Abstract:

【Objective】 The aim of the experiment was to study the salinity tolerance of rice (Oryza sativa L.) genotypes as affected by nutrients (K+, Ca2+ and Mg2+) at seedling stage, and supply some knowledge for further studies on the physiological mechanisms and improvement of crop salinity tolerance. 【Method】 A water culture experiment was conducted at phytotron in International Rice Research Institute (IRRI) during Jan.-Apr. 2009, and the water supply, temperature, illumination and nutrients supplying, were strictly controlled to study on the effect of nutrients (K+, Ca2+ and Mg2+) concentrations on salinity tolerance of rice genotypes under salt stress at the seedling stage. 【Result】 The salt tolerant genotypes (FL478 and IR651), when compared with the sensitive genotypes (IR29 and Azucena), had lower content of Na+ and lower ratios of Na+/K+, Na+/Ca2+ and Na+/Mg2+, but had higher content of K+ in plant under salt stress (100 mmol?L-1 NaCl), that’s why tolerant genotypes have higher tolerant ability than sensitive genotypes. The content of Na+ and ratios of Na+/K+, Na+/Ca2+ and Na+/Mg2+ in plant could be declined significantly, the effect of salt stress on plant growth was alleviated significantly, the salinity tolerance of rice was improved significantly and the influence of Ca2+ treatment was higher than Mg2+ treatment, when the concentrations of Ca2+ and Mg2+ in culture solution were increased (60 mg?L-1). However, the effect of K+ treatment on the above parameters was lower than Ca2+ and Mg2+ treatments respectively, that’s why the effect of K+ treatment on salinity tolerance of rice is not significant. 【Conclusion】 The salinity tolerance of rice can be affected by the changes of nutrients contents and nutrients ratios of plant tissues. Salinity tolerance of plant can be improved significantly by properly increasing the concentrations of available plant nutrients (Ca2+ and Mg2+) in culture solution, and the effective of Ca2+ is higher than Mg2+ significantly, but the effect of K+ on salinity tolerance of rice is not significant.

Key words: rice (Oryza sativa L.), salt stress, seedling stage, nutrients (K+, Ca2+ and Mg2+), genotypes