ECO-MORPHIC RESPONSE TO SALT STRESS IN TWO HALOPHYTIC GRASSES FROM THE CHOLISTAN DESERT, PAKISTAN

Abstract

A study was conducted to evaluate the ecotypic difference in salinity tolerance in two halophytic grass species Aeluropus lagopoides and Sporobolus ioclados from the Cholistan Desert, Pakistan in a hydroponic system. Three populations of each of the two grass species were collected from ecologically different habitats, i.e., lesser salt-affected Derawar Fort (DF), moderately salt-affected Bailahwala Dahar (BD), and highly salt-affected Ladam Sir (LS). Genetic variation for salinity tolerance was found in all populations of both A. lagopoides and S. ioclados, its magnitude corresponded to the selection pressure of the habitats. The lesser saline DF populations of both grass species were the least tolerant to salt stress in relation to most of the agro-morphological characteristic measured. The moderately saline BD populations were relatively less affected due to salt stress and 100 mM NaCl stimulated their growth measured in terms of plant height, root length and fresh and dry weights of shoots and root. The highly saline LS populations were the most tolerant among all populations of both grasses and optimal growth was recorded at 200 and 300 mM NaCl of the growth medium. Of the two grasses, A. lagopoides was superior to S. ioclados in salinity tolerance because its all three populations were relatively more tolerant as compared to those of the latter grass species.