Plant growth regulators are involved in promoting and inhibiting germination process, and include the brassinosteroids. The objective of the research was evaluate the performance of different concentrations of 24-epibrassinolide on the seed physiological quality and seedling growth in two lots of rice cv. IRGA 422CL. The experiment was carried out in the Seed Laboratory and at in the greenhouse in the Botany Departament, Pelotas Federal University (UFPel). The seeds of both lots were treated with increasing concentrations of 24-epibrassinolide, zero, 0.01, 0.1, 0.4 and 1.0 μM, for a period of two hours and evaluated by the tests of germination, the first germination count, the germination speed index, emergence, emergence speed index, electrical conductivity, shoot and root length and shoot and root fresh and dry matter. A randomized complete design with three replications was used with three replications. Means were compared by the Tukey test at 5% probability and subjected to polynomial regression analysis. Lower (0.01 and 0.1 μ M) 24-epibrassinolídeo concentrations increased the seed physiological potential of cv. IRGA 422CL and therefore provided higher growth rates in the initial period of crop establishment. The increase in the plant hormone concentration accelerated the seed deterioration process reducing the viability and vigor of cultivar seedsstudied. Generally in all the determined characteristics, concentrations less than or equal to 0.4 μM 24-epibrassinolide produced a positive response in the seed physiological quality rice cv. IRGA 422CL.
brassinosteroids; germination; Oryza sativa L
