Physiological and Biochemical Characterization of Rice Varieties under Salt and Drought Stresses

Abstract

A well-focused approach combining the physiological and biochemical aspects of stress tolerance is essential to evaluate the drastic effects of salinity and drought. This strategy involves comparative investigation of various morphological, physiological, biochemical responses together with ionic relationship at vegetative stage under salt stress coupled with drought. Two salt-tolerant (CSR 10 and CSR 36) and two susceptible (IR 29 and Pusa 44) varieties of rice were subjected to salt stress coupled with drought stress conditions. Results showed significant decline in growth, chlorophyll content, number of tillers, productive tillers, biomass and yield in sensitive varieties, while tolerant varieties were less affected due to stress conditions. Total soluble sugars, proline and protein content increased with inclined stress in all the varieties, which showed osmotic adjustment in terms of accumulation of compatible solutes. The varieties CSR 10 and CSR 36 accumulated less Na+ ion in leaves under stress. Under combined stresses, the highest value of K+/Na+ ratio was recorded in CSR 36, whereas, lowest in IR 29. In comparison with control treatment, at 100mM NaCl along with 25% water deficit (WD) and 50% WD, highest reduction in grain yield was shown by IR 29 (96.6%) followed by Pusa 44 (80.64% and 98.6%), CSR 36 (44.86% and 52.7%) and CSR 10 (21.0% and 28.3%). Study concluded that growth parameters, physiological and biochemical traits had a significant varietal variation, indicating that these parameters could be used as screening criteria for selecting the tolerant and sensitive cultivars exposed to water limiting stresses (salinity and drought).