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Effects of A. nodosum seaweed extracts on spinach growth, physiology and nutrition value under drought stress
... Seaweed extracts (SWEs) are effective plant biostimulants, such as Ascophyllum nodosum extracts (Xu and Leskovar, 2015;Spann et al., 2011). Other common sources are Caulerpa sertularioides, Durvillaea potatorum, Ecklonia maxima, Laminaria spp., Padina gymnospora, Solanum lycopersicum L., Sargassum liebmannii, Sargassum johnstonii and Ulva lactuca (Xu and Leskovar, 2015;Kumari et al., 2011). ...
... Seaweed extracts (SWEs) are effective plant biostimulants, such as Ascophyllum nodosum extracts (Xu and Leskovar, 2015;Spann et al., 2011). Other common sources are Caulerpa sertularioides, Durvillaea potatorum, Ecklonia maxima, Laminaria spp., Padina gymnospora, Solanum lycopersicum L., Sargassum liebmannii, Sargassum johnstonii and Ulva lactuca (Xu and Leskovar, 2015;Kumari et al., 2011). Additionally, groups of advantageous bacteria or fungi are included in the category of biostimulants. ...
... 27. Seaweed extracts (SWEs) Spinacia oleracea (Spinach) Increases in antioxidant defence mechanisms such as CAT, SOD, and APX activity, as well as non-enzymatic antioxidants, were also seen, as was a reduction in lipid peroxidation. Xu and Leskovar (2015) Salinity stress 28. ...
Pesticide and fertilizer usage is at the center of agricultural production to meet the demands of an ever-increasing global population. However, rising levels of chemicals impose a serious threat to the health of humans, animals, plants, and even the entire biosphere because of their toxic effects. Biostimulants offer the opportunity to reduce the agricultural chemical footprint owing their multilevel, beneficial properties helping to make agriculture more sustainable and resilient. When applied to plants or to the soil an increased absorption and distribution of nutrients, tolerance to environmental stress, and improved quality of plant products explain the mechanisms by which these probiotics are useful. In recent years, the use of plant biostimulants has received widespread attention across the globe as an ecologically acceptable alternative to sustainable agricultural production. As a result, their worldwide market continues to grow, and further research will be conducted to broaden the range of the products now available. Through this review, we present a current understanding of biostimulants, their mode of action and their involvement in modulating abiotic stress responses, including omics research, which may provide a comprehensive assessment of the crop's response by correlating molecular changes to physiological pathways activated under stress conditions aggravated by climate change.
... Salinity and drought stresses can be similarly mitigated by a reduction of osmotic potential to avoid excessive water loss. This involves osmoprotectants accumulation, such as proline, carbohydrates, organic acids and proteins, and stimulation of stomatal closure, which can be enhanced by BME, such as AN extracts on asparagus (Al-Ghamdi and Elansary, 2018) and spinach (Xu and Leskovar, 2015), or Cystoseira sp. extract on rapeseed (Hashem et al., 2019). ...
... BME also elicit the upregulation of cellulose synthase-like E1, UDP-glucose 4-epimerase 1 and pectin acetylesterase 8 genes, responsible for the development and strengthening of plant cell walls . BME can improve the plant photosynthetic system by upregulating betaine aldehyde dehydrogenase and choline monooxygenase genes involved in the photosynthetic process (Xu and Leskovar, 2015). They also trigger the upregulation of glycine betaine biosynthesis genes that prevent chlorophyll degradation and delay photosynthetic activity loss, and the downregulation of chlorophyll degradation genes (Genard et al., 1991;Nair et al., 2012). ...
... They also trigger the upregulation of glycine betaine biosynthesis genes that prevent chlorophyll degradation and delay photosynthetic activity loss, and the downregulation of chlorophyll degradation genes (Genard et al., 1991;Nair et al., 2012). Both processes resulted in increased leaf chlorophyll content and enhanced photosynthetic activity, as observed after AN extract application on spinach (Fan et al., 2013;Xu and Leskovar, 2015). ...
The worldwide growing food demand and the excessive use of synthetic and chemical inputs compel the agricultural sector to find innovative and sustainable solutions to enhance or at least maintain crop yields in times of increased abiotic stresses levels linked to global change. Currently, great research efforts are carried out on brown seaweeds as their environment lead them to produce a broad range of compounds, with osmoregulatory, antioxidant, pro-bacterial, and plant-growth promoting activities. Indeed, numerous studies are looking at different combinations of algal species, extraction processes, plant species and environments of plant culture to highlight the various effects of algal extracts on plant growth and development, and resistance to abiotic stresses. Consequently, a wide variety of novel commercial products are emerging, presenting diversified chemical compositions, formulations and means of application. Such products allow the biostimulation of plants and soil by alleviating abiotic stresses such as drought, frost, and salt. The action of brown macroalgal extracts on plant and soil health has been repeatedly demonstrated, yet the precise relation between the extract chemical composition and its subsequent effect is still to be elucidated, as molecular synergy is suspected to play an important role. In this review, we present the interest of using brown macroalgal extracts to produce biostimulants with beneficial action on soil health, plant growth and development, as well as resistance against abiotic stresses, in relation to the molecular changes occurring.
... Among the innovative practices of dry-farming in recent years, the possibility of the combined use of biostimulants and soil conditioners is assuming an important role [7][8][9][10]. The knowledge and know-how of these innovative amendments must be improved to use them as a valid alternative to non-natural molecules to obtain a higher crop yield and decrease the undesirable effects on the environment of their use in agriculture [10]. ...
... These results disagree with other authors [29,30]; however, few studies report the effect of seaweed biostimulant obtained from A. nodosum on spinach gas exchanges. Under full irrigation on spinach, there would seem to be no effect on leaf gas exchange, while under water stress conditions, a positive effect on photosynthesis has been demonstrated [8]. The growth of the spinach plants was not significantly influenced by the different compared treatments; however, the number of leaves was higher in the Bios treatment, equal to 8 (Table 2). ...
... ostimulant obtained from A. nodosum on spinach gas exchanges. Under full irrigation on spinach, there would seem to be no effect on leaf gas exchange, while under water stress conditions, a positive effect on photosynthesis has been demonstrated [8]. The growth of the spinach plants was not significantly influenced by the different compared treatments; however, the number of leaves was higher in the Bios treatment, equal to 8 ( Table 2). ...
Among the innovative practices of dry-farming in recent years, the possibility of the combined use of biostimulants and soil conditioners is assuming an important role. In a preliminary pot experiment, this study aimed to verify the combined effects of Ascophyllum nodosum-based biostimulant and zeolite applied to the soil on gas-exchange and spinach growth. We also monitored the soil water content to study the effect on spinach soil water uptake. Pots were filled with soil to which zeolite and an Ascophyllum nodosum-based biostimulant were added. Spinach plants grew into pots and were subjected to four treatments: (1) soil plus zeolite at a percentage of 1%, (2) soil plus the biostimulant, (3) soil plus zeolite at 1% and biostimulant, (4) bare soil as control. The use of the zeolite and the A. nodosum-based biostimulant led to a higher (+10%) soil water content, highlighting the positive role in allowing a good water uptake by the spinach plant. Plant growth was not changed, while only photosynthesis showed an increase equal to 6% in spinach plants. These results are discussed with the soil water content variation according to modification induced by treatments. The combined use of zeolite and A. nodosum-based biostimulant can be considered a strategy to improve water storage and, at the same time, improve spinach cultivation in terms of sustainability.
... Spinach, whose leaves are consumed fresh, is an important vegetable containing multiple minerals and vitamins, especially vitamin C, which is necessary for human health (Ekinci et al., 2015). In addition, it constitutes an important dietary product and is rich in glucuronic acid and p-coumaric acid derivatives with strong antioxidant activity (Xu and Leskovar, 2015). ...
... Several studies have reported the negative effects of flooding stress conditions on the chlorophyll content (Jaiswal and Srivastava, 2015;Seymen, 2021;Khosravi et al., 2023;Seymen et al., 2023). A significant increase in the carotenoid content was reported in lettuce (Basahi et al., 2014) and spinach (Xu and Leskovar, 2015) under stress conditions. The melatonin applications under flooding stress conditions increased the chlorophyll contents in corn (Zhang et al., 2021), cauliflower and cabbage (Can, 2023). ...
... F V /F M was not affected by the deficit irrigation, and biostimulants did not affect this parameter. This was also the case for the treatment of spinach under drought with a seaweed-based biostimulant [59]. ...
... Biostimulants can also act by postponing drought stress, as in the study of Campobenedetto et al. (2021) where a seaweed-based biostimulant reduced the ABA concentration in tomato compared with the untreated control grown under the same mild drought conditions [61]. In other vegetables, such as spinach and broccoli, the application of seaweed-based biostimulants significantly increased stomatal conductance [59,62]. In contrast, the biostimulants in our trials had no significant effect on the stomatal conductance of Hydrangea paniculata grown under drought conditions. ...
To adapt to climate change and water scarcity during dry, hot summers, more sustainable, or even deficit, irrigation is required in the ornamental sector, as it uses large amounts of water to sustain high-value crop production. Biostimulants, especially seaweed extracts, could offer a sustainable solution against drought stress as they are known to increase plant tolerance to abiotic stress. The effect of four seaweed extracts based on Ascophyllum nodosum, Soliera chordalis, Ecklonia maxima, and Saccharina latissima and one microbial biostimulant were tested on container-grown Hydrangea paniculata under drought stress conditions for two years. During the first trial year, in 2019, overall irrigation was reduced by 20%. In 2021, plants were subjected to repeated drying and wetting cycles. In general, less irrigation, and thus a lower substrate moisture content, reduced stomatal conductance, biomass production, and root development, but increased plant compactness. The biostimulants showed minor effects, but these were not observed in both experiments. Treatment with the A. nodosum extract resulted in longer branches and more biomass under deficit irrigation but tended to accelerate flowering when repeated drying and wetting cycles were applied. The E. maxima extract negatively affected the branching of Hydrangea under repeated drying and wetting cycles.
... In the present study, A. nodosum extract seed treatment/drench application was shown to improve the growth of baby leaf lettuce plants exposed to a salinity stress of 40 mM NaCl L −1 and the growth of Batavia lettuce plants exposed to a mild water stress under organic management. In line with our results, Xu and Leskovar observed a significant increase in dry biomass of spinach treated with A. nodosum extract when grown under drought stress [50]. ...
... For both organic and conventional growing systems, beneficial effects of A. nodosum extract, fulvic acid, and humic acid were observed on lettuce submitted to abiotic or biotic stress, while no effect was observed on lettuce under non-stressful conditions. Similarly, A. nodosum-based biostimulants were shown to increase yields of lettuce plants and dry biomass of spinach plants when plants were grown under stressful conditions, while no yield or dry biomass increases were observed when plants were grown under non-stressful conditions [50,51]. A meta-analysis of the plant growth response to humic substances conducted by Rose et al. revealed that plants are more likely to respond positively to applications of humic substances when they are submitted to high or moderate stressful conditions [52]. ...
Plant biostimulants are substances or microorganisms aimed at promoting plant growth by increasing the mineral nutrition efficiency, tolerance to environmental stress, and crop quality traits. This new category of crop inputs has been capturing the interest of both researchers and agriculture takeholders in light of the promising effects they could have on crop productivity and sustainability. This study investigated a variety of biostimulants for their effect on germination rates, plant health, chlorophyll fluorescence parameters, SPAD index, and growth of baby leaf lettuce and Batavia lettuce submitted to biotic (absence/presence of Pythium ultimum in the growing medium) or abiotic (0, 40, 80, and 120 mM NaCl L−1 concentrations and −0.5, −2, −4, and −6 kPa water potentials) stresses when grown in a greenhouse under conventional and organic cultivation. The results obtained show that lettuce response to biostimulants was influenced by the type or level of stress applied and the growing system used. The effects of the tested biostimulants varied from strongly detrimental to strongly beneficial.
... Many commercial bio-stimulants contain the extracts of A. nodosum, which has been shown to considerably increase crop production, biometric traits, quality and it also imparts tolerance against various abiotic stresses (Ali et al., 2016;Shukla et al., 2019;Goni et al., 2018). Many researchers have reported that SW extracts (biostimulants) promoted growth, increased yield and quality of vegetables crops such as cucumber (Sarhan et al., 2011), tomato (Kumari et al., 2009), broccoli (Mattner et al., 2013), spinach (Xu and Leskovar, 2015) and bean (Beckett et al., 1994). Also, a plethora of studies explained that A. nodosum has bio-stimulation effects on various agricultural and horticultural crops, such as watermelon Koukounaras, 2022, 2023), tomato Ikuyinminu et al., 2022), wheat (Langowski et al., 2022), soybean (Repke et al., 2022), sweet pepper (Rajendran et al., 2022), pea (Rashad et al., 2022), maize (Shukla and Prithiviraj, 2021) and okra . ...
Recently, hydroponic system for vegetable production is very popular across the globe. In a hydroponic system selection of suitable growing substrate is an important factor as it directly involved in development of plant roots and shoots. As well as nutrition solution has a great effect on high crop production along with crop quality. Thus, an experiment was carried out within the controlled environment of a glasshouse consisting with the four different compositions of growing substrates i.e., GM1 = 60% rice husk + 30% coconut coir + 10% vermicompost, GM2 = 60% coconut coir + 30% perlite + 10% vermicompost, GM3 = 60% sawdust + 30% perlite + 10% vermicompost, and GM4 = 60% ash + 30% perlite + 10% vermicompost along with three levels of bio-stimulant (Ascophyllum nodusum) solutions (Bs1 =1ml/l, Bs 2 = 2ml/l, and Bs 3 =3ml/l). In the experiment amongst the different growing substrate, the substrates with 60% coconut coir, 30% perlite and 10% vermicompost (GM2) exhibits best performance on the growth (Number branches per plant), yield (Fruits number, length, girth, weight, Number of seeds per fruit). In case of quality parameters (Ascorbic acid, total carotenoids, protein, TSS and reducing sugars were also found in higher site with the substrates of 60% coconut coir + 30% perlite + 10% vermicompost. The application of bio-stimulants was also found to be ideal for increasing the fruit number and fruit weight, respectively. The highest fruit weight of 176.49gm was obtained from the treatment with the combination of GM2 and BS1.
... Spinach has been proven to be a vital source of dietary fibers, beta-carotene, ascorbic acid, phosphorus, calcium, potassium, iron, and bioactive components like polyphenols, glucuronic acid, and 20-hydroxyecdysone. Furthermore, it is abundant source of many essential minerals and vitamins, particularly vitamin C, which confers advantageous effects on human wellbeing (Ekinci et al., 2015;Xu and Leskovar, 2015;Massa et al., 2018;Bokov et al., 2020). Throughout the dietary manufacturing sector, consumer interest in the spinach continues to rise substantially (Nguyen et al., 2019). ...
The growth of crop plants, particularly spinach (Spinacia oleracea L.), can be significantly impeded by salinity and drought. However, pre-treating spinach plants with traditional biofertilizers like Jeevamrit and Beejamrit (JB) substantially reverses the salinity and drought-induced inhibitory effects. Hence, this study aims to elucidate the underlying mechanisms that govern the efficacy of traditional fertilizers. The present work employed comprehensive biochemical, physiological, and molecular approaches to investigate the processes by which JB alleviates abiotic stress. The JB treatment effectively boosts spinach growth by increasing nutrient uptake and antioxidant enzyme activity, which mitigates the detrimental effects of drought and salinity-induced stress. Under salt and drought stress conditions, the application of JB resulted in an impressive rise in germination percentages of 80 and 60%, respectively. In addition, the application of JB treatment resulted in a 50% decrease in electrolyte leakage and a 75% rise in the relative water content of the spinach plants. Furthermore, the significant reduction in proline and glycine betaine levels in plants treated with JB provides additional evidence of the treatment's ability to prevent cell death caused by environmental stressors. Following JB treatment, the spinach plants exhibited substantially higher total chlorophyll content was also observed. Additionally, using 16S rRNA sequencing, we discovered and characterized five plant-beneficial bacteria from the JB bio-inoculants. These bacterial isolates comprise a number of traits that contribute to growth augmentation in plants. These evidences suggest that the presence of the aforesaid microorganisms (along with additional ones) is accountable for the JB-mediated stimulation of plant growth and development.
... Plant extract, as a kind of biostimulants, contain a variety of phytochemical compounds and nutrients, which improve physiological and biochemical processes of plant [16,17]. In recent years, seaweed extracts (SWE) have been widely used in vegetable and crop research, and study has indicated that application of SWE may increase phytochemical such as phenolic and flavoniods as well as antioxidant capacity [18,19]. Elansary et al. [20] reported that application of SWE can increase plant height and dry weight of Spiraea nipponica and Pittosporum eugenioides by regulating stomatal conductance and photosynthetic rate. ...
Drought stress is a major factor affecting plant growth and crop yield production. Plant extracts as natural biostimulants hold great potential to strengthen plants to overcome drought impacts. To explore the effect of Polygonum minus extract (PME) in enhancing drought tolerance in plants, a study was set up in a glasshouse environment using 10 different treatment combinations. PME foliar application were designed in CRD and effects were closely observed related to the growth, physiology, and antioxidant system changes in maize (Zea mays L.) under well-watered and drought conditions. The seaweed extract (SWE) was used as a comparison. Plants subjected to drought stress exhibited a significant reduction in fresh weight, dry weight, relative water content (RWC), and soluble sugar, but they stimulated the phenolic, flavonoid, proline, glutathione (GSH), malondialdehyde (MDA) and antioxidant enzyme (catalase, CAT; peroxidase, POD; superoxide dismutase, SOD) activities. Foliar application of PME improved fresh and dry weight (FW: 33.1%~41.4%; DW: 48.0%~43.1%), chlorophyll content (Chl b: 87.9%~100.76%), soluble sugar (23.6%~49.3%), and soluble protein (48.6%~56.9%) as well as antioxidant enzyme activities (CAT and POD) compared to CK under drought conditions. while decreasing the level of MDA. Notably, the mitigating effect of PME application with high concentration was more effective than those of SWE. Our study reveals that PME could alleviate drought stress by regulating osmoprotectant content and antioxidant defense system and can be used as an economical and environmentally friendly biostimulants for promoting maize growth under drought stress.
... Spinach (Spinacea oleracea L.) is an economically valuable vegetable plant species with great importance in human nutrition. Spinach is considered an important dietary product as it contains high levels of vitamins and minerals that are essential for human health (Ekinci et al. 2015), in addition to having glucuronic acid and p-coumaric acid derivatives that exhibit a strong antioxidant activity (Xu and Leskovar 2015). Approximately 26.2 million tons of spinach is produced globally, with China leading the production at 23.8 million tons, followed by America (USA) at 0.34 million tons and Turkey at 0.23 million tons (FAO 2021). ...
Melatonin, an important phytochemical, encourages plants to redirect growth in response to environmental stresses. The study aims to investigate the changes in the morphological, physiological, biochemical, and molecular properties of spinach subjected to the exogenous application of melatonin (MEL) at different doses under different water stress. The following four irrigation levels were applied: I100 (complete irrigation), I80 (20% water deficit), I60 (40% water deficit), and I40 (60% water deficit). MEL was applied through a spray on the leaves in three doses—0, 50, and 100 µM. In the present study, the application of MEL50 exhibited no significant decrease in water use efficiency (WUE) at the I80 irrigation level compared to the I100 irrigation level, while a significant decrease in the WUE was observed beyond this point. The application of MEL contributed to influencing the morphological parameters while also positively affecting the photosynthesis activity and, contribution to the antioxidant defense system. It was observed that the genes involved in the carbon metabolism of photosynthesis), the antioxidant mechanism, and the continuity of photosynthesis, all of which affect the expression of melatonin, facilitated water stress reduction in spinach. Therefore, it was inferred that the application of MEL50I80 could serve as an important irrigation strategy in semi-arid regions with limited water resources.
... Due to their ability to promote growth, extracts from seaweeds have been extensively employed as bio-stimulants in crop management (Mukherjee and Patel, 2020;Chen et al., 2021). In several other crops, including spinach, extracts from seaweeds have been demonstrated to be useful in enhancing stress resistance (Xu and Leskovar, 2015). Seaweed extracts are known to cause many beneficial effects on plants, as they contain many growth-promoting hormones such as indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), cytokinins, trace elements (Fe, Cu, Zn, Co, Mo, Mn, and Ni), vitamins, and amino acids (Latique et al., 2020). ...
... The results obtained are similar to those reported by Xu and Leskovar [32], who indicate that a simulated mild stress had no effect on the chlorophyll content in spinach. Other authors mention that in sage plants (Salvia officinalis L.) with drought stress induction treated with algae extracts, the concentration of chlorophyll increased [33]. ...
Water stress is one of the main factors affecting the development of agricultural crops. An innovative alternative to improve tolerance to water stress is the application of biostimulants. In the present study, the efficacy and physiological and biochemical responses of different biostimulants were evaluated in beans under moderate and severe stress. The treatments consisted of three types of irrigation: FC100, without water stress; FC75, irrigation reduced by 25% (moderate water stress); and FC50, irrigation reduced by 50% (severe water stress). In the treatments with water deficits, foliar biostimulants were applied: zinc oxide nanoparticles plus chitosan, Codasil®, Osmoplant®, Stimplex® and salicylic acid. Foliar application of ZnO + chitosan nanoparticles benefited biomass accumulation and yield under moderate water stress (FC75) and Codasil® and Osmoplant® under severe water stress (FC50). Proline, free sugars and gas exchange were higher with the application of ZnO + chitosan nanoparticles under moderate water stress and with Codasil® and Osmoplant® under severe water stress. Depending on the severity of water stress, ZnO + chitosan nanoparticles, Codasil® and Osmoplant® are viable products to increase tolerance in green bean cv. Strike plants.
... Introduction Spinach (Spinacia oleracea L.) is a big-leaf variety, which belonged to the spinach genus Chenopodiaceae (annual herbaceous plant), as an important leafy green vegetable its leaves and shoots that contain large quantities of bioactive compounds, minerals, and vitamins like A, B, and C and nutrients [1,2]. It can scavenge free radicals and has several medical and food applications [3]. ...
Chemcial fertilizer as the main strategy for improving the vegetable yields was excessively applied in recent years which led to progressively serious soil problems such as the soil acidification. According the situation, five different biofertilizer treatments [no fertilizer (CK), inoculations of Bacillus subtilis ( Bs , T1), combination of Bs and Bacillus mucilaginosus ( Bs+Bm , T2), Bs and Bacillus amyloliquefaciens ( Bs+Ba , T3), and Bm+Ba (T4)] were conducted to investigate the effect of the growth, leaf physiological indices, and chlorophyll fluorescence of spinach seedlings in the growth chamber. The growth and physiological indices of the spinach seedlings attained a maximum under the T2 treatments. Under the T2 treatment, the ABS/RC (Absorption flux per RC), TR 0 /RC (Trapping flux per RC), and ET 0 /RC (Electron transport flux per RC) was significantly increased, while the DI 0 /RC [Dissipated energy flux per RC (at t = 0)] was decreased. The OJIP curve was improved under of the inoculations of fertilizers, and the increasing range was the largest under the T2 treatment. The leaf light response curve (LC) was also significantly increased under the T2 treatment. The plant growth characteristics [leaf length (LL), leaf weight (LW), plant height (PH)] were positively correlated with the J-I-P test chlorophyll fluorescence parameters [PI ABS (Performance index for energy conservation from exciton to the reduction of intersystem electron acceptors), φP 0 (Maximum quantum yield of primary photochemistry), φE 0 (Quantum yield of electron transport), ψ 0 (The probability that a trapped exciton moved an electron in electron transport chain further than QA ⁻ ), TR 0 /RC, and ET 0 /RC] while negatively correlated with φD 0 (Quantum yield of energy dissipation) and DI 0 /RC. The leaf physiological characteristics [SP (soluble protein concentrations), SC (soluble carbohydrate concentrations), Chl a (chlorophyll a), Chl b (chlorophyll b), Chl a+b, Chl a/b, and WP (water potential)] were positively correlated with the J-I-P test chlorophyll fluorescence parameters (PI ABS , φP 0 , φE 0 , ψ 0 , ABS/RC, TR 0 /RC, and ET 0 /RC) while negatively correlated with φD 0 and DI 0 /RC. These results indicated that the combination of Bs + Bm inoculations promoted the growth of the spinach and improved the adaptability of the vegetable to acid soil while Ba inoculation didn’t have any effects to plants.
... Pusa Gold [54] under oxidative stress conditions. Seaweeds, especially brown seaweed, are rich in phenolic compounds [55] which is consistent with the present study. ...
Background
Due to the important economic role of pistachio (Pistacia vera L.) the cultivation of this valuable crop has been extended. Various abiotic stresses harm the growth and performance of pistachio. Seaweed extract containing various substances such as pseudo-hormones that stimulate growth, nutritional elements, and anti-stress substances can cause more resistance to abiotic stresses, and increase the quantity and the quality of the fruit. The present study was conducted to evaluate the effect of foliar application of Ascophyllum nodosum (L.) Le Jol. seaweed extract on some biochemical traits related to abiotic stress in Pistacia vera L. cv. Kaleh-Ghoochi. The first factor of foliar spraying treatment included A. nodosum seaweed extract at four levels (0, 1, 2, and 3 g/L), and the second factor was the time of spraying solution which was done at three times (1- at the beginning of pistachio kernel growth period at the end of June, 2- at the stage of full kernel development at the end of August, and 3- Spraying in both late June and August).
Results
The results showed that all investigated traits were significant under the treatment of seaweed extract compared with the control. The seaweed extract concentrations had a significant effect on all traits except soluble carbohydrates, but the time of consumption of seaweed extract on soluble carbohydrates, protein, peroxidase, ascorbate peroxidase, and superoxide dismutase enzymes was significant, while had no significant effect on the rest of the traits. According to the interaction effect of time and concentration of consumption of seaweed extract, the highest values of the biochemical characters were as follows: total phenol content: 168.30 mg CAE/g DW, flavonoid content: mg CE/g DW, catalase: 12.66 µmol APX min− 1 mg− 1 protein, superoxide dismutase: 231.4 µmol APX min− 1 mg− 1 protein, and ascorbate peroxidase: 39.53 µmol APX min− 1 mg− 1 protein.
Conclusions
Based on the results of this study, it seems that it is possible to use fertilizers containing A. nodosum seaweed extract with a concentration of 3 g/L in August to increase the tolerance of the pistachio cultivar “Kaleh-Ghoochi” to abiotic stresses.
... Also, Calcium (Ca 2+ ) in SwE contributed to cell elongation, cell stability, and enzyme activation in treated plants (Ahmed et al., 2021). Xu and Leskovar (2015), reported the application of SwE in spinach plants led to a large leaf area and high photosynthetic rate by improving leaf water relations, maintaining cell turgor pressure, and reducing stomatal limitation. Stimulation of the root system growth by SwE may result from the action of phytohormones like auxins and cytokinins. ...
The purpose of this experiment was to compare the growth and quality of cucumber fruits, in response to different concentrations (C0, C0.75, and C1.5 g L-1) and different application methods (M1: foliar sprays, M2: fertigation, M3: combined foliar sprays and fertigation) of seaweed extract (SwE). The simultaneous use of the method and different concentration of SwE increased the fresh weight of the leaf, fruit weight, yield, number of leaves, evaporation, fruit length, fruit diameter and firmness, stomatal conductance, and nitrate concentration of fruit. On the other hand, the highest amount of fruit firmness (69.25 and 69.27 N) was observed in M2C0.75 and M2C1.5 compared to other treatments, respectively. The M1C0.75 treatment increased the fruit diameter by 26.52% more than the M1C0 treatment. Fruit weight, fruit length, and yield were in the following order in different treatments, M1C1.5˃ M1C0.75 ˃ M3C1.5. So that only in the M1C1.5 treatment, fruit weight, yield, and fruit length were 25, 52.55, and 25.86% higher than the M1C0 treatment, respectively. Generally, the M1 and M3 in concentrations of 0.75 and 1.5 created better plant growth, fruit shape, and quality characteristics compared to the second method (M2) and the C0 treatment. Therefore, the concentration of 1.5 g L-1 and the use of foliar spraying methods, and the combination of foliar spraying and fertigation can be recommended to achieve the maximum yield and quality of cucumber fruits.
... Moreover, the exogenous application of AsA improves plant growth and development efficiently by maintaining different processes like phytohormones' signaling, ion transport mechanism, cell expansion, and oxidative defense mechanism under both stress and non-stress environments [15,22,[29][30][31][32]. In addition, exogenously applied AsA eliminates the negative role of water deficit stress on plants [33,34]. ...
To counteract the effects of drought stress, scientists have adopted several approaches including the use of different chemicals both inorganic and organic, which is contemplated as a highly efficient and cost-effective shot-gun approach. Ascorbic acid (AsA) is a potential organic substance, which widely occurs in plants, and is considered to be an effective antioxidant to counteract reactive oxygen species (ROS). Thus, a pot experiment was performed to assess the relative mitigating impacts of synthetic AsA and naturally occurring AsA in the form of lemon juice (LJ) and orange juice (OJ) on two cultivars of okra (Abelmoschus esculentus L.) namely Sabz Pari and Bhindi Sanwali under varying water deficit conditions. After 30 days of seed germination, okra seedlings were subjected to different irrigation regimes, i.e., water deficit stress [(65% and 50% F.C.) and control conditions (100% F.C.)]. Different levels of AsA [control (no spray), 14 mg L⁻¹ LJ, 24 mg L⁻¹ OJ and 150 mg L⁻¹ AsA] obtained from different sources were applied as a foliar spray to control and water-stressed plants. Drought stress prominently reduced plant growth and yield attributes of the okra cultivars. Water-deficit conditions (65% and 50% F.C.) substantially decreased the fruit chlorophyll (a, b) pigments and the activity of superoxide dismutase (SOD) enzyme, while an increase was observed in the contents of fruit’s hydrogen peroxide (H2O2), malondialdehyde (MDA), total phenolics, total soluble sugars, AsA, and total soluble proteins. Drought stress also increased the activities of antioxidant enzymes like peroxidase (POD) and catalase (CAT). However, plant growth and yield attributes, fruit chlorophyll pigments, total phenolics, total soluble sugars, total free amino acids, total soluble proteins, AsA, GB, H2O2, and the activities of antioxidant enzymes (POD and CAT) were increased by the AsA exogenous treatment in both okra cultivars under water deficit and control conditions. Overall, LJ and OJ were more effective than the synthetic AsA in upregulating the physiological and metabolic processes of okra plants. So, cost-effective as well as multi-nutrient natural sources of AsA could be suggested for alleviating the harmful effects of water deficit stress on plants.
... Once water stress increased to 50% (FC50), the FC50 treatment obtained the highest values in total chlorophyll. The results obtained are similar to those reported by [24], who indicate that a simulated mild stress had no effect on the chlorophyll content in spinach. Other authors mention that in sage plants (Salvia officinalis L.) with drought stress induction treated with algae extracts, the concentration of chlorophyll increased [25]. ...
Water stress is one of the main factors affecting the development of agricultural crops. An inno-vative alternative to improve tolerance to water stress is the application of biostimulants. In the present study, the efficacy and physiological and biochemical responses of different biostimulants were evaluated in beans under moderate and severe stress. The treatments consisted of three types of irrigation: FC100, without water stress, FC75, irrigation reduced by 25% (moderate water stress) and FC50, irrigation reduced by 50% (severe water stress). In the treatments with water deficit, foliar biostimulants were applied: zinc oxide nanoparticles plus chitosan, Codasil®, Osmoplant®, Stimplex® and salicylic acid. Foliar application of ZnO + chitosan nanoparticles benefited biomass accumulation and yield under moderate water stress (FC75) and Codasil® and Osmoplant® under severe water stress (FC50). Proline, free sugars and gas exchange were higher under the application of ZnO + chitosan nanoparticles under moderate water stress and under Codasil® and Osmoplant® under severe water stress. Depending on the severity of water stress, ZnO + chitosan nanoparticles, Codasil® and Osmoplant® are viable products to increase tolerance in green bean cv. Strike plants.
... The increase in yield in these cases was in range of 8-25% over control. Similarly, biostimulants obtained from A. nodosum have on a number of horticultural crops such as strawberries [60], carrots [2], spinach [111], cabbage [110], tomato [24]. Various quality parameters such as antioxidant content of the produce, the fiber and carbohydrate, and nutrient contents were enhanced due to application of seaweed biostimulants. ...
Chapter 9
Adoption of Climate Smart Agriculture (CSA) Technologies in Sri Lanka: Scope, Present Status, Problems, Prospects, Policy Issues, and Strategies
... Seaweed extracts contain a variety of nutrients like P, Ca, Mg, and Fe, secondary metabolites, and other biochemicals that have beneficial effects on plants, including yield enhancement (Rouphael & Colla, 2020). Seaweed extract attenuating the adverse effects of drought, cold, and salinity was found to be mediated by the accumulation of non-structured carbohydrates that enhance energy storage, metabolism, and water regulation, as well as proline accumulation (Dalal et al., 2019;Xu & Leskovar, 2015). ...
Drought has a deleterious impact on the growth, physiology, and yield of various plants, including soybean. Seaweed extracts are rich in various bioactive compounds, including antioxidants, and can be used as biostimulants for improving yield and alleviating the adverse effect of drought stress. The purpose of this study was to evaluate the effect of soybean growth and yield with different concentrations (0.0%, 5.0%, and 10.0% v/v) of water extracts of the red seaweed Gracilaria tenuistipitata var. liui under well-watered (80% of field capacity (FC) and drought (40% of FC)) conditions. Drought stress decreased soybean grain yield by 45.58% compared to well-watered circumstances but increased the water saturation deficit by 37.87%. It also decreased leaf water, chlorophyll content, plant height, and the fresh weight of the leaf, stem, and petiole. Drought stress decreased soybean grain yield by 45.58% compared to well-watered circumstances but increased the water saturation deficit by 37.87%. It also decreased leaf water, chlorophyll content, plant height, and the fresh weight of the leaf, stem, and petiole. Under both drought and well-watered situations, foliar application of seaweed extracts dramatically improved soybean growth and production. Under drought and well-watered situations, 10.0% seaweed extract increased grain yield by 54.87% and 23.97%, respectively in comparison to untreated plants. The results of this study suggest that red seaweed extracts from Gracilaria tenuistipitata var. liui may be used as a biostimulant to improve soybean yield and drought tolerance in the presence of insufficient water. However, the actual mechanisms behind these improvements need to be further investigated in field conditions.
... Seaweed extracts contain a variety of nutrients like P, Ca, Mg, and Fe, secondary metabolites, and other biochemicals that have beneficial effects on plants, including yield enhancement (Rouphael & Colla, 2020). Seaweed extract attenuating the adverse effects of drought, cold, and salinity was found to be mediated by the accumulation of non-structured carbohydrates that enhance energy storage, metabolism, and water regulation, as well as proline accumulation (Dalal et al., 2019;Xu & Leskovar, 2015). ...
... Burchett et al. [176] observed that using AnE increased barley's winter toughness and cold tolerance. It was reported that AnE improved the leaf water relations, maintained the cell turgor pressure, and enhanced the growth of spinach by reducing stomatal limitations under drought stress conditions [145]. The expression of glutathione-S transferase was elicited by bioactive substances of AnE, resulting in the reduction of salinity-induced oxidative damage in A. thaliana [177]. ...
Algae are existing macroscopic materials with substantial benefits, including as important growth regulators and macronutrients and micronutrients for the growth of healthy crop plants. Biofertilizers obtained from algae are identified as novel production fertilizers or innovative biofertil-izers without the detrimental impacts of chemicals. Seaweeds contain many water-soluble minerals and nutrients that plants can easily absorb and that are valuable for crop plants' growth. At present, Ascophyllum nodosum (L.) Le Jolis extract outperforms chemical fertilizers in terms of increasing seed germination, plant development, and yield, as well as protecting plants from severe biotic and abiotic stresses. A. nodosum contains bioactive compounds that exhibit an array of biological activities such as antibiotic, anti-microbial, antioxidant, anti-cancer, anti-obesity, and anti-diabetic activities. A. nodosum extract (AnE) contains alginic acid and poly-uronides that improve soil's water-carrying ability, morsel structure, aeration, and capillary action, stimulating root systems in plants, increasing microbial activity in soil, and improving mineral absorption and availability. The scientific literature has comprehensively reviewed these factors, providing information about the different functions of A. nodosum in plant growth, yield, and quality, the alleviation of biotic and abiotic stresses in plants, and their effects on the interactions of plant root systems and microbes. The application of AnE significantly improved the germination rate, increased the growth of lateral roots, enhanced water and nutrient use efficiencies, increased antioxidant activity, increased phenolic and flavonoid contents, increased chlorophyll and nutrient contents, alleviated the effects of abiotic and biotic stresses in different crop plants, and even improved the postharvest quality of different fruits.
... Then, roots and shoots were separated, dried, and weighted. To measure changes in leaf relative water [29]. The relative water content was determined from the following Eq. ...
Salinity, a severe worldwide issue, compromises the economic production of medicinal plants including mints and causes drug-yield decline. γ-Aminobutyric acid (GABA) is a tolerance-inducing signaling bio-molecule in various plant physiological processes. Pineapple mint (Mentha suaveolens Ehrh.) is a valuable medicinal herb with an exhilarating scent of citrus fruit. Piperitenone oxide is the major bioactive constituent of its essential oil, having significant demand by pharmaceutical industries. Nonetheless, modeling and optimizing the effective concentration of GABA remain within twin foci of interest. Therefore, a two factor-five level (NaCl 0-150 mM and GABA 0-2.4 mM) central composite designe was conducted to model and optimize drug yield and physiological responses of M. suaveolens. Based on the design of experiments (DoE) approach, different linear, quadratic, cubic, and quartic models were assigned to the response variables. Change trends of shoot and root dry weights followed a simple linear model, whereas sophisticated models (i.e., multiple polynomial regression) were fitted to the other traits. NaCl stress inevitably reduced root and shoot dry weight, piperitenone oxide content, relative water content, pigments content, and maximum quantum yield of PSII. However, content of malondialdehyde (MDA) content,and total flavonoid content, and DPPH radical scavenging activity were enhancedincreased under salinity. Under severe NaCl stress (150 mM), the essential oil content (0.53%) was increased three times in comparison with control (0.18%). Optimization analysis demonstrated that the highest amount of essential oil (0.6%) and piperitenone oxide (81%) as a drug yield-determining component would be achievable by application of 0.1–0.2 mM GABA under 100 mM NaCl. The highest dry weight of root and shoot is was predicted to be achieved at 2.4 mM GABA. Overall, extremely severe NaCl stress (i.e., more than 100 mM) in which a sharp drop in yield components value was observed seemed to be out of M. suaveolens salinity tolerance range. Hence, it will beis rationale to compensate diminishment the decrease of drug yield components by foliar application of a dilute GABA solution (i.e., 0.1–0.2 mM) under 100 mM NaCl stress or lower levels.
... A study using A. nodosum extract in spinach showed enhanced biomass, protein content, chlorophyll and carotenoid content, flavonoids and antioxidant activity. The increase in biomass is associated with an increase in the expression of the Glutamine synthetase 1 (GS1) which is involved in nitrogen integration (Xu and Leskovar 2015). The increased expression of glutathione reductase (GR), and choline monooxygenase (CMO) was linked to increase in chlorophyll content. ...
Agriculture sector is facing a lot of constraints such as climate change, increasing population and the use of chemicals, and fertilizers which have significant influence on sustainability. The excessive usage of chemical fertilizers and pesticides has created a significant risk to humans, animals, plants, and the environment. To reduce the dependency on chemical fertilizers and pesticides a biological-based alternative is required. Seaweeds are essential marine resources that contain bioactive compounds and they have several uses in agriculture. The use of seaweed extracts in agriculture can mitigate stress, enhance nutrient efficiency, and boost plant growth. The use of seaweed extracts and their components activate several signaling pathways and defense-related genes/enzymes. In this review, an attempt has been made to explain how seaweed extracts and their bioactive components induce tolerance and promote growth under stress conditions.
... The application of these ANE formulations to the salt affected Solanum lycopersicum decreased the water potential and enhanced the water movement throughout the plants (Di Stasio et al., 2018). The ANE application to the drought affected Spinacia oleracea improved water relations (indicated by increased RWC) and also helped to maintain cell turgor pressure, thereby enhanced plant growth (Xu and Leskovar, 2015). Yildiztekin et al. (2018) also found that the Pro content was reduced with the ANE in the salt stressed C. annuum plants and showed better tolerance to salt stress. ...
Ascophyllum nodosum extract (ANE) is considered as an effective source of biostimulants that have the potential of ameliorating the negative impact of different abiotic stresses in plants. Considering the growth-promoting ability and other regulatory roles of ANE, the present investigation was executed to evaluate the role of ANE in conferring arsenic (As) tolerance in rice (Oryza sativa L. cv. BRRI dhan89). Rice seedlings (35-D-old) were exposed to two doses of sodium arsenate (As 1 − 50 mg As kg-1 soil; As 2 − 100 mg As kg-1 soil) at 25 days after transplanting through irrigation, whereas only water was applied to the control. Foliar application of 0.1% ANE was also supplemented under control as well as As-stressed conditions at 7 days intervals for 5 times. Arsenic-induced oxidative stress was evident through a sharp increase in lipid peroxidation, hydrogen peroxide, meth-ylglyoxal, and electrolyte leakage in the As-treated plants. As a consequence, plant growth and biomass, leaf relative water content, as well as yield attributes were reduced noticeably. On the other hand, ANE supplemented plants accumulated enhanced levels of ascorbate and glutathione, their redox balance, and the activities of antioxidant and glyoxalase enzymes viz. ascorbate peroxidase, monodehydroascorbate reductase, dehy-droascorbate reductase, glutathione reductase, catalase, glutathione peroxidase, and activities of glyoxalase I and glyoxalase II, respectively. Furthermore, relative water content, plant growth, yield attributes and yield were increased in the As-treated rice plants with ANE supplementation. The results reflected that foliar spray with ANE alleviated As-induced oxidative stress in rice plants by modulating the antioxidative defense and glyoxalase system.
... The increase in yield in these cases was in range of 8-25% over control. Similarly, biostimulants obtained from A. nodosum have on a number of horticultural crops such as strawberries [60], carrots [2], spinach [111], cabbage [110], tomato [24]. Various quality parameters such as antioxidant content of the produce, the fiber and carbohydrate, and nutrient contents were enhanced due to application of seaweed biostimulants. ...
... The increase in yield in these cases was in range of 8-25% over control. Similarly, biostimulants obtained from A. nodosum have on a number of horticultural crops such as strawberries [60], carrots [2], spinach [111], cabbage [110], tomato [24]. Various quality parameters such as antioxidant content of the produce, the fiber and carbohydrate, and nutrient contents were enhanced due to application of seaweed biostimulants. ...
NIL
... The increase in yield in these cases was in range of 8-25% over control. Similarly, biostimulants obtained from A. nodosum have on a number of horticultural crops such as strawberries [60], carrots [2], spinach [111], cabbage [110], tomato [24]. Various quality parameters such as antioxidant content of the produce, the fiber and carbohydrate, and nutrient contents were enhanced due to application of seaweed biostimulants. ...
... The increase in yield in these cases was in range of 8-25% over control. Similarly, biostimulants obtained from A. nodosum have on a number of horticultural crops such as strawberries [60], carrots [2], spinach [111], cabbage [110], tomato [24]. Various quality parameters such as antioxidant content of the produce, the fiber and carbohydrate, and nutrient contents were enhanced due to application of seaweed biostimulants. ...
Seaweeds are important component in the marine ecosystem. In the global scenario, about 221 species are having commercial utility but only 10 species are being commercially cultivated and has a market value of 11.7 billion US$. Among the 10 species, Eucheuma sp. (35%), Laminaria japonica (27%), Gracilaria sp. (13%), Undaria pinnadifida (8%), Kappaphycus alvarezii (6%), and Porphyra sp. (4%), have a major share in global seaweed biomass production. Seaweeds are the only resources for commercially important phycocolloids such as agar, carrageenan, and alginic acid production. In 2015, seaweed’s phycocolloids production was 93,035 tons wt and had a market value of 1058 million US$. Hectare level cultivation of K. alvarezii (carrageenan yielding seaweeds) can sequester 643.80 tons CO2/ha/yr, whereas Gracilaria edulis and Gracilaria debilis (agar yielding seaweeds) can sequester 10.71 tons CO2/ha/yr. Seaweeds are an excellent biosorbent for the removal of heavy metal ions. Seaweed biochar, an effective adsorbent for wastewater treatment systems. For bioremediation of eutrophicated water, green seaweeds Ulva sp., Cladophora coelothrix, and Cladophora parriaudii; red seaweeds Porphyra sp. and Gracilaria sp. are used. Seaweed has high protein content as it is being used by many of the countries like Japan, China, Korea, Malaysia, Thailand, Indonesia, Philippines, and other South East Asia. Seaweeds like Ulva sp., Enteromorpha sp., Caulerpa sp., Codium sp., Monostroma sp., Sargassum sp., Hydroclathrus sp., Laminaria sp., Undaria sp., Macrocystis sp., Porphyra sp., Gracilaria sp., Eucheuma sp., Laurencia sp., and Acanthophora sp. are used in the preparation of soup, salad and curry, salad vegetable or as garnish material for fish. Ascophyllum, Ecklonia, and Fucus are the general species sold as soil additives and functioned as both fertilizer and soil conditioner. Red seaweeds K. alvarezii, G. edulis, a green seaweed Caulerpa spp. Ulva spp., etc., have been commercially exploited for biostimulant production and increase in crop yield was found in the range of 8–25% over control.
... The positive effect on spinach leaves growth under stress after foliar and /or drench application of an Ascophyllum nodosum extract at 0.5% concentration was attributed to the improvement of leaf water relations. However, SE application did not alter chlorophyll content and fluorescence Fv/Fm of spinach plants under full irrigation and drought stress regimes (Xu et al. 2015). This was similar to the present study where the application of different SE had no effect on leaves chlorophyll index, Fv/Fm, PI abs, and NDVI during the WWP and RP. ...
Prolonged drought periods cause a cascade of biochemical alterations in plants and lead to reduction in plant growth and crop productivity. Seaweed extracts are a category of plant biostimulants that are effective in alleviating drought stress on plants. However, the effect of seaweed extracts on attenuating the negative impact of drought on Faba bean (Vicia faba L.) under arid and semi-arid conditions has received little attention. This study was conducted to evaluate the performances of extracts made from Fucus spiralis (FSE), Ulva lactuca (ULE), Laminaria ochroleuca (LOE), and Ascophyllum nodosum (ANE) in mitigating drought stress in Faba bean. The biochemical profile of the extracts was characterized, and key physiological and biochemical parameters of Faba bean plants were assessed during both drought and recovery phases. All investigated extracts positively affected plant biomass under drought stress conditions. Plants that received LOE had a higher relative water content and lower malondialdehyde concentration in comparison with stressed control plants. The positive effect of ANE and FSE was mainly attributed to proline accumulation in plant tissues under stress. FSE and ULE application resulted in a higher concentration of soluble sugars in treated plants in comparison to the control plants. It was concluded that seaweed extracts originating from different sources and extracted using different protocols act differentially in altering plant-related stress traits. Overall, seaweed extracts are potentially an effective solution to manage the negative impact of water scarcity on Faba bean.
... Moreover, global arable land is decreasing due to urbanization, degradation and climate change [1]. To address such challenges, several biotechnological approaches have been tried in recent years, namely the use of biostimulants to optimize the productivity of crop plants [2][3][4][5][6]. Biostimulants can be defined as products that do not contain nutrients and have a beneficial effect on plant growth. ...
By 2050, the world’s population will reach about 10 billion people, which will the need for food by about 60% more than is available today. To meet this need, new processes are emerging to allow more efficient and sustainable intensification of agriculture. In this context, the use of biostimulants has received increasing attention, due to their ability to improve plant quality and yield, stress tolerance, and/or improve the availability of nutrients in the soil. When it comes to Cyanobacteria, the preferred ones are N2-fixing species, which increase organic nitrogen in the soil, and produce hygroscopic exopolysaccharides, which alter the distribution of water by reducing soil hydrophobicity. Therefore, they decrease soil evaporation and retain moisture, improving soil stability. Wild strains of filamentous N2 fixing Nostoc 135, Nostoc 136, Nostoc 137, and Anabaena 4, provided by Alga2O Lda., were grown in the laboratory with the aim of selecting those that presented the necessary physiological characteristics to be efficiently grown in the laboratory. Therefore, the growth rate, productivity, and exopolysaccharides (EPS) contents were analysed. The EPS obtained from each strain culture (3% g/L) was applied to lettuce seeds (Lactuca sativa), to determine the germination rate, primary root length and number of primary leaves produced. As confirmed by other authors, Cyanobacteria are interesting biostimulants regarding germination rates. Other effects to be tested in the future are heat and drought tolerance, water, nutrients, essential oil, and pigment content, all of which are positive aspects that have been previously reported for other Nostoc and Anabaena species.KeywordsAnabaena sp.Nostoc sp.Growth rateExopolysaccharidesBiostimulant
Lactuca sativa
Germination rateLongest root length
Climate change driven by uncertain weather events is increasing in the 21st century. Agriculture is a major source of
food, income and nutritional security for the majority of people. However, due to the acceleration of climate change,
crops are experiencing a severe impact from abiotic stresses. Agricultural production around the world has increased
in the past few decades. However, it faces serious challenges due to climate change-induced abiotic stresses. These
challenges include extreme temperatures, water stress (excess or deficit), and issues with edaphic stresses such as
poor soil fertility, salinity and alkalinity. In the recent past, aberrant weather patterns, such as heavy rainfall in a short
time and sudden increases in temperature changes in winter, caused big losses to crop productivity across the globe,
thereby affecting plant’s growth, their metabolism, and ultimately the yield. Additionally, socio-economic dimensions
like having small landholders, market linkage, poor infrastructure, market price volatility and literacy make these
issues more complex. Several abiotic stress adaptation, mitigation and management strategies have been developed
to address these challenges such as climate-resilient varieties, improved cultural practices, precision irrigation,
biostimulants and protected agriculture.
The interactions between microbes and plants are a crucial component of our terrestrial environment. The most intriguing from the perspective of microbial ecology, however, are particular interactions created by pathogenic and plant-beneficial microorganisms (either nonsymbiotic or symbiotic). Microorganisms such as endophytes, plant growth-promoting rhizobacteria (PGPR), and arbuscular mycorrhizal fungi (AMF) are examples that are pivotal in reducing abiotic stresses and subsequently enhancing plant development. Complex processes in the plant cellular system are modulated as a result of the interaction between the plant and the microbe. The local microbial flora is an essential part of plants' natural defenses since it also inhibits phytopathogens. Understanding the function of the plant microbiome in the delivery of nutrients is significant for maintaining sustainable production in view of the growing environmental concerns. It is also necessary to identify the elements that enable plants to draw beneficial microbial species and the defense mechanisms against potential diseases. The literature study also shows that beneficial microorganisms, like PGPRs, AMFs, and endophytes, use a variety of ways to minimize the negative consequences of diverse pressures. The goal of this chapter is to encourage and gather current research on the variety and ecology of plant-associated microbiomes, as well as on the genetic and metabolic interactions between microbes and plants. We present a conceptual framework that demonstrates the importance of interactions between microbiota members for the creation and upkeep of host-microbial homeostasis. Applications of microbe-plant relationships are widespread. In this chapter, we show new reports of applications in the fields of remediation, carbon sequestration, biocontrol, production of bioactive compounds and biomaterials, and plant growth promotion. Each field's difficulties, restrictions, and prospects for the future are addressed.
This factorial experiment was conducted in a greenhouse during the period of May 3, 2021 to August 5, 2021 at the research farm belongs to the Horticulture Department, College of Agricultural Engineering Sciences, University of Sulaimani, Sulaimani, Iraq. The experiment was designed to study the effect of some biostimulants, individually and their combinations, on cucumber plants performance under greenhouse conditions; in addition to compare the results with 100% of chemical fertilizers application. The treatments consisted of control (without adding any kinds of biostimulants) recommended dose of 100% chemical fertilizers (RDCF), seaweed extracts (SE), moringa leaf extract (MLE), bacterial-based biostimulant of Fulzym-plus (FP), that contains Bacillus subtilis and Pseudomonas putida, (SE+MLE), (SE+FP), (MLE+FP), and (SE+MLE+FP). The experiment was laid out in simple-RCBD with 3 replications. The results showed that the application of different biostimulants, individually and their combinations, significantly improved the root growth characteristics at P≤ 0.05. However, the highest values of lateral roots number per plant, lateral root length, lateral root diameter and root system dry weight were recorded by the application of recommended dose of chemical fertilizer (RDCF). While, this treatment was not different substantially with the triple combination of the tested biostimulants (SE+FP+MLE) in all studied root characteristics. In addition, untreated plants registered the minimum value of all the mentioned characters. In addition, majority of the biostimulant treatments showed positive effective on the vegetative growth characteristics compared to untreated plants, but the triple combination between them (SE+MLE+FP) was more affective. Even though the chemical fertilization treatment (RDCF) recorded the longest plant shoot, highest number of nodes per plant, thickest stem, maximum plant leaf area, highest percentage of leaf dry matter and highest intensity of chlorophyll pigment in the leaves. At the same time, this treatment was not various markedly with the co-application of the biostimulants (SE+MLE+FP) in all mentioned traits related to the vegetative growth. Also, control plants recorded minimum values for all vegetative measurements. Furthermore, applying the biostimulants, individually and their combinations, had a substantial impact on improving the concentration of macronutrients (N, P and K) and micronutrients (Fe and Zn) if compared to control, with exception to the individual effect of (MLE) and (FP) on Fe concentration as well as dual application between (SE+FP) on Zn concentration. Despite the recommended dose of chemical fertilizer (RDCF) resulted in the highest concentration of N, P and Fe; and applying bacterial-based biostimulant of FP obtained the highest concentration of K and Zn. While, these treatments were not different statistically with the treatment of (SE+FP+MLE) in all measured nutrients. The control treatment recorded the minimum concentration of all the measured nutrients. Additionally, our results revealed that the application of biostimulant treatments had a significant impact on improving some reproductive growth and plant yield characteristics of cucumber plants if compared to untreated plants. Though the application of (RDCF) observed the minimum number of aborted flowers per plant, highest fruit set percentage, maximum number of fruits per plant and consequently highest plant yield; as well as applying the (SE) resulted in the highest fruit weight. While, these treatments were not differed substantially with the triple combination of the biostimulants (SE+FP+MLE) in all studied characteristics related to the reproductive growth and yield components. On the other hand, untreated plants recorded the maximum number of aborted flowers per plant; minimum fruit set percentage, lowest fruit number per plant and plant yield. Regarding the quality characteristics, the longest fruit was recorded by the application of (SE+MLE+FP). However, it was not different substantially from (RDCF), (SE) and (MLE+FP). In addition, the maximum fruit diameter was obtained by the applications of (RDCF), (SE+FP) and (SE+MLE+FP), However, they did not differ significantly from the other bistimulant treatments. On the other side, untreated plants produced the shortest fruits and smallest fruits diameter. All the cucumber plants that treated with the biostimulants did not differ significantly with (RDCF) in fruit dry matter %. Additionally, all the biostimulant treatments, except the (SE+MLE), were markedly increased this trait as compared to control. Concerning the fruit non-enzymatic antioxidants content, the application of SE recorded the highest content of total phenolic content (TPC), and it was significantly superior over the other treatments. Furthermore, the highest content of total flavonoid content (TFC) was found by the applying of (SE+MLE+FP); which it was significantly superior over
Various strategies are needed to reduce the negative impacts of drought stress on plant productivity. A study was conducted to investigate the effects of using seaweed extract (SE) and phosphate-solubilizing bacteria (PSB) biofertilizers, either alone or in combination, on the morphophysiological and biochemical traits, as well as the essential oil content of Calendula officinalis under drought stress. The study used a randomized complete block design with three replications, and each replication included five plants. It was designed as a factorial experiment. The treatments included 1 % SE, 4 % PSB, and the combination of both (CB) under three levels of drought stress, which were 100, 70 and 40 % of the field capacity. The study found that the CB treatment at 40 % of field capacity resulted in the highest increase in relative water content (39.80 %), chlorophyll a (45.19 %), chlorophyll b (46.62 %), total chlorophyll (45.49 %), flavonoids (13.33 %), flavonols (4.35 %), proline (6.87 %), catalase (127.27 %), and ascorbate peroxidase enzyme activity (37.93 %) when compared with the control group. The CB treatment at 100 and 70 % field capacity showed the highest improvement in essential oil content, with an increase of 118.18 and 116.25 %, respectively, compared to the control. All treatments resulted in significant differences in carotenoid, anthocyanin, lignin, and soluble protein content. However, the CB treatment at 100 % field capacity showed the highest distinction, achieving 71.83, 159.23, 223.63 and 200.13 % promotion, respectively, compared to the control. Although morpho-physiological and biochemical traits and essential oil content were decreased with increasing drought severity, using CB biofertilizer mitigated the adverse effects of drought stress and proved to be the most effective strategy for the sustainable agriculture of C. officinalis.
Never has the reality of climate change and its ramifications been so obvious around the world. Humankind is currently living in times when the reality of global climate change is unequivocal. The recent Intergovernmental Panel on Climate Change AR6 report further depicts the veracity of climate change by highlighting historically changing patterns of precipitation and temperature across the world, amidst heightened and varied levels of vulnerability around the world. This book is planned along the increasingly complex and daunting nature of climate change. The broad scope is intentional and aims at eliciting scholarship from across the globe and from varied areas of climate change research. Thus, as varied and broad as the intentions are, so too are the book’s contents. The thirteen peer-reviewed chapters are organized into four sections. Section 1 introduces the concept of climate change and other global perspectives and trends. Section 2 focuses on climate risk, resilience, and vulnerability. Section 3 explores varied perspectives on climate risks, sensitivity, and exposure with a focus on monitoring and assessment. Finally, Section 4 explores climate change adaptation and mitigation. The multidisciplinary nature of this book will appeal to a varied readership including governments, municipal authorities, and daily grassroots users of environmental resources.
Water scarcity has widely affected agricultural production and food security, particularly in arid regions. There is little information available on the concurrent effects of water stress and organic amendment application on the water holding capacity of soil as well as the growth and yield responses of quinoa as a drought-resistant plant. In addition, there are limited reports on the optimum levels of deficit irrigation as a promising strategy for enhancing the water use efficiency and production of quinoa plant. Therefore, the aim of this study is to investigate the moisture holding capacity of soil as well as the morphological and physiological responses of quinoa to the interactive effects of drought and organic amendment under field conditions. Three levels of water stress (full-irrigation, moderate drought, and severe drought) and four treatments of organic amendment including control (without the use of organic matter), vermicompost (20 t ha−1), biochar (20 t ha−1), and the composition of vermicompost and biochar (at an equal rate of 10 t ha−1 each) were applied as the subsidiary factor. Result indicated that severe drought reduced the plant yield significantly (21.7%) as compared to control, whereas moderate drought showed no significant effect. Drought increased the proline content, whereas reduced all other traits including crop growth rate, 1000-seeds weight, bush height, panicle length, leaf area index, chlorophyll, proline, carotenoids, protein, and relative water content. However, the application of biochar, vermicompost, and Bvrm relative to the control treatment increased WUE by 12.3, 36.8, and 45.6%, soil moisture content by 2.0, 20.1 and 28.9%, and the quinoa yield by 1.0, 21.9, and 28.6%, respectively. There was an inverse relationship between water use efficiency and the grain yield of quinoa. The simultaneous effect of drought and biofertilizer on the quinoa grain yield (Y) was demonstrated based on soil moisture content (θ) using a linear relationship (Y = 168.5(θ) − 4.74; R2 = 0.994, p < 0.01). The results also indicated that WUE was reduced linearly with increasing soil moisture content. Among different relationships, logarithmic function exhibited the best performance for predicting the yield of quinoa based on the amount of irrigation water. The findings of this study revealed the important role of soil moisture as a manageable characteristic in facing environmental stresses such as drought and achieving the sustainability of crop production.
Green synthesis of NPs is preferred due to its eco-friendly procedures and non-toxic end products. However, unintentional release of NPs can lead to environmental pollution affecting living organisms including plants. NPs accumulation in soil can affect the agricultural sustainability and crop production. In this context, we report the morphological and biochemical response of spinach nanoprimed with MgO–NPs at concentrations, 10, 50, 100, and 150 µg/ml. Nanopriming reduced the spinach root length by 14–26%, as a result a reduction of 20–74% in the length of spinach shoots was observed. The decreased spinach shoot length inhibited the chlorophyll accumulation by 21–55%, thus reducing the accumulation of carbohydrates and yield by 46 and 49%, respectively. The reduced utilization of the total absorbed light further enhanced ROS generation and oxidative stress by 32%, thus significantly altering their antioxidant system. Additionally, a significant variation in the accumulation of flavonoid pathway downstream metabolites myricitin, rutin, kaempferol-3 glycoside, and quercitin was also revealed on MgO-NPs nanopriming. Additionally, NPs enhanced the protein levels of spinach probably as an osmoprotectant to regulate the oxidative stress. However, increased protein precipitable tannins and enhanced oxidative stress reduced the protein digestibility and solubility. Overall, MgO-NPs mediated oxidative stress negatively affected the growth, development, and yield of spinach in fields in a concentration dependent manner.
Deciphering phytomicrobiomes for sustainable crop production: recent findings and future perspectives
Agriculture is the science of growing crops and rearing animals for sustainable food production and enhanced livelihood. Crops growing under favourable conditions often go through different environmental stresses which can be biotic or abiotic. Plants synthesise protective compounds as a response to the abiotic stresses such as salt, temperature, drought and mineral regulation. These compounds are usually produced within the plant metabolic pathways. In modern agriculture, agronomists are focusing on the development of biological functional compounds or biostimulants which can contribute to the enhancement of plant abiotic stress tolerance and productivity in adverse environmental conditions. Biostimulant also regulates the nutritional quality of the crops making them fit to consume. Biostimulants ensure little or no use of chemical fertilisers. Although some of the biostimulant applications are widely practised by the farmers, some modern technologies, such as the use of microbial biostimulant, are still unknown to many. Therefore, in this chapter, we aim to give an overview of recent advances in the research related to the theory and practice of biostimulants which will impart knowledge among the young researchers, agricultural industries, farmers and business collaborators for better understanding of the molecular processes and implementation of biostimulants in growing different crops.
Integrating plant bio-stimulants to promote low external input and sustainable agriculture (LEISA)-based agricultural systems in abiotic-challenged situations appears to be a realistic alternative, especially for resource poor farmers. Bio-stimulants improve nutrient uptake, nutrient use efficiency of fertilizers and impart stress tolerance through regulation of physiological processes, plant-water relations and induction of antioxidant defence mechanism. The present review describes concept of plant bio-stimulants, its broad classifications, underlying mechanism associated to improve abiotic stress tolerance and method of its application including crop stages. The regulatory status of bio-stimulants with special emphasis on India and complying with regulations governing its application, highlights of research case studies conducted in both controlled and field conditions in agricultural and horticultural crops are also reported.
Owing to the increased global warming, drought severity has increased in many regions, threatening food security, especially in arid and semi-arid areas. Therefore, it is imperative to mitigate the impact of drought on plants in water-stressed areas. The utilization of plant-growth-promoting rhizobacteria (PGPRs) serves as an environmentally friendly approach to enhance the resilience of plants exposed to abiotic stress, specifically drought. This research focuses on examining the effects of 35 PGPR isolates, possessing significant ACC (1-aminocyclopropane-1-carboxylic acid) deaminase activity, which were obtained from diverse plant-rhizosphere soil samples encompassing approximately 17,000 km2 of semi-arid regions. The investigation was conducted on watermelon plants experiencing varying degrees of water stress (30% and 60% water stress). An increase in water stress exerted a detrimental effect on agro-morphological parameters, such as biomass (root + shoot), leaf number, and leaf area of non-inoculated plants. PGPRs stimulated plant growth and increased water use efficiency, especially under severe water-stress (60% water stress) conditions compared to non inoculated plants (control). Furthermore, some PGPRs such as B7, B22, B26 and B28 supported carotenoid synthesis, which plays an important role in photosynthesis, whereas some alleviated the effect of water stress in watermelon plants by stimulating the antioxidant defense system. The outcomes of principal component, where the data were collectively assessed, demonstrated the superior efficacy of certain PGPRs. Specifically, under water-stress conditions, PGPR isolates B31, B32, and B35 exhibited significant growth-promoting effects on watermelon. Additionally, isolates B13 and B15 demonstrated the activation of antioxidant defense mechanisms, including proline, catalase, and peroxidase. PGPRs showed considerable results on the agro-morphological, physiological, and biochemical properties of watermelon under 60% water-stress conditions compared with those under 30% water stress. In conclusion, PGPRs promoted growth and alleviated severe water stress in watermelon plants compared to their control. The results of this study elucidate PGPR-triggered response mechanisms in water-stressed watermelon plants.
Climate change is resultant from modern-day chemical agriculture, which is creating negative impacts on crop production. Global agriculture is now facing various problems arising due to abiotic stresses such as flood, drought, temperature extremes, light extremes, salinity, heavy metal stress, nutrient toxicity/deficiency. These stresses not only hamper the growth and production but also reduce the quality of crops through morphological, physiological, biochemical changes and synthesis of ROS. Further, they negatively impact on entire environment specially soil health. Deterioration of yield and quality often occurs due to lack of essential inputs to plants under abiotic stresses. Although plants adopt defensive mechanisms, such abiotic stresses need to be addressed properly with various eco-friendly organic farming approaches. Different organic inputs like organic manures, biofertilizers, bio-priming with micro-organisms, bio-stimulants (seaweed extracts, humic acid, micro-organisms, etc.), mulches, biochar are known to alleviate abiotic stresses under climate change scenario. Further, various organic agronomic practices viz. crop rotation, intercropping, tillage, sowing methods and time, nutrient, water and intercultural operations, use of PGPB, organic formulations, grafting, selection of resistant/tolerant varieties and other scientific/wise uses of organic inputs can mitigate/escape the negative impacts of abiotic stresses resulting in upliftment in crop production as well as the quality of produce.
In this study, five registered cultivars and seven lines of safflower (Carthamus tinctorius L.) for drought stress tolerance with recovery capacities were examined during moderate (5 days) and severe (7 days) drought and following re-irrigation periods (5 days) using polyphasic chlorophyll α fluorescence kinetics and some physiological parameters. The drought stress induced decrease in leaf water potential, photosynthetic efficiency and pigment contents, and an increase in membrane damage in all genotypes. After re-watering periods, RB-05 and AD-L/14 genotypes were able to recover by overcoming these adverse effects due to drought. Twelve genotypes were classified according to pigment and membrane factor indexes, and drought and recovery factor indexes. Moreover, principal component analysis clearly showed the relationship between the treatment groups and revealed a clear homogeneity in the physiological status of plants. Additionally, drought tolerance levels of the selected genotypes were characterized in detail by chlorophyll α fluorescence kinetics and some JIP test parameters (efficiencies and quantum yields and specific energy flux parameters). Chlorophyll fluorescence data revealed drought and re-watering period changes as well as specific differences between tolerant and sensitive safflower genotypes. Evaluation of the results showed that sensitive genotypes (LN and AD-L/12) tried to overcome the negative effects caused by drought, while tolerant genotypes (RB-05 and AD-L/14) exhibited better photosynthetic performance and recovered with re-watering. As a result, RB and AD-L/14 could be recommended to be used as genetic material in breeding programs and grown in drought-prone areas.
Abiotic stresses, including salinity stress, affect numerous crops, causing yield reduction, and, as a result, important economic losses. Extracts from the brown alga Ascophyllum nodosum (ANE), and compounds secreted by the Pseudomonas protegens strain, CHA0, can mitigate these effects by inducing tolerance against salt stress. However, the influence of ANE on P. protegens CHA0 secretion, and the combined effects of these two biostimulants on plant growth, are not known. Fucoidan, alginate, and mannitol are abundant components of brown algae and of ANE. Reported here are the effects of a commercial formulation of ANE, fucoidan, alginate, and mannitol, on pea (Pisum sativum), and on the plant growth-promoting activity of P. protegens CHA0. In most situations, ANE and fucoidan increased indole-3-acetic acid (IAA) and siderophore production, phosphate solubilization, and hydrogen cyanide (HCN) production by P. protegens CHA0. Colonization of pea roots by P. protegens CHA0 was found to be increased mostly by ANE and fucoidan in normal conditions and under salt stress. Applications of P. protegens CHA0 combined with ANE, or with fucoidan, alginate, and mannitol, generally augmented root and shoot growth in normal and salinity stress conditions. Real-time quantitative PCR analyses of P. protegens revealed that, in many instances, ANE and fucoidan enhanced the expression of several genes involved in chemotaxis (cheW and WspR), pyoverdine production (pvdS), and HCN production (hcnA), but gene expression patterns overlapped only occasionally those of growth-promoting parameters. Overall, the increased colonization and the enhanced activities of P. protegens CHA0 in the presence of ANE and its components mitigated salinity stress in pea. Among treatments, ANE and fucoidan were found responsible for most of the increased activities of P. protegens CHA0 and the improved plant growth.
Drought has become an increasing problem in agriculture in recent years with fresh water becoming a scarce resource. One of the solutions to potentially alleviate detrimental effects of drought is the use of commercial seaweed-based biostimulants. The aim was to better understand their effects. Tomato plants (Solanum lycopersicum L.) were grown in soil under drought stress conditions with a 40% reduction in irrigation compared to control plants in 2020, and a 67% reduction in 2021. Plant responses to (i) drought stress, and (ii) a combination of drought stress and application of four selected seaweed biostimulants were continuously measured with sap flow and stem diameter variation sensors and compared to well-watered plants in each year. No differences were observed in overall yield and fruit size between treatments, indicating a potential water saving of at least 40% as confirmed by the sap flow measurements. Although no differences were observed in yield, some of the tested biostimulants did impact plant functioning. The Ascophyllum nodosum-based biostimulant resulted in water uptake during drought comparable to well-watered control plants, whilst the Saccharina latissimi-based biostimulant resulted in significantly lower water uptake than stressed control plants but with comparable yield as well-watered plants, increasing plant water-use efficiency. Therefore the recommendation is to use plant sensors for future objective quantification of water use and growth effects of featured biostimulants, and as part of the experiments to unravel modes of action of different biostimulants in crops.
This study presents foliar application effect of Kappaphycus alvarezii (5-15%) extract on yield and seed quality of green gram at flowering stage. Application of K. alvarezii (cone. 10.0%) significantly increased seed yield (30.11 %) compared to control, due to increase in yield of pods, weight of pods as well as seed yield per plant and 100 seed weight. This treatment also improved nutritional quality of seed as follows: protein, 19.43; carbohydrate, 5.17; P, 3.61; and Mo, 52.63%.
An experiment was carried out in the plastic house of Horticulture Department/college of Agriculture/ Duhok University on Cucumber plants during 2009 growing season to determine the effect of bread yeast and seaweed extracts Alga 600 and sea force 2 on growth, yield and its component on Cucumber C.V. shadi. The results showed that spraying bread yeast or seaweed extract resulted in positive significant difference in shoot characteristics and in all yield traits as compared to untreated treatment. The interaction between yeast and seaweed extract was significantly enhanced all detected traits. Since cucumber plant received 6 g.l-1 bread yeast and sprayed with a mixture of 0.33ml.l-1 Alga 600 +2.5 ml.l-1 Sea force 2 were characterized by the highest values of all shoot and yield characteristics.
Elucidation of the precise roles of seaweed extracts in agriculture has been restricted by a widespread 'one-size-fits-all' approach to extraction, development and functional validation. In this study, we classify extracts of seaweed on the basis of their extraction, biochemical and functional properties therein and demonstrate discrete roles for high and low temperature-derived extracts of Ascophyllum nodosum in enhancing plant growth and tolerance to abiotic and biotic stresses. In brief, the biochemical properties of extracts were characterised and their potential influence on plant growth and health was investigated. Higher antioxidant levels were observed for a high temperature (HT)-derived extract (Super Fifty®) compared with a low-temperature (LT)-derived extract (Ecolicitor®), with a 32-fold difference detected (FRAP assay), therefore suggesting benefits conferred by HT-derived extracts in abiotic stress situations. Analysis of growth in saline and non-saline conditions gave contrasting results. In non-saline conditions, no significant difference between treatments was observed. However, in conditions of high salinity, a 42.5% increase in lettuce weight on treatment with HT-derived extract was observed compared to 28.5% with (LT)-derived extract. In contrast, the effects of biotic stresses were reduced more by LT-derived extract than by HT-derived extract, with local and systemic reductions in Sclerotinia sclerotiorum and Alternaria brassicae lesion diameters achieved on treatment with LT-derived extract. In conclusion, this study demonstrates a significant level of specificity linked to extraction type and supports a 'fitness-for-purpose' approach to validation of seaweed extract properties and their specific applications in agriculture.
Plant growth and associated soil microbials were examined in several strawberry cultivars following treatment with extracts from the marine algae Ascophyllum nodosum [soluble Ascophyllum extract powder (SAEP)]. Greenhouse and field experiments were established over plots of Albion, Camarosa, Chandler, and Festival strawberries from 2009 to 2011. Soluble Ascophyllum extract powder was applied once or twice per week, or once per 2 wk at rates of 0 (control), 1, 2 or 4 g L-l over approximately 8 wk. Subsequent rooting studies examined weekly applications of SAEP at 0, 0.2, 0.4, 1 or 2 g L-1. Results indicate that maximum plant and berry productivities were found at 1 and 2 g SAEP L-1 in both field and greenhouse. Chandler was the cultivar most responsive to SAEP application, while Albion was the least responsive. Soluble Ascophyllum extract powder increased colony counts in greenhouse and field soil samples with maximum colony counts at 4 g L-1 SAEP in the greenhouse, and 1 and 2 g L-1 SAEP in the field. Metabolic activities of soil microbes were found to increase following SAEP applications. Using the Biolog microbial analysis system, maximum average well colour development (AWCD), substrate diversity (H), substrate evenness (E), and substrate richness (S) responses were found at 4 g L-1 SAEP in the greenhouse. However, in field trials, AWCD, H, E, and S responses to extract treatment showed successive increases at 1 and 2 g L-1 SAEP, but reduced effect at 4 g L-1. Soluble Ascophyllum extract powder treatment showed highest respiration rates between 0.10 and 0.40 g per week per plant while in vitro soil treatments with 4 g L-1 SAEP reduced microbial respiration. This study suggests that SAEP applications increased strawberry root and shoot growth, berry yield and rhizosphere microbial diversity and physiological activity.
Photosynthesis and drought adaptation in leaves of field grown rape (Brassica napus L. cv. Global) were investigated in 1992 under temperate climatic conditions in plants grown in lysimeters in a sand and in a loam soil. Light-saturated net photosynthesis (Amax), leaf conductance to water vapour (ge), leaf water potential (Ψe), leaf osmotic potential at full turgor (Ψπ100), specific leaf area (SLA), spectral reflection index (RI) used as a measure of leaf area, and leaf nitrogen content, were determined in irrigated plants and in plants exposed to soil drying.
In the early growth stages before flowering, Amax was 35-45 μmol m-2 s-1 and ge was 1-1.5 mol m-2 s-1. Maximum rates of CO2 assimilation greater than 30 μmol m-2 s-1 were obseved for up to 19 days. Stomata partly closed in ageing leaves maintaining a constant CI/Ca ratio. Both photosynthetic nitrogen use efficiency (NUE; Amax per unit of nitrogen) and photosynthetic water use efficiency (WUE; Amax/ge) were high compared with efficiencies of stems and husks and of other C3 plants. In bracts Amax and ge were 10-15 μmol m-2 s-1 and 0.2-0.7 mol mol m-2 s-1, respectively. Both Amax and ge varied linearly with leaf nitrogen content.
When soil water was depleted, both Ψπ100 and RI decreased relative to controls on both soil types before any significant decrease in Ψπ occurred. On loam with slow soil drying SLA, ge and Amax decreased before any significant decrease in Ψe occurred. We suggest that these responses might have been triggered by a non-hydraulic signal transmitted from the roots. When water was more depleted, rape maintained positive turgor down to Ψe of -1.6 MPa. Rape had a high TW/DW ratio (9-11) and a 6 limited ability to adjust osmotically, ΔΨe100 being at most 0.3-0.4 MPa.
The chemical constituents and biological activity of Pinus cembra L. (Pinaceae), native to the Central European Alps and the Carpathian Mountains, are not well known. The aim of the present work was to examine the phenolic content, antioxidant and antimicrobial effects of hydromethanolic extracts of Pinus cembra L. bark and needles. Bark extract had higher concentrations of total phenolics (299.3 vs. 78.22 mg gallic acid equivalents/g extract), flavonoids (125.3 vs. 19.84 mg catechin equivalents/g extract) and proanthocyanidins (74.3 vs. 12.7 mg cyanidin equivalents/g extract) than needle extract and was more active as a free radical scavenger, reducing agent and antimicrobial agent. The EC₅₀ values in the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) and reducing power assays were 71.1, 6.3 and 26 mg/mL for bark extract and 186.1, 24 and 104 mg/mL for needle extract, respectively. In addition, needle extract showed ferrous ions chelating effects (EC₅₀ = 1,755 μg/mL). The antimicrobial effects against Staphylococcus aureus, Sarcina lutea, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans were assessed by the agar diffusion method. Both extracts (4 mg/well) were active against all the microorganisms tested; bark extract showed higher inhibition on all strains. These results indicate that Pinus cembra L. bark and needles are good sources of phytochemicals with antioxidant and antimicrobial activities.
A biostimulant is an organic material that, when applied in small quantities, enhances plant growth and development such that the response cannot be attributed to the application of traditional plant nutrients. This review is aimed at highlighting developments in the processing of macroalgae for agricultural biostimulants (AB), summarising the biologically active components of brown macroalgae and examining the factors supporting the use of macroalgal AB for managing abiotic and biotic stresses in crop plants. The policy drivers supporting the use of macroalgal-derived ABs in agriculture are also emphasised. We examine the use of macroalgal ABs in crop production and evaluated the benefits of seed priming, foliar application, soil drenches and hydroponic treatments. The use of macroalgal ABs on crop plants can generate multiple benefits with reported effects including enhanced rooting, higher crop and fruit yields, freezing, drought and salt tolerance, enhanced photosynthetic activity and resistance to fungi, bacteria and virus. ABs can be applied as an alternative, or used in conjunction with synthetic crop protection products and plant growth regulators, and may have a role in maintaining crop production levels, health and quality in the future when many active ingredients will be lost to the industry due to changes in European Union regulations. Worldwide, macroalgae remain largely unexploited, we highlight some of the future research and development priorities.
The study was conducted to evaluate the effect of seaweed, salt water and drainage water on germination percentage, rate and seedling growth of tomato (Lycopersicum spp.). Seeds were germinated in sterile distilled water as control 0 dsm-1, salt water (2.5, 5 dsm-1) and drainage water (2.7 dsm-1) in Petri dishes with 3 levels of seaweed (0.2%, 0.1%, 0.05%) in addition to the combination between them. In general results showed that most percentage and rate of germination, plumule and radicle length, fresh and dry seedling weight varied with control treatment. Salt water and drainage water having varying effects on germination percentage and rates. Besides, seedlings growth was more sensitive than germination in tomato. Seaweed treatments have no effects, while mixed with salt water and drainage water was improved germination and seedlings growth.
Seaweed extracts are used as nutrient supplements, biostimulants, or biofertilizers in agriculture and horticulture to increase plant growth and yield. In this study, we examined the effect of liquid seaweed extracts (LSEs) made from Ulva lactuca, Caulerpa sertularioides, Padina gymnospora, and Sargassum liebmannii as biostimulants on the germination and growth of tomato (Solanum lycopersicum) under laboratory and greenhouse conditions using foliar and soil drench applications of LSEs. We assessed LSEs at different concentrations (0.2, 0.4, and 1.0 %) on germination parameters (percentage, index, mean time, energy, and seedling vigor index) and growth parameters (plumule length, radical length, shoot length, root length, fresh weight, and dry weight) of tomato seedlings. Our results indicate that seeds treated with LSEs of U. lactuca and P. gymnospora at lower concentrations (0.2 %) showed enhanced germination (better response in germination rate associated with lower mean germination time, high germination index and germination energy, and consequently greater seedling vigor and greater plumule and radicle length). Application as a soil drench was found to be more effective in influencing the height of the plant (up to 79 cm) than the foliar spray application (75 cm). Plants receiving LSEs of U. lactuca and P. gymnospora showed increased shoot length, root length, and weight. Furthermore, U. lactuca and P. gymnospora were found to be more successful and better candidates for developing effective biostimulants to improve the growth of tomato plants. This study provides important information on the identification and utilization of Mexican seaweed resources for agriculture and is the first study to report on the uses of these seaweeds as a source of liquid extracts as biostimulants in agriculture.
The seaweed extract Goemar GA 14 (2.5 g L-1), when applied as a foliar spray to two varieties of Spinacia oleracea L., 4 and 6 weeks after sowing, increased the total fresh matter production of the leaves by 12 to 15%, after 8 weeks of culture. However the O2 evolution rate of chloroplasts from plants treated with seaweed extract did not exhibit a significant increase compared to the control plants.
In a replicated field plot study conducted during 1994 and 1995 in the Sacramento Valley, California, U.S.A., combinations of three levels each of soil-applied organic fertilizing materials and foliar-applied seaweed and fish powder were tested on processing tomato (Lycopersicon esculentum Mill.), cv. Orsetti's Halley 3155 to determine effects on crop yield, fruit quality and economics. The experimental design was a factorial split plot arranged in a randomized complete block with four replicates. Main plot treatments consisted of three soil fertility levels: (1) control, (2) woolypod vetch (Vicia villosa Roth ssp. varia [Host] Corbiere), cv. Lana and (3) Lana vetch and poultry manure compost. Subplot treatments consisted of three foliar spray levels: (1) control, (2) seaweed and fish powder applied at label rate, and (3) seaweed and fish powder applied at twice the label rate. The study was designed to simulate practices used by growers of organic processing tomatoes in the area. No significant differences were found for yield or quality of marketable fruit in any soil and foliar treatment combination in either year. Because no significant differences for yield or fruit quality were detected, no economic benefit for seaweed and fish powder can be inferred under the experimental conditions.
Publisher Summary This chapter presents detailed information on chlorophylls and carotenoids to give practical directions toward their quantitative isolation and determination in extracts from leaves, chloroplasts, thylakoid particles, and pigment proteins. The chapter focuses on the spectral characteristics and absorption coefficients of chlorophylls, pheophytins, and carotenoids, which are the basis for establishing equations to quantitatively determine them. Therefore, the specific absorption coefficients of the pigments are re-evaluated. This is achieved by using a two-beam spectrophotometer of the new generation, which allows programmed automatic recording and printing out of the proper wavelengths and absorbancy values. Several procedures have been developed for the separation of the photosynthetic pigments, including column (CC), paper (PC), and thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC). All chloroplast carotenoids exhibit a typical absorption spectrum that is characterized by three absorption maxima (violaxanthin, neoxanthin) or two maxima with one shoulder (lutein and β-carotene) in the blue spectral region.
This study examined the effects of Stimplex™, a marine plant extract formulation from Ascophyllum nodosum, on some common cucumber fungal pathogens. Greenhouse cucumber plants were sprayed and/or root drenched using Stimplex™ at
0.5% or 1% concentration twice at 10-day intervals. Treatments also included application of fungicide (chlorothalonil, 2gL−1) alternating with Stimplex™ application. Treated plants were inoculated with four cucumber fungal pathogens including Alternaria cucumerinum, Didymella applanata, Fusarium oxysporum, and Botrytis cinerea. Stimplex™ application resulted in a significant reduction in disease incidence of all the pathogens tested. The disease
control effect was greater for Alternaria and Fusarium infection, followed by Didymella and Botrytis. Combined spray and root drenching with Stimplex™ was more effective than either spray or root drenching alone. The alternation
of one fungicide application, alternated with Stimplex™ application, was highly effective and found to be the best treatment
in reducing the disease ratings. Plants treated with Stimplex™ showed enhanced activities of various defense-related enzymes
including chitinase, β-1,3-glucanase, peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, and lipoxygenase. Altered
transcript levels of various defense genes, including chitinase, lipoxygenase, glucanase, peroxidase, and phenylalanine ammonia
lyase were observed in treated plants. Cucumber plants treated with Stimplex™ also accumulated higher level of phenolics compared
to water controls. These results suggest that seaweed extracts enhance disease resistance in cucumber probably through induction
of defense genes or enzymes.
Keywords
Ascophyllum
–Cucumber–Fungal diseases–Resistance–Mechanism
Experiments were conducted on tomato to study the potential of brown alga Sargassum johnstonii as a biofertilizer. Seaweed extract was applied as a foliar spray, soil drench, and soil drench + foliar spray to assess
its effect on plant growth, yield, and concentration of lycopene and vitamin C. The main objective of the study was to enhance
the biochemical constituents with neutraceutical and antioxidant values in tomato fruit. Different concentrations (0.1%, 0.4%,
0.8%, 2%, 6%, 8%, and 10%; v/v) of seaweed extract were used and growth was observed over a period of 7months. A total of 14 sprays/drenches were applied
at 15-day intervals during the entire vegetative and reproductive phase. A statistically significant increase in vegetative
growth (plant height, shoot length, root length, and number of branches), reproductive parameters (flower number, fruit number,
and fresh weight), and biochemical constituents (photosynthetic pigments, proteins, total soluble sugars, reducing sugars,
starch, phenols, lycopene, and vitamin C) was recorded following all three methods of treatment at higher concentrations of
seaweed extract. The study also reports auxin- and cytokinin-like activity, and the presence of macro- (Ca, Mg, Na, and K)
and micronutrients (Fe, Cu, Zn, and Mn), in seaweed extract of S. johnstonii, which makes it a potential biofertilizer.
KeywordsBiofertilizer–Nutrients–Lycopene–
Lycopersicon esculentum
–Seaweed extract–Vitamin C
Both micro- and macroalgae have long been used to augment plant productivity and food production in various regions of the
world through their beneficial effects when applied to soils. Interactions of algae with the soil community undoubtedly are
complex and benefits are dependent on the crop and the local environmental conditions. This has resulted in much speculation
as to mechanisms involved as well as the validity of the results reported. It is now 60years since the first commercial seaweed
extract was manufactured for agricultural use. These aqueous extracts allowed for the first time the direct application of
soluble seaweed constituents to specific plant organs such as leaves and roots. The earlier concept that benefits of seaweeds
and their extracts were due mainly to their manurial value or to their micronutrient suites is no longer tenable. Seaweeds
likewise have been used for millennia as fodder supplements to improve animal nutrition and productivity. Recent research
is focusing on their mode of action, specific health benefits, and the mechanisms of action in animals. Improved analytical
techniques and instrumentation coupled with the use of molecular genetic tools are establishing that seaweed extracts can
modify plant and animal responses at a fundamental level. It therefore seems appropriate to review key developments over the
years and to remark on novel findings. A new and exciting vista has opened for seaweed extracts in both plant and animal applications.
KeywordsAlgae–Growth hormones–Pathogen resistance–Animal health–Polymers
Marine algal seaweed species are often regarded as an underutilized bioresource, many have been used as a source of food,
industrial raw materials, and in therapeutic and botanical applications for centuries. Moreover, seaweed and seaweed-derived
products have been widely used as amendments in crop production systems due to the presence of a number of plant growth-stimulating
compounds. However, the biostimulatory potential of many of these products has not been fully exploited due to the lack of
scientific data on growth factors present in seaweeds and their mode of action in affecting plant growth. This article provides
a comprehensive review of the effect of various seaweed species and seaweed products on plant growth and development with
an emphasis on the use of this renewable bioresource in sustainable agricultural systems.
BACKGROUND: There is not adequate literature on effects of seaweed extracts (SWE) on yield and nutritional status of olive trees as well as olive oil quality. In this work, a study of the effects of a seaweed extract applied foliarly (0.5% v/v) in addition to soil application of N (500 g NH4NO3 per tree) and B (150 g borax per tree) on productivity, fruit parameters, nutritional status and olive oil quality of a Greek olive cultivar was performed.
RESULTS: In contrast to the trees treated with N (NH4NO3) or N + B (NH4NO3 + borax), the additional application of seaweed extract (treatments N + SWE and N + B orax + SWE) increased the productivity and oil content and accelerated maturation of the olive fruits. In particular, the best results concerning productivity, oil content and earliness of maturity (colour and firmness) were observed in the trees treated with N + B + SWE. The additional application of SWE also increased K, Fe and Cu concentrations and reduced the concentrations of Mn in olive leaves compared to the corresponding treatments without SWE. Total phenol concentration in oil was minimized in all fertilization treatments but, particularly, the additional application of SWE did not affect it. The application of N + B + SWE led to a significant increase in linolenic as well as oleic acid concentrations, and to a decline in palmitoleic, stearic and linoleic acid concentrations in olive oil.
CONCLUSION: The fertilizer treatments of this experiment and especially the combination of NH4NO3 + borax + SWE should be recommended for the studied olive orchards, in order to increase tree productivity and improve their nutrition status and various olive oil quality parameters.
Leaf expansion rate varies with leaf temperature, photon flux density
(PPFD), evaporative demand and soil water status. In most simulation
models, it is calculated every day by multiplying the amount of
carbohydrate available to leaves by specific leaf area (SLA). However,
leaf expansion rate is considerably reduced by mild water deficits
which do not affect photosynthesis, and is not affected by a reduction
in the PPFD intercepted during rapid leaf expansion. Specific leaf area
undergoes a several-fold variability depending on PPFD, soil water
status and time of day. It is increased when environmental conditions
have a greater depressive effect on expansion rate than on
photosynthesis, and is decreased in the opposite case. It is therefore
appropriate to model leaf expansion independently of the plant carbon
budget. Consistent characteristics can be deduced from a series of
experiments, allowing a model of leaf expansion to be proposed. (i)
Time courses of relative leaf expansion rate and of epidermal cell
division rate are well conserved within a plant and across a large
range of environmental conditions, provided that durations and rates
are expressed in thermal time. Maximum relative rates are common to all
zones of a leaf and to all leaves of a plant, in maize and sunflower.
(ii) A water deficit, or a reduction in intercepted PPFD, imposed in
the first half of the period of leaf development affects the relative
expansion rate in the deficit only, but permanently affects the
absolute expansion rate. In contrast, a reduction in PPFD causes no
effect on leaf expansion if imposed in the rapid expansion period when
the leaf is autotrophic. (iii) Expansion rate is related to evaporative
demand and to the concentration of ABA in the xylem sap with
relationships that apply under both field and laboratory conditions.
(iv) Tissue expansion and epidermal cell division behave as independent
processes which determine epidermal cell area at each time.
Eighteen strawberry genotypes were evaluated for their phenolic content and antioxidant capacity using several methods. High antioxidant capacity was found for 'Harmonie','Saint-Jean d'Orleans', and 'Saint-Laurent d'Orleans', which were reported to have better shelf life than 'Kent'. 'Harmonie', 'Saint-Jean d'Orleans', 'Orleans', and some advanced selections had higher hydroxycinnamic acids, benzoic acids, and flavonols than 'Kent'. The significant variation in antioxidant capacity and total phenolic compounds clearly shows the potential value of certain new cultivars and advanced lines as parents in a breeding program. The future plan is to examine individual antioxidant and their role in disease resistance and extension of shelf life and to use selected genotypes as parents to developed new lines.
A replicated commercial field trial evaluated the effects of Ascophyllum nosodum marine plant extract (Acadian Liquid Seaweed Concentrate; LSC) on yield and cluster quality of Thompson seedless grapes. Treatments consisted of a control, LSC at 2.34 and 3.5 L/ha applied at pre-bloom, post-bloom and sizing stages, and LSC at 2.34 L/ha with an additional treatment at bud break. Plots received a standard fertility management program in addition to specific treatments. Compared to the control, LSC at 2.34 L/ha, LSC at 3.5 L/ha and LSC at 2.34 L/ha with bud break treatment gave yield increases of 25, 14 and 13%, respectively. Heaviest individual clusters were harvested from the LSC 2.34 L/ha treated plots that averaged 0.431 kg/cluster, a 9% increase over the control. LSC at 2.34 L/ha with bud-break treatment produced berries that were 25% heavier than controls. LSC (at 2.34 L/ha) treated berries were 22.4% heavier than controls. A series of commercial samplings was also undertaken to explore effects on a wider range of varieties and locations. Results indicate a consistent increase in berry size (from 6.1 to 8.6%), weight (from 3.2 to 29%) and firmness (from 8.6 to 27.1%) for several varieties and locations. However, Brix levels tend to be lower in treated berries. This information is discussed.
'Hamlin' sweet orange trees on 'Carrizo' citrange and 'Swingle' citrumelo rootstocks were treated weekly with a commercial extract of the brown seaweed Ascophyllum nodosum at 5 and 10 mL[1]L-1 as either a soil drench or foliar spray. Half of the trees in each treatment were subjected to drought stress [irrigated at 50% of evapotranspiration (ET)], whereas the other half remained fully irrigated (100% ET). Drought stress reduced shoot growth and leaf photosynthesis but increased root and total plant growth relative to the amount of water applied, thus increasing whole plant water use efficiency. Trees treated with seaweed extract and drought-stressed had significantly more total growth than untreated drought-stressed trees for both rootstocks. The maintenance of growth by the seaweed extract under drought stress conditions was unrelated to photosynthesis. However, the seaweed extract treatment did have a significant effect on plant water relations. Soil drench-treated trees had more growth and higher stem water potential than foliar-treated or control trees after 8 weeks of drought stress. These results indicate that seaweed extract may be a useful tool for improving drought stress tolerance of container-grown citrus trees.
The spectrophotometric technique for total antioxidant activity (TAA)1,2 measures the relative abilities of a.ntioxidants to scavenge the 2,2′-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS*+) radical cation (ABTS*+) in comparison with the antioxidant potency of standard amounts of Trolox, the water-soluble vitamin E analogue. This method is based on the progressive consumption of antioxidant activity by ABTS*+ as it is generated in the reaction cuvette and can be automated with a spectrophotometric analyzer. Several different analytical strategies are possible using the same reagents, enabling the assay system to be used to determine the antioxidant activity of plasma, saliva, lipoprotein fractions, foods and beverages. To determine the activity of pure antioxidant substances, a hydrogen peroxide concentration of 75 μM is used, together with a 6 min measuring time. For biological samples with endogenous peroxidase activity the hydrogen peroxide concentration is increased fivefold and the measuring time shortened to 3.25 min. Assays with improved sensitivity are described for low-density lipoprotein (LDL) preparations and saliva. Use of a spectrophotometric endpoint makes the assay simple to carry out without special laboratory equipment. Measurement at 734 nm avoids a range of potential interfering factors, such as sample turbidity and non-specific absorbance by sample constituents. Current applications of the ABTS antioxidant assay are described and discussed.
A fully automated-continuous flow 40-sample/ hour procedure was adapted from the Singleton-Rossi method of analysis for total phenols in wine and other plant extracts. It was compared with small-volume manual and semiautomated versions of this analysis. The agreement in mg of gallic acid equivalent phenol (GAE) per liter among a series of dry wines was excellent by all three procedures. The coefficients of variation in replicate analyses averaged 5.8% for the manual, 6.2% for the semi-automated and 2.2% for the automated procedure. This greater reproducibility, plus savings of about 70% in labor and up to 40% in reagents, makes the automated procedure attractive for laboratories doing enough total phenol analyses to recoup the cost of the automating equipment. For continuous flow, color development with the Folin-Ciocalteu reagent in alkaline solution must be hastened by heating compared to slower room temperature development for the manual methods. Heating of sugar-containing samples in the alkaline solution gives interference presumably from endiol formation. Examples are given of corrections which were used successfully to estimate the true phenol content of sweet wines.
This study investigated whether kelp extract from Durvillaea potatorum and Ascophyllum nodosum (Seasol Commercial®) stimulates broccoli establishment and growth. Under controlled conditions in the glasshouse, weekly applications of kelp extract significantly increased the leaf area, stem diameter and biomass of broccoli by up to 70%, 65% and 145%, respectively. Also in the glasshouse, lower strength dilutions of kelp extract (1:200 to 1:500) were most effective in stimulating early growth of broccoli, whereas higher strength dilutions (1:25 to 1:100) were most effective later in plant development. In the field, application of kelp extract as a drench to a clay-loam soil (Sodosol) significantly increased the leaf number, stem diameter and leaf area of establishing broccoli seedlings by 6%, 10% and 9%, respectively, irrespective of application rate (three applications at 2.5 or 25 l ha− 1). Furthermore, kelp extract significantly reduced the early incidence of white blister, caused by Albugo candida, on broccoli by 23%. In a sandy soil (Podosol), the effect of kelp extract was less pronounced, with only the leaf area of broccoli seedlings increasing significantly following treatment with kelp applied at the highest rate. It is hypothesized that differences in cation exchange capacity, organic matter and/or leaching properties contribute to variation in the response of broccoli to kelp extract in different soils. Future research is proposed to examine the capacity of kelp extract to offset the high nutrient inputs needed at establishment in the broccoli industry.
Many vegetable and ornamental bedding plant crops are grown in plug trays and cell packs under greenhouse conditions prior to transplantation into the field or landscape. The development of a large, healthy root system is important for young seedlings to help withstand the inevitable transplantation shock. Commercial extracts of Ascophyllum, are known to improve root development of horticultural plants as well as to help alleviate some symptoms typically associated with abiotic stresses such as drought. Greenhouse experiments in
Cornwallis, Nova Scotia were designed to test the effects of Acadian® seaweed extract on root development in lettuce, melon, tomato, pepper, celery, petunia, pansy and cosmos. Acadian® treatments, in combination with 10-52-10 N-P-K fertilizer, were applied as a drench and compared to plants which received only 10-52-10 as control. The roots and leaves of plants from each treatment were examined with WinRhizo® root and WinFolia® leaf image analysis systems. Time lapse videos were also used to record results. Replicated trials showed significant improvements in root length, surface area, volume and leaf area when the Acadian® was applied in combination with fertilizer. Further studies examined the effects of this commercial seaweed extract on water stress in pepper, lettuce, tomato, petunia and pansy. Results showed that plants treated with Acadian® plus fertilizer were more water stress tolerant than those treated with fertilizer only. The application of Acadian® extended the time before the plants began to succumb to water stress compared to fertilizer treated controls. These results suggest that applications of the Ascophyllum-based, commercial extract improves early root and shoot development and provides protection against water stress under the conditions tested. All of these positive attributes have important commercial applications, particularly for greenhouse operators and suppliers of bedding plants.
Regular consumption of fruits and vegetables is linked with a lowered risk of heart disease, cancer and stroke. Two different pilot studies were set up in Greece (potato), and Ireland (onion) to study the effect of a commercial cold process seaweed extract from Ascophyllum nodosum on the yield and phytochemical content of potato and onion. Results from this study indicated that there was an increase in phenolic and flavonoid content in onion while in potato significant differences were detected only in flavonoid content. There were no statistically significant differences in yield in either crop, although seaweed treated potato plants had higher yields. These results indicate the potential of seaweed extracts in increasing the phytochemical content of vegetables.
Vegetable amaranth (Amaranthus spp.) is a promising C4 crop for semi-arid regions due to its high
nutritive value and an ability to adapt to drought stress. A pot experiment in a temperature-controlled
greenhouse was conducted to investigate the effects of drought stress on biomass production, partitioning,
and water use efficiency (WUE) of four genotypes of vegetable amaranth, viz. ‘Hin Choi’ (A.
tricolor), ‘Co.2’ (A. tricolor), ‘WS80-192’ (A. blitum), and ‘RRC 1027’ (A. cruentus). Drought stress
significantly decreased plant total dry mass, but the proportion of changes differed among root, stem,
and leaf. Under drought, root dry mass ratiowas increased in Co.2, WS80-192, andRRC1027, whereas
leaf dry mass ratio was decreased in Hin Choi, Co.2, and RRC 1027. Leaf area per root dry mass was
decreased by drought stress in all genotypes examined. These results indicate that drought induced a
more conservative balance betweenwater-losing andwater-obtaining organs. Specific leaf area (SLA)
was decreased by drought stress and differed between genotypes. WUE of the four genotypes of vegetable
amaranth was unaffected by drought stress, and ranged from 2.9 to 3.8 gDMkg−1 H2O, being
the highest in RRC 1027 and the lowest in WS80-192. A negative relationship between SLA and
WUE was observed over the four genotypes of vegetable amaranth under well-watered conditions.
The antioxidant activities of ethanolic crude extract (ECE) and its four different solvent sub-fractions (namely, petroleum ether fraction (PEF), ethyl acetate fraction (EAF), n-butyl alcohol fraction (BAF) and the rest fraction (RF)) from Tuber indicum were investigated using several in vitro antioxidant assays. ECE and four sub-fractions possessed different antioxidant and radical-scavenging activities in different assays. BAF showed the most potent radical-scavenging activity on DPPH radicals, superoxide anion radicals and reducing power, with EC50 values of 1.38, 0.96, 16.0mg/ml, respectively. EAF exhibited the highest hydroxyl radical-scavenging and ferrous ion chelating activities with EC50 values of 3.31 and 0.70mg/ml, respectively. The total phenolics (TP) and total flavonoids (TF) were also determined. BAF had the highest TP and TF contents, and the next was EAF. These results showed that the amounts of phenolics and flavonoids were in accordance with higher effectiveness in scavenging radicals and chelating ferrous ions.
Carbon isotope discrimination (Δ) and specific leaf area (SLA) have been shown to be correlated with water-use efficiency (WUE) of peanut (Arachis hypogaea L.) and SLA has been proposed as an indirect selection criterion for Δ and WUE. The effect of high temperature and water deficit on WUE, Δ, and SLA, and relations between them, was investigated in controlled environments. Five Spanish (A. hypogaea ssp. fastigiata) and three Virginia (A. hypogaea ssp. hypogaea, botanical type) lines were grown at mean temperatures of 27 and 34°C and at 50 and 100% available soil water (ASW) from first flowering to maturity, and WUE, Δ and SLA measured at maturity. Virginia genotypes had higher total dry matter, water use and WUE (P ≤ 0.01), but were more sensitive to high temperature (P ≤ 0.01) than Spanish genotypes. Water deficit reduced water use and SLA, and increased WUE. The only water deficit x temperature interaction (P < 0.05) was for Δ, where water deficit reduced the value of Δ at 27°but not at 34°C. High temperature had no effect on water use, but decreased WUE and increased SLA. Across all water deficit and temperature treatments (n = 32), WUE was correlated with Δ (r = -0.78, P < 0.001) and SLA (r = -0.70, P < 0.001), and SLA correlated with Δ (r = 0.75, P < 0.001) with no difference associated with botanical type. Temperature and water deficit had significant (P ≤ 0.05) effects on the intercept, but not the slope of these relations. The results support the view that SLA can be used as an indirect selection criterion for Δ and WUE in genotypic selection.
Because of its relationship with water-use efficiency (W), carbon isotope discrimination in leaves (Delta) was proposed to be useful for identifying genotypes with greater water use efficiency. In this study we examined the relationship between W and Delta in four peanut (Arachis hypogaea L.) genotypes. The genotypes were grown in and around mini lysimeters embedded in soil and were subjected to two drought regimes, intermittent and prolonged water deficit conditions, by varying the irrigation timing and amount. Automated rain-out shelters prevented any rain from reaching the experimental plots during the treatment period. The mini-lysimeters allowed accurate measurement of water use and total dry matter (including roots) in a canopy environment. Water-use efficiency, which ranged from 1.81 to 3.15 g kg(-1), was negatively correlated with Delta, which ranged from 19.1 to 21.8%. Tifton-8 had the highest W (3.15 g kg(-1)) and Chico the lowest (1.81 g kg(-1)), representing a variation in W of 74% among genotypes. Variation in W arose mainly from genotypic differences in total dry matter production rather than from differences in water use. It is concluded that Delta is a useful trait for selecting genotypes of peanut with improved W under drought conditions in the field. A strong negative relationship existed between W and specific leaf area (SLA, cm(3) g(-1)) and between Delta and SLA, indicating that genotypes with thicker leaves had greater W. SLA could therefore be used as a rapid and inexpensive selection index for high W in peanut where mass spectrometry facilities are not available.
A seaweed extract (Goemar Spring Citricos(R)) from Ascophyllum nodosum was applied to trees of 'de Nules' clementine mandarin and Navelina orange at bud sprouting, at full bloom and at the end of the June drop, at a concentration from 0.15% to 0.30%. The seaweed extract increased the yield of 'de Nules' clementine mandarin by 11%. The application of 6 mg L-1 gibberellic acid (GA(3)) to this cultivar at full bloom increased the yield by 22%, and the combination of seaweed extract and GA3 resulted in a 41% increase of yield. Mean fruit weight was reduced by the GA(3)-seaweed extract combination, but the amount of marketable fruit was increased. In Navelina orange, seaweed extract at a concentration of 0.15% increased the yield by 8% whereas at a concentration of 0.30% it increased the yield by 15%. No significant differences were observed in the mean fruit weight of this cultivar.
The seaweed concentrate Kelpak, made fromEcklonia maxima, and applied as a foliar spray or a root drench at transplanting, improved both the vegetative and reproductive growth of marigolds. Of particular significance is that the overall production of seeds (fruits) was increased by as much as 50% in some instances. Very low concentrations of seaweed concentrate were not always effective, while the higher dosages decreased vegetative growth.
The effect of the seaweed concentrate Kelpak on the yield of the tepary bean (Phaseolus acutifolius L.) grown under conditions of varying nutrient supply was investigated. Kelpak significantly increased the yield of plants growing at all concentrations of nutrient supply by increasing bean weight rather than bean number. Kelpak also tended to increase the N concentration of the beans. The results suggest that Kelpak did not act simply as a fertilizer, but as some kind of biostimulant.
Seaweed concentrate prepared fromEcklonia maxima (Osbeck) Papenfuss, when applied as a soil drench, significantly improved the growth of tomato seedlings. Application as a foliar spray had no effect on young plants. In a second experiment SWC-treated plants exhibited early fruit ripening and a total fruit fresh weight increase of 17%. The number of harvested fruit were improved by about 10%. In this instance foliar applied SWC was more beneficial than SWC applied to the soil. The significance of these findings is discussed.
Several Vietnamese seaweed species have economic importance as food for humans, as industrial materials, as ingredients in
traditional medicine, and as biofertilizers. The nutritional values of nine representative Vietnamese seaweed species were
analyzed. In this report, all of the species studied are rich in proteins, lipids (especially polyunsaturated fatty acids),
vitamins, pigments, and macro- and micro-elements. The effect of the physiological activities of the green alga, Ulva reticulata, on hepatic fatty acid metabolism were examined in mice. The results indicate that Vietnamese seaweeds are abundant and have
high quality materials for industrial and agricultural purposes.
The antiradical activities of various antioxidants were determined using the free radical, 2,2-Diphenyl-1-picrylhydrazyl (DPPH*). In its radical form. DPPH* has an absorption band at 515 nm which dissappears upon reduction by an antiradical compound. Twenty compounds were reacted with the DPPH* and shown to follow one of three possible reaction kinetic types. Ascorbic acid, isoascorbic acid and isoeugenol reacted quickly with the DPPH* reaching a steady state immediately. Rosmarinic acid and δ-tocopherol reacted a little slower and reached a steady state within 30 min. The remaining compounds reacted more progressively with the DPPH* reaching a steady state from 1 to 6 h. Caffeic acid, gentisic acid and gallic acid showed the highest antiradical activities with a stoichiometry of 4 to 6 reduced DPPH* molecules per molecule of antioxidant. Vanillin, phenol, γ-resorcylic acid and vanillic acid were found to be poor antiradical compounds. The stoichiometry for the other 13 phenolic compounds varied from one to three reduced DPPH* molecules per molecule of antioxidant. Possible mechanisms are proposed to explain the experimental results.
Screening of potential antioxidant activities of water and 70% acetone extracts from ten species of Icelandic seaweeds was performed using three antioxidant assays. Significant differences were observed both in total phenolic contents (TPC) and antioxidant activities of extracts from the various species evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorbance capacity (ORAC) and ferrous ion-chelating ability assays. Acetone extracts from three Fucoid species had the highest TPC and consequently exhibited the strongest radical scavenging activities. High correlation was found between TPC of seaweed extracts and their scavenging capacity against DPPH and peroxyl radicals, indicating an important role of algal polyphenols as chain-breaking antioxidants. However, water extracts generally had higher ferrous ion-chelating activity than 70% acetone extracts and no correlation was found with their TPC, suggesting that other components such as polysaccharides, proteins or peptides in the extracts were more effective chelators of ferrous ions than phenolic compounds.
