Abstract:
Five potential salt tolerant forage grasses (Aeluropus lagopoides, Cymbopogon
jwarancusa, Ochthochloa compressa, Lasiurus scindicus and Sporobolus ioclados) were
collected from the salt affected habitats of Cholistan desert to assess their adaptive
components of salt tolerance to saline stress by determining various morpho-anatomical
and physiological attributes. The degree of salt tolerance of the ecotypes of all five
grasses from the differentially saline habitats was compared in a hydroponic system. In
general, the ecotypes from the highly saline Ladam Sir (LS) habitat of all five grasses
performed better under high salinities than their counterparts from the moderately saline
Bailahwala Dahar (BD) and least saline Derawar Fort (DF). All these species showed
specific adaptive modifications in their structure and physiology as well as definite
mechanisms to deal with high salinity levels of external environment. The LS ecotypes of
A. lagopoides and O. compressa generally tended to exclude toxic ions through leaves
and this salt exclusion mechanism responsible for their successful survival under highest
salinity levels. The LS ecotypes of S. ioclados and C. jwarancusa were tolerated
moderate salinities and more relied on restricted uptake of toxic ions and succulence
while L. scindicus was the sensitive to high salinities and relied more on the
accumulation of free amino acids and proline. In conclusion, the present study on the salt
tolerance of natural populations of five desert grass species confirms that natural
selection had a considerable impact on the development of adaptive components of salt
tolerance in these grasses which clearly depict that plant growing in prevailing saline
environments must have specific genetic makeup developed as a result of natural
selection over long period of time.
