Exploring drought mitigation options for improvement of physiology, yield and water use efficiency of aerobic rice (Oryza sativa)

Abstract

An experiment was conducted during summer seasons of 2022 and 2023 in Wetland Farms at Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu to mitigate the ill effects of moisture stress during the flowering stage of rice (Oryza sativa L.) by moisture stress mitigating chemicals. The trial was laid out in split plot design (SPD) with 3 main plots and 4 sub-plots, and replicated thrice. In main plot, irrigation at IW/CPE ratio 1.0 from emergence to physiological maturity (M1); withholding irrigation (drought stress) for 8 days from heading stage (M2); and withholding irrigation (drought stress) for 12 days from heading stage (M3) and in sub-plot drought stress mitigating chemicals, viz. no spray (S1); salicylic acid spray @100 ppm (S2); sodium selenate @20 ppm (S3); and pink pigmented facultative methylotrophs (PPFM) @1% (S4) were tested. Results revealed that irrigation at IW/CPE 1.0 from crop emergence to physiological maturity along with foliar spray of selenium @20 ppm at heading stage had beneficial impact on growth, physiological parameters, yield attributes and yield. Drought stress given for 8 days from heading stage with selenium spray recorded lesser detrimental effect on growth characters, yield attributes and yield when compared to drought stress given for 12 days from heading stage in aerobic rice cultivation. The yield reduction in drought stress for 12 days from heading stage with selenium @20 ppm spray and drought stress for 8 days from heading stage with selenium @20 ppm spray were 23.6 and 16.5% respectively, when compared to irrigation at IW/ CPE ratio 1.0 from crop emergence to physiological maturity with selenium spray @20 ppm. Water use efficiency and water profitability also increased by the application of stress mitigating chemical of sodium @20 ppm. From this study, it is recommended that, in aerobic rice cultivation if there is any drought occurrence during heading stage of crop, the selenium application @20 ppm can withstand drought even up to 8 days from heading stage.