Survival Strategies in Khavi Grass [Cymbopogon jwarancusa (Jones) Schult.] Colonizing Hot Hypersaline and Arid Environments

摘要

Deserts are generally prone to a number of ecological hazards which act as agents for the development of particularly a very diverse group of grasses, which can resist to salt stress through multiple morpho-anatomical and physio-biochemical mechanisms. Of such grasses, Cymbopogon jwarancusa is found inhabiting different saline patches of the Cholistan desert, so its different populations were selected from five saline habitats [least saline Derawar Fort (DF); moderately saline Trawaywala Toba (TW) and Bailahwala Dahar (BD), and high saline Ladam Sir (LS) and Pati Sir (PS)] and tested for their salt tolerance mechanism. Differentially adapted populations of this grass showed specific modifications in terms of anatomical features, mainly increased sclerification in both external hypodermis and internal endodermis, cortical layers, and increased size of xylem vessels with increase in salinity of the habitat. Increased endodermal thickness may control radial movement of water in roots. The reduction in leaf area is found to be the principal strategy that makes C. jwarancusa promising to attenuate the effects of the reduced availability of water under saline stress. Thick epidermis with dense cuticle and large bulliform cells area can be particularly considered as an important adaptation of this grass against physiological drought. Moreover, increased density of trichomes is found critical for checking undue water loss through the leaf surface and increase in these tissues at high salinity level may indicate that this species has better adapted to saline habitat.