Influence of the24-epibrassinolide on tolerance to salt stress in rice seedlings

Salinity can be considered a limiting factor to the growth and development of plants to affect various physiological processes. The aim of this study was to determine the effect of 24 - epibrassinolide in emergence, seedling growth, leaf area and chlorophyll concentration in two cultivars of rice in salt stress condition. The study was conducted at the research laboratory of seeds and greenhouse of the Department of Botany UFPel. Rice seeds of cvs. BRS Bojuru tolerant to salinity and BRS Querencia not tolerant, were soaked for two hours in water, 100 mMNaCl and 100 mMNaCl solutions supplemented with 24 - epibrassinolide at concentrations of 0.01, 0,1 and 1.0 mM and sown in expanded polypropylene tray. The experimental design was completely randomized with five treatments, two cultivars and four replications. Means were compared by Tukey test (p < 5 %), within each cultivar. In cv. BRS Querencia the application of 24 - epibrassinolide increased chlorophyll concentration, leaf area, seedling length and dry mass of shoots, reducing the effects caused by salinity. However, cv. BRS Bojuru, tolerant to salinity, the application of the 24 - epibrassinolide 0.01 mM did not affect the growth characteristics, but the concentrations of 0.1 and 1.0 mM reduced the same, no affecting the concentration of chlorophyll. The 24 - epibrassinolide in cv. BRS Querencia, induces an increase in all growth characteristics, minimizing the deleterious effects of salinity on the sensitive cultivar. In cv. BRS Bojuru, higher concentrations reduce the growth characteristics, not by changing the concentration of chlorophyll.