I made a study to investigate the ionic contents and nutritive value of big saltbush (A. lentiformis) and old man saltbush (A. nummularia) during the different seasons of the year.
I found some results needed to explanations:
1- during high temperature conditions the plants tend to increase the Na, K and Cl in leaves, while under low temperature conditions they tend to minimize the concentration of that ions.
2- during the high temperature conditions the phosphorus concentrations and water content were declined.
3- the crude protein in the tested plants increased in low temperature and decreased in high temperature.
I suggest that these plants increase their Na , K and Cl in heat condition and minimize water content to make osmotic adjustment to minimize the water loss during high temperature condition.
If that correct can any one help me with some literature references?
My Dear Mamdouh Alsayed Eissa; Here are few links. Please go through them for your research. Regards
https://books.google.co.in/books?id=fqussIGJ0NcC&pg=PA468&lpg=PA468&dq=halophyte+plant+reduce+water+loss+during+the+heat&source=bl&ots=ai8VnZtIQR&sig=i5HJ8LG5kUil54JUQhtbWRLkv4w&hl=en&sa=X&ei=jc3xVLf2Eo2TuASwvYDACQ&ved=0CCQQ6AEwAQ
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB0QFjAA&url=http%3A%2F%2Fwww.infoplease.com%2Fdk%2Fscience%2Fencyclopedia%2Fplant-survival.html&ei=jc3xVLf2Eo2TuASwvYDACQ&usg=AFQjCNHLNxM7RV6SBGUsFcZ9wmLLZsb6sg&sig2=uw4pD9Tc2IHQboQAZehz1A&bvm=bv.87269000,d.c2E
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCcQFjAC&url=http%3A%2F%2Fdata2.xjlas.ac.cn%3A81%2FUploadFiles%2Fsdz%2Fcnki%2F%25E5%25A4%2596%25E6%2596%2587%2FELSEVIER%2Fbalance%2520water%2520and%2520salt%2F18.pdf&ei=jc3xVLf2Eo2TuASwvYDACQ&usg=AFQjCNG-7PsUCG_WglVrVQZ3yFJ8RZlEAQ&sig2=vrjHLGZYciW8qGY4_l9qng&bvm=bv.87269000,d.c2E
There is a thick vax coating in many halophytes over the leaves. The stomata are sunken. The leaves are thick and fleshy.
they manintain a very high osmoticum and the osmolytes are plenty
Mamdouh,
The very basic idea is that a halophyte is in fact, a special case of xerophytes, due to physiological drought of salt affected soils. Consequently, all morphological and anatomical adaptations of halophytes are of xerophytic nature (succulence, reduced leaves, thick cuticle, wax coating, sometimes sunken stomata). Salinity induces dehydration and osmotic stress in the same time. Halophytes accumulate ions during higher intensity of stress (salt, drought) in order to achieve an osmotic adjustment required to cope with harmful environmental conditions. Please note that Atriplex nummularia has vezicular hairs (salt hairs), where salt is accumulated on the leaves surface, in order to be eliminated.
I suggest you our book - Marius-Nicuşor Grigore, Lăcrămioara Ivănescu, Constantin Toma, 2014, Halophytes. An integrative anatomical study. Springer, Cham, Heidelberg, New York, Dordrecht, London, as well a survey of my papers uploaded on Researchgate, dealing with structural aspects of halophytes.
I suggest to measure proline contents in leaves. In soybean this product is tjhe mechanism to deal with hydric stress.
Dear Mamdouh
I think usually the changes in concentration of these cations , I mean Na and K are associated with osmotic adjsutment within plant cells and of course it is one of the most important plant mechanisms used for dehydration avoidance. Also indirectly it plays a role in the stomata conductance of plant leaves, I mean opening and closure during drought stresses. so you are in the right track for the scientific explantion of your results.
During long-term exposure to salinity, plants experience ionic stress, which can lead to premature senescence of adult leaves, and thus a reduction in the photosynthetic area available to support continued growth (Cramer & Nowak, 1992). In fact, excess sodium and more importantly chloride has the potential to affect plant enzymes and cause cell swelling, resulting in reduced energy production and other physiological changes (Larcher 1980). Ionic stress results in premature senescence of older leaves and in toxicity symptoms (chlorosis, necrosis) in mature leaves due to high Na+ which affects plants by disrupting protein synthesis and interfering with enzyme activity (Hasegawa, Bressan, Zhu, & Bohnert, 2000; R. Munns, 2002; R Munns & Termaat, 1986). Many plants have evolved several mechanisms either to exclude salt from their cells or to tolerate its presence within the cells. I mainly discuss about soil salinity, its effects on plants and tolerance mechanisms which permit the plants to withstand stress, with particular emphasis on ion homeostasis, Na+ exclusion and tissue tolerance. Moreover we give a synthetic overview of the two major approaches that have been used to improve stress tolerance: exploitation of natural genetic variations and generation of transgenic plants with novel genes or altered expression levels of the existing genes. A fundamental biological understanding and knowledge of the effects of salt stress on plants is necessary to provide additional information for the dissection of the plant response to salinity and try to find future applications for ameliorating the impact of salinity on plants, improving the performance of species important to human health and agricultural sustainability.
Mainly through accumulation of certain molecules , capable of working like osmoregulants to balance the osmotic pressure of cell cytoplasm , thereby, physiological adjustments are made by halophytes.
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