Article

Sap Concentrations in Halophytes and Some Other Plants

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Abstract

Freezing point depression in xylem sap of mangroves was found to range from 0.05 to 0.5 degrees , in desert plants from 0.01 to 0.16 degrees . In crush juices from leaves of Batis and Salicornia, 90% or more of the freezing point depression was made up of sodium and chlorine ions; in mangroves they constituted 50 to 70%, the rest probably being organic solutes. Plants growing in seawater have -30 to -60 atmospheres pressure in the xylem sap. As shown earlier, at zero turgor pressure the intracellular freezing point of the parenchyma cells matches closely the negative pressure in the xylem sap. This agrees with the present data, that the fluid which exudes from the xylem by applying gas pressure on the leaves is practically pure water; freezing point is rarely above 0.01 to 0.02 degrees . To perform this ultrafiltration, the plasma membrane is subjected to a hydrostatic pressure gradient which in some cases may exceed 100 atmospheres.

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... At present, two methods are used to determine xylem ion concentrations: pressure exudation of xylem sap with subsequent direct ion analysis (e.g. Scholander et al., 1966) and calculation from measurements of both transpiration rate and rate of shoot ion accumulation (e.g. Rozema et al., 1981). ...
... Concentrations in the xylem have also been obtained from measurements on sap which has been exuded under pressure from excised shoots. Scholander et al. (1966) obtained values ranging from 5 to 122 mol m"^ for chloride in a range of mangrove species growing at the salinity of seawater, although attempts to obtain sap by pressure exudation in other dicotyledonous species have often met with failure due to the inability to apply sufflcient pressure (Yeo & Flowers, 1986). To our knowledge, only a single report for [Naj^ in temperate dicotyledonous species by this method exists: in Atriplex littoralis and A. hastata growing at 200 mol m~3 salt, [Nal^ was 29-7 and 47 3 mol m"^ respectively (Rozema e?«/., 1981). ...
Article
Rates of ion transport and transpiration were measured during the day and night in whole seedlings of Suaeda maritima growing over a range of salinities, in order to calculate concentrations of sodium and potassium in the xylem during these periods. Mean sodium concentration in the xylem was maximal at 56 mol m−3 Na with an external salinity of 200 mol m−3 NaCl. The sodium concentration in the xylem was greater in the dark than in the light at all external salinities investigated. Comparison of the external sodium with that in the xylem indicated that sodium was more strongly excluded from the transpiration stream as salinity increased. The mean concentration of potassium in the xylem declined as external NaCl concentration increased, although selectivity for potassium increased at higher salinities. Results are discussed in relation to osmotic adjustment in S. maritima.
... Mangroves grow in saline waters but have sodium chloride concentrations in their xylem that are only small fractions of those in surrounding saline media (Scholander et al., 1962(Scholander et al., , 1966. Scholander (1962) reported experiments on mangroves which indicated that there are two major methods of mangrove ion regulation: by salt exclusion and by salt excretion. ...
... Mangroves cope with the saline environment by a number of techniques; indeed, individual species probably utilize a variety of methods as suggested by Albert (1975). All mangroves probably have root membranes that exclude salt to a degree (Scholander et al., 1966) Rhizophora mangle excludes salt well, but not perfectly, and so takes in small amounts of salt with its transpiration water, which it apparently disposes of by storing in the leaves and fruits. Laguncularia racemosa is a semi-efficient salt excluder, and excretes salt through glands on its leaves, but also, under hyper-saline conditions, Laguncularia develops thickened succulent leaves and may also lose salt in the discard of its senescent leaves. ...
Chapter
Mangroves are the trees and shrubs that grow in the edge of the sea and thus are cultivated with saline waters. Their principal product is wood, a renewable resource that substitutes for fossil fuels. Management of mangroves requires little fossil fuel expenditure and mangrove forests produce prawns, finfish and shellfish as byproducts. It is proposed that attention to aspects of mangrove management, physiology and ecology, breeding and selection, and biological spin-off products should make it possible to increase mangrove area and productivity for the benefit of people living along many tropical and subtropical shores of the world.
... In addition, some mangrove plant species have adapted to a saline environment by salt exclusion at the roots, salt secretion through salt glands, and salt sequestration into senescent leaves (Scholander et al. 1962;Scholander 1968;Tomlinson 2016). Rhizophora species do not have salt glands, but they keep the salinity of xylem sap water low by ultrafiltration at the membranes of root cells (Scholander et al. 1966), which are able to filter up to 99% of salt from the surrounding soil pore water (Scholander 1968). This could increase the salinity around roots (Passioura et al. 1992). ...
Article
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Purpose There is increased recognition of the importance of mangroves worldwide, with efforts being made to sustainably manage these ecosystems for forestry and fishery use. Although successive monitoring of mangrove growth after planting has been conducted in some afforestation stands, measurements of soil environmental changes accompanying plant growth have not been made in most stands. In this study, we observed the interactive relationship between the underground root biomass of mangrove, Rhizophora stylosa, and soil chemical properties at an afforestation stand on Tarawa atoll, Kiribati. Methods We first estimated underground root biomass in the stand. Next, we measured the concentrations of dissolved phosphorus, nitrogen, and other ions (Br⁻, Ca²⁺, K⁺, Na⁺, Cl⁻, and SO4²⁻) in soil pore water, as well as the isotopic ratio of leaf carbon and nitrogen in mangrove patches of different ages. Results Estimated underground root biomass was positively related with phosphate and nitrate concentrations in soil pore water, indicating the formation of a rhizosphere environment. Leaf δ¹⁵N analysis suggested that the discrimination of nitrogen isotopes during nitrification and/or uptake of NH4⁺ and NO3⁻ occurs in accordance with plant growth. Differences in salt stress among the patches were reflected in leaf δ¹³C, suggesting it would be a good indicator of the physiological response of mangrove plants to salinity. Conclusions Our findings revealed the changes that occur on a yearly basis in the chemical properties of mangrove leaves and soil pore water after mangrove plantation. These data help to improve our understanding of environmental succession during the formation of mangrove ecosystems.
... The impacts of salt are included in the soil water potential that is assumed to be dominated by the osmotic component of salt stress for well-watered or irrigated conditions. Salinity increases in the plant as a result of salt water uptake from the soil (Scholander et al., 1966;Scholander, 1968;Glenn et al., 1999;Khan et al., 2000) until a 'chemical-equilibrium' is attained between leaf and soil salt concentration (see section 'Plant water flux'). When such equilibrium is reached, filtration theory can be used to link leaf to soil salt concentration using simplified models of filtration efficiency. ...
Article
Salinity is known to affect plant productivity by limiting leaf‐level carbon exchange, root water uptake, and carbohydrates transport in the phloem. However, the mechanisms through which plants respond to salt‐exposure by adjusting leaf gas‐exchange and xylem‐phloem flow are still mostly unexplored. A physically‐based model coupling xylem, leaf, and phloem flows is here developed to explain different osmoregulation patterns across species. Hydraulic coupling is controlled by leaf water potential,ѱI, and determined under four different maximization hypotheses: water uptake (i), carbon assimilation (ii), sucrose transport (iii), or (iv) profit function ‐ i.e., carbon gain minus hydraulic risk. All four hypotheses assume finite transpiration occurs, providing a further constraint on ѱI. With increasing salinity, the model captures different transpiration patterns observed in halophytes (non‐monotonic) and glycophytes (monotonically decreasing) by reproducing the species‐specific strength of xylem‐leaf‐phloem coupling. Salt tolerance thus emerges as plant capability of differentiating between salt‐ and drought‐induced hydraulic risk, and to regulate internal flows and osmolytes accordingly. Results are shown to be consistent across optimization schemes (i‐iii) for both halophytes and glycophytes. In halophytes, however, profit‐maximization (iv) predicts systematically higher ѱI than (i‐iii), pointing to the need of an updated definition of hydraulic cost for halophytes under saline conditions. This article is protected by copyright. All rights reserved.
... 3.4.4.1 Determinación del potencial hídrico de la parte aérea Para la realización de las mediciones se empleó el método de cámara de presión de Scholander (Scholander, PF. 1964;1965;1966), utilizando una cámara de presión ARIMAD 2, con aire no respirable comprimido como gas a presión y realizando las mediciones a temperatura ambiente. ...
... s éco physiologiques de cette espèce permet de renforcer nos connaissances sur les stratégies adoptées par les plantes xérophiles dans un écosystème désertique changeant. C'est dans ce contexte que notre étude s'intègre et dont l'objectif est d'évaluer les potentialités productives et adaptatives de Stipa lagascae en conditions de déficit hydrique. Scholander et al. (1965). Volume IABC(21). Published January, 31, 2016 www.jnsciences.org ISSN 2286-5314 ...
... One of these strategies is the elevation of the plant osmotic pressure in the cellular juices, surpassing those values obtained by mesophytes. Mesophytes usually present osmotic pressure values lesser than 25 atm, while the highest values have been obtained for the genera Sarcocornia, Batis (Scholander et al. 1966) and ...
Chapter
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In Sabkhat, plant ecology will depend on the soil characteristics, according to the type and dynamics of sediments and to water movement, dynamized by salt concentration and climate. Soil profile defines the ability of species to develop under its influence, according to critical variables such as soil salinity, water table depth and granulometry. Also, plant growth and development will depend on special physiological and morphological characteristics that are suited to extreme conditions in sabkhat. In America, sabkhat are the habitat of halophytic species, dwelling characteristic genera that can be found from the Columbia Basin to the Monte ecoregion. In this review soil conditions, plant characteristics and their interactions in saline basins of America will be discussed. Hydrology controls the sediment and solute chemistry, forming a dynamic cycle with halophyte vegetation. When the water table is depressed, deflation is enabled and medium-coarse particles are deposited over small hummocks, usually by the form of dunes or over tussocks, forming nabkhat. Aeolian dust may be responsible for the development and maintenance of plant communities along a salinity gradient towards the adjacent dunes in the periphery. Sabkhat hold an important pool of plant functional groups according mainly to soil salinity and water table depth. Such functional groups perform important ecological functions in the soil-plant-climate triad, such as soil formation, facilitation and zonation. These processes have a dynamic behaviour according to seasonality and climate interannual and decadal variability, assisted by anthropic impacts such as fire, overgrazing or even climatic change.
... The perfusion solution used was 1.0% seawater, filtered through 0.2 μm Millipore syringe filters (Millex GS filter, Millipore Corrigtwohill Co, Cork, Ireland). This solution is similar to the ionic concentration of the sap within a mangrove stem (Scholander et al. 1966;Ball 1988;Choat et al. 2011). ...
Article
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AimsNatural sedimentation rates may not affect mangrove trees adversely, but large and sometimes episodic delivery of sediment may result in decreased growth, dieback or mortality. In this study, we aim to assess the effects of different levels of partial sediment burial on mangrove tree structure and function. Methods Trees of Avicennia marina, Ceriops tagal and Rhizophora mucronata were experimentally buried with terrestrial sediment to simulate different sedimentation levels (15, 30 and 45 cm). After 14 months, branch hydraulic conductivity, xylem structure and stomatal properties were assessed. ResultsSedimentation resulted in general increase in hydraulic conductivity following intermediate levels of burial. The process is also associated with varied anatomical modification in vessel grouping, vessel lumen size and potential conductive area in the three investigated mangrove tree species. Additionally, stomatal adjustment was observed in C. tagal with up to 37% reduction of total stomata area in leaves of buried trees. Conclusions Although sedimentation may stimulate modification in vessel and stomatal properties of buried mangrove trees after a relatively short period of exposure, these traits may not necessarily be important in ensuring hydraulic conductivity which either increases or remains the same as in control following burial.
... Two hours after the start of the photoperiod, leaf and root w were measured. Leaf w was measured in the first fully expanded leaf using a pressure chamber (Soil Moisture Equipment, Santa Barbara, CA, United States) (Scholander et al., 1966). Root w was measured using C52 sample chambers coupled to a HR-33T Dew Point microvoltmeter (Wescor). ...
Article
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Drought provokes a number of physiological changes in plants including oxidative damage. Ascorbic acid (AsA), also known as vitamin C, is one of the most abundant water-soluble antioxidant compound present in plant tissues. However, little is known on the regulation of AsA biosynthesis under drought stress conditions. In the current work we analyze the effects of water deficit on the biosynthesis of AsA by measuring its content, in vivo biosynthesis and the expression level of genes in the Smirnoff-Wheeler pathway in one of the major legume crop, soybean (Glycine max L. Merr). Since the pathway has not been described in legumes, we first searched for the putative orthologous genes in the soybean genome. We observed a significant genetic redundancy, with multiple genes encoding each step in the pathway. Based on RNA-seq analysis, expression of the complete pathway was detected not only in leaves but also in root tissue. Putative paralogous genes presented differential expression patterns in response to drought, suggesting the existence of functional specialization mechanisms. We found a correlation between the levels of AsA and GalLDH biosynthetic rates in leaves of drought-stressed soybean plants. However, the levels of GalLDH transcripts did not show significant differences under water deficit conditions. Among the other known regulators of the pathway, only the expression of VTC1 genes correlated with the observed decline in AsA in leaves.
... Salt exclusion mechanisms, in contrast, rely on water filtration at the root level to reduce the amount of salt entering the plant (Albert, 1975;Aziz & Khan, 2001a;Glenn et al., 1999;Khan & Aziz, 2001;Scholander, 1968;Scholander et al., 1966). Finally, compartmentalization of Na 1 and Cl 2 avoids cell damage (Aziz & Khan, 2001b;Tomlinson, 2016) by accumulating Na 1 and Cl 2 at the cellular and intracellular level, preventing in this way the buildup of toxic ions concentrations within the cytoplasm (Blum, 2017;Chen & Jiang, 2010;Hinckley et al., 1978Hinckley et al., , 1980Jones & Gorham, 1983;Munns & Tester, 2008). ...
Article
Soil salinity affects plant transpiration and growth through two main pathways: the osmotic effect of salt in the soil (osmotic stress; analogous to water stress), and the toxic effect of salt within the plant (ionic stress; salt-specific). However, the drastic and sudden reduction of transpiration exhibited by most species in response to an increase of salinity in the root zone is mainly associated with the osmotic phase, while ionic stress appears at a later time, causing the premature senescence of leaves and the reduction of the plant photosynthetic area. To better investigate the effects of salinity on plant-water relations, we introduce a parsimonious soilplant-atmosphere continuum (SPAC) model accounting for both salt-exclusion at the root level and osmoregulation – i.e. the adjustment of internal water potential in response to salt-stress. The model is used to interpret a paradox observed in salt-tolerant species where transpiration is maximum at an intermediate value of salinity (CTr,max⁡), and is lower in more fresh (C<CTr,max⁡) and more saline (C>CTr,max⁡) conditions. Such non-monotonic transpiration-salt concentration (Tr – C) patterns can be largely explained by plant osmoregulation, while the peak of transpiration at CTr,max⁡ tends to disappear over longer time scales, when ionic stress appears and morphological adaptations become predominant. Osmoregulation emerges here as a water-saving behavior similar to the strategies that xerophytes use to cope with aridity. The maximum of transpiration at CTr,max⁡ is thus the result of a trade-off between the enhancement of salt-tolerance and optimal carbon assimilation.
... The exclusion of salt, however, is only partial and elevated salt concentrations are known to be tolerated in the cell apoplast (from 1 to 10% seawater salinity). Mangroves have been suggested to take advantage of elevated salt concentrations in the apoplast and symplast to decrease water potential, thus reducing the challenge to primary walls in vessels and to cell membranes (Scholander et al., 1966;Parida and Jha, 2010;Reef and Lovelock, 2015). ...
Article
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Some of the most striking features of Rhizophoraceae mangrove saplings are their voluminous cylinder-shaped hypocotyls and thickened leaves. The hypocotyls are known to serve as floats during seed dispersal (hydrochory) and store nutrients that allow the seedling to root and settle. In this study we investigate to what degree the hypocotyls and leaves can serve as water reservoirs once seedlings have settled, helping the plant to buffer the rapid water potential changes that are typical for the mangrove environment. We exposed saplings of two Rhizophoraceae species to three levels of salinity (15, 30, and 0–5h, in that sequence) while non-invasively monitoring changes in hypocotyl and leaf water content by means of mobile NMR sensors. As a proxy for water content, changes in hypocotyl diameter and leaf thickness were monitored by means of dendrometers. Hypocotyl diameter variations were also monitored in the field on a Rhizophora species. The saplings were able to buffer rapid rhizosphere salinity changes using water stored in hypocotyls and leaves, but the largest water storage capacity was found in the leaves. We conclude that in Rhizophora and Bruguiera the hypocotyl offers the bulk of water buffering capacity during the dispersal phase and directly after settlement when only few leaves are present. As saplings develop more leaves, the significance of the leaves as a water storage organ becomes larger than that of the hypocotyl.
... Intrinsic leaf water use efficiency was calculated from gas exchange of CO 2 and H 2 O as the ratio of CO 2 assimilation (A) to stomatal conductance (g s ) at photon fluxes of 300 (net irradiance) and 1500 μmol m −2 s −1 (saturating irradiance), using a portable infra-red gas analyser (GFS-3000FL, Heinz Walz GmbH, Effeltrich, Germany). The water potential (Ψ leaf ) (Scholander et al., 1966) of the second youngest leaf with a fully expanded ligule was measured using a pressure chamber (Skye Instruments Ltd., Llandrindod Wells, UK). Leaf samples were excised at pre-dawn and midday, placed in aluminium folders to prevent transpiration and transferred to the laboratory, where they were measured immediately after each sampling under low light conditions. ...
Article
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Background and aims: Water deficit and salinity stresses are often experienced by plants concurrently; however, knowledge is limited about the effects of combined salinity and water deficit stress in plants, and especially in C4 bioenergy crops. Here we aim to understand how diverse drought tolerance traits may deliver tolerance to combinations of drought and salinity in C4 crops, and identify key traits that influence the productivity and biomass composition of novel Miscanthus genotypes under such conditions. Methods: Novel genotypes used included M. sinensis and M. floridulus species, pre-screened for different drought responses, plus the commercial accession Miscanthus × giganteus (M×g.). Plants were grown under control treatments, single stress or combinations of water deficit and moderate salinity stress. Morphophysiological responses, including growth, yield, gas exchange and leaf water relations and contents of proline, soluble sugars, ash and lignin were tested for significant genotypic and treatment effects. Key results: The results indicated that plants subjected to combined stresses showed more severe responses compared with single stresses. All novel drought-tolerant genotypes and M×g. were tolerant to moderate salinity stress. Biomass production in M. sinensis genotypes was more resilient to co-occurring stresses than that in M×g. and M. floridulus, which, despite the yield penalty produced more biomass overall. A stay-green M. sinensis genotype adopted a conservative growth strategy with few significant treatment effects. Proline biosynthesis was species-specific and was triggered by salinity and co-occurring stress treatments, mainly in M. floridulus. The ash content was compartmentalized differently in leaves and stems in the novel genotypes, indicating different mechanisms of ion accumulation. Conclusions: This study highlights the potential to select novel drought-tolerant Miscanthus genotypes that are resilient to combinations of stress and is expected to contribute to a deeper fundamental knowledge of different mechanistic responses identified for further exploitation in developing resilient Miscanthus crops.
... The osmotic pressure of leaf sap was measured by the cryoscopic method (Walter, 1949) and described by El-Sharkawi and Abdel-Rahman (1974). The plant sap was obtained by crushing portions of washed leaves according to Scholander et al. (1966). The sap obtained used for measurement of osmotic potential by the cryoscopic method of Walter (1931a) using a Beckman differential thermometer (calibrated to 0 AE 01 C). ...
Article
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The outstanding role of spermine in eliciting defense adaptation of soybean to different levels of water deficit (0, -0.1, -0.5 and -1.1 MPa) was investigated by determining the changes in growth, photosynthetic pigments, osmolytes, water relations, and antioxidants. All the studied traits clearly revealed cultivar-dependent variation in response to water deficit where cv. Giza 111 was tolerant and cv. Giza 21 was sensitive. Both cultivars came in agreement that photosynthetic limitation (chlorophylls reduction) was the troubling shot induced by water deficit. Such limitation was reflected on three directions (a) disturbances of water relations (stomatal conductance, transpiration rate, relative water content and water use efficiency), (b) down regulation of metabolites which affect osmotic adjustment and (c) elevated reactive oxygen species (increased hydrogen peroxide) and destruction of membrane stability (increment of electrolyte leakage and lipid peroxidation). The damaging impacts of water deficit on these parameters were obviously coined for sensitive cultivar compared to tolerant one. Although spermine priming did not have apparent stimulatory role on well-watered plants, unequivocal inversion from a state of down regulation to up-regulation was distinct under water stress. In this regard, spermine enhanced pigments, osmolytes accumulation, up-regulated water relations and enhanced membrane stabilization. Furthermore, spermine pre-sowing decreased oxidative stress by lowering hydrogen peroxide via activation of anthocyanins, total antioxidants and phenolic compounds.
... cal and physiological adaptations to prevent waterlogging of the leaves, but also to maintain adequate water potential (Ball, 1996) (Lovelock & Feller, 2003). However, as the osmotic potential of seawater is approximately -2.5 MPa (Sperry et al., 1988), mangrove leaf water potentials have to range between -2.5 and -6.0 MPa (M. A. Khan & Aziz, 2001;P. F. Scholander et al., 1966;Sobrado & Ewe, 2006). Salinity stress causes low stomatal conductance, which decreases the rate of CO2 accumulation and uptake, rate of transpiration and increase in xylem tension (Ball & Farquhar, 1984 Major planted species are Avicenna officinalis and Sonneratia apetala. Others are Excoecaria agallocha, Bruguiera gymnorhiza) and Nypa f ...
Article
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Currently, researchers in medical and pharmaceutical disciplines have been looking for alternative drug sources for better specificity and less cytotoxicity and, thus, heavily depend upon natural medicinal plants, seaweeds, marine micro-algae, etc., to fulfill the pharmaceutical demands. In marine habitats, both seaweed and microalgae serve as the component of bioresources, but very few of those are explored as a source of food, fodder, medicine, and valuable chemical ingredients. Against the backdrop of the current concept of 'Blue-Economy,' the algal resources of the Bay of Bengal deserve scrutiny so that their potentiality could be identified and used. The present review has been aimed to explore the various marine algal use over a global scale. Of the algal bioresources, the Genus: Cladophoropsis Børgesen includes green filamentous marine algal species growing naturally in the coastal belt of the Bay of Bengal. The present review reveals that the species is promising with its pharmacological values due to antimicrobial, anticancer, antioxidant, cytotoxic, anti-aging activities, and so on. So, to ensure its future use, an attempt has been made to compile the latest pharmacological information on Cladophoropsis sp. based on recently published scientific information. This review study will pave the way to satisfy the substantial pharmacological knowledge on Cladophoropsis spp.
... Measurement of plant water status during the day is leaf water potential (LWP) and can be estimated by using the pressure chamber and the osmotic potential of the xylem sap in leaves. LWP quantification is carried out using a pressure chamber according to the procedure defined by Scholander (1966). Pure water has a water potential of 0 (Zero) MegaPascals (MPa). ...
Chapter
Innovation is the utilization of information to viable prerequisites. Green developments envelop different parts of innovation, which assist us with diminishing the human effect on Earth and make methods of realistic development. Social equality, economic practicality, and manageability are the key boundaries for green developments. Today, Earth is hurtling toward the tipping point at which we cannot repair the harms we have caused. Our current activities are pulling the world toward a natural failure, which would make devastation unavoidable. Green developments are a methodology for saving Earth. Green innovation uses sustainable resources that never run out in new and innovative ways. Green nanotechnology that incorporates eco-friendly designs and scientific principles is one of the most recent types of innovations. One of the significant variables for natural contamination is the removal of waste. Green innovations can handle that too. It can successfully change consumption and creation such that it does not hurt the planet and we can make improvements toward environmental friendliness. Among the potential areas where these manifestations and developments can originate from are environmentally friendly energy sources, natural agriculture, eco-accommodating materials, green structure developments, and the assemblage of related items and materials to help green businesses develop. Other than different types of green innovations, the energy field primarily relies on sun-based energy and nonrenewable energy sources. These have no adverse impacts on the planet and will not recharge. A group of people yet to come could profit from them without hurting the planet. This chapter discusses types of green innovations and the advantages that they provide.
... Mangrove trees have the ability to survive and flourish in hypersaline conditions of the tropical intertidal forest community, and are called as natural "seawater desalinizer". This plant absorbs seawater and eliminates excess salt by an ultrafiltration process of its roots, and transports the water to the leaves by the capillary force via the small vessel channels connecting the roots to the leaves [32,33]. When exposed to sunlight, mangroves sediment high concentrations of salt as a result of transpiration on leaf surface, and the salt is then rejected from the salt glands densely distributed on the leaf surface. ...
Article
Floating solar still is considered as a land-saving, easy-operating and environmental-friendly approach for freshwater production. However, the low yield and work instability in actual weather conditions limits its application. To overcome these disadvantages, a bionic floating solar still inspired by water intake of plant roots was presented in this paper. The channels for water supply were distributed in array and wrapped in a whole thermal insulation sheet. With the design of simulating roots, the present desalination system achieves low heat losses, water-absorbing uniformity and structural stability. Cellulose fabric and glass were separately selected as evaporation and condensation materials of the experimental prototype after preliminary test. The outdoor experiment was conducted in Xingtai, China, and the accumulated radiation in the test day was 21.96 MJ/m 2. The maximum evaporation temperature and daily freshwater yield reached 59.2 • C and 1.5 kg/m 2 /d, respectively , which were the highest in comparison with existing floating solar stills. Next, the effect of rolling motion on humid air flow inside the still was investigated by CFD simulation. The results of this study will contribute to the further development of floating solar still, as well as the application of such small-scale desalination technologies.
Chapter
Many halophytic plants have epidermal glands on their leaves and stems which secrete salt (Metcalfe and Chalk, 1950). These glands have been considered efficient devices for the secretion of excess salt which accumulates in the tissue (Haberlandt, 1914; Helder, 1956; Scholander, 1968; Scholander et al., 1962; 1965; 1966). Helder (1956) indicated that salt glands were common in the families Plumbaginaceae and Frankeniaceae but only occurred in a few scattered species outside these families. However, many other plants are known to have trichomes, glands, and glandular structures, but in many instances further investigations are needed to determine their secretion products. Many of these may possibly be salt glands (i.e. specialized structures which secrete minerals and ions) and an understanding of the general distribution and significance of salt glands must await further information.
Article
Soil salinity seriously restricts agricultural production, especially for salt-sensitive crops. Understanding salt-tolerant plants will open new opportunities to crop breeders in attempts to increase salt tolerance in conventional crops. However, until now, few fundamental research findings related to halophytes have been applied to crop plants. Research has shown that apoplastic barriers, including Casparian bands (CBs) and suberin lamellae (SL), play an important role in Na⁺ and Cl- exclusion in both a few reported cases in halophytes and in some crop plants. In this paper, we discuss the role of CBs and SL in ion exclusion during plant salt tolerance, to evaluate whether they should be a key target for breeding salt-tolerant crops.
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The stability of the salt content in Salicornia pacifica Standi, var. utahensis (Tide-strom) Munz in relation to environmental changes was investigated. Salicornia pacifica communities have a characteristic soil pH of 7.5 to 8.0 ± 0.2 and a constant subsurface soil moisture level of 25 to 35 percent. The ion content in the tissue of S. pacifica remained constant despite increased moisture stress throughout the growing season. The concentrations of the salts were significantly higher in the surface soil layers than in the subsurface layers around the roots. Normal metabolic processes in the tissues of S. pacifica appear to occur even though some fluctuations in the ionic balance and concen-tration of ions in the plant occur.
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Salt-secreting structures of halophytes are very specialized salt devices involved in removal from plant organs. They represent an important strategy in halophytes' life facing with a high amount of salts in their environment. The structural diversity of these is quite limited to some basic types, although there is an extended language describing them. This could be sometimes confusing; our researches lead to the idea that the anatomical approach could be useful in order to clarify the role of secreting structures in the whole adaptive set of anatomical features in halophytes.
Article
Freeze-fracture electron microscopy was used to investigate intramembranous particle (IMP) densities and particle distributions in the plasma membrane and tonoplast of the cells of secreting and nonsecreting leaves of Avicennia germinans (L.) Steam. Intramembranous particle densities of the protoplasmic (P) and exoplasmic (E) face of the plasma membrane and tonoplast were significantly higher in hypodermal cells of secreting leaves than of nonsecreting leaves. In contrast, no significant differences in the frequency of intramembranous particles were found in any membrane faces of secreting or nonsecreting mesophyll cells. However, particle densities were higher in the plasma membrane and tonoplast of the mesophyll cells, compared to the hypodermal cells, with the exception of the P-face of hypodermal plasma membranes of secreting tissue, which had the highest particle density measured. Particle distributions were dispersed and no discernible patterns such as paracrystalline arrays or other multi-IMP structures were observed. Results support the hypothesis that secretion is coupled to changes in membrane ultrastructure, and the possibility that salt secretion is an active process driven by integral membrane proteins such as the H⁺/ATPase. Additionally, the hypodermal cells of the leaf may function as storage reservoirs for salt as well as water, suggesting a regulatory role in salt secretion.
Chapter
“Mangrove” is an ecological term referring to a taxonomically diverse association of woody trees and shrubs that form the dominant vegetation in tidal, sahne wetlands along tropical and subtropical coasts (Tomlinson, 1986). There, moist lowland rainforest gives way to mangrove vegetation where the forest experiences tidal inundation with saline water. There is an abrupt transition from rainforest, with its high diversity of tree species, to mangrove forest of relatively few species. The diverse assemblage of life forms so common in rainforest gives way to forest where vines, palms, ferns, and epiphytes are poorly represented and conifers are absent (Tomlinson, 1986). For example, Tomlinson (1986) conservatively recorded 114 species from 66 genera in his treatment of the floristics of mangrove forests worldwide, with species richness being greatest in the Indo-Pacific region. Thus, fewer mangrove species are found worldwide than one might encounter in a few hectares of moist tropical forest, particularly in areas supporting the greatest biodiversity (Whitmore, 1992).
Chapter
“Mangrove” is an ecological term referring to a taxonomically diverse association of woody trees and shrubs that form the dominant vegetation in tidal, saline wetlands along tropical and subtropical coasts (Tomlinson 1986). The photosynthetic characteristics of mangroves are clearly those of plants utilizing C3 photosynthetic biochemistry (Ball 1986). There is, however, a remarkable feature of the gas exchange characteristics of mangroves. Despite growing in environments with an abundant water supply, they transpire slowly and maintain high water use efficiencies for C3 plants (Ball and Farquhar 1984a,b). These water use characteristics become increasingly conservative with increase in the salinities in which the plants are grown and with increase in the salt tolerance of the species (Ball 1988a). Conservative water use may have adaptive significance for survival in saline environments, but such behavior has far-reaching consequences for plant functioning. Maximizing carbon gain relative to water use is a whole-plant phenomenon involving a complex balance between several levels of plant function: stomatal behavior in relation to photosynthesis, variation in leaf properties in relation to light interception and evaporative demand, and the partitioning of carbon between structures supplying and those consuming carbon-based assimilates (Cowan and Farquhar 1977; Cowan 1986). Differences in water use characteristics thus find expression at all levels of plant form and function, and indeed are major determinants of mangrove forest structure along natural salinity gradients (Ball 1988a).
Article
Since the publication of the first edition of this book ten years ago, international research into the physiological ecology of plants in the tropics has increased enormously in quantity and quality. This brand new edition brings the story right up to date. New approaches have been developed in remote sensing. At the other end of the scale, molecular biology has come on in leaps and bounds, particularly regarding ecological performance of tropical plants, e.g. in understanding the adaptation of resurrection plants to the extreme habitat of inselbergs. In this fully revised and updated second edition the wealth of new information has made it necessary to break large chapters down into smaller ones. Tropical forests which occupy about half of the entire volume of the book are now arranged in five chapters covering structure and function under the influence of environmental cues and including epiphytes and mangroves as part of the tropical forest complex. Savannas are now treated in two chapters. Meanwhile, coastal salinas have been combined with a new section on the Brazilian restingas in a chapter on coastal sand plains.
Chapter
Halophytes are plants which complete their life cycle in an environment which has a high salt content and may be contrasted with glycophytes which are plants that are intolerant of such high salt levels. Mangroves are classed as halophytes as they are trees and shrubs that grow primarily in saline habitats. The definition is vague in two important aspects, namely the nature of the salts involved and their concentrations. For species such as Rhizophora stylosa which grows in seawater, the concentration of salt water content is set by the composition of sea water (Table 1). Higher concentrations will naturally occur during periods of high insolation between tides and lower concentrations during periods of rainfall. Other species, such as Aegiceras corniculatum, appear to prefer less saline habitats. Table 2 shows some data on the effect of salinity on growth of five species of mangrove. It is clear that there are some discrepancies in this data but that for these species at least there is some evidence for salt mediated growth. This does not mean that these mangroves require salt for successful growth and most mangroves probably grow reasonably well in freshwater. Indeed, it has been suggested by Snedaker (1979) that freshwater is a physiological requirement and salt water is an ecological requirement. The former prevents excess respiratory losses and the latter prevents invasion and competition of non-halophytes. It may be reasonable therefore to assume that most mangroves are not obligate halophytes.
Article
The rise of sap in mangroves has puzzled plant physiologists for many decades. The current consensus is that negative pressures in the xylem exist which are sufficiently high to exceed the osmotic pressure of seawater (2.5 MPa). This implies that the radial reflection coefficients of the mangrove roots are equal to unity. However, direct pressure probe measurements in xylem vessels of the roots and stems of mangrove (Rhizophora mangle) grown in the laboratory or in the field yielded below-atmospheric, positive (absolute) pressure values. Slightly negative pressure values were recorded only occasionally. Xylem pressure did not change significantly when the plants were transferred from tap water to solutions containing up to 1700 mOsmol kg−1 NaCl. This indicates that the radial reflection coefficient of the roots for salt, and therefore the effective osmotic pressure of the external solution, was essentially zero as already reported for other halophytes. The low values of xylem tension measured with the xylem pressure probe were consistent with previously published data obtained using the vacuum/leafy twig technique. Values of xylem tension determined with these two methods were nearly two orders of magnitude smaller than those estimated for mangrove using the pressure chamber technique (−3 to −6MPa). Xylem pressure probe measurements and staining experiments with alcian blue and other dyes gave strong evidence that the xylem vessels contained viscous, mucilage- and/or protein-related compounds. Production of these compounds resulting from wound or other artifactual reactions was excluded. The very low sap flow rates of about 20–50 cm h−1 measured in these mangrove plants were consistent with the presence of high molecular weight polymeric substances in the xylem sap. The presence of viscous substances in the xylem sap of mangroves has the following implications for traditional xylem pressure measurement techniques, development of xylem tension, and longdistance water transport: (1) high external balancing pressures in the pressure chamber are needed to force xylem sap to the cut surface of the twig; (2) stable tensions much larger than 0.1 MPa can be developed only occasionally because viscous solutions provide nucleation sites for gas bubble formation; (3) the frequent presence of small gas bubbles in viscous solutions allows water transport by interfacial, gravity-independent streaming at gas/water interfaces and (4) the increased density of viscous solutions creates (gravity-dependent) convectional flows. Density-driven convectional flows and interfacial streaming, but also the very low radial reflection coefficient of the roots to NaCl are apparently the means by which R. mangle maintains water transport to its leaves despite the high salinity of the environment.
Article
The relative changes in osmolality of leaf tissue, xylem sap and leaf secretion, as well as leaf gas exchange characteristics of the mangrove A. germinans, cultivated under moderate salinity (0 to 428 mol NaCl m-3) and hypersaline conditions (856 mol NaCl m-3), were examined. Water content and net amount of solutes per unit leaf area increased at moderate salinity, and then declined under hypersalinity. Osmolality of xylem sap increased with salinity treatment in actively transpiring plants as well as at night when transpiration was minimized. However, osmolality values of salt-treated plants were higher at night than during the day, which indicated the dependence of this parameter on water flow. At moderate salinity, salt secretion increased with salinity treatment. This allowed plants to reduce water uptake slightly and to maintain relatively high carbon assimilation. However, under hypersaline conditions, salt secretion tended to be limited, which may be the result of a saturated process. Salt secretion is a highly active mechanism and involves several metabolically controlled steps. Therefore, in hypersaline conditions, decreases in the solutes carried to leaves were more important. Thus. stomatal conductance of A. germinans was severely reduced. However, this lead also to a drastic reduction in carbon assimilation rates.
Article
In order to determine the drip irrigation zone adequate to control drought stress, we investigated the influence of drought stress under different ratios of the irrigation zone on citrus trees. The results showed that there was a clear correlation between the irrigation zone and drought stress of trees. It was indicated that, in the case of young trees, a greater than 50% irrigation zone out of the root zone was required in order to protect them from overdryness. In the case of adult trees, over 19.5% was necessary for 13-year-old ‘Shiranui’, and over 14.2% for 21-year-old ‘Haraguchi-wase’. Drip tubes should be placed within 100 cm from trunks where fine roots are densely distributed. An appropriate irrigation time was estimated to be 20 minutes in granite soil, 20–60 minutes in basalt soil, and 60 minutes in andesite and volcanic ash soils. In addition, it was indicated that the dripper interval should be more than 20 cm in granite soil and more than 30 cm in the three other kinds of soil to reduce water wastage.
Article
Three Atriplex species (Chenopodiaceae) native to saline areas of north-west India were grown in leak proof polythene begs under control (S 0), 8 dS/m (S1) and 16 dS/m (S2) salinity. It was observed that the plant height, shoot fresh weight, shoot dry weight, water content and ion contents increased with increasing salinity from control to 16 dS/m in Atriplex nummalaria and Atriplex amnicola but in Atriplex lentiformis these growth parameters declined at 16 dS/m. It concluded that the A. nummularia and A. amnicola were hyper accumulators and used for the restoration and rehabilitation of saline degraded lands. A. lentiformis was used for reclamation of soil up to 8 dS/m.
Chapter
The physiology of the roots of mangroves has received relatively little attention. The present experiments are concerned with the mangrove Avicennia marina and the accepted behaviour of this mangrove was described by Scholander (1962, 1966). It is believed that this mangrove only partially excludes salt at its roots but that it is capable of excreting large quantities of salt from its leaves. The xylem sap concentration for Avicennia is stated as being 10–20% of the NaCI present in seawater.
Chapter
Salt glands—identified and described as early as the mid-nineteenth century—represent sophisticated anatomical devices involved in the removal of salts in excess from aerial parts of halophytes. Major types of secretory structures are being discussed in respect to the large diversity of taxonomical representatives: salt glands (typical to Plumbaginaceae, Frankeniaceae, Tamaricaceae, Primulaceae, and mangroves), salt (vezicular) bladders of Chenopodiaceae species, and epidermal bladder cells found in Mesembryanthemaceae.
Article
Full-text available
Sonneratia caseolaris is a pioneer species in mangrove. It can naturally grow in both saltwater and freshwater. The study was aimed at investigating and comparing the anatomical character of the S. caseolaris plants growing in different conditions and how they coped with salinity. The anatomical characteristics of roots, stems, petioles and leaf blade were investigated. The plant samples were prepared into permanent slides using a paraffin method, while the wood samples were made into permanent slides using a sliding microtome technique. Tissue clearing of leaf blade and scanning electron microscopic analysis of wood were performed. In addition, sodium chloride content in various organs and tissues was examined. It was found that cable root, stem and leaf blade showed some different anatomical characteristics between the two conditions. Periderm is a prominent tissue in saltwater roots. Tanniferous cells were observed in pneumatophores, petioles, stems and leaf blades of saltwater plants, but not found in pneumatophores and lamina of freshwater plants. Mesophyll thickness was lower in the saltwater condition. The vessel density was significantly higher in the saltwater condition than in the freshwater condition, whereas the vessel diameters in the freshwater condition were significantly higher than those in the saltwater condition. From the results, it can be concluded that root periderm plays an important role in salt exclusion, and the occurrence of tanniferous cells is associated with salt elimination.
Article
Dry matter production of Salicornia is correlated directly to NaCl-concentration of the nutrient solution. In Salicornia there could be demonstrated a clear antagonism between Na⁺ and K⁺, as well as between Na⁺ and alkaline earths; while Na⁺ is accumulated proportionally with increasing NaCl- concentration, K⁺-, Ca2 +- and Mg2 +-content of the plants is reduced. Less than 10% of the total Ca2 +-content is water soluble. In the water extract the ratio of Ca2 + to Mg2 + is 0.05, in the hydrochloric acid extract the ratio is 0.6. Whereas the accumulation of Cl⁻-ions by Salicornia corresponds to the salt supply, there is no significant NaCl-effect on nitrate-absorption. Plants growing in a salt-free medium contain less phosphate than those cultivated in a saline solution.
Article
The seasonal water relations of four plant species native to Death Valley were studied which were growing under both natural and irrigated conditions. These species included the winter annual, Camissonia claviformis, a summer-active herbaceous perennial, Tidestromia oblongifolia, and two evergreen perennials, Atriplex hymenelytra and, Larrea tridentata. Camissonia a plant with a high photosynthetic capacity had characteristics typical of most mesophytes under natural conditions and maintained high tissue water contents as well as high water and osmotic potential. Irrigation had little effect on these parameters for Camissonia. Tidestromia, which also has an unusually high photosynthetic capacity as well as a high rate of transpiration under natural conditions also has water balance characteristics not unlike many mesophytes although not to the same degree as Camissonia. The evergreen drought-enduring species which have a comparatively low photosynthetic capacity maintain low water and solute potentials at all seasons. Even at dawn when irrigated these species have low water potentials especially during the summer. In these xerophytes solute potential decreases during the course of the day. During the summer the plants under natural conditions have turgor pressures close to zero. The differential inherent photosynthetic capacities of these species are apparently strongly related to their inherent water balance characteristics.
Article
Il est montré que les communications relatives aux caractéristiques physiologiques des végétaux halophiles ou résistant aux sels vont permettre d'analyser: • le comportement de ces plantes vis-à-vis de fortes doses de NaCl; • la dilution des sels que peut créer la construction d'organes succulents; • l'alimentation minérale et hydrique des végétaux placés en milieu salé; • les particularités de la respiration, de la photosynthèse et du métabolisme azoté des halophytes.
Chapter
The deficiencies in present knowledge concerning the behaviour of ionic species within the plant are discussed, with particular reference to the leaf; and a possible experimental approach to these problems is developed. Briefly, a distinction must be made between ions entering plant tissue and subsequent partition of ions between extracellular and cellular compartments. With techniques at present available the dynamic state of the extracellular compartment with respect to any particular ion can be determined. Using tissue slices, and duplicating the native state of the leaf cell, information on the ionic and water relations of the leaf cell could be obtained. Extrapolation of such data to the native state may enable distinction to be drawn between the ‘osmotic’ and ‘specific ion toxicity’ theories of salt damage.
Article
Aims: The objective of this study was to investigate the change pattern of leaves photosynthesis and stem sap flow of Tamarix chinensis in under different groundwater salinity, which can be served as a theoretical basis and technical reference for cultivation and management of T. chinensis in shallow groundwater table around Yellow River Delta. Methods: Three-year-old T. chinensis, one of the dominated species in Yellow River Delta, was selected. Plants were treated by four different salinity concentrations of groundwater - fresh water (0 g·L⁻¹), brackish water (3.0 g·L⁻¹), saline water (8.0 g·L⁻¹), and salt water (20.0 g·L⁻¹) under 1.2 m groundwater level. Light response of photosynthesis and the diurnal courses of leaf transpiration rate, stem sap flux velocity and environment factors under different groundwater salinity were determined via LI-6400XT portable photosynthesis system and a Dynamax packaged stem sap flow gauge based on stem-heat balance method, respectively. Important findings: The result showed that groundwater salinity had a significant impact on photosynthesis efficiency and water consumption capacity of T. chinensis by influencing the soil salt. The net photosynthetic rate (Pn), maximum Pn, transpiration rate, stomatal conductance, apparent quantum yield and dark respiration rate increased first and then decreased with increasing groundwater salinity, while the water use efficiency (WUE) continuously decreased. The mean Pn under fresh water, brackish water and salt water decreased by 44.1%, 15.1% and 62.6%, respectively, compared with that under saline water (25.90 μmol·m⁻²·s⁻¹). The mean WUE under brackish water, saline water and salt water decreased by 25.0%, 29.2% and 41.7%, respectively, compared with that under fresh water (2.40 μmol·mmol⁻¹). With the increase of groundwater salinity from brackish water to salt water, light saturation point of T. chinensis decreased while the light compensation point increased, which lead to the decrease of light ecological amplitude and light use efficiency. Fresh water and brackish water treatment helped T. chinensis to use low or high level light, which could significantly improve the utilization rate of light energy. The decrease in Pn of T. chinensis was mainly due to non-stomatal limitation under treatment from saline water to fresh water, while the decrease in Pn of T. chinensis was due to stomatal limitation from saline water to salt water. With increasing groundwater salinity, stem sap flux velocity of T. chinensis increased firstly and then decreased, reached the maximum value under saline water. The mean stem sap flux velocity under fresh water, brackish water and salt water decreased by 61.8%, 13.1% and 41.9%, respectively, compared with that under saline water (16.96 g·h⁻¹). Tamarix chinensis had higher photosynthetic productivity under saline water treatment, and could attained high WUE under severe water deprivation by transpiration, which was suitable for the growth of T. chinensis.
Article
Nature‐driven designs for water crisis have shown much interest in energy‐efficient water treatment. This review discusses four different bioinspired systems, aquaporin membranes, mussel‐inspired amine‐based membranes, supramolecular architectures, and cactus/mangrove desalination. The authors have also delineated their contributions and mechanisms toward forming water pathways for effective desalination. The discussion is mainly channelized toward constructing generic approaches based on membranes with diverse shapes and dimensions, including hierarchically structured membranes. The separation properties of these bioinspired systems stem from their chemical and physical structures imparting selectivity in the separation of ions, pollutants, etc. Further, this review covers the practical methodologies for next‐generation energy‐efficient membranes and outlines the perspectives regarding the upcoming developments in water technology. This review starts by featuring the significant difficulties associated with nature‐motivated frameworks and recommend some comparing healing measures. Along these lines, the arising advancements in the creation of nature‐motivated layers toward the components administered by channels give biomimetic films including aquaporin biomimetic layers, layers propelled from mangrove trees and water pathway channels roused from desert plant, supramolecular biomimetic layers, and mussel‐enlivened layers.
Article
We investigated the relationships among interstitial salinity leaf sclerophylly, plant vigor, and population density for the leaf galling insect Cecidomyia avicennine (Diptera: Cecidomyiidae) on its host plant Avicennia germinans (Avicenniaceae). Sampling was done in six mangrove stands and in one varzea forest of Maranhao, northeast Brazil. At each site, ten shoots were randomly taken on five A, germinans trees. From each shout we counted the coral number of galls and recorded the shout length (cm). We also recorded the average length, width, total area, and biomass of leaves per shoot. Leaf sclerophylly was quantified by leaf biomass per unit area (g/cm(2)). Samples of interstitial water were taken by a 1.3-cm PVC tube with 80 cm of depth, and salinity (ppt) was measured with a refractometer. Leaf sclerophylly showed a positive relationship with interstitial salinity (R(2) = 0.77, P < 0.05). We also observed positive relationships between gall density per unit of leaf area (cm(2)) and salinity (r = 0.36, P ( 0.05), and between gal density and leaf sclerophylly (r = 0.40, P < 0.05). The salinity and the leaf sclerophylly together explained 22 percent of the variation in gall density of C. avicenniae. We found a negative relationship between the number of galls per centimeter and shoot length (R(2) = 0.50, P < 0.05). Thus, longer shoots of A. germinans showed lower gall density. Our results suggest that the gall density of C. avicenn iae on A. germinans is affected by the salinity of host plant habitat and by leaf sclerophylly along an interstitial salinity gradient.
Article
Possible sites of iron pumping associated with glandular salt excretion from the leaf of the mangrove Avicennia marina were investigated using energy-dispersive X-ray analysis and ATPase cytochemistry. The collecting cells of the gland had low sodium and chlorine ratios and high potassium ratios. This contrasted with the stalk/excretory cells of the gland which had very high chlorine ratios and lower potassium ratios. Considerable ATPase activity was localized at the stalk cell plasmalemma in the region of the stalk cell / collecting cell interface, and at the collecting cell plasmalemma. It is suggested that these are sites of active ion influx into the gland. The low chlorine ratio within the collecting cells by comparison to the xylem vessels and the surrounding spongy mesophyll suggests that the collecting cells are at the endpoint of a symplastic and possibly an apoplastic downhill ion gradient. ATPase activity associated with the plasmalemma of the excretory cells suggests that efflux from the gland is also an active process.
Chapter
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Chapter
Transport is an important feature of the contact between plants and their environment. In many lower plants, the plant body, or the population of cells is predominantly of a single type and this cell type mediates all the exchanges between the plant and its environment. This is partly the reason why certain algal cells (Part A, Chap. 6) and fungal hyphae (Part A, Chap. 7) have become standard systems for study of transport processes (e.g. Chara, Chlorella, Neurospora).
Article
Advantages, disadvantages and precautions of using the pressure chamber and thermocouple psychrometers for determinations of plant water potential. and osmotic and turgor pressures are discussed. Comparison of results obtained with both instruments will be influenced by the sampling technique, consistency in both sampling and measurement procedures, and errors inherent to the method itself. In-situ readings of either plant or soil water potential with thermocouple psychrometers are perhaps worthless, or worse (they may even be misleading). Use of thermocouple psychrometers is strictly limited to the laboratory where isothermal conditions can be obtained. The method to determine the water relations of plant tissues should be chosen according to the plant material and the research objectives.
Article
Impedance measurement is a widely used technique for monitoring ion species in various applications. In plant cultivation, the impedance system is used to measure the electrical conductivity (EC) of nutrient solutions. Recent research has shown that the quality and quantity of horticultural crops, e.g. tomato, can be optimized by controlling the salinity of nutrient solutions. However, understanding the detailed response of a plant to a nutrient solution is not possible until the fruit is fully grown or by sacrificing the stem. To overcome this issue, horticultural crop cultivation requires real-time monitoring of the EC inside the stem. Using this data, the growth model of a plant could be constructed, and the response of the plant to external environment determined. In this paper, we propose an implantable microneedle device equipped with a micro-patterned impedance measurement system for direct measurement of the EC inside the tomato stem. The fabrication process includes silicon-based steps such as microscale deposition, photolithography, and a deep etching process. Further, microscale fabrication enables all functional elements to fulfill the area budget and be very accurate with minimal plant invasion. A two-electrode geometry is used to match the measurement condition of the tomato stem. Real-time measurement of local sap condition inside the plant in which real-time data for tomato sap EC is obtained after calibration at various concentrations of standard solution demonstrate the efficacy of the proposed device.
Article
Full-text available
The scarcity of fresh water is a global challenge faced at present. Several desalination methods have been suggested to secure fresh water from sea water. However, conventional methods suffer from technical limitations, such as high power consumption, expensive operating costs, and limited system durability. In this study, we examined the feasibility of using halophytes as a novel technology of desalinating high-concentration saline water for long periods. This study investigated the biophysical characteristics of sea water filtration in the roots of the mangrove Rhizophora stylosa from a plant hydrodynamic point of view. R. stylosa can grow even in saline water, and the salt level in its roots is regulated within a certain threshold value through filtration. The root possesses a hierarchical, triple layered pore structure in the epidermis, and most Na+ ions are filtered at the first sublayer of the outermost layer. The high blockage of Na+ ions is attributed to the high surface zeta potential of the first layer. The second layer, which is composed of macroporous structures, also facilitates Na+ ion filtration. This study provides insights into the mechanism underlying water filtration through halophyte roots and serves as a basis for the development of a novel bio-inspired desalination method.
Article
Zusammenfassung Salicornia-Pflanzen salzreicher Böden zeichnen sich gegenüber Pflanzen weniger haliner Standorte durch prostraten Wuchs, verringertes Frisch- und Trockengewicht und verminderten Stickstoffgehalt aus. Die Chlorophyllbildung ist stark herabgesetzt, dafür kommt es aber zur vermehrten Ausbildung von Betacyanen. Durch eine zusätzliche Stickstoffdüngung über wöchentliche Besprühung von Versuchsparzellen derartiger Salicornieta mit 1 % Harnstoff in Meerwasser lassen sich diese Mangelerscheinungen — bei Aufrechterhaltung aller übrigen Milieufaktoren — nahezu oder völlig aufheben. Die hervorragende Bedeutung des Stickstoffs vor allem für die Zunahme des Chlorophyllgehaltes und für die Verminderung der Betacyansynthese wird unter besonderer Berücksichtigung des Halophytenproblems diskutiert, und es wird die Schlußfolgerung gezogen, daß nicht ausschließlich der erhöhte Salzgehalt und ein Mangel an Nährstoffen im Substrat, sondern auch deren erschwerte Ausbeute seitens des Wurzelsystems der Pflanze die Ursache für das beschriebene Verhalten der Pflanzen auf stark halinen Standorten darstellt.
Article
A method is described which permits measurement of sap pressure in the xylem of vascular plants. As long predicted, sap pressures during transpiration are normally negative, ranging from -4 or -5 atmospheres in a damp forest to -80 atmospheres in the desert. Mangroves and other halophytes maintain at all times a sap pressure of -35 to -60 atmospheres. Mistletoes have greater suction than their hosts, usually by 10 to 20 atmospheres. Diurnal cycles of 10 to 20 atmospheres are common. In tall conifers there is a hydrostatic pressure gradient that closely corresponds to the height and seems surprisingly little influenced by the intensity of transpiration. Sap extruded from the xylem by gas pressure on the leaves is practically pure water. At zero turgor this procedure gives a linear relation between the intracellular concentration and the tension of the xylem.
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