Comparative Effect of Drought Stress on Growth and Physiological Performance of Three Different Rice Cultivars

Rising global temperatures are causing prolonged droughts that reduce rice growth.This study investigated the impacts of drought stress and the rewatering period on rice's growth and physiological characteristics (Oryza sativa L.) cv.KHAO DAWK MALI 105 (KDML105), MALI DAM NONG KHAI 62 (MDNK62) and POKKALI.The 28-day-old rice seedlings of the three cultivars were cultured under water deficit for 19 days (drought stress period) before rewatering for 9 days (rewatering period).Growth and physiological features were investigated at the end of the drought stress and rewatering periods.Drought stress inhibited the growth of all three cultivars, such as tiller number per clump, leaf size, root length, and biomass, while shoot length, leaf rolling score, and drought score of leaf increased compared to the control.All growth features of the three rice cultivars improved after rewatering.The physiological characteristics of KDML105 and MDNK62 rice cultivars differed from POKKALI under drought stress.Chlorophyll a content, total chlorophyll content, Fv'/Fm', Fv/Fm, and relative water content of KDML105 and MDNK62 rice cultivars decreased but increased in POKKALI.Electrolyte leakage percentage and MDA content of the three rice cultivars increased compared to the control group during drought stress and rewatering.Growth and physiological aspects including the drought tolerance index (DTI) for MDNK62 showed moderate adaptation to drought stress, while KDML105 exhibited better adaptability compared to MDNK62 and POKKALI.This research provides important information for rice growth improvement in regions facing drought challenges.

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