Combined effect of high temperature and salinity on growth and physiology of rice (Oryza sativa L.)

High temperature and salinity are the major climatic factors affecting the productivity of rice. Combined effect of both the stresses can cause severe yield reduction in rice. Therefore, objective of this study was to assess the combined effect of high temperature and salinity on three rice genotypes (MO-16 - popular high yielding variety; N-22 - tolerant to high temperature and drought and NL-44 - tolerant to high temperature). The experiment was laid out in completely randomized design with three replications. The three genotypes of rice were grown in non-saline conditions at optimum temperature until booting stage. At booting stage, plants were irrigated with 250mM NaCl for three days and exposed to high temperature (38ºC) for 10 days. High temperature combined with salinity significantly affected the physiological processes and yield parameters. Tolerant genotype, N-22 showed higher proline content, cell membrane stability index, superoxide dismutase activity, pollen viability, spikelet fertility percentage, yield per plant and less malondialdehyde content and Na⁺/K⁺ ratio compared to other genotypes.