The effects of salinity on the germination of seeds of various species have shown that the germination period increased significantly with the presence of soluble salts in the soil. The brassinosteroids are hormones involved in plant elongation and cell division and are associated with the increased tolerance of plants to biotic and abiotic stresses. We evaluated the effect of 24-epibrassinolide on the germination of rice seeds subjected to salt stress using the Querencia and BRS Bojurú varieties, respectively susceptible and tolerant to salinity. The experiment consisted of five treatments: one with distilled water (zero), one with a solution of 100 mM NaCl, and three treatments consisting of a solution of 100 mM NaCl supplemented with 24-in epibrassinolide concentrations of 0.01, 0.1, and 1.0 mM. The seeds of the two cultivars were soaked for two hours in the solutions and evaluated for: germination, first count germination, germination speed index, electrical conductivity (at 3 and 24 hours) and length and dry weight of shoot and root. The treatments comprised a factorial 2x5: two cultivars and the five experimental solutions. The experimental design was completely randomized with four replications. Means were compared by the Tukey test (p <5%). The germination and vigor of the BRS Querencia were restored by supplementing the saline with 24-epibrassinolide. The percentage germination of the BRS Bojurú did not decrease when treated with a solution of 100 mM NaCl and the addition of 24-epibrassinolide at the lower concentration, 0.01 mM, increased the germination potential. However, the highest concentration reduced germination in this rice variety. It can be concluded that the 24-epibrassinolide can reverse the effect of salt on rice seed which is susceptible to salinity but does not act in the same way in more tolerant cultivars.
salinity; vigour; viability; brassinosteroids
