EFFECT OF EXOGENOUSLY APPLIED NITRIC OXIDE ON WATER RELATIONS AND IONIC COMPOSITION OF RICE (ORYZA SATIVA L.) PLANTS UNDER SALT STRESS

Abstract

The aim of present experiment was to assess the effect of exogenously applied nitric oxide on water relation attributes and pattern of uptake of inorganic ions in rice plants under salt stress. The experiment comprised four rice cultivars, two coarse (KS-282 and IRRI-6) and two fine (Shaheen Basmati and Basmati PB-95) rice cultivars, two NaCl levels (0 and 80 mM), and three levels (0, 0.1, and 0.2 mM) of nitric oxide. Salt stress caused a significant increase in leaf water and osmotic potentials while decreased leaf turgor potential and relative water content in all four rice cultivars. Of inorganic ions, shoot and root Cl- and Na+ concentrations increased significantly, while in contrast, K+ and Ca2+ concentrations and K+ /Na+ ratio decreased markedly. Pre-sowing seed treatment with nitric oxide significantly decreased leaf osmotic and water potentials and shoot and root Cl- and Na+ concentrations, while it increased leaf relative water content, leaf turgor potential, K+ and Ca2+ concentrations and K+ /Na+ ratio in both shoots and roots of salt stressed rice plants. Of nitric oxide levels, 0.1 mM was more effective, while of the four rice cultivars, Shaheen basmati and IRRI-6 performed better as compared to the other two cultivars.