Response of rice genotypes to sodic waters and Zn rates

Identification of rice genotypes that are tolerant to both sodicity and Zn deficiency is necessary before any rice genotype is cultivated in these stressed environments. We conducted anopen field pot trial to evaluate the response of three rice genotypes (Shandar, NIA-19/A, and NIA-102) to various levels of NaHCO3 (0, 40 and 80 mM) and Zn application rates (0 and 15 kg Zn ha-1).The rice plants were harvested at maturity (110 days after transplantation) and analyzed for various growth and yield components, and ions content. Sodic waters (40 and 80 mM NaHCO3) significantly reduced most of the growth and yield traits of rice genotypes. Rice plants irrigated with 40 and 80 mM NaHCO3 had 15% and 35%, respectively, less grain yield when compared with the plants irrigated with non-sodic water. This adverse effect on growth and yield components may be associated to high Na+ content in rice tissues (straw and grain), which was two-to-three fold higher in rice plants irrigated with sodic waters (40 and 80 mM NaHCO3) than the plants irrigated with nonsodic water. Zinc application at the rate of 15 kg Zn ha-1 was not always effective in improving the growth and yield components; the effect was variable with sodic water levels and rice genotypes. Relatively Shandar was tolerant to sodic waters and responsive to Zn application, hence may be grown in sodic environments, provided the Zn is included in rice cropping.