Salinity effect on mineral nutrient distribution along roots and shoots of rice (Oryza sativa L.) genotypes differing in salt tolerance

The aim of this study was to investigate the effects of salinity on mineral nutrient distribution along roots and shoots of seven selected rice (Oryza sativa L.) genotypes, namely Pokkali, PVSB9, PVSB19, PNR381, PNR519, NS15 and Iratom24 differing in salt tolerance. The rice plants were grown in pots and subjected to varying levels of salinity stress (0, 3, 6, 9, 12 and 15 dS m(-1)). Mineral nutrients distribution in shoots and roots was measured after harvesting the plants at 95 days after transplanting. The responses of salt stress on mineral nutrient uptake and distribution along plant organs significantly differed among the rice genotypes. The contents of Na+ and Cl- in the roots and shoots of resistant genotypes (PVSB9, PNR381 and Pokkali) were significantly lower than the susceptible rice genotype (NS15). The concentrations of Na+ and Na+/K+ in shoots of sensitive rice genotype (NS15) sharply increased with increasing salinity above 6 dS m(-1) than those of tolerant genotypes. The highest concentration of K+ was obtained in shoots of resistant genotype PVSB9 and this K+ content decreased more slowly with increasing salinity than those of other genotypes.