Potencial fisiológico das sementes de arroz da cultivar BRS AG em resposta ao estresse salino

Abstract

The rice cultivar BRS AG was recently developed in order to meet regional agronomic traits for the production of ethanol. However, it is a new cultivar of rice, with prospects to be included in the agricultural market, being necessary to evaluate their behavior in adverse environments. The objective of the study was to evaluate the physiological quality of rice seeds of BRS AG and BRS Pampa under different saline levels. The seeds were subjected in four concentrations of sodium chloride (NaCl), zero, 50, 100 and 150 mM and the responses of the seeds of these variations were evaluated by germination, first count, seedling shoot and root length and dry weight, respiratory activity and stress tolerance index. The experimental design was a completely randomized in factorial design with two rice cultivars and four concentrations of NaCl, with three replicates per treatment with four each subsample. The experimental data were subjected to variance analysis and when significant, qualitative variables were compared by Tukey test at 5% probability and quantitative variables submitted to polynomial regression analysis. It was observed for seeds germination of both cultivars the same behavior when subjected to salt stress. However, the seeds germination of BRS Pampa presented more sensitive to the deleterious effects of NaCl. For the variables of growth and dry matter accumulation, there was the same behavior observed in seeds germination, the BRS AG seeds germinated more than BRS Pampa seeds. The respiratory activity of seeds of both cultivars is affected by excess salts in the hydration process, providing variations throughout the hydration time. Therefore, the experimental conditions, the rice seeds of BRS AG had become less sensitive to the damaging effects of NaCl.