Effects of Salt Stress on Ion Balance at Vegetative Stage in Rice (Oryza sativa L.)

Abstract

Rice (Oryza sativa L.) plants were subjected to NaCl stress within 35 days. The shoot dry weight, root dry weight, total survival percentage and contents of inorganic ions in dry samples of stressed plants were measured to identify the physiological adaptive mechanisms by which rice plants at vegetative stage tolerate salt stresses. Laboratory testing of the 10 rice cultivars showed that the salt concentration for the treatment is especially significant for assessment of the relationship between ion accumulation and salt tolerance. Salt treatment strongly stimulated accumulations of Na⁺, Na⁺/K⁺ ratio, Cl^- in shoot and root and reduced K⁺, NO₃^- contents in both organs under 1.2% NaCl stress condition, but not always under 0.6% NaCl concentration. It was shown significantly negative correlation (p<0.5) between the Na+ content and dry weight of shoot and root under 1.2% NaCl stress condition. Also, was founded significantly negative impact (p<0.5) of Cl^- ions on biomass growth and survival rice plants and positive relationship (p<0.5) among the root dry weight and K⁺, NO₃^- content under the high NaCl concentration (1.2% NaCl). So, in addition to Na⁺, the contributions of Cl^- to abiotic stresses of rice should not be ignored.