SALT TOXICITY IN A NATURAL HABITAT INDUCES STRUCTURAL AND FUNCTIONAL MODIFICATIONS AND MODULATE METABOLISM IN BERMUDA GRASS (CYNODON DACTYLON [L.] PERS.) ECOTYPES.

We investigated salt toxicity effects and related physiological as well as anatomical changes for adaptation in Cynodon dactylon. Eleven ecotypes from different areas of Pakistan were examined for their survival capacity in a controlled environment. The experiment was designed in a two factor Completely Randomized Design (ecotypes and 4 salt levels 0, 100, 200, 300 mM NaCl). Differently adaptive populations displayed specific structural and functional adaptations with respect to photosynthesis and photosynthetic pigments to withstand salinity. The ecotypes from saline and waterlogged areas exhibited higher Photosynthetic rate to same level of increase in salinity level. Transpiration rate of all ecotypes showed variations with different salinity levels and stomatal conductance increased in all ecotypes with increasing salinity. Similarly, all ecotypes responded significantly as far as chlorophyll contents were concerned. Most ecotypes consistently showed high leaf blade thickness and sclerenchyma thickness with elevated salinity except for plants collected from saline, waterlogged and salt affected wasteland. Different salt levels decreased the metaxylem cell area while phloem area increased in the ecotypes correspondingly. Cynodon ecotypes possessed low abaxial stomatal density at 300 mM salinity. Overall, physiological and anatomical adaptations to saline environments appeared very specific in grasses and supported life cycle under salt stress. [ABSTRACT FROM AUTHOR]