Potential utilisation of halophytes for the rehabilitation and valorisation of salt-affected areas in Tunisia (original) (raw)
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Introduction to the Special Issue: Halophytes in a changing world
Aob Plants, 2015
Climate change will bring about rising sea levels and increasing drought, both of which will contribute to increasing salinization in many regions of the world. There will be consequent effects on our crops, which cannot withstand significant salinization. This Special Issue looks at the roles that can be played by halophytes, extremophiles that do tolerate salinities toxic to most plants. In an ecological context, papers deal with the conservation of a rare species, the effects of rising concentrations of CO 2 and flooding on coastal vegetation, and the consequences of tree planting in inland plains for salinization. Physiological studies deal with the different effects of chlorides and sulfates on the growth of halophytes, the ability of some parasitic plants to develop succulence when growing on halophytic hosts and the interesting finding that halophytes growing in their natural habitat do not show signs of oxidative stress. Nevertheless, spraying with ascorbic acid can enhance ascorbic acid-dependent antioxidant enzymes and growth in a species of Limonium. Enzymes preventing oxidative stress are expressed constitutively as is the case with the vacuolar H-ATPase, a key enzyme in ion compartmentation. A comparison of salt-excreting and non-excreting grasses showed the former to have higher shoot to root Na + ratios than the latter. A particularly tolerant turf grass is described, as is the significance of its ability to secrete ions. A study of 38 species showed the importance of the interaction of a low osmotic potential and cell wall properties in maintaining growth. From an applied point of view, the importance of identifying genotypes and selecting those best suited for the product required, optimizing the conditions necessary for germination and maximizing yield are described. The consequence of selection for agronomic traits on salt tolerance is evaluated, as is the use of halophytes as green manures. Halophytes are remarkable plants: they are rare in relation to the total number of flowering plants and they tolerate salinities that most species cannot. It is clear from the papers published in this Special Issue that research into halophytes has a distinct place in aiding our understanding of salt tolerance in plants, an understanding that is likely to be of importance as climate change and population growth combine to challenge our ability to feed the human population of the world.
A critical review on halophytes: Salt tolerant plants
academicjournals.org
Present work deals with the different mechanisms which are present in salt tolerant plants against high salt concentrations of the soil by combining information from different research papers to make a comprehensive account of halophytes. It covers all the aspects of halophytes regarding their classification, mechanisms against high salt concentrations (both at physiological and molecular level). Furthermore, the article discusses the importance of halophytes and some aspects regarding the transformation of non-salt tolerant plants to salt tolerant plants. ~400 million hectares land is affected by salinity and this area is increasing day by day due to excessive irrigation practices also the world population is tremendously increasing hence we need a large amount of food supply. The crops cannot be grown on a salt affected land but nature has provided us with a unique group of plants that is, halophytes. Owing to the consumption of fossil fuels we need the fuel that can be obtained from plants and halophytes can be a good approach in this respect. They can be grown on salt affected lands, by identifying the genes present in them functioning against salinity production of transgenic crops can be done.
Freshwater resources will become limited in near future and it is necessary to develop sustainable biological production systems, which can tolerate hyper-osmotic and hyper-ionic salinity. Plants growing in saline conditions primarily have to cope with osmotic stress followed by specific ion effects, their toxicities, ion disequilibrium and related ramifications such as oxidative burst. This is an exclusion criterion for the majority of our common crops. In order to survive under such conditions, suitable adjustments are necessary. Beside the control of the entrance on root level, the ability to secrete ions (excreter) or to dilute ions (succulents) helps to preserve a vital ion balance inside the tissues.
† Background Freshwater comprises about a mere 2. 5 % of total global water, of which approximately two-thirds is locked into glaciers at the polar ice caps and on mountains. In conjunction with this, in many instances irrigation with freshwater causes an increase in soil salinity due to overirrigation of agricultural land, inefficient water use and poor drainage of unsuitable soils. The problem of salinity was recognized a long time ago and, due to the importance of irrigated agriculture, numerous efforts have been devoted towards improving crop species for better utilization of saline soils and water. Irrigating plants with saline water is a challenge for practitioners and researchers throughout the world. † Scope Recruiting wild halophytes with economic potential was suggested several decades ago as a way to reduce the damage caused by salinization of soil and water. A range of cultivation systems for the utilization of halophytes have been developed, for the production of biofuel, purification of saline effluent in constructed wetlands, landscaping , cultivation of gourmet vegetables, and more. This review critically analyses past and present halophyte-based production systems in the context of genetics, physiology, agrotechnical issues and product value. There are still difficulties that need to be overcome, such as direct germination in saline conditions or genotype selection. However, more and more research is being directed not only towards determining salt tolerance of halophytes, but also to the improvement of agricultural traits for long-term progress.
Responses of Halophytes to Salt Stress
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca: Horticulture, 2007
Halophytes. plants naturally adapted to conditions of high salinity in the soil. have been the subject of many different studies but. paradoxically. not so much to investigate the mechanisms of salt tolerance at the biochemical and molecular level. Halophytes can be considered important. but underutilised. genetic resources for the identification of salt tolerance determinants. We present here a brief summary of the initial results of our ongoing. multidisciplinary studies on the general responses to salt stress in halophytes of the genera Plantago and Juncus. focusing on the effect of NaCl on seed germination. vegetative growth. reproductive development. and on the accumulation of mono and divalent cations and putative osmolytes in the aerial part of the plants
Evaluation of salt tolerance in selected Qatari halophytes at the two initial growth stages
2016
Scarcity of water and availability of land for agricultural production are the most environmental issues that facing the (GCC) countries and Qatar one of them. Qatar lies in region which characterized by having high evaporation rate and minimum rate of precipitation, so the salt built on the soil in relatively high concentration. The natural vegetation of Qatar is scarce, scattered and limited to certain areas. Halophytes could play a major role to minimize adverse environmental impacts, such as global warming and the enhancement of primary productivity. The present study is kind of the first in screening for local halophytes to quantify their level of tolerance to saline environment. The outcome of this research is expected to serve future research in investigating halophyte economical values and their utilization of the salt effected lands in coastal and in inland areas of Qatar. Seven treatment levels of different concentrations of NaCl including the control treatment (0, 50, 100, 200, 400, 600 and 800 mM NaCl) were used to evaluate both seed germination stage and seedling growth of selected Qatari halophytes. Eight halophyte species were selected for the seed germination experiment those are: Salsola setifera, Halopeplis perfoliata, Caroxylon imbricatum, Suaeda aegyptiaca, Acacia tortilis, Limonium axillare, Tetraena qatarensis and Aeluropus lagopoides. In general the seed germination experiments showed a decrease in the rate of germination as the salt concentration increased. Most of the studied species had a degree of germination up to 200 mM NaCl. The recovery of seeds subjected to high salt concentration have shown a rapid high percentage recovery up to 94% after being subjected to 600 mM NaCl for Halopeplis perfoliata. Five halophytes species were selected to be used for the seedling growth experiments. The two measured parameters used to evaluate the effect of salt concentrations on seedling growth are plant height and dry weight (biomass) for both above and belowground parts. The obtained results from all measured parameters showed no significant differences among seedlings of Caroxylon imbricatum, Suaeda aegyptiaca and Tetraena qatarensis. In respect to different salinity concentrations, Our results indicated that future utilizing of these plants for any commercial product will be valuable to secure drinking water and food in Qatar.
Salt Tolerance and Crop Potential of Halophytes
Critical Reviews in Plant Sciences, 1999
Although they represent only 2% of terrestrial plant species, halophytes are present in about half the higher plant families and represent a wide diversity of plant forms. Despite their polyphyletic origins, halophytes appear to have evolved the same basic method of osmotic adjustment: accumulation of inorganic salts, mainly NaCl, in the vacuole and accumulation of organic solutes in the cytoplasm. Differences between halophyte and glycophyte ion transport systems are becoming apparent. The pathways by which Na + and Clenters halophyte cells are not well understood but may involve ion channels and pinocytosis, in addition to Na + and Cltransporters. Na + uptake into vacuoles requires Na + /H + antiporters in the tonoplast and H + ATPases and perhaps PP i ases to provide the proton motive force. Tonoplast antiporters are constitutive in halophytes, whereas they must be activated by NaCl in salt-tolerant glycophytes, and they may be absent from salt-sensitive glycophytes. Halophyte vacuoles may have a modified lipid composition to prevent leakage of Na + back to the cytoplasm. Becuase of their diversity, halophytes have been regarded as a rich source of potential new crops. Halophytes have been tested as vegetable, forage, and oilseed crops in agronomic field trials. The most productive species yield 10 to 20 ton/ha of biomass on seawater irrigation, equivalent to conventional crops. The oilseed halophyte, Salicornia bigelovii , yields 2 t/ha of seed containing 28% oil and 31% protein, similar to soybean yield and seed quality. Halophytes grown on seawater require a leaching fraction to control soil salts, but at lower salinities they outperform conventional crops in yield and water use efficiency. Halophyte forage and seed products can replace conventional ingredients in animal feeding systems, with some restrictions on their use due to high salt content and antinutritional compounds present in some species. Halophytes have applications in recycling saline agricultural wastewater and reclaiming salt-affected soil in arid-zone irrigation districts.
Salt tolerance of selected halophytes at the two initial growth stages for future management options
Scientific Reports, 2021
Scarcity of water and the small area of the agricultural land are considered as the crucial environmental issues challenged the Arabian Gulf countries. In this study, experiments were conducted to identify the salt tolerance during the germination and the seedling stages of some native halophytes in the State of Qatar. Seeds of eight native species (Salsola setifera, Halopeplis perfoliata, Caroxylon imbricatum, Suaeda aegyptiaca, Acacia tortilis, Limonium axillare, Tetraena qatarensis and Aeluropus lagopoides) were investigated. Except for Tetraena qatarensis, Acacia tortilis and Suaeda aegyptiaca, all achieved ≥ 30% of seed germination at a concentration of 200 mM NaCl. Around 30% of Salsola setifera seeds were able to germinate in a salt concentration of 400 mM. Germination recovery of seeds that have been treated with 800 mM NaCl for 3 weeks was the greatest for Halopeplis perfoliata (94%) and the lowest for Aeluropus lagopoides (22%). Five halophytes were investigated for seedli...
Coping with Saline Environment: Learning from Halophytes
Plant Ecophysiology and Adaptation under Climate Change: Mechanisms and Perspectives I
Salt stress is a crucial barrier to crop growth, development, and production and hence negatively affects food security globally. In addition, the current trends of climate change increase the frequencies and severities of drought and heat which accelerate and spread the processes of salt mobilization and accumulation within the upper horizons of arid and semiarid soil. Elevated salinization in arid and semiarid regions necessitates development of economic and environmentally friendly saline agriculture to be comparable with world population increase. As salt stress is a multi-factorial phenomenon caused by various factors or a combination of factors leading to a complex tolerance mechanism, the utilization of suited