Effect of Ethanol Pretreatment on Growth and Drought Stress Tolerance of Alfalfa Plants

Abstract

To study the effects of external ethanol pretreatment on growth and drought tolerance in alfalfa, 21-day-old plants were pretreatedwith ethanol at 0-1000 mM for 4 days and then subjected to drought stress for 9 days. Ethanol pretreatment significantly enhancedplant survival under drought conditions, with the highest survival rate observed in the 250 mM treatment. In contrast, fresh weightand dry weight were not significantly affected by ethanol pretreatment. Relative water content was increased 7.15% at 250 mMethanol treatment compared to 0 mM ethanol treatment. Chlorophyll content decreased compared to the control, while carotenoidcontent remained unchanged. total soluble carbohydrate content was reduced by ethanol pretreatment. Hydrogen peroxide (H2O2) levelswere maintained only in plants treated with 250 mM ethanol, whereas lower and higher concentrations resulted in significantlydecreased H2O2 content. These results suggest that ethanol pretreatment does not affect alfalfa growth, but significantly improvessurvival rate under drought conditions by maintenance of relative water content. Furthermore, it suggests that chemical priming usingethanol pretreatment could be applied as a method to improve drought tolerance of alfalfa plants.