Understanding physiological and molecular adaptations of three diverse halophytic grasses under saline and sodic stresses

Abstract

Physiological and biochemical analyses of three halophytes were conducted to explore their tolerance andphytoremediation potential. The halophytes Urochondra setulosa, Sporobolus marginatus and Leptochloafusca were categorised based on gas exchange attributes, antioxidant system, biomass production under soilsalinity (ECe 30-50 dS/m) and sodicity (pH 9.5-10). L. fusca and S. marginatus produced slightly higherbiomass under the sodic condition of pH 9.5, while in U. setulosa, it increased under salinity stress. Under sodicconditions, L. fusca showed less reduction in potassium content and maintained a higher K /Na ratio in their + +leaf tissues. A maximum decrease in net photosynthesis was observed in L. fusca (28.55%) at ECe ~ 50 dS m-1while minimum in S. marginatus (13.73%) at pH ~ 10.0. Comparatively, U. setulosa showed higher stomatalconductance and transpiration rate than L. fusca and S. marginatus. At the highest pH and salinity, theantioxidant activities of enzymes APX, SOD, GR and POX increased in all three halophytes. Quantitativeexpression of MnSOD, NHX1 and FuSOS1 genes in all three halophytes increased with salt stresses. Basedon these indicators, these halophytes were categorised as salt-tolerant or alkaline-stress-tolerant.