accumulation to desalinization and that shoot biomass could be used as an indicator of the desalinization performance of halophytes. ...
... In this study, desalinization by halophytes was similar in the pot experiments and field experiments (Figure 3), and shoot Cl − accumulation contributed more to desalinization in pot experiments than in field experiments ( Figure 5; Supplementary Figure S2). Pot experiments could control leaching (Qadir et al., 1996;Qadir et al., 2005;Rabhi et al., 2009;Gharaibeh et al., 2011), thereby soluble ions that should have been leached out of the rhizosphere would be absorbed by the plants. So, it should be noted that pot experiments would magnify the contribution of aboveground salt accumulation to desalinization. ...
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Soil salinization threatening natural and agricultural production challenges global food security. Halophytes are of great interest in soil desalinization in recent years; yet, there is a lack of a comprehensive quantitative overview of biotic and abiotic factors for halophytes’ desalinization performance across global scales. Here, a meta-analysis was conducted using 400 observations from 53 peer-reviewed studies to assess desalinization by halophytes in relation to 27 variables. Results showed that soil salinity was significantly decreased in halophytes field on average by 37.7% compared to control on a global scale (p < 0.05). Desalinization performance was better in cold and hot regions than in temperate regions, in dry regions than in wet regions, in alkaline saline soils than in neutral saline soils, and in conditions with low sand content than high sand content. Under aboveground harvest treatment, desalinization increased with the years of cultivation, while no trends were detected under no harvest treatment, indicating the importance of aboveground accumulation. Desalinization was not related to soil CaCO3 content but was accompanied by soil structure improvement, nutrition enrichment, and microbe propagation, implying other root-microbe-soil interactions rather than CaCO3 dissolution play important roles. Shoot biomass could be used as an indicator of the desalinization performance, and the performance would not be decreased due to the high uptake selectivity for K⁺ over Na⁺. Notably, desalinization was similar in the pot experiments and field experiments, but pot experiments would magnify the contribution of aboveground salt accumulation to desalinization. Our findings can help to expand the applicability and efficiency of halophytes for sustainable agricultural development in saline soils.
... Over time, the reduced soil salinity creates conditions suitable for the growth of non-halophytic or glycophytic plants (Lastiri-Hernández et al. 2019). It is considered a sustainable approach to soil remediation since it relies on the natural processes of halophytic plants thus minimizes the need for external inputs or energy-intensive interventions, making it a cost-effective and environmentally friendly technique (Rabhi et al. 2009). ...
... Additionally, phytodesalination allowed H. vulgare plants to maintain a high-water content and develop greater biomass with relatively high potassium and low sodium contents. The results demonstrated a significant role of shoot Na + accumulation in rhizosphere desalination (Rabhi et al. 2009). The desalination capabilities of the two native halophytes, A. indicum and S. fruticosa, were compared with that of the introduced halophyte, Sesuvium portulacastrum L. ...
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Purpose:Heavy metals pose a significant environmental threat due to their widespread occurrence and harmful effects on ecosystems and human health. This study aims to explore the extent of heavy metal contamination and to evaluate the potential of phytoremediation as a sustainable solution for mitigating heavy metal pollution. Methods: The study reviews the release of heavy metals into the environment through industrial activities and natural processes, leading to their accumulation in environmental entities. The mechanisms of heavy metal uptake, translocation, and tolerance in plants are analyzed to understand how certain plant species act as hyperaccumulators.Results: The hazard index for heavy metals such as Cr and Pb was found to be significantly higher in children, being 7 and 7.5 times greater, respectively, than in adults. The lifetime cancer risk for chromium exposure in children, through various soil contact scenarios, was calculated at 5.361 × 10−4 mg Kg−1, placing it at the lower edge of the acceptable range for potential cancer risk. Phytoremediation emerges as a promising, eco-friendly technology for addressing heavy metal contamination, with specific plant species demonstrating effective hyperaccumulation capabilities.Conclusion: Phytoremediation presents a sustainable and promising approach for the remediation of environments contaminated with heavy metals. While challenges such as plant species selection, soil chemistry influence, and the time required for remediation exist, this review provides valuable insights into the current state of phytoremediation technology and suggests directions for future research to effectively tackle heavy metal pollution.
... This species has a minimal irrigation demand, can thrive in very salty soils, and can remove 1,088 kg in 0.4 acres. Under greenhouse circumstances, Rabhi et al. (2009) investigated the potential of Suaeda fruticosa and Tecticornia indica for soil desalination. Trees, shrubs, and grasses grown in salt-affected areas and/or with high saline water tables will provide two main benefits: (i) control of taking over to or withdrawal from groundwater; and (ii) use of saline drainage water or piped spring water to reduce salty water tables. ...
... Among the species tested, S. maritima and S. portulacastrum had higher salt build-up in their tissues, resulting in better reclaimed salt-damaged soil. Rabhi et al. (2009) assessed the desalinization capacity of two native (Tunisia) species, Arthrocnemum indicum and Suaeda fruticosa, in their rhizospheric zone under non-leaching conditions. They compared the salt removal abilities of these two species to that of an introduced halophyte, Sesuvium portulacastrum. ...
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The current chapter is on the global problem of salty sand sodic soils, which has an impact on the numerous ecosystem services (ES) of land and soil. The restoration of such lands is the most difficult task for scientific communities, and it can not only improve soil quality but also increase the area under cultivation for food and fodder crops. The following 10 primary headings are associated with the concept of saline and sodic soils; salinity and sodicity influenced soils: Land degradation in terms of soil salinity and sodicity, restoration, and its dynamics, halophytes: characteristics, distribution, classification, and halo-remediation; adaptation mechanism of halophytes under saline conditions; ecological significance of halophytes under saline conditions; potential use of halophytes under saline conditions The role of agroforestry in soil reclamation, as well as experience from the Indian subcontinent, are highlighted. Agroforestry and its role in soil reclamation are further elaborated with scientific information on tree species selection; halophytes for agroforestry; an assortment of multifunctional species for salt-affected areas; and multifunctional agroforestry systems such as silvipastoral, silvi-agric, horti-agricultural, and sequential agroforestry systems. In this effort, the scientific explorations for saline and sodic soil remediation from the Indian subcontinent were explained under the following sub-headings: salt-tolerant plants/halophytes, suitable planting techniques, agroforestry systems on saline areas, grassland/pastoral systems, afforestation of coastal saline areas, knowledge on afforestation/agroforestry on alkali and or sodic soils, planting techniques. This is the first endeavor from India’s arid region to elaborate on the restorative dynamics of saline and salt-damaged soils, namely reclamation, remediation, and rehabilitation. Furthermore, thorough and comparative classifications, as well as species from other halophytic categories, were discussed. Finally, research gaps in the usage of several halophytes for restoration of such lands were identified. Our understanding of the physiological and biochemical mechanisms underlying halophytes under varying salinities is particularly limited. Thus, physiological and molecular research into the underlying mechanisms of these processes is critical. It would be important to find the genes that are linked to the high biomass phenotype and then make transgenic plants with better features for cleaning up pollution.
... Recently, phytodesalination has emerged as a realistic biological approach based on the use of Na-hyperaccumulating halophytes to remove Na + ions from sodic and saline-sodic soils. In this context, several halophytes were tested for their phytodesalination potential and showed encouraging results (Jlassi et al., 2013;Lastiri-Hernández et al., 2019;Rabhi et al., 2009;Ravindran et al., 2007). ...
... g −1 DW (which corresponds to 5.8 mmol Na + . g −1 DW), a value that is similar to that obtained by Rabhi et al. (2009) and Sassi et al., (2017) following the addition of 2.5 and 1 g NaCl. kg −1 soil, respectively. ...
Article
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The aim of the present work was to study the possibility of coculture of the two halophytes Sesuvium portulacastrum–Sulla carnosa under saline and non-saline conditions with a special focus on plant vigour and phytodesalination potential. Plants were grown for 2 months in unperforated pots filled with agricultural soil added or not with 1.5 g NaCl. kg⁻¹. Thereafter, shoots were harvested for growth, water status, and mineral composition. Soil samples were also analysed. Plant productivities and phytodesalination potentials were estimated based on shoot dry weights and sodium contents as well as soil soluble sodium contents. As grown for only 2 months in monoculture, S. carnosa could not desalinate the slightly saline soil, unlike S. portulacastrum, which extracted a quarter of the added sodium quantity. Nevertheless, such a noticeable phytodesalination capacity of S. portulacastrum did not reduce soil salinity and soluble sodium content. S. carnosa growth and productivity were enhanced by both salinity and coculture under non-saline conditions, which can be explained respectively by S. carnosa halophytic behaviour and probably a positive allelopathy exerted by S. portulacastrum. By contrast, a negative allelopathy seems exerted by S. carnosa under both saline and non-saline conditions. Under moderately saline conditions, both halophytes should be grown in monoculture. The stimulatory effect of S. portulacastrum on S. carnosa under non-saline conditions needs further investigations.
... Since a number of these salt-tolerant species are characterized by Na uptake activity, they would permit soil phytodesalination by exploiting a halophyte's natural capacity to absorb toxic Na + ions, while simultaneously increasing the amount of water available for crop cultivation and lowering the freshwater footprint of individual crops. The efficiency of Na uptake has been evaluated in different trials for multiple species [15][16][17]. Similarly, the study of crop rotation and intercropping of salt-sensitive and salt-resistant species in saline environments has been successfully explored with the majority of experiments concluding that the saltsensitive species can benefit from the phytodesalination performed by the salt removing species [18][19][20][21]. ...
... Similarly, the study of crop rotation and intercropping of salt-sensitive and salt-resistant species in saline environments has been successfully explored with the majority of experiments concluding that the saltsensitive species can benefit from the phytodesalination performed by the salt removing species [18][19][20][21]. Such trials are mainly performed under soil conditions, yet soilless systems are known to achieve better water use efficiency compared to field conditions [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], and growing crops in hydroponics under saline conditions has already been successfully tested. However, to-date, the literature still lacks data from intercropping salt-sensitive and salt-tolerant crops in hydroponic conditions. ...
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Competition for freshwater is increasing, with a growing population and the effects of climate change limiting its availability. In this experiment, Lactuca sativa plants were grown hydroponically with or without a 15% share of seawater (12 dS m−1) alone or intercropped with Salsola soda to demonstrate if L. sativa benefits from sodium removal by its halophyte companion. Contrary to the hypothesis, saline-grown L. sativa plants demonstrated reduced growth compared to the control plants regardless of the presence or absence of S. soda. Both limitations in CO2 supply and photosystem efficiency may have decreased CO2 assimilation rates and growth in L. sativa plants grown in the seawater-amended solutions. Surprisingly, leaf pigment concentrations increased in salt-treated L. sativa plants, and most notably among those intercropped with S. soda, suggesting that intercropping may have led to shade-induced increases in chlorophyll pigments. Furthermore, increased levels of proline indicate that salt-treated L. sativa plants were experiencing stress. In contrast, S. soda produced greater biomass in saline conditions than in control conditions. The mineral element, carbohydrate, protein, polyphenol and nitrate profiles of both species differed in their response to salinity. In particular, salt-sensitive L. sativa plants had greater accumulations of Fe, Ca, P, total phenolic compounds and nitrates under saline conditions than salt-tolerant S. soda. The obtained results suggest that intercropping salt-sensitive L. sativa with S. soda in a hydroponic system did not ameliorate the growing conditions of the salt-sensitive species as was hypothesized and may have exacerbated the abiotic stress by increasing competition for limited resources such as light. In contrast, the saline medium induced an improvement in the nutritional profile of S. soda. These results demonstrate an upper limit of the seawater share and planting density that can be used in saline agriculture when intercropping S. soda plants with other salt-sensitive crops.
... In addition, these soils often have high pH. Root respiration has been conjectured to lower the soil pH near the root surface through the formation of carbonic acid, which can increase dissolution of free lime and make more calcium available for exchange with sodium (Nye, 1981;Marschner & Römheld, 1983;Qadir et al., 1996aQadir et al., , 1996bQadir et al., , 2000Qadir et al., , 2003Qadir et al., , 2006aQadir & Oster, 2002;Rabhi et al., 2009Rabhi et al., , 2010Rasouli et al., 2013;Walker et al., 2014;Youssef & Chino, 1989). ...
... Another benefit of phytoremediation is that plant roots create pores for air and water infiltration and root exudates help rebuild soil structure (Traoré et al., 2000). Plant growth also can add organic matter to the soil through residue addition, aiding soil structure and providing food sources to soil microbes to stimulate their activity (Ahmad et al., 1990;Ammari et al., 2013;Rao & Pathak, 1996;Pathak & Rao, 1998;Li et al., 2006;Wong et al., 2009) and remove salts, specifically sodium, through accumulation in biomass (Qadir et al., 2006b;Ahmad et al., 1990;Ashraf et al., 2010;Rabhi et al., 2009Rabhi et al., , 2010Ammari et al., 2013;Shelef et al., 2012). But if plant litter is returned rather than physically removed, the effectiveness of reducing sodium levels in the area may be unsuccessful (Qadir et al., 2000;Minhas et al., 2007;Shekhawat et al., 2006;Gharaibeh et al., 2011). ...
Article
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Revegetation of saline–sodic soils is challenging. Over 10 million saline–sodic hectares are intertwined with highly productive soils in the Northern Great Plains, with 3.4 million ha in South Dakota. Establishing salt‐tolerant perennial plants provides soil cover and remediates barren areas. Two perennial salt‐tolerant grass mixes [Mix 1: slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners) + beardless wildrye (Leymus triticoides [Buckley] Pilg.); Mix 2: slender wheatgrass + creeping foxtail (Alopercurus arundinaceus Poir.) + western wheatgrass (Pascopyrum smithii [Rydb.] Á. Löve) + ‘AC Saltlander’ green wheatgrass (Elymus hoffmannii K.B. Jensen & K.H. Asay)] were dormant‐planted in 2018 and 2019 along a soil catena with high [electrical conductivity (EC1:1) = 0.39 dS m–l; 72 mg kg–1 Na⁺], moderate (EC1:1 = 1.64 dS m–l; 343 mg kg–1 Na⁺), and low (EC1:1 = 3.87 dS m–l; 1,680 mg kg–1 Na⁺) productivity zones. Vegetative biomass was measured after seeding (2018, 2019) and during growth (2020, 2021), and compared with areas seeded to maize (Zea mays L.) and a nonplanted area. Biomass varied with year and productivity zone. Except in 2018, grasses had greater biomass in the moderate and low productivity zones than maize. The sodium content of grass biomass in 2020 and 2021 was 10× greater in the low than in the high and moderate productive zones (0.25 vs. 0.02%, respectively) but could be suitable for livestock feed. By 2021, grass biomass was similar for both mixes in all zones, and the grasses spread into nonplanted areas.
... Adaptive agronomic phytoremediation strategy for farming systems was expected to improve saline-sodic soils and sustain agricultural production (Manousaki and Kalogerakis, 2011b;Zakery-Asl et al., 2014;Ashraf et al., 2010;Nouri et al., 2017). Suaeda salsa and Alfalfa were classified as popular halophytes that could be used as a promising tool for removal of excess salinity and sodium from saline-sodic soils (Rabhi et al., 2009;Qadir et al., 2003a). In this present study, we tried to propose a new cotton/halophytes intercropping system [such as cotton/Suaeda salsa intercropping (CSSI) and cotton/aflafla intercropping (CAI) systems] based on the traditional monocropping cotton (MC) film-mulched drip irrigation system. ...
... This might be attributed to the following three possible mechanisms that showed in Fig. 8. Firstly, in our study, Suaeda salsa and alfalfa could enhance salt removal in no mulch strips by taking up soil salt and accumulate in aboveground dry matter (Table 4 and Fig. 8). Similar study reported by Rabhi et al. (2009) indicated that the Suaeda salsa could take up soil salt through their roots and store it in their tissues, thereby decreasing soil salinity. Panta et al. (2014) and Zhao (1991) also demonstrated that the Suaeda salsa could not only take up sodium ions through their roots but also conduct them to their shoots, thereby reducing sodium ions content in the saline-sodic soils. ...
Article
Soil salinization has become a severe threat deteriorating soil quality and restricting sustainable agricultural development in arid and semi-arid areas. The objective of this study was therefore to propose a new cotton/ halophytes intercropping system [such as cotton/Suaeda salsa intercropping (CSSI) and cotton/alfalfa inter-cropping (CAI) systems] to improve soil salinization and crop production based on the traditional monoculture cotton (MC). A three-year field experiment was conducted to explore the effects of the MC, CSSI, and CAI systems on soil salt accumulation, salt removal, soil physicochemical properties, root mass density, aboveground biomass, seed cotton yield, and irrigation water productivity (IWP). Experiment treatments consisted of three cropping systems: MC, CSSI, and CAI systems, respectively. All treatments were designed using a randomized complete block with three replications. The result indicated that the CSSI and CAI systems could decrease soil EC 1:5 , salt accumulation, bulk density, Na + content, and pH in no mulch strips and increase salt removal, soil porosity, and organic carbon content compared with the MC system. Compared with the MC system, the CSSI system increased root mass density in 0− 20 cm soil depth. No significant differences in seed cotton yield and IWP were found among the MC, CSSI, and CAI systems in 2014. However, total aboveground biomass, seed cotton yield, and IWP were significantly higher in the CSSI and CAI systems than that of the MC system in 2015 and 2016. This study suggested that the cotton/halophytes intercropping system showed greater salt removal and crop productivity than the MC system. Therefore, the CSSI and CAI systems should be recommended as a long-term agronomic remediation method for improving soil salinization and increasing cotton yield in the arid area of northwest China.
... Remove sodium from the soil by accumulating it in shoots Rabhi et al. (2009) Arundo donax Hyperaccumulation of salts Devi et al. (2008) Atriplex nummularia ...
... Suaeda fruticosa Desalinized rhizosphere by salt leaching.Rabhi et al. (2009) Suaeda maritime Hyperaccumulation of salts in their tissues as well as higher reduction of salts in the soil medium system, excluder plants avoid salts from penetrating their tissues; accumulator plants pick up and accumulate salts in their tissues when conducting plants absorb salts and excrete them by salt glands, leading salts from t ...
Chapter
SoilSoilsalinitySalinity is a rising human concern and a significant challenge to biodiversityBiodiversity, since high salinity makes the soilSoil inappropriate for most plants. The contamination of soils due to salinity damages almost one-fourth of agriculturalAgricultural land. Soil salinization is a natural process and is amplified by several anthropogenicAnthropogenicpractices. SalineSaline soil affects the growth and development of the majority of the plants. The remediation of soil salinity is an economically expensive challenge of the present era. Since the last few decades, several approaches for amelioration of salt-affected soil have been used but among these techniques, few are less expensive. Though most of the plants are severely affected by soil salinization, some plants develop many tolerance mechanisms and detoxification strategies to remove excess salt from the soil. Plants are utilized to remove excess salt is nowadays considered as one of the effective and less expensive useful options. Such kind of remediation is also called as phytoremediationPhytoremediation or green remediation. Plant-based remediation now has gained much attention as it facilitates benefit in various types of salt-affected habitats worldwide. This chapter reviews various plant-based strategies of bioremediationBioremediation of salt-affected soil.
... Halophytes are salt tolerant species due to various adaptation mechanisms such as the exclusion of salt ions in excess at the root level, the uptake and sequestration of these ions in cells of the aerial organs (accumulator halophytes), or the ion excretion at leaf surfaces (recretohalophytes) (Yensen and Biel 2006). Most of the halophyte species studied for their ability to remediate saltaffected soils and effluents are accumulators (Brown et al. 1999;Doni et al. 2015;Jesus et al. 2014; Khandare and Govindwar 2015;Manousaki and Kalogerakis 2011;Masciandaro et al. 2014;Padmavathiamma et al. 2014;Pouladi et al. 2016;Qadir et al. 2007;Rabhi et al. 2009). These studies focus on the capacity of accumulators to sequester saline ions in the aboveground biomass. ...
... Chloride is a micronutrient useful for plants, e.g. in photosynthesis, but can be phytotoxic at high levels (White and Broadley 2001). Some halophyte species are known for their capacity to accumulate chloride (Devi et al. 2016(Devi et al. , 2008Krishnapillai and Ranjan 2005;Rabhi et al. 2009Rabhi et al. , 2008Hasanuzzaman et al. 2014). In this context, the most studied species are Atriplex spp., Avicennia spp., Phragmites spp., Salicorna spp., Sesuvium spp., Suaeda spp., Tetragonia spp., and Typha spp. ...
Article
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Anthropogenic activities can be the source of saline solid wastes that need to be treated to reduce their salt load to meet the purposes of reuse, valorization or storage. In this context, chloride remediation can be achieved using high-salt accumulating plants. However, there is very limited information on the comparative potential of different species in the same environment, and only scarce data concerning their efficiency as a function of growth stage. In order to rationalize these selection criteria, three macrophytes i.e., common reed (Phragmites australis), sea rush (Juncus maritimus), and cattail (Typha latifolia), were cultivated at two growth stages (6-months old and 1-year old) for 65 days in Cl⁻ spiked substrates (from 0 up to 24 ‰ NaCl). The plants’ survival and potential capacity for removal of Cl⁻ from substrates and accumulation in shoots were investigated. For the three studied species, mature and juvenile plants display a high tolerance to salinity. However, mature specimens with higher shoot biomass and Cl⁻ contents are capable of greater chloride removal than juvenile plants. The sole exception is P. australis which displays just the same phytoremediation potential for both mature and juvenile specimens. Moreover, P. australis has the lowest potential when compared with other species, being 1.5 and 3 times lower than for J. maritimus and T. latifolia. When considering the plant growth and the shoot biomass production, chloride removal rates from the substrate point that mature J. maritimus should preferentially be used to design an operational chloride remediation system. The results highlight the relevance of considering the growth stage of plants used for Cl⁻ removal. Highlights 1) Mature and juvenile specimens of J. maritimus, P. australis, and T. latifolia have high salinity tolerance in solid media spiked up to 24 ‰ NaCl. 2) Mature plants have generally better Cl⁻ removal and phytoremediation performances than juvenile specimens. 3) J. maritimus is the most effective species for chloride phytoremediation with high survival and high Cl⁻ sequestration in shoots. 4) T. latifolia has high Cl⁻ removal in shoots and good remediation capacities but also shows sign of stress. 5) P. australis shows low Cl⁻ sequestration and is a poor candidate for chloride remediation from substrate.
... Adaptive agronomic phytoremediation strategy for farming systems was expected to improve saline-sodic soils and sustain agricultural production (Manousaki and Kalogerakis, 2011b;Zakery-Asl et al., 2014;Ashraf et al., 2010;Nouri et al., 2017). Suaeda salsa and Alfalfa were classified as popular halophytes that could be used as a promising tool for removal of excess salinity and sodium from saline-sodic soils (Rabhi et al., 2009;Qadir et al., 2003a). In this present study, we tried to propose a new cotton/halophytes intercropping system [such as cotton/Suaeda salsa intercropping (CSSI) and cotton/aflafla intercropping (CAI) systems] based on the traditional monocropping cotton (MC) film-mulched drip irrigation system. ...
... This might be attributed to the following three possible mechanisms that showed in Fig. 8. Firstly, in our study, Suaeda salsa and alfalfa could enhance salt removal in no mulch strips by taking up soil salt and accumulate in aboveground dry matter (Table 4 and Fig. 8). Similar study reported by Rabhi et al. (2009) indicated that the Suaeda salsa could take up soil salt through their roots and store it in their tissues, thereby decreasing soil salinity. Panta et al. (2014) and Zhao (1991) also demonstrated that the Suaeda salsa could not only take up sodium ions through their roots but also conduct them to their shoots, thereby reducing sodium ions content in the saline-sodic soils. ...
Article
Soil salinization has become a severe threat deteriorating soil quality and restricting sustainable agricultural development in arid and semi-arid areas. The objective of this study was therefore to propose a new cotton/halophytes intercropping system [such as cotton/Suaeda salsa intercropping (CSSI) and cotton/alfalfa intercropping (CAI) systems] to improve soil salinization and crop production based on the traditional monoculture cotton (MC). A three-year field experiment was conducted to explore the effects of the MC, CSSI, and CAI systems on soil salt accumulation, salt removal, soil physicochemical properties, root mass density, aboveground biomass, seed cotton yield, and irrigation water productivity (IWP). Experiment treatments consisted of three cropping systems: MC, CSSI, and CAI systems, respectively. All treatments were designed using a randomized complete block with three replications. The result indicated that the CSSI and CAI systems could decrease soil EC1:5, salt accumulation, bulk density, Na⁺ content, and pH in no mulch strips and increase salt removal, soil porosity, and organic carbon content compared with the MC system. Compared with the MC system, the CSSI system increased root mass density in 0−20 cm soil depth. No significant differences in seed cotton yield and IWP were found among the MC, CSSI, and CAI systems in 2014. However, total aboveground biomass, seed cotton yield, and IWP were significantly higher in the CSSI and CAI systems than that of the MC system in 2015 and 2016. This study suggested that the cotton/halophytes intercropping system showed greater salt removal and crop productivity than the MC system. Therefore, the CSSI and CAI systems should be recommended as a long-term agronomic remediation method for improving soil salinization and increasing cotton yield in the arid area of northwest China.
... The findings here indicate potential benefit of Salicornia brachiata if resorted and integrated to crop production system in saline soils intruded with seawater for enhancement of scope of sustainable marine ecosystem and as remedial measure Table 16.1) which is of immense help to the producers with a new alternative cropping system having high industrial potential for its valued nutritional salt and linoleic rich oil and plant bioactive derivatives. Rabhi et al. (2009Rabhi et al. ( , 2010 reported that Arthrocnemum indicum, Suaeda fruticosa and Sesuvium portulacastrum seedlings grown on a saline soil significantly reduced the soil salinity by absorbing soluble salts mainly sodium ions. They also further reported that Sesuvium portulacastrum was able to accumulate nearly 30% of Na + content in shoot. ...
... Bioremediation or bioreclamation of salt-affected soils is an economic solution mainly for developing countries since engineering options like drainage are expensive. Several authors (Ke-Fu 1991; Rabhi et al. 2009) have reported that the potential of halophytic plants to accumulate enormous salt quantities depends often on the capacity of their green biomass (hyper-accumulating plants). This ability could be of great importance, particularly in arid and semi-arid regions, where insufficient precipitations and inappropriate systems are unable to reduce the salt burden in the rhizosphere of plants (Shiyab et al. 2003). ...
Chapter
Agricultural salinity and sodicity of soils and irrigation waters are an environmental problem in the arid and semi-arid regions of the world. While this problem is natural in its genesis in the coastal regions, it occurs primarily due to anthropogenic activities in the irrigation command areas resulting from over-irrigation in inland areas. It is the product of complex interaction of many variables, which lessen the current and/or potential capability of soil to produce goods and services. In India, reports indicate occurrence of 6.73 Mha of salt-affected soils. Many areas in the coastal belt of 8129-km-long sea coast in India with diverse climatic, physiographic and physical features remain vulnerable to seawater ingress, water logging and salinity problems resulting in the continued crop losses and its economic prosperity. Vast areas are in imminent danger of turning barren, and production and productivity have simply declined due to secondary salinization. Soil salinity problems are further compounded where the groundwater is highly saline, and such areas by and large remain barren for want of economically viable technological interventions. The coastal region is likely to face severe challenges in the future due to rise in sea level resulting from global warming. The region, however, is endowed with rich diverse natural resources, and thus, the management of its natural resources, ecological balance and economic prosperity are of paramount importance. Planning for effective and sustainable development of this ecosystem requires adoption of integrated approach to soil and water management in the first place and, through it or otherwise, necessary measures to conserve the ecology. To make agriculture viable and sustainable in the coastal environment, the major emphasis should be aimed at (1) soil management, (2) use of poor-quality waters, (3) selection of crops/varieties to suit the environment, (4) suitable agro-techniques including water management and irrigation technologies and water conservation measures through appropriate rainwater harvesting strategies, (5) farming system studies and (6) biosaline agriculture through halophytic interventions. In the present paper, while presenting detailed account of on-farm technologies developed with economic halophytes like Salvadora persica and halophytic forage grasses, emphasis has also been made to explore the possibilities of using potential halophytes having importance of food, fodder, fuel, oils, healthcare, ecorestoration, bioremediation applications and their role in restoring the coastal saline soils.
... Remediation of saline soils and salinity stress mitigation using halophytes is very important for many cash crops to cope with this stress (Rabhi et al. 2009;Shabala 2013). Accumulating plant species, such as Atriplex nummularia, C. album, Phragmites australis, and Salicornia europaea have been used throughout the world to remediate saltaffected lands (Hamidov et al. 2007;McSorley et al. 2016;Morteau 2016;Silva et al. 2016). ...
Article
The present paper discusses the growth responses of Chenopodium album L. to salinity and its possible use in the context of reducing salt stress considering the fact that soil salinity is a major problem caused by climate change and anthropogenic activities. Salt tolerance potential and phytodesalination ability of C. album growing in the same salt-affected soil of two different textures (clay and clay loam) over a range of salinity [non-saline (EC e is 0-2 dS m −1), slightly salinized (EC e is 2-4 dS m −1), moderately salinized (EC e is 4-8 dS m −1), highly salinized (EC e is 8-16 dS m −1), and extremely heavily salin-ized (EC e > 16 dS m −1) of two different rates, extreme 1 (EC e is 16-20 dS m −1) and extreme 2 (EC e is 25-30 dS m −1)], were studied and compared. According to investigated growth traits, the plants growing in clay soils revealed better adaptation reaction than the plants growing in clay loam soils, and an increase in the main part of examined indices was observed until reaching high degree of salinity, after which the plants demonstrated symptoms of stress in all growth parameters. C. album, maintaining the survivability in parallel with increase in salinity, intensively accumulated toxic ions like Na + and Cl − that promoted the feasibility of this plant for phytodesalination of saline degraded soils. The results obtained can contribute to a deeper comprehension of an alternative phytotechnology for remediation of saline soils by tolerant and productive plant C. album to provide favorable conditions for growth and production of various cash crops.
... In addition to the effects of climate change and the constant increase in the population worldwide, it is essential to develop and establish sustainable crops that are resistant to soils affected by salinity and in turn have a positive effect on the environment. In recent years, halophyte plants have been investigated due to their ability to support and eliminate salts present in soils, thanks to their different adaptation mechanisms such as ion compartmentation, osmosis, ion transport and absorption, inclusion or excretion of salt ions, among others (Hasanuzzaman et al., 2014;Ashraf et al., 2010;Rabhi et al., 2009Rabhi et al., , 2008. ...
... Moreover, the use of autochthonous species from saline environments may have advantages due to their better tolerance to edaphoclimatic conditions, besides having several uses (Hasanuzzaman et al., 2014;Santos et al., 2017b;Cortinhas et al., 2019Cortinhas et al., , 2020Cortinhas et al., , 2021. For phytodesalinization purposes the species used include among others Atriplex halimus L. (Gharaibeh et al., 2011), Arthrocnemum indicum (Rabhi, 2008(Rabhi, , 2009, Limonium bicolor (Bunge) Kuntze (Sakai et al., 2012), M. crystallinum (Abdelly et al., 2006), Salicornia persica Akhani (Ebadi et al., 2018) Suaeda fruticosa (Zorrig et al., 2012) (Table 5). In S. soda and P. oleracea pot experiments in soils with different levels of salinity and Na in exchangeable fraction and irrigated with tap water, it was observed a decrease of EC, between 2 and 4-fold depending on salinity level and species, compared to the initial values (Karakaş et al., 2017). ...
... One gram soil (in 5 mL distilled water) was used as soil-water extract to estimate Na + , Mg 2+ , and Ca 2+ using a flame atomic absorption spectrophotometer [32]. Sodium adsorption ratio (SAR) was calculated from the following formula: ...
Article
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Soils contaminated with potentially toxic elements (PTEs) and salt manifest a large number of physical, chemical, and structural problems by various processes such as reduced water availability, water and air movement in soil space, water holding capacity of soil, as well as perilous effects on plant growth and physiology. Halophytes have the ability to grow in saline environments and are better adapted to accommodate environmental constraints including PTE ions. An experiment was designed to study the response of the halophyte Atriplex halimus to a range of salinities and different concentrations of Cd and Ni. Tolerance and soil remedial potential of the plant were quantified in terms of PTE uptake and portioning, plant biomass, root/shoot ratio, chlorophyll and anti-oxidative enzyme production, along with stress markers such as lipid peroxidation, proline, and glycine betaine. The plant was also evaluated for its potential to phytoremediate PTE contaminated soil. The results suggest that A. halimus can tolerate moderate concentrations of both the PTEs and salt. The species holds promise for bio-reclamation of saline and PTE-contaminated soil.
... Several authors encourage the use of Na + and Clhyperaccumulating halophytes for soil desalination since species such as Suaeda maitima, Suaeda portulacastrum, Suaeda fruticosa, Suaeda salsa, Suaeda calceoliformis, Kalidium folium, Sesuvium portulacastrum, Arthrocnemum indicum, Atriplex nummularia, and Atriplex prostrata have been reported to accumulate high concentrations of salt in their above ground tissues, and consequently, saline soils can be upgraded by harvesting the plants on a regular basis (Ravindran et al., 2007;Glenn et al., 1999;Rabhi et al., 2009;Chaudhri et al., 1964;Zhao 1991;Critsenko and Chritsenko 1999;Zhao et al., 2005). Chaudhri et al., (1964), reported that Suaeda fruticosa removed more than 2400 lbs (1088.6 kg) of salt from 1 acre by a single harvest of the aerial parts per year. ...
Article
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Climate change is a global phenomenon and is occurring continuously since the earth came into existence. Soil is the most important renewable natural resource. It is the medium of plant growth and supports different types of living organisms on the earth. Climate change is threatening the food, fodder and nutritional security globally. Countries like India are more vulnerable in view of the varied physiographic features viz. different types of soils, topography, land slope and local climate that influence the form and species composition of plant communities. Climate change is projected to have significant impact on agriculture production, productivity and livestock production. It is anticipated that global climate change would have a variety of consequences on soil processes and properties which are very important for restoring soil fertility and productivity. Climate change predominantly effects soils by altering soil moisture conditions, enhancing soil temperature, carbon dioxide levels and salt accumulation. In this review we highlighted about the effect of elevated salt ions, phytodesalination, CO 2 and temperature on soil health and forage crops.
... 5 This plant has good potential to be used for desalination of salt-affected soils or reclamation of saline soil. 6,7 S. portulacastrum is a perennial halophyte with medicinal properties and esthetic value and it produces industrially important ecdysones besides having significant tolerance to heavy metals. 2 The leaves of S. portulacastrum have been identified as a useful source to procure natural antimicrobial and antioxidant agents for human health. ...
Article
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Background Leafy vegetables play an important role by contributing to most nutrients intake for health and human well‐being. Some of these leafy vegetables are cooked before consumption. But the effect of the cooking process on the nutritional value of leafy vegetables is not well known. This research aimed to evaluate the effect of the cooking process on the nutritional value of Sesuvium portulacastrum leaves. To do that, fresh leaves were collected, air dried and divided into raw and cooked. The raw and cooked samples were analyzed to determine the physico‐chemical properties (pH, humidity, ash, polyphenols, tannins and proteins) and minerals (nitrogen, calcium, magnesium, sodium and potassium). Results Based on physico‐chemicals, the raw and cooked leaves contained a good concentration of polyphenol (155.58 mg ± 14.98 and 53.45 mg ± 10.97), tannin (107.62 mg ± 9.8 and 59.59 mg ± 4.17), nitrogen (0.41% ± 0.02 and 0.38% ± 0.02) and protein (2.59% ± 0.12 and 2.38% ± 0.14). The cooking process caused the loss of nitrogen (N), proteins, tannins and polyphenols from 8% to 66%. S. portulacastrum leaves contented also an important proportion of minerals. The raw and cooked contained sodium (30% and 21.28%), potassium (30% and 13.08%), magnesium (16.71% and 19.9%) and calcium (6.5% and 24%). The cooking process increased and reduced significantly calcium (270.42%) and potassium (56.42%), respectively. Conclusion S. portulacastrum leaves were an important source of nutritional value that could contribute to improved health and well‐being.
... For example, phytoremediation removes salts more uniformly and at greater depths than gypsum and is suitable for the treatment of other contaminants at the same time (Devi et al., 2016;Qadir et al., 2001). Plants can also help to reduce the water table and improve drainage; otherwise, poor drainage leads to salinity, and the intake of NaCl by the shoots also prevents it from seeping into the groundwater (Rabhi et al., 2009;Stirzaker et al., 1999). Many aspects of phytoremediation, including the direct or indirect mechanisms of plants and their implications, the performance of specific plant species, and how environmental conditions may affect their performance, still need to be clarified. ...
Article
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In the present study, three ecotypes of Xanthium strumarium L. were collected from different ecological regions, i.e., Uchalli (E1), Sargodha (E2), and Samundri (E3) in Punjab province, Pakistan. All ecotypes were assessed for their salt resistance and remediation capacity at different NaCl levels (T1 (control), T2 (50 mM), T3 (100 mM), and T4 (150 mM)). Xanthium responses to varied NaCl levels were investigated for growth, anatomical, and physio-biochemical attributes. A comparative account of different attributes revealed a performance difference between three ecotypes. Biomass of all ecotypes was reduced, but the minimum reduction in biomass was noticed in E1 as compared to other ecotypes. Comparison of control and NaCl-treated Xanthium plants indicated highest reduction (96.3%) for both chlorophyll a and chlorophyll b observed under T4 in E3 as compared to E1 and E2. Maximum increase in carotenoids was observed in E2 (82.2%) under T4. Shoot Na⁺ correspondingly increased in all ecotypes with NaCl levels and maximum Na⁺ in E3. Minimum absorption of Cl⁻ ion was observed in E1. Osmoprotectants in three ecotypes were much higher under elevated NaCl levels than that of control plants. A significant increase in total soluble sugars was recorded in E1 (76.82%) and E2 (45.35%) as compared to E3. Additionally, significant anatomical changes in stem, leaf, and root of X. strumarium L. were observed in all three ecotypes grown under NaCl conditions. E1 ecotype showed large vascular bundle cell area (119.23%), (110.95%), (56.34%), epidermal thickness (152.21%), (187.40%), (117.28%) of leaf, root, and stem, respectively, as compared to E2 and E3 ecotypes. Similarly, E1 ecotypes showed the highest percentage increase in root sclerenchyma cell area (93.46%), stem epidermal cell area (246.66%), stem cortical cell area (114.23%), and stem sclerenchyma cell area (92.5%) as compared to E2 and E3 ecotypes. These findings endorse differential capabilities of different ecotypes of the same plant with reference to the changes in studied attributes. Overall, results indicate that X. strumarium L. withstood high NaCl stress (150 mM) and can be an eco-friendly source for the phytoremediation of saline soils. It could serve as a foundation for future research on the plant adaptability. We recommend use of this plant for restoring saline-degraded and marginal soils.
... Arthrocnemum indicum L. is a succulent perennial shrub, from family Chenopodiaceae widely encountered in salt marshes (Rabhi et al. 2009). The halophyte A. indicum is particularly interesting because it is one of the rare species that has proved extremely well adapted to hypersaline and harsh environmental conditions (Redondo-Gómez et al. 2010). ...
Chapter
In recent years, the level of arsenic in soil has increased dramatically in many countries, which has raised concern to develop new environmentally friendly techniques to solve problems such as arsenic, which is highly soluble and has toxic effects. It is an environmental issue and a global health matter because of its poisonous and carcinogenic characteristics. It is known that arsenic influenced farmland and plant productivity by disturbing their most essential activity like photosynthesis. Plants subjected to arsenic cause reactive oxygen species' (ROS') generation and engender lipid peroxidation leading to plant cell membrane destruction and its connected component replacing chlorophyll's Mg ion through which arsenic affects chlorophyll biosynthesis and therefore altering the enzyme involved in chlorophyll biosynthesis, electron movement disruption in light mechanism, and influencing several enzymes in dark reactions. Plants subjected to arsenic show a loss in photochemical efficiency and photosynthetic electron movement indicated by parameters of chlorophyll fluorescence. “This type of photosynthetic response indicates the physiological state of the whole plant organism. Therefore, the change in photosynthetic activity assessed by chlorophyll fluorescence represents one of the most reliable and useful physiological biomarkers for the detection of toxic effects of pollutants. This leads us to determine the mechanism related to the arsenic (As) impact on physiological feedback altering plant weight and fruitfulness, inhibition of the chlorophyll biosynthetic or degradation pathway and may lead to dysfunction of plants. Therefore, this chapter contains comprehensive data in relation to the arsenic incidence on photosynthetic pigments, the photosynthetic status, and reactions to light and dark. Thus, the study looked at the incidence of metabolic stress with or without salt stress on the content of photosynthetic pigments, namely chlorophylls a and b and carotenoids and further on the photosynthetic apparatus.
... Panta et al. (2014) have reviewed the potential of halophytes for desalinization of salinized soils, and they showed that it was ranged from 0.66 to 6.35 t ha −1 year −1 . The desalinization ability of the ice plant was comparable to that of Suaeda fruticosa (2.0 t ha −1 year −1 ; Rabhi et al., 2009), Kalidium folium (2.79 t ha −1 year −1 ; Zhao et al., 2005), and Suaeda salsa (2.06 t ha −1 year −1 ; Ke-Fu, 1991). These results indicated that the ice plant has a high NaCl accumulation ability similar to halophytes used for desalinization. ...
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Halophytes are salt-tolerant plant that grows naturally in saline areas where almost all conventional crops die due to NaCl toxicity. The common ice plant, Mesembryanthemum crystallinum L., an annual halophyte native to South Africa, tolerates high salinity levels and accumulates NaCl in a shoot at a high level. To check the availability of the ice plant for desalinization of soils, we cultured the ice plant in soils collected from 16 sites located along coastal regions in the prefectures of Miyagi and Iwate, where were attacked by the tsunami disaster in the wake of the 2011 earthquake off the Pacific coast of Tohoku on 11 March 2011. In the soils obtained from some tsunami affected areas, the growth was better than that in the non-contaminated soil. The factors associated with growth inhibition were suggested to be water ratio (an index of water content) and soil water permeability. The ice plant’s estimated biological yield ranged from 0.33 to 14.6 kg m⁻², equivalent to 2.3 to 101.7 t ha⁻¹. The sum of Na⁺ and Cl⁻ was about 9.5 g in the shoot (31.8% on a dry weight basis), and the estimated total amount of these ions removed from salinized soil was 2.38 t ha⁻¹. These results indicated that the common ice plant could be used as a crop under salinity and a tool for ameliorating NaCl from salinized soils.
... As a result, in these areas planting of the native halophyte species is the effective tool to combat salinity problems. Recent research by many scientists has shown the ability of plants to eradicate salts from saline soils have been explored and acknowledged (Ashraf & Akram, 2005, Rabhi, 2009). In views of (Flowers & Colmer, 2008), plants able to persist and reproduce in saline soils in which salt concentration goes beyond 200mM of sodium chloride ions are characterized as halophytes. ...
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Salt-affected Soils hindering plant biomass production is the burning issue of the world to meet demands for food, fiber and shelter. Recent study was conducted to evaluate two halophytes shrubs species Capparis decidua and Haloxylon salicornicum towards salinity stress. Antioxidant enzymes activities and phytoremediation capabilities (Na+ & K+ concentration) were measured. The experiment was conducted in greenhouse at different salinity levels (0, 70, 140 and 210 mM NaCl). One year old seedlings of Capparis decidua and Haloxylon salicornicum grown through cuttings in the polythene tubes in the nursery area were shifted to hydroponic medium for various parameters. The results revealed that under highly saline conditions H. salicornicum was found more salt tolerant and produced maximum number of leaves (27) than C. decidua (19) at 210 mM NaCl. Chlorophyll contents in C. decidua and H. salicornicum increased till 140 mM NaCl (0.24) and (0.48) and decreased (0.06) and (0.33) at 210 mM NaCl respectively. Uptake of Na+ concentration was increased with the elevated salinity treatments while K+ concentrations were decreased in both species. Na+ concentrations were found maximum in H. salicornicum (60117ppm) at 210 mM NaCl while it was (23225ppm) at 0 mM NaCl. Antioxidant enzymes activities of superoxide dismutase (SOD) increased with increasing salinity while the Catalase (CAT) activity was at highest value at 0 mM NaCl (37.66) and its value decrease with the increasing salinity in both species. The results concluded that the H. salicornicum is more salt tolerant species. Both species can be used for phytoremediation of salinity from saline soils and successful revegetation of deserts.
... The last technique includes approaches such as phytodesalinization, which uses salt-tolerant plants or halophytes to decrease soil salinity and thus increase crop production [8][9][10][11]. This approach is increasingly investigated, both in field studies [12][13][14][15] and under controlled laboratory conditions [10,[16][17][18] since water ponding is difficult to apply in water-limited areas and less effective in fine-textured soils [4,19,20]. ...
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Soil salinity due to irrigation is a major constraint to agriculture, particularly in arid and semi-arid zones, due to water scarcity and high evaporation rates. Reducing salinity is a fundamental objective for protecting the soil and supporting agricultural production. The present study aimed to empirically measure and simulate with a model, the reduction in soil salinity in a Vertisol by the cultivation and irrigation of Echinochloa stagnina. Laboratory soil column experiments were conducted to test three treatments: (i) ponded bare soil without crops, (ii) ponded soil cultivated with E. stagnina in two successive cropping seasons and (iii) ponded soil permanently cultivated with E. stagnina with a staggered harvest. After 11 months of E. stagnina growth, the electrical conductivity of soil saturated paste (ECe) decreased by 79–88% in the topsoil layer (0–8 cm) in both soils cultivated with E. stagnina and in bare soil. In contrast, in the deepest soil layer (18–25 cm), the ECe decreased more in soil cultivated with E. stagnina (41–83%) than in bare soil (32–58%). Salt stocks, which were initially similar in the columns, decreased more in soil cultivated with E. stagnina (65–87%) than in bare soil (34–45%). The simulation model Hydrus-1D was used to predict the general trends in soil salinity and compare them to measurements. Both the measurements and model predictions highlighted the contrast between the two cropping seasons: soil salinity decreased slowly during the first cropping season and rapidly during the second cropping season following the intercropping season. Our results also suggested that planting E. stagnina was a promising option for controlling the salinity of saline-sodic Vertisols.
... Thus, the released sodium makes the soil more basic (Al-Muwayhi, 2020; Guo et al 2020). As in our study, Rabhi et al. (2009) also report an alkalizing effect of halophytic plants on the soil. However, Rezkallah et al. (2014) contrary to our results reported that A. halimus plants do not increase soil EC and has no effect on the evolution of pH. ...
Article
Soil fertility depends on vegetation cover, climatic conditions and soil-specific edaphic factors that regulate transformation processes of plant residues and organic matter. Soil physicochemical characteristics in drylands negatively affect evolutionary process of soil materials resulting in fertility loss. This study investigated the variability of soil physicochemical parameters and fertility estimates in three types of semi-arid steppe rangelands of North Africa, viz. Stipa tenacissima, Artemisia herba-alba and Atriplex halimus. The effect of soil parameters on the evolution of soil fertility was appraised using soil organic carbon (SOC), available phosphorus (AP) and C:P ratio as fertility indicators. In two semi-arid regions with haplic calcisols, soil was sampled in six replicates at each steppe rangeland and a control (bare soil). Using standard protocols, each sample was analyzed to determine pH, electrical conductivity (EC), SOC, AP, C:P ratio, total and active CaCO3. All the soil physicochemical parameters tested, except total CaCO3, showed positive increases in A. halimus and S. tenacissima steppe rangelands. The variation of pH and EC values among rangelands was significant, with A. halimus rangelands had significantly the highest scores and A. herba-alba rangelands the lowest scores. The redundancy analysis showed that the edaphic factors triggering significant increases in scores of soil fertility indicators, when compared to the control, were active CaCO3, EC and pH. These physicochemical parameters positively determined the accumulation of AP and SOC, especially in A. halimus rangelands. The high values of stochiometric C:P ratio were associated to soil characteristics of S. tenacissima and A. herba-alba rangelands. Our findings suggest that soil physicochemical parameters of semi-arid steppe rangelands ‒ compared to bare soil ‒ influenced the evolution of soil fertility and stoichiometric C:P ratio. The type of steppe vegetation differently affects the physicochemistry and stoichiometry of the soil.
... Approximately 10% of the total arable land is currently affected by salinity and sodicity, with further increases due to global changes and human activities (Becerra et al., 2019;FAO, I., 2015;Ruiz-Lozano et al., 2012;Shahid et al., 2018). Halophytes can potentially be used for desalination and restoration of saline soils in a process known as phyto-desalination (Rabhi et al., 2009;Riadh et al., 2010;Saddhe et al., 2020). The succulent Salsola drummondii is one of the most Na + -hyperaccumulating plants with a Na + concentrations in roots, stems, and leaves of 7.01, 24.7, and 98.4 mg/g dry weight, respectively, Attiat Elnaggar and Kareem A. Mosa authors contributed equally to this work. ...
Article
Salsola drummondii is a perennial habitat-indifferent halophyte growing in saline and non-saline habitats of the Arabian hyperarid deserts. It offers an invaluable opportunity to examine the molecular mechanisms of salt tolerance. The present study was conducted to elucidate these mechanisms through transcriptome profiling of seedlings grown from seeds collected in a saline habitat. The Illumina Hiseq 2500 platform was employed to sequence cDNA libraries prepared from shoots and roots of non-saline-treated plants (controls) and plants treated with 1200 mM NaCl. Transcriptomic comparison between salt-treated and control samples resulted in 17,363 differentially expressed genes (DEGs), including 12,000 upregulated genes (7870 in roots, 4130 in shoots) and 5363 downregulated genes (4258 in roots and 1105 in shoots), and 272,643 unigenes were functionally annotated. The majority of identified DEGs are known to be involved in transcription regulation (79), signal transduction (82), defense metabolism (101), transportation (410), cell wall metabolism (27), regulatory processes (392), respiration (85), chaperoning (9), and ubiquitination (98) during salt tolerance. This study identified potential genes associated with the salt tolerance of S. drummondii and demonstrated that this tolerance may depend on the induction of certain genes in shoot and root tissues. These gene expressions were validated using reverse-transcription quantitative PCR, the results of which were consistent with transcriptomics results. To the best of our knowledge, this is the first study providing genetic information on salt tolerance mechanisms in S. drummondii. This article is protected by copyright. All rights reserved.
... This technique provides uniform salt removal from deeper soil layers compared to gypsum application (Qadir et al., 2001), while being environmentally friendly and removing contaminants at the same time depending on the physiology of the crop used (Greenberg et al., 2007;Manousaki and Kalogerakis, 2011;Shelef et al., 2012;Cameselle and Gouveia, 2019;Ma et al., 2019). Using plants prevents salt from leaching into groundwater as salt is taken up by the shoots (Rabhi et al., 2009). Plants may also be used to lower the water table and enhance drainage (Stirzaker et al., 1999). ...
Article
Soil salinization is a widespread problem affecting global food production. Phytoremediation is emerging as a viable and cost-effective technology to reclaim salt-affected soil. However, its efficiency is not clear due to the uncertainty of plant responses in saline soils. The main objective of this paper is to propose a phytoremediation dynamic model (PDM) for salt-affected soil within the process-based biogeochemical denitrification-decomposition (DNDC) model. The PDM represents two salinity processes of phytoremediation: plant salt uptake and salt-affected biomass growth. The salt-soil-plant interaction is simulated as a coupled mass balance equation of water and salt plant uptake. The salt extraction ability by plant is a combination of salt uptake efficiency (F) and transpiration rate. For water filled pore space (WFPS), the statistical measures RMSE, MAE, and R2 during the calibration period are 2.57, 2.14, and 0.49, and they are 2.67, 2.34, and 0.56 during the validation period, respectively. For soil salinity, RMSE, MAE, and R2 during the calibration period are 0.02, 0.02, and 0.92, and 0.06, 0.04, and 0.68 during the validation period, respectively, which are reasonably good for further scenario analysis. Over the four years, cumulative salt uptake varied based on weather conditions. At the optimal salt uptake efficiency (F = 20), cumulative salt uptake from soil was 16–90% for alfalfa, 11–70% for barley, and 10–80% for spring wheat. While at the lowest salt uptake efficiency (F = 40), cumulative salt uptake was nearly zero for all crops. Although barley has the highest peak transpiration flux, alfalfa and spring wheat have greater cumulative salt uptake because their peak transpiration fluxes occurred more frequently than in barley. For salt-tolerant crops biomass growth depends on their threshold soil salinity which determines their ability to take up salt without affecting biomass growth. In order to phytoremediate salt-affected soil, salt-tolerant crops having longer duration of crop physiological stages should be used, but their phytoremediation effectiveness will depend on weather conditions and the soil environment.
... Chloride is a micronutrient useful for plants, e.g. in photosynthesis, but can be phytotoxic at high levels (White and Broadley, 2001). Some halophyte species are known for their capacity to accumulate chloride (Devi et al., 2016(Devi et al., , 2008Krishnapillai and Ranjan, 2005;Rabhi et al., 2009Rabhi et al., , 2008Hasanuzzaman et al., 2014). In this context, the most studied species are Atriplex spp., Avicennia spp., Phragmites spp., Salicorna spp., Sesuvium spp., Suaeda spp., Tetragonia spp., and Typha However, little is known about how the age of a plant affects its aclimation to harmful saline media and its capacity to take up and store ions, and speci cally chloride. ...
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Anthropogenic activities can be the source of saline solid wastes that need to be treated to reduce their salt load to meet the purposes of reuse, valorization or storage. In this context, chloride remediation can be achieved using high-salt accumulating plants. However, there is very limited information on the comparative potential of different species in the same environment, and only scarce data concerning their efficiency as a function of growth stage. In order to rationalize these selection criteria, three macrophytes i.e. common reed ( Phragmites australis) , sea rush ( Juncus maritimus) and cattail ( Typha latifolia ) were cultivated at two growth stages (6-months old and 1-year old) for 65 days in Cl ⁻ spiked substrates (from 0 up to 24 ‰ NaCl). The plants’ survival and potential capacity for removal of Cl ⁻ from substrates and accumulation in shoots were investigated. For the three studied species, mature and juvenile plants display a high tolerance to salinity. However, mature specimens with higher shoot biomass and Cl ⁻ contents are capable of greater chloride removal than juvenile plants. The sole exception is P. australis which displays just the same phytoremediation potential for both mature and juvenile specimens. Moreover, P. australis has the lowest potential when compared with other species, being 1.5 and 3 times lower than for J. maritimus and T. latifolia . When considering the plant growth and the shoot biomass production, chloride removal rates from the substrate point that mature J. maritimus should preferentially be used to design an operational chloride remediation system. The results highlight the relevance of considering the growth stage of plants used for Cl ⁻ removal.
... soils and alleviate water shortage crisis, which would be an attractive method for soil remediation (Masters et al., 2007;Rabhi et al., 2009;Manousaki et al., 2013). Therefore, application of planting halophytes to improve soil salinity is very promising, which has become a widespread subject of interest to researchers (Tsao, 2003;Nouri et al., 2017). ...
Article
Sugar beet (Beta vulgaris L.), as a salt-tolerant plant, has been widely cultivated in saline-alkali soils, e.g. southern Xinjiang of China, due to its effective capability of reducing soil salinity. A two-year field experiment was conducted on drip-fertigated sugar beet under plastic mulch to explore to effects of three irrigation amounts (W1: 0.60 ETc, W2: 0.80 ETc and W3: 1.00 ETc, where ETc is the crop evapotranspiration) and six nitrogen application rates (N1: 25 kg N ha⁻¹, N2: 60 kg N ha⁻¹, N3: 120 kg N ha⁻¹, N4: 240 kg N ha⁻¹, N5: 360 kg N ha⁻¹ and N6: 480 kg N ha⁻¹) on sugar beet growth, ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake. The results showed that the year and the two-way interaction of irrigation and nitrogen fertilization had significant effects on dry matter, ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake, but there was no significant effect of the three-way interaction of year, irrigation and nitrogen fertilization on ash salt accumulation, plant Ca²⁺ and Mg²⁺ uptake. The dry matter, ash salt accumulation, Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake of N1 were significantly lower than those of other treatments. Nitrogen fertilization increased the dry matter and ash salt accumulation, Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake of sugar beet. The ash salt, K⁺ and Ca²⁺ were mainly distributed in the leaf and petiole, while Na⁺ and Mg²⁺ were mainly distributed in the taproot. Among the four ions, the average contents of K⁺ and Na⁺ were larger in all treatments, which were 1.79 % and 1.62 % in the two years, respectively. The average content of Mg²⁺ was 0.36 % in all treatments in the two years, and the average content of Ca²⁺ was lowest in all treatments, which was 0.14 % in the two years. Compared to W1 and W2, W3 decreased the dry matter and ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake. The ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake increased with the increasing dry matter accumulation. Based on the response surface methodology, the relationships between water-nitrogen inputs and dry matter, ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake were established. The results can provide a theoretical basis for the phytoremediation of sugar beet in southern Xinjiang of China and maybe elsewhere with similar arid and semi-arid climates.
... However, notwithstanding the better performance of H. maritimum in comparison with H. vulgare after stress removal, all the considered parameters did not reach values comparable to those of the cultivated species under control conditions. [76]. In these salt-affected ecosystems, this species significantly contributes to annual biomass production and results very useful for fodder production, like sorghum in arid areas of Iran [77][78][79][80][81]. ...
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Hordeum maritimum With. is a wild salt tolerant cereal present in the saline depressions of the Eastern Tunisia, where it significantly contributes to the annual biomass production. In a previous study on shoot tissues it was shown that this species withstands with high salinity at the seedling stage restricting the sodium entry into shoot and modulating over time the leaf synthesis of organic osmolytes for osmotic adjustment. However, the tolerance strategy mechanisms of this plant at root level have not yet been investigated. The current research aimed at elucidating the morphological, physiological and biochemical changes occurring at root level in H. maritimum and in the salt sensitive cultivar Hordeum vulgare L. cv. Lamsi during five-weeks extended salinity (200 mM NaCl), salt removal after two weeks of salinity and non-salt control. H. maritimum since the first phases of salinity was able to compartmentalize higher amounts of sodium in the roots compared to the other cultivar, avoiding transferring it to shoot and impairing photosynthetic metabolism. This allowed the roots of wild plants to receive recent photosynthates from leaves, gaining from them energy and carbon skeletons to compartmentalize toxic ions in the vacuoles, synthesize and accumulate organic osmolytes, control ion and water homeostasis and re-establish the ability of root to grow. H. vulgare was also able to accumulate compatible osmolytes but only in the first weeks of salinity, while soon after the roots stopped up taking potassium and growing. In the last week of salinity stress, the wild species further increased the root to shoot ratio to enhance the root retention of toxic ions and consequently delaying the damages both to shoot and root. This delay of few weeks in showing the symptoms of stress may be pivotal for enabling the survival of the wild species when soil salinity is transient and not permanent.
... Trees act as biological pumps to provide a more uniform removal of salts at higher depths and clean the rhizosphere zone (Nouri et al. 2017). They uptake the salts into the shoots and minimize their leaching to groundwater (Rabhi et al. 2009). In addition, trees (hperaccumulators) remove salt and other pollutants from the soil simultaneously (Shelef et al. 2012). ...
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Salinity is a widespread soil and underground water contaminant threatening food security and economic stability. Phytoremediation is an efficient and environmental-friendly solution to mitigate salinity impacts. The present study was conducted to evaluate the phytoremediation potential of five multipurpose trees: Vachellia nilotica, Concorpus erectus, Syzygium cumini, Tamarix aphylla and Eucalyptus cammaldulensis under four salinity treatments: Control, 10, 20 and 30 dS m⁻¹. Salinity negatively impacted all the tested species. However, E. cammaldulensis and T. aphylla exhibited the lowest reduction (28%) and (35%) in plant height respectively along with a minimal reduction in leaf gas exchange while V. nilotica, S. cumini and C. erectus showed severe dieback. Similarly, the antioxidant enzymes increased significantly in E. cammaldulensis and T. aphylla as Superoxide Dismutase (87% and 79%), Catalase (66% and 67%) and Peroxidase (89% and 81%), respectively. Furthermore, both of these species maintained optimum Na/K ratio reducing the highest levels of soil ECe and SAR, suggesting the best phytoremediation potential. The present study identifies that E. cammaldulensis and T. aphylla showed effective tolerance mechanisms and the highest salt sequestration; therefore, may be used for phyto-amelioration of salinity impacted lands. Novelty statement Although previous studies evaluated the tolerance potential of many tree species, comparative and physiochemical evaluation of multipurpose tree species has been remained unexplored. In this scenario, eco-physiological characterization of multipurpose tree species may inform tree species for phytoremediation of saline soils according to the level of salinity. Optimizing tree species selection also improves the success of wood for energy and revenue generation while restoring degraded soils.
... Under saline conditions, there is + unreceptive diffusion of Na ions during injured membranes and decreased effectiveness of prohibiting mechanism which results in elevated concentration of sodium in leaf sap (Leidi and Saiz, 1997). Potassium influx transporters arbitrate sodium influx into root cells (Rabhi et al., 2007) under saline condition. There was encouraging association of grain yield and quality with the alternating application of canal water and tube well water in this study which shows that dissolved soluble salts and supply of plant nutrients to plant sustain constructive ionic composition helps to tolerate saline conditions. ...
Article
Aim: To study the effect of FYM and different sources of water on growth, yield and soil chemical properties after harvest of wheat (Triticum aestivum L) in salt affected soils of Gujarat. Methodology: A field trial was conducted with two levels of FYM viz., F0: 0 t FYM ha-1 and F1: 10.0 t FYM ha-1 and three sources of irrigation viz., I1: Sole application of tube well water, I2: Sole application of canal water and I3: Alternate application of tube well and canal water which was replicated four times in factorial randomized block design on wheat variety Raj-3077. Results: The treatment 10 t FYM ha-1 achieved significantly superior grain (5130 kg ha-1 Location-I and 4940 kg ha-1 Location-II) and straw (6517 kg ha-1 Location-I and 6252 kg ha-1 Location-II) yields of wheat over no FYM use on pooled results. In contrast, the alternate application of tube well and canal water gave significantly higher grain yield (4458 kg ha-1 Location-I and 4991 kg ha-1 Location-II) of wheat over sole use of tube well as well as canal water on pooled basis. Interpretation: Stand on this study it is accomplished that use of 10 t FYM ha-1 and rotate application of tube well and canal water should be used for receiving superior yield and net income from wheat as well as maintaining encouraging soil nutrient status.
... Some authors have concluded that the time required for plants to remove Na from the soil make direct removal an impractical solution for the treatment of dispersive soils (Barrett-Lennard, 2002;Qadir et al., 2007), particularly in rainfed production systems where plant biomass production is low (Barrett-Lennard, 2002). However, other authors have reported significant direct Na removal from salt affected soils by a variety of plant species (Al-Nasir, 2009;Jesus et al., 2015;Rabhi et al., 2010;Rabhi et al., 2009;Ravindran, Venkatesan, Balakrishnan, Chellappan, & Balasubramanian, 2007). Some crops can sustain relatively high productivity under saline/sodic conditions, and accumulate relatively high leaf tissue concentrations of Na, and thus present the option of phytoremoval. ...
Article
Dispersive soils limit crop growth and significantly impact world food production. Although numerous reviews have examined soil dispersion, many focus on irrigated systems and fail to differentiate the approaches required for rainfed agriculture. This review seeks to fill this gap by focusing on the impact, identification and management of dispersive soils in rainfed areas. Dispersive soils can have large impacts on crop production because of their adverse physical, chemical and biological effects, with this impact particularly large in rainfed systems where irrigation water is unavailable to supplement crop water supply and assist with amelioration. However, the identification of these soils is challenging and tests that can reliably relate soil characteristics to crop performance are lacking. Recent work has found that first identifying consistently lower yielding locations (using yield mapping or proximal/remote sensing) and then using traditional soil testing to identify the potential cause/s of the yield loss may be a promising approach, although this requires refinement. Knowledge of the type of dispersive soil (e.g., saline/non-saline, acidic/alkaline/neutral) and where constraints occur in the profile (surface or subsoil) must also be determined during identification as this will affect management approaches, particularly where multiple constraints need to be treated together to achieve yield increase. Improved understanding of how to economically use ameliorants and combine them to achieve maximum benefit in the presence of multiple constraints is needed. Greater appreciation of how to use agronomic management to improve crop growth in the presence of dispersive behaviour is also likely to increase profitability in rainfed systems where amelioration is often impractical or uneconomical. Dispersive soils are a major challenge for rainfed cropping, and so the refinement of our management approach can help improve profitability and productivity. Highlights • Dispersive soils limit crop growth and significantly impact world food production • We examine the impact, identification and management of dispersive soils in rainfed agriculture • Improvements in the identification of dispersive soils are required to improve management • Refinement of ameliorant use and agronomic management will improve profitability and productivity
... This ability can be confirmed by detecting a decrease in the concentration of salts in the soil, along with its increase in plant tissues. This could be corroborated for different species, both native and exotic, either under controlled greenhouse conditions (Rabhi et al. 2009) or in field experiments (Hamidov et al. 2007). ...
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Soil salinization is the cause of soil degradation affecting the functional health of ecosystems, the habitat and the local biodiversity. No climatic zone in Latin America (LA) is completely free from salinization, although the most vulnerable areas are located in arid and semi-arid regions. Specific local cases in Argentina, Chile, Colombia, Paraguay and Mexico are described. Considering that global food production will need to increase by 38% by 2025 and by 57% by 2050, careful attention must be devoted to all degraded lands, especially those affected by salinity or sodicity. The threat increases when such lands trigger a feedback effect on the climate system. In turn, climate can affect ecosystem functions and food security. The combined result is a greater sensitivity of crops and pastures to drought. Adaptation requires a technological control of land-use/land-cover change, cropping types, cropping periods, agronomic practices, and water management. A new paradigm is growing in recent years that aims at remediating, restoring and converting degraded lands into protected areas to preserve the habitat as well as the local flora and fauna. Protection is usually accompanied by processes of carbon sequestration in plants and soils that mitigate the emission of greenhouse gases to the atmosphere.
... This ability can be confirmed by detecting a decrease in the concentration of salts in the soil, along with its increase in plant tissues. This could be corroborated for different species, both native and exotic, either under controlled greenhouse conditions (Rabhi et al. 2009) or in field experiments (Hamidov et al. 2007). ...
Chapter
Under arid and semiarid climates, the natural process of soil formation can cause the accumulation of salts that limit plant growth and development. The Northeast region of Brazil has an extensive area under semiarid climate with drought most of the time. Additionally, the inadequate management of irrigation has promoted the accumulation of salts in soils, degrading them. Some of such areas are becoming unproductive and are abandoned. Reclamation techniques that involve drainage, use of chemical and organic conditioners, are expensive and difficult to implement. Phytoremediation of salt-affected soils is a low cost alternative. Plants adapted to the environment, which tolerate high levels of salts, can grow and produce biomass, should be studied. It is also important that the plants used are able to absorb the salts, extracting them from the soils. However, phytoremediation results are not observed in the short term. But, over time, phytoremediation promotes the return of vegetation to degraded soils, as well as the associated microbiota and protects the soil surface. This chapter reports trials in Brazil, evaluating some plant species for their ability to survive and improve soil quality.
... This ability can be confirmed by detecting a decrease in the concentration of salts in the soil, along with its increase in plant tissues. This could be corroborated for different species, both native and exotic, either under controlled greenhouse conditions (Rabhi et al. 2009) or in field experiments (Hamidov et al. 2007). ...
Chapter
The accumulation of soluble salts in soils is one of the main environmental factors that contribute to the productive capacity limitations of Argentina’s arid ecosystems. Salinization processes lead to critical states of degradation and deser- tification. The challenge to recover and improve the productivity of such degraded areas is complex because it should consider restoration strategies that will be inte- grated with local economic, cultural, and social activities. The integrative use and management of native species in remediation programs are an attractive restoration tool that could improve the productivity capacity of degraded areas. Native species have developed numerous strategies and adaptations that could ensure their survival in saline environments. Nevertheless, species selection, management, and appro- priate technologies to be used in afforestation programs may be limited because of partial information on the potential and requirements of each native species and the environmental characteristics of each site. In this chapter, we analyze not only the problem of soil salinization and the challenge of restoring saline environments in Argentina, but also the characteristics of native species of trees, shrubs, and grasses of the Monte region, considering their salt tolerance and the provision of goods and services to local populations, which can be useful in restoration programs.
... Many studies on the wielding of halophytes in soil desalinization are reported within the literature. Suaeda maritima and Sesuvium portulacastrum have been used to accumulate salts in their tissues and reduce soil salinity (Ravindran et al., 2007;Rabhi et al., 2009). Similarly the obligate halophyte, S. portulacastrum was shown to be successful in desalinization of soils with the potential to get rid of up to 1 t Na + ha − 1 through sequestration in roots and shoots (Rabhi et al., 2008(Rabhi et al., , 2010. ...
Chapter
Halophytic plants are known to be capable to adapt themselves to harsh conditions such as high salt and inorganic ion concentration (heavy metals), xerothermic atmosphere, improper irrigation, and cold seasonal temperatures. To mitigate the hazardous effects of heavy metals and saline environment, halophytic plants have evolved biological detoxification mechanisms in terms of avoidance or exclusion, evacuation, and accumulation of toxic ions. Halophytes restrain the toxic effects of high ion concentration by regulating certain biochemical pathways and physiological modifications. These detoxification mechanisms shield the plants against the production of reactive oxygen species (ROS) and free radicals and protect them from biomolecular damage. One of the most important defense mechanisms includes production of antioxidants. This chapter explores the detoxification mechanism of halophytic plant system for salt and heavy metal stress by their inherent potential to accumulate certain nonenzymatic antioxidants such as secondary metabolites and to absorb and safely handle toxic ions
... Arthrocnemum indicum (Willd.), Suaeda fruticosa et Sesuvium portulacastrum L ont diminué considérablement la salinité du sol CE(pate saturée), de 19 dS/m dans le sol initialement à 12 dS/m (Rabhi et al., 2009). ...
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Cette étude vise à évaluer le potentiel du chou fourrager (Brassica napus L.) pour le dessalement d'un sol salin. Pour cela, des choux ont été plantées sur un sol extrêmement salin et irrigué par une eau saline pendant 84 jours sans drainage. Puis, ils ont été soumis à différentes concentrations de chlorure de sodium pendant 7 irrigations de stress salin. La comparaison des résultats des analyses du sol avant la mise en culture avec les résultats des analyses du sol irrigué par l’eau de robinet a montré une diminution de la conductivité électrique (CE) de 14.5%, le TDS (les sels dissout totaux) de 18%, le chlorure (Cl-) de 13%, le sodium (Na+) de 0.3%, le potassium (K+) de 42% et le calcium (Ca++) de 58%. Cependant, le magnésium (Mg++) et le SAR (sodium adsorption ratio) ont augmenté respectivement par 89% et 9%. L’application d’un stress salin a entrainé une augmentation du Na+ du sol par respectivement 4% et 38%, le SAR de 23% et 42%. Le TDS (total dessolved salts) du sol n’a augmenté de 13% qu’après le stress par un surplus de 100mM.l-1. La culture du chou fourragère (Brassica napus L.) a exporté dans sa biomasse jusqu'à 9 g/pot et 1,59 t.ha-1 de sels minéraux et cette quantité a augmenté parallèlement à la concentration en NaCl. Le chlorure est l'élément le plus exporté par la biomasse du chou fourrager jusqu'à 8078mg/pot et le sodium exporté est plus de 110mg/pot. De ce fait, la culture de Brassica napus L. semble être une culture efficace pour la préservation des sols contre la salinisation et pour la phytoremédiation des sols salins.
Article
In the context of changes in global climate and land uses, biodiversity patterns and plant species distributions have been significantly affected. Soil salinization is a growing problem, particularly in the arid areas of Northwest China. Halophytes are ideal for restoring soil salinization because of their adaptability to salt stress. In this study, we collected the current and future bioclimatic data released by the WorldClim database, along with soil data from the Harmonized World Soil Database (v1.2) and A Big Earth Data Platform for Three Poles. Using the maximum entropy (MaxEnt) model, the potential suitable habitats of six halophytic plant species (Halostachys caspica (Bieb.) C. A. Mey., Halogeton glomeratus (Bieb.) C. A. Mey., Kalidium foliatum (Pall.) Moq., Halocnemum strobilaceum (Pall.) Bieb., Salicornia europaea L., and Suaeda salsa (L.) Pall.) were assessed under the current climate conditions (average for 1970–2000) and future (2050s, 2070s, and 2090s) climate scenarios (SSP245 and SSP585, where SSP is the Shared Socio-economic Pathway). The results revealed that all six halophytic plant species exhibited the area under the receiver operating characteristic curve values higher than 0.80 based on the MaxEnt model, indicating the excellent performance of the MaxEnt model. The suitability of the six halophytic plant species significantly varied across regions in the arid areas of Northwest China. Under different future climate change scenarios, the suitable habitat areas for the six halophytic plant species are expected to increase or decrease to varying degrees. As global warming progresses, the suitable habitat areas of K. foliatum, S. salsa, and H. strobilaceum exhibited an increasing trend. In contrast, the suitable habitat areas of H. glomeratus, S. europaea, and H. caspica showed an opposite trend. Furthermore, considering the ongoing global warming trend, the centroids of the suitable habitat areas for various halophytic plant species would migrate to different degrees, and four halophytic plant species, namely, S. salsa, H. strobilaceum, H. gbmeratus, and H. capsica, would migrate to higher latitudes. Temperature, precipitation, and soil factors affected the possible distribution ranges of these six halophytic plant species. Among them, precipitation seasonality (coefficient of variation), precipitation of the warmest quarter, mean temperature of the warmest quarter, and exchangeable Na+ significantly affected the distribution of halophytic plant species. Our findings are critical to comprehending and predicting the impact of climate change on ecosystems. The findings of this study hold significant theoretical and practical implications for the management of soil salinization and for the utilization, protection, and management of halophytes in the arid areas of Northwest China.
Chapter
The increasing population has led to increased demand for food, in combination with the shrinking availability of good lands and good-quality water for crop cultivation. The relevance of biosaline agriculture comes into the forefront under these conditions. By examining recent research, technological advancements, and case studies, this chapter elucidates the pivotal role that domestication of halophytes can play in enhancing crop productivity, mitigating soil salinity, and ensuring sustainable food production in regions prone to salinization. Halophytes are a versatile group, having uses beyond conventional agriculture and extending into ecological restoration through phytoremediation aspects and food, fodder, and biofuel domains. Through the prism of case studies spotlighting successful assimilation of halophytes into agricultural paradigms, the potential of halophytes as cornerstones of profitable biosaline agriculture is effectively accentuated. However, the success of biosaline agriculture faces challenges, including the intricate dynamics of genetic diversity, the adaptation of agronomic methodologies, the interplay of market forces, and the imperative of consumer acceptance. The crucial role of persistent endeavors in fully harnessing the latent promise of domesticated halophytes within the tapestry of biosaline agriculture is also highlighted, which can address global food security challenges and pave the way for economically viable biosaline agriculture.
Chapter
Halophytes are a group of plants that can be found in a variety of arid and saline soils. These have been recognized as valuable sources of food, fodder, and useful metabolites for an array of industrial applications, such as nutraceuticals, essential oils, biofuels, alcohol, latex, cosmetics, and fibers. Moreover, halophyte cultivation represents a pioneering frontier in sustainable agriculture and environmental management. In this chapter, the importance of the morphological and anatomical characteristics of the species in saline ecosystems and their potential applications in agriculture, medicine, and industry have been highlighted. Halophyte cultivation is a promising and innovative approach to address issues related to water scarcity, food and nutrition insecurity, environmental degradation, and even job creation amidst the challenges posed by climate change. The cultivation of halophytes, especially in saline environments, has emerged as a successful and sustainable agricultural endeavor, showcasing the potential of halophytes to boost resilience, enhance biodiversity, and contribute to sustainable food systems. It is advocated to identify areas with saline or brackish soils for cultivation, considering the specific requirements of the chosen plant species. Case studies from around the world that have been successfully integrated into agricultural systems have been discussed. These real-world case studies underscore their successful implementation and serve as practical illustrations of the potential to use the world’s natural resources for obtaining fodder, grass forage, and medicinal and oil raw materials, as well as biological agents for reclaiming degraded lands, especially in arid regions, where food shortages are observable.
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Soils is considered one of the most biologically diverse habitats on Earth. The degradation of soil biodiversity has highly negative consequences for multiple ecosystem functions and services. Currently, soil biodiversity is threatened by global anthropogenic activities, such as land-use intensification, deforestation and also extreme climatic events. The management of soil biodiversity offers many opportunities to address significant societal issues such as environmental remediation of polluted soils and sediments, plant production, and food quality. Restoration of soil is a remedy for conservation of soil and its qualities.
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With the increasing shortage of water resources, the current management of saline–alkali lands in semi-arid and arid areas has gradually transformed from “flooding irrigation with drainage” in the past to the combination of controlling regional water and salt balance, phytoremediation, and comprehensive utilization of halophyte resources. However, soil salinization caused by natural and anthropogenic factors has still been a major global environmental problem, which changes the chemical and physical properties of soil, deteriorates the quality of underground water, and decreases biodiversity, contributing to the loss of soil productivity and the succession of the halotolerant species. Euhalophytes, as the materials for phytoremediation, have been confirmed to be effective species in improving saline–alkali soils. They can redistribute salts in soil profile through the interaction of their desalinization potential and irrigation water leaching, thereby preventing secondary salinization and improving soil productivity for long-term reclamation of saline soil. In this review, the adaptation mechanisms of euhalophytes to saline soils are generalized from the views of morphological, physiological, and molecular aspects and evaluated for their potential to remediate saline soil through salt removal and promoting leaching. Euhalophytes can not only sequestrate salts inside the central vacuole of cells to tolerate higher salt stress by means of organ succulence, ion compartmentalization, and osmotic adjustment but facilitate water infiltration and salts leaching through root–soil interaction. The root system’s mechanical penetration increases soil porosity, decreases soil density, as well as stabilizes soil aggregates. Moreover, the suitability of phytoremediation in arid situations with low precipitation and non-irrigation and some agricultural practices need to be taken into account to avoid salts returning to the soil as forms of litter and deep tillage altering salt distribution. Hence, euhalophytes planting in semi-arid and arid areas should be evaluated from their adaptation, desalinization, and prospective commercial values, such as foods, biofuels, and medical development to alleviate soil secondary salinization crisis and enhance the productivity of arable agricultural land.
Chapter
World agricultural productivity is deteriorating due to various ill effects of climate change, temperature rise, and abiotic stresses. Salt is essential for living organisms, but its increasing concentration in growing media might affect the system. Salinity severely offends soil fertility, which subsequently retards crop growth and production by affecting cellular or metabolic processes. Of the several eco-friendly techniques, microorganisms in reducing soil salinity and crop loss are gaining momentum. Microorganisms facilitate plant tolerance toward salinity through various mechanisms such as osmoregulation, producing ACC deaminase, antioxidants, EPS, or volatile compounds. Microbial inoculation along with organic amendments not only helps in the development of sustainable agricultural practices for crop production but also improves the growing environment under these stressed conditions. This chapter reviews the microbe-mediated mechanisms of salt tolerance to improve plant growth and yield besides sustaining soil health.
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تقع منطقة الدارسة على طول الشريط الساحلي لمنطقتي دريانة برسس، ضمن إقليم المناطق الجافة وشبة - الجافة. في العام 1980 قامت المؤسسة الروسية (Selkhozprom Export ) بدارسة هذه المنطقة و تصنيفها الي وحدات تربة بناء على النظام الروسي لتصنيف الترب. في العام 2010 ، تم تحديد موقع 12 قطاع باستخدام نظام تحديد المواقع (GPS)، لدارسة خصائص هذه الترب والتغرات التي طرات عليها منذ العام 1980 . تشير النتائج إلي وجود تغيرات واضحة في بعض الخصائص المورفولوجية والفزيائية والكيميائية لترب منطقة الدارسة. حيث لوحظ انتشار القشور الملحية على اسطح معظم القطاعات وتحول بعض هذه القطاعات إلي سبخة أو لاتربة (شواطئ رممية). كما دلت النتائج على ان عمليات التمليح كانت من اهم العمليات المسؤلة عن تدهور ترب منطقة الدارسة. في هذه الدارسة تم اقتراح سبل استصلاح هذه الترب و المحافظة عليها من التأثيرات السيئة المحتملة لارتفاع مستوى سطح البحر. اوصت الدارسة بزيادة الاهتمام بالترب الساحلية واعتبارها من المناطق الواعدة لزيادة الرقعة الزارعية.
Article
Salinity is a significant constraint in crop productivity. Halophytes are highly salt-tolerant plants that grow in saline soils such as seashore, salt lakeshores, and inland salt marshes. Studies on the cultivation of halophytes using saline water irrigation indicated that halophytes could be used for food, feed, oil, biofuels, medicine, and phytoremediation. By elucidating molecular mechanisms in salt tolerance of halophyte, the salt-tolerance of crops may be improved. Establishment of farming methods that utilize high salt-tolerant plants will help increase agricultural production in salinized regions. In this review, we will show examples of usage of halophytes in agricultural production and discuss the potential of halophytes as genetic resources and alternative crops.
Article
Background and Objective: The shoot succulent halophyte Sesuvium portulacastrum was previously shown to take up sodium (Na+) from the soil and accumulate it within its shoot tissues and was therefore chosen as a good plant for the phytodesalination of saline-sodic soils. The present investigation aimed to evaluate the ability of this halophyte to take up sodium and potassium (K+) from a saline medium and to check therefore its possible use in the phytodesalination of saline waters such as reject brines. Materials and Methods: Plants were hydroponically grown for one month in the presence of 200 mM NaCl, KCl or Na2SO4. At the harvest, leaves, stems and roots were weighed fresh and oven-dried then analyzed for K+ and Na+ contents. A One-Way-ANOVA test was used for data analysis. Results: Sesuvium portulacastrum showed a high tolerance to the three salts in terms of biomass production and water content. Plants accumulated high Na+ and K+ quantities, Na+ being more accumulated. Conclusion: The accumulated K+ quantities allow this halophyte to be used in the phytodesalination of saline waters such as reject brines
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Salinity has been a major threat to the agricultural fields both in arid and semiarid areas. For the last few decades attempts has been made to impart salinity tolerance in crop plants but most of the research were not fruitful. In this scenario, halophytes with an inherent potential to survive in extreme saline conditions is suggested as a resource for the effective desalination of salt affected agricultural lands. The process in which plants are utilized as agents of desalination are termed as phytodesalination. Halophytes acquire several morphological and physiological adaptive strategies towards salinity like salt exclusion, salt excretion and effective compartmentation so as to mitigate the excess salt ions. In addition, recent researches have also revealed the molecular strategies behind the regulation of basic metabolic processes like photosynthesis, transpiration, regulation of stomatal movements and the uptake of salt ions under salinity stress. Several salt tolerant genes were characterized from halophytes and have successfully incorporated in many crop plants. Phytodesalination using halophytes will be a sustainable approach in the field of agriculture in saline lands and it will also be helpful for the reclamation of salt affected lands. In this chapter attempts have been made to review the phytodesalination technology with a detailed description of the mechanism underlying salt tolerance in halophytes. A brief outline of the genetic engineering approaches of phytodesalination and the current status of the technology in the field of agriculture is also provided. Keywords: climate change; halophytes; phytodesalination; salinity; salt tolerance
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In Tunisia, some local halophyte species are potentially interesting for fodder production. However, their biomass production is often limited by water, particularly in arid zones. Thus, seawater irrigation could improve halophytes productivity. As part of this approach, growth, water nutrition and mineral status of two fodder halophytes, Suaeda fruticosa and Spartina alterniflora, were studied in condition of seawater irrigation supplied or not with nutrients. Our results have shown that these two halophytes species have expressed low biomass production (less than 10 % of maximal growth) when plants were grown on 50 % seawater. In addition, supplying diluted seawater with nitrogen or phosphorus has improved significantly growth of plants and increased nitrogen and phosphorus tissues concentration, relatively to control plants cultivated on diluted seawater not supplied with nutrients. However, these effects were more pronounced for nitrogen than phosphorus. These results indicate that nitrogen and at lesser extent phosphorus were the most growth limiting nutrient for culture on seawater. Biomass production of plants grown on seawater added only with phosphorus and nitrogen was similar to that of plants cultivated on full nutrient solution. This result showed that, except for nitrogen and phosphorus, macro and micronutrients concentrations in seawater were optimum for plant growth.
Article
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Growth and nutrient acquisition in sour orange (Citrus aurantium L.) were studied under salt stress in vitro. Microshoots were transferred to Murashige and Skoog (MS) solid proliferation media containing 8.9 µM BA (6‐Benzyladenine) and 0.5 µM NAA (naphthaline acetic acid). Salinity was induced by incorporating different concentrations [0.0 (control), 50, 100, 150, 200, or 300 mM] of sodium chloride (NaCl) to the culture media. Microshoots were exposed to direct or gradual salinity shock. Slight reduction was obtained in growth (shoot length, shoot number, leaf number, and dry weight) when microshoots were directly exposed to NaCl stress from 0.0 to 150 mM. At 200 and 300 mM NaCl, growth parameters were adversly affected and microshoots died thereafter. Gradual NaCl shock was studied by transferring microshoots sequentialy every week to different NaCl concentraions (0.0, 50, 100, 150, 200, or 300 mM). Growth was monitored at each concentration until the end of the last week of incubation at 300 mM NaCl. Growth (shoot length, shoot number or leaf number, and dry weight) generally decreased with elevated salinity level, but was less impaired than the direct shock. The percentage of shoot content of phosphorus (P), potassium (K), and iron (Fe) in the direct Nail shock experiment were reduced with elevated salinity level. This reduction was less in the gradual shock treatments. Sodium Chloride level strongly reduced Fe acquisition under both direct and gradual salinity stress. Tissue contents of sodium (Na), zinc (Zn), and manganese (Mn) were increased with the imposed salinity treatments in both experiments.
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Soil salinization is one of the major causes of declining agricultural productivity in many arid and semiarid regions of the world. Excessive salt concentrations in soils, in most cases, cannot be reduced with time by routine irrigation and crop management practices. Such situations demand soil amelioration. Various means used to ameliorate saline soils include: (a) movement of excess soluble salts from upper to lower soil depths via leaching, which may be accomplished by continuous ponding, intermittent ponding, or sprinkling; (b) surface flushing of salts from soils that contain salt crusts at the surface, a shallow watertable, or a highly impermeable profile; (c) biological reduction of salts by harvest of high-salt accumulating aerial plant parts, in areas with negligible irrigation water or rainfall available for leaching; and (d) amelioration of saline soils under cropping and leaching. Among these methods, cropping in conjunction with leaching has been found as the most successful and sustainable way to ameliorate saline soils. Cropping during leaching or between leachings causes an increase in salt-leaching efficiency because a decrease in soil water content occurs under unsaturated water flow conditions with a concurrent decrease in large pore bypass and drainage volume. Consequently, anaerobic conditions in soil may occur during leaching that can affect crop growth. Thus, in addition to the existing salt-tolerant crop genotypes, research is needed to seek out or develop genotypes with increased tolerances to salinity and hypoxia. Since salt leaching is interacted by many factors, evaluation of the traditional concepts such as the leaching requirement (LR), the leaching fraction (LF) and the salt balance index (SBI) demands incorporation of a rapid, efficient and economical way of monitoring changes in soil salinity during amelioration. Besides this, numerous models that have been developed for simulating movement and reactions of salts in soils need evaluation under actual field conditions. Copyright © 2000 John Wiley & Sons, Ltd.
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The growth of the halophyte Sesuvium portulacastrum, commonly known as sea purslane, is impeded by NaCl only at high (600–1000 mM) concentration. Therefore, the goal of this investigation was to identify the mechanisms which set the limit of the salt resistance of S. portulacastrum. 21-day-old cuttings were grown for 45–50 d under split-root conditions in which one half of the root system was immersed in complete nutrient solution supplemented with 800 mM NaCl, while the other half was immersed in a NaCl-free medium, containing all nutrients or being deprived of potassium or calcium or nitrogen. Using this approach, we demonstrate that K⁺ and N uptake was impaired in roots exposed to NaCl. Concerning Ca²⁺, there was no indication of uptake inhibition by NaCl. However, restriction of K⁺ uptake by roots was compensated by an increase in the K⁺-use efficiency, so that growth was not inhibited. Concerning N, our analysis shows that NO and/or NH uptake, but not their assimilation, was limited by salt treatment. Thus, we conclude that at high salinity levels, the growth of S. portulacastrum is limited by the restrictions imposed by NaCl on N uptake, perhaps in addition to inhibiting effects of excessive Na⁺ accumulation in shoot.
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Usually saline soils were reclamized by chemical or mechanical remediation, since the cost of leaching technique for saline soil reclamation is higher in India. In the present study an attempt has been made to investigate to identify the fast and luxuriantly growing halophytic herbs which are salt accumulators and to assess the feasibility of salt bioaccumulation. From the results it is concluded that among six species studied Suaeda maritima and Sesuvium portulacastrum exhibited greater accumulation of salts in their tissues as well as higher reduction of salts in the soil medium.
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Tolerance to high soil [Na(+)] involves processes in many different parts of the plant, and is manifested in a wide range of specializations at disparate levels of organization, such as gross morphology, membrane transport, biochemistry and gene transcription. Multiple adaptations to high [Na(+)] operate concurrently within a particular plant, and mechanisms of tolerance show large taxonomic variation. These mechanisms can occur in all cells within the plant, or can occur in specific cell types, reflecting adaptations at two major levels of organization: those that confer tolerance to individual cells, and those that contribute to tolerance not of cells per se, but of the whole plant. Salt-tolerant cells can contribute to salt tolerance of plants; but we suggest that equally important in a wide range of conditions are processes involving the management of Na(+) movements within the plant. These require specific cell types in specific locations within the plant catalysing transport in a coordinated manner. For further understanding of whole plant tolerance, we require more knowledge of cell-specific transport processes and the consequences of manipulation of transporters and signalling elements in specific cell types.
Article
Soil salinization is one of the major causes of declining agricultural productivity in many arid and semiarid regions of the world. Excessive salt concentrations in soils. in most cases, cannot be reduced with time by routine irrigation and crop management practices. Such situations demand soil amelioration. Various means used to ameliorate saline soils include: (a) movement of excess soluble salts from upper to lower soil depths via leaching, which may be accomplished by continuous pending, intermittent pending, or sprinkling; (b) surface flushing of salts from soils that contain salt crusts at the surface, a shallow watertable, ol a highly impermeable profile; (c) biological reduction of salts by harvest of high-salt accumulating aerial plant parts, in areas with negligible irrigation water or rainfall available for leaching; and (d) amelioration of saline soils under cropping and leaching. Among these methods, cropping in conjunction with leaching has been found as the most successful and sustainable way to ameliorate saline soils. Cropping during leaching or between leachings causes an increase in salt-leaching efficiency because a decrease in soil water content occurs under unsaturated water flow conditions with a concurrent decrease in large pore bypass and drainage volume. Consequently, anaerobic conditions in soil may occur during leaching that can affect crop growth. Thus, in addition to the existing salt-tolerant crop genotypes, research is needed to seek out or develop genotypes with increased tolerances to salinity and hypoxia. Since salt leaching is interacted by many factors, evaluation of the traditional concepts such as the leaching requirement (LR), the leaching fraction (LF) and the salt balance index (SBI) demands incorporation of a rapid, efficient and economical way of monitoring changes in soil salinity during amelioration. Besides this, numerous models that have been developed for simulating movement and reactions of salts in soils need evaluation under actual field conditions. Copyright (C) 2000 John Wiley & Sons, Ltd.
Article
The effect of Amshot grass (Echinochloa stagninum) compared to ponding and gypsum on reducing the alkalinity and salinity of highly saline sodic soil in Northern Egypt, near Manzala lake, was investigated for 2 years. In a field experiment over an area of 273 m2, 12 plots were prepared for three treatments. Each treatment had four replicates. The treatments were ponding (5–10 cm water depth), gypsum (10 tons per feddan, where 1 feddan = 4200 m2) and Amshot cultivation.Amshot reduced the exchangeable sodium percent (ESP) of the surface layer more than ponding or gypsum treatments in both years. The reduction was significant, especially after the second year.The relative ESP was 79.3, 73.3 and 67.3% of its initial value at the surface layer for ponding, gypsum and Amshot, respectively, for the first year. The corresponding values for the second year were 55.0, 47.0 and 33.6%. The reduction in exchangeable sodium was accompanied by a decrease in the sodium adsorption ratio (SAR) at the upper 45 cm layers. The relative SAR for this upper zone after 1 year compared to its initial value was in the range of 78–90 for ponding, 60–82 for gypsum and 65–78 for Amshot. The reduction was even greater for the second year and reached its maximum with Amshot (42–45%). Amshot significantly reduced the salinity of the soil compared to either ponding or gypsum, and produced higher fresh yield than clover cultivated in such soils. Therefore, Amshot could benefit both the soil and the livestock fodder in this area of Egypt.
Article
A normally grown crop of sunflower on red sandy loam soils was found to remove considerable quantities of chloride and sodium. On heavy clay soils with saline patches sunflower plants removed large quantities of sodium followed by chloride and sulphate. In view of its salt tolerance, it is suggested that intercropping or rotation with sunflower might help reduce soil salinity and improve soil conditions where salinity problems are coming up especially in heavy clay soils with low permeability. re]19720711
Article
The authors found five sodium (Na+) and chloride (Cl-.) hyperaccumulating halophytes in the Temperate Desert of Xinjiang, China and studied two of them (Suaeda salsa (L.) Pall. and Kalidium folium (Pall.) Moq.). K. folium and S. salsa had a NaCl content of 32.1% and 29.8%, respectively, on a dry weight basis. X-ray microanalysis of the Na+ in the vacuole, apoplasts and cytoplasm of the two plants indicated a ratio of 7.3:5.6:1.0 in K. folium and 7.3:6.6:1.0 in S. salsa. These data show that K. folium and S. salsa both have a high Na+ and Cl- accumulating capacity, which is related to high activity of tonoplast H+-ATPase and H+-PPase. (Managing editor: Ping HE)
Article
In various plant materials changes in turgor pressure, following hyper- or hypo-osmotic stress, were associated with the activation or inactivation of the plasma membrane H+-ATPase, respectively. To see if the turgor changes might indirectly influence H+-ATPase activity by regulating ion fluxes through plasma membrane, we investigated, in cultured cells of Arabidopsis thaliana (L.) Heynh., the early effects of hyper- and hypo-osmotic stress on Cl− fluxes in comparison, in the case of hyper-osmotic treatment, with its effect on net H+ extrusion. The results obtained showed that hyper-osmotic stress (200 mM mannitol) quickly reduced Cl− efflux (−70%) from cells preloaded with 36C1− for 18 h. This inhibiting effect was independent of the simultaneous mannitol-induced stimulation of Cl− influx and rapidly reversible after removal of the hyper-osmotic treatment. The inhibition of Cl− efflux was associated with a stimulation of net H+ extrusion, and these two effects showed the same dependence on the external mannitol concentration. Fusicoccin (FC, 20 µM), which stimulated H+ extrusion to about the same extent as 200 mM mannitol, did not affect Cl− efflux. When cells preloaded with 36C1− for 18 h in the presence of mannitol (from 25 up to 200 mM) were eluted in a mannitol-free medium an early and strong increase in Cl− efflux was found. The increase of Cl- efflux was already detectable for a small hypo-osmotic jump (25 mM), and was reduced (−50%) by the anion channel inhibitor A9C (300 µM). These results lead to exclude a direct causal relationship mediated by Em changes between the effects of osmoticum on Cl− efflux and net H+ extrusion, and favour the view that the changes in turgor pressure induced by hyper/hypo-osmotic stress may respectively induce an early inactivation/activation of stretch-sensitive anion channels.
Article
A field experiment was carried out at the University of Agriculture, Faisalabad (Pakistan) during 1988–90 to evaluate the comparative efficiency of chemical and biological methods for the reclamation of a calcareous saline‐sodic soil (pHs pHs = pH of saturated soil paste = 8.2–8.6; ECe ECe = Electrical conductivity of the saturation extract = 7.4–9.0 dS m ⁻¹ ; SAR SAR = Sodium adsorption ratio = 55.6–73.0 for upper 30 cm layer). Five treatments were assessed, three involved cropping: sesbania ( Sesbania aculeata ), sordan ( Sorghum bicolor x Sorghum sudanese ), and kallar grass ( Leptochola fusca ) and two were non‐cropped (control and gypsum at 100.0 per cent GR‐15·0 cm) were employed. Water of low electrolyte concentration (EC = 0.27 dS m ⁻¹ ) was used for irrigation and leaching. Sesbania and kallar grass were found to be effective biotic materials for soil reclamation. These plant species produced substantial biomass and also improved the soil environment by lowering the EC and SAR of the soil. Sordan was relatively less‐effective due to its sensitivity to high temperature and sodicity during germination and early seedling stages. After two cropping seasons, wheat (cultivar LU 26S) was sown as a test crop. Efficiency of treatments as indicated by wheat grain yield was in the order: sesbania = gypsum > kallar grass > sordan > control.
Article
With a world-wide occurrence on about 560 million hectares, sodic soils are characterized by the occurrence of excess sodium (Na+) to levels that can adversely affect crop growth and yield. Amelioration of such soils needs a source of calcium (Ca2+) to replace excess Na+ from the cation exchange sites. In addition, adequate levels of Ca2+ in ameliorated soils play a vital role in improving the structural and functional integrity of plant cell walls and membranes. As a low-cost and environmentally feasible strategy, phytoremediation of sodic soils — a plant-based amelioration — has gained increasing interest among scientists and farmers in recent years. Enhanced CO2 partial pressure (PCO2) in the root zone is considered as the principal mechanism contributing to phytoremediation of sodic soils. Aqueous CO2 produces protons (H+) and bicarbonate (HCO3-). In a subsequent reaction, H+ reacts with native soil calcite (CaCO3) to provide Ca2+ for Na+ Ca2+ exchange at the cation exchange sites. Another source of H+ may occur in such soils if cropped with N2-fixing plant species because plants capable of fixing N2 release H+ in the root zone. In a lysimeter experiment on a calcareous sodic soil (pHs = 7.4, electrical conductivity of soil saturated paste extract (ECe) = 3.1 dS m-1, sodium adsorption ratio (SAR) = 28.4, exchangeable sodium percentage (ESP) = 27.6, CaCO3 = 50 g kg-1), we investigated the phytoremediation ability of alfalfa (Medicago sativa L.). There were two cropped treatments: Alfalfa relying on N2 fixation and alfalfa receiving NH4NO3 as mineral N source, respectively. Other treatments were non-cropped, including a control (without an amendment or crop), and soil application of gypsum or sulfuric acid. After two months of cropping, all lysimeters were leached by maintaining a water content at 130% waterholding capacity of the soil after every 24±1 h. The treatment efficiency for Na+ removal in drainage water was in the order: sulfuric acid > gypsum = N2-fixing alfalfa > NH4NO3-fed alfalfa > control. Both the alfalfa treatments produced statistically similar root and shoot biomass. We attribute better Na+ removal by the N2-fixing alfalfa treatment to an additional source of H+ in the rhizosphere, which helped to dissolve additional CaCO3 and soil sodicity amelioration.Protonenabgabe durch N2-fixierende Pflanzenwurzeln: ein möglicher Beitrag zur Phytomelioration von kalkreichen NatriumbödenBei einem weltweiten Vorkommen auf etwa 560 Millionen Hektar sind Natriumböden durch einen Überschuss an Natrium (Na+) gekennzeichnet, der das Wachstum und den Ertrag von Kulturpflanzenbeständen nachteilig beeinflussen kann. Die Melioration solcher Böden erfordert Calcium (Ca2+), um überschüssiges Na+ von Kationen-Austauscherplätzen zu verdrängen. Außerdem spielt Ca2+ eine wichtige Rolle bei der Verbesserung der strukturellen und funktionellen Integrität pflanzlicher Zellwände und Membranen. Als kostengünstige und umweltfreundliche Strategie hat die Phytomelioration von Natriumböden — eine auf Pflanzen beruhende Melioration — in den letzten Jahren zunehmendes Interesse bei Wissenschaftlern und Landwirten gefunden. Ein erhöhter CO2-Partialdruck (PCO2) in der Rhizosphäre wird als hauptsächlicher Mechanismus angesehen, der zur Phytomelioration von Natriumböden beiträgt. In Wasser gelöst, erzeugt CO2 Protonen (H+) und Bikarbonate (HCO3-). Anschließend reagiert H+ mit nativem Calcit (CaCO3), wobei sich Ca2+ löst und Na+ von Austauscherplätzen verdrängt. Eine weitere H+-Quelle könnte die H+-Abgabe von Wurzeln N2-fixierender Pflanzen sein, da diese in der Lage sind, H+ in die Rhizosphäre abzugeben. In einem Lysimeterversuch mit einem kalkreichen Natriumboden (pHs = 7, 4; ECe = 3, 1 dS m-1; SAR = 28, 4; ESP = 27, 6; CaCO3 = 50 g kg-1) wurde die Möglichkeit einer Phytomelioration mit N2-fixierender Luzerne (Medicago sativa L.) im Vergleich zu einer mit mineralischem N ernährten Luzerne (NH4NO3) untersucht. In weiteren Varianten (Applikation von Gips bzw. Schwefelsäure) wurde die chemische Melioration einer nicht behandelten Kontrolle gegenübergestellt. Beide Ernährungsformen führten zu statistisch ähnlicher Wurzelund Sprossmasse der Luzerne. Nach zweimonatigem Pflanzenwachstum erfolgte alle 24±1 h eine Dränung der Lysimeter durch Zugabe einer Wassermenge von 130% der maximalen Wasserkapazität zum Boden. Hinsichtlich der Effizienz, Na+ über Auswaschung aus dem Boden zu entfernen, zeigte sich folgende Reihenfolge: Schwefelsäure > Gips = N2-fixierende Luzerne > NH4NO3-ernährte Luzerne > Kontrolle. Wir führen das bessere Meliorationsergebnis in der Variante der N2-fixierenden Luzerne auf eine zusätzliche H+-Quelle in der Rhizosphäre zurück, die zur Lösung von zusätzlichem CaCO3 beitrug.
Article
The worldwide occurrence of saline sodic and sodic soils on more than half a billion hectares warrants attention for their efficient, inexpensive and environmentally acceptable management. These soils can be ameliorated by providing a source of calcium (Ca2+) to replace excess sodium (Na+) from the cation exchange sites. Although chemical amendments have long been used to ameliorate such soils, the chemical process has become costly during the last two decades in several developing countries. As a low-cost and environmentally acceptable strategy, the cultivation of certain salt tolerant forage species on calcareous sodic and saline sodic soils, i.e. phytoremediation, has gained interest among scientists and farmers in recent years. In a field study conducted at three calcareous saline sodic sites (pHs=8.1–8.8, ECe=7.8–12.5 dS m–1, SAR=30.6–76.1) in the Indus Plains of Pakistan, we compared chemical and phytoremediation methods. There were four treatments; two involved plants: Kallar grass (Leptochloa fusca (L.) Kunth), and sesbania (Sesbania bispinosa (Jacq.) W. Wight). The other two treatments were uncropped: soil application of gypsum and an untreated control. All treatments were irrigated with canal water (EC=0.22–0.28 dS m–1). The plant species were grown for one season (5–6 months). Sesbania produced more forage yield (34 t ha–1) than Kallar grass (23 t ha–1). Phytoremediation and chemical treatments resulted in similar decreases in soil salinity and sodicity, indicating that phytoremediation may replace or supplement the more costly chemical approach. The soil amelioration potential of sesbania was similar to that of the Kallar grass, which suggests that moderately saline sodic calcareous soils can be improved by growing a forage legume with market value.
Article
The halophyte, Suaeda salsa, was grown in saline soil in pots and watered with a NaCl solution containing 0.2 g L-1 Na-ions. S. salsa accumulated Na during a 120-day growing period and caused a net reduction in the Na content of the soil. S. salsa also decreased the Na content of saline soil in a field experiment. The Na content of the soil at depth 20–30 cm was reduced by 4.5% with S. salsa at a density of 15 plants m-2 and by 6.7% with a density of 30 plants m-2. In contrast, the Na content was decreased by only 1% with Medicago sativa at 15 plant m-2 and increased by 3.8% with bare soil. The results confirm that S. salsa is an effective salt absorber in saline soils.
Article
Amelioration of sodic and saline-sodic soils by chemical amendments requires high capital input. Cultivation of salt tolerant grasses may mobilize the native lime (CaCO3) in these soils through root action to substitute the chemical approach. A saline-sodic soil (pHs = 9.1, ECe = 9.8 dS m−1, SAR = 103, CaCO3 = 9.4%, CEC = 122 mmolc L−1, texture = sandy clay loam) was experimented for reclamation. Concrete cylinders (60 cm long, 30 cm internal diameter) were used to prepare the soil columns. The bottom of each column was padded with a 5 cm layer of gravel and sand to facilitate leaching. In each lysimeter, soil was added in small increments to obtain a uniform soil column. The soil was packed to a height of 40 cm, making the soil depth in each column 35 cm. Four treatments, one cropped i.e. kallar grass (Leptochloa fusca) and three non-cropped (control, gypsum @ 50%, and 100% gypsum requirement) were leached with four leaching cycles (LC1 to LC4) at different time intervals. Canal water (EC =0.28 dS m−1, SAR = 0.8) was used for leaching. Two leaching cycles, LC2 and LC3, were completed during the peak growth of kallar grass (summer) and the remaining two, LC1 and LC4, were completed during winter when its growth was very slow. After the completion of LC4, soil samples were collected from the lysimeters at 0–15 and 15–30 cm depths. The treatment receiving gypsum at higher rate (100% GR) removed the greatest amount of Na+ from the soil columns and caused a substantial decrease in soil salinity (EC) and sodicity (SAR). Performance of the grass treatment in enhancing the leaching of Na+ was between the gypsum treatments. Kallar grass removed more Na+ during summer than during winter. Effectiveness of the treatments for soil reclamation was in the order: 100% GR > kallar grass > 50% GR > control.
Article
La production de biomasse et le prélèvement d'éléments nutritifs majeurs (N, P, K) dans une parcelle mise hors pâturage en bordure de la sebkha d'Enfidha (100 km au sud de Tunis, étage bioclimatique semi-aride inférieur) ont été suivis au cours de 2 années consécutives, l'une particulièrement sèche et l'autre relativement pluvieuse. Environ la moitié de la biomasse aérienne sur la parcelle correspond à des halophytes pérennes caractéristiques de sols à forte salinité. Au cours de l'année pluvieuse, 40% de la production primaire de l'écosystème sont dus aux espèces annuelles, parmi lesquelles Medicago ciliaris (L) Krock, M polymorpha L, M truncatula Gaertn, et M minima Grufb sont dominantes. La réaction de ces Medicago au stress salin a été étudiée au laboratoire. Au stade végétatif, la production de MS est restreinte par NaCI (110 mM et 160 mM) chez tous les Medicago. Cet effet est lié à une réduction de la surface foliaire plutôt qu'à une baisse de la vitesse d'assimilation nette. Le sel diminue la production de graines en limitant le nombre de gousses, sans affecter le nombre de graines par gousse ni le poids individuel de la graine. La viabilité des graines n'est que très faiblement affectée. En dépit de leur origine (bordure de sebkha peuplée d'halophytes), les Medicago se sont révélés relativement sensibles à la salinité. La dynamique de leur reproduction dépend du maintien de la salinité à un niveau faible. Ces résultats suggèrent que ces plantes exploitent un horizon superficiel moins salé que celui qui supporte la croissance des halophytes. La présence des halophytes pourrait favoriser le maintien d'un horizon peu salé et relativement fertile, occupé périodiquement par les Medicago annuels. Episodic association of strict halophytes and glycophytes in a saline, hydromorphic ecosystem in semi-arid zones. The biomass production and the uptake of mineral nutrients (N, P, K) in an ungrazed area edging the sebkha of Enfidha (100 km south-east of Tunis; semi-arid bioclimatic zone) were studied for 2 successive years; the first year was particularly dry, the second relatively rainy. Half the aerial biomass was produced by perennial halophytes. Annual plants were responsible for a large part of the ecosystem productivity in the second year. Among them, Medicago ciliaris (L) Krock, M polymorpha L, M truncatula Gaertn and M minima Grufb were the dominant species (40% of ecosystem primary production). We studied their response to salinity in controlled culture conditions. Vegetative growth (dry matter production) was reduced by NaCl (110 or 160 mM) in all Medicago species. This effect was related to a reduction in leaf area rather than in assimilation efficiency. The number of seeds produced per plant and per unit biomass was severely reduced in the presence of salt. In contrast, individual seed weight, as well as their germinating power, were only weakly affected. In spite of their origin (edge of sebkha crowded by halophytes), the Medicago species studied appeared to be glycophytic, on the basis of their growth and nutritional responses to NaCl. Their reproduction depended on the maintenance of the salt concentration at low levels. These results suggest that these plants exploit the upper horizon layer, which is less salty than the deeper ones, which support the halophytes. The presence of halophytes might contribute to maintaining a fertile and less salty superficial layer, occupied periodically by annual Medicago species.
Article
Irrigation has long played a key role in feeding the expanding world population and is expected to play a still greater role in the future. As supplies of good-quality irrigation water are expected to decrease in several regions due to increased municipal-industrial-agricultural competition, available freshwater supplies need to be used more efficiently. In addition, reliance on the use and reuse of saline and/or sodic drainage waters, generated by irrigated agriculture, seems inevitable for irrigation. The same applies to salt-affected soils, which occupy more than 20% of the irrigated lands, and warrant attention for efficient, inexpensive and environmentally acceptable management. Technologically and from a management perspective, a couple of strategies have shown the potential to improve crop production under irrigated agriculture while minimizing the adverse environmental impacts. The first strategy, vegetative bioremediation--a plant-assisted reclamation approach--relies on growing appropriate plant species that can tolerate ambient soil salinity and sodicity levels during reclamation of salt-affected soils. A variety of plant species of agricultural significance have been found to be effective in sustainable reclamation of calcareous and moderately sodic and saline-sodic soils. The second strategy fosters dedicating soils to crop production systems where saline and/or sodic waters predominate and their disposal options are limited. Production systems based on salt-tolerant plant species using drainage waters may be sustainable with the potential of transforming such waters from an environmental burden into an economic asset. Such a strategy would encourage the disposal of drainage waters within the irrigated regions where they are generated rather than exporting these waters to other regions via discharge into main irrigation canals, local streams, or rivers. Being economically and environmentally sustainable, these strategies could be the key to future agricultural and economic growth and social wealth in regions where salt-affected soils exist and/or where saline-sodic drainage waters are generated.
Soil salinity – causes and controls. In: Techniques for Desert Reclamation
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