Physiological performance of rice (Oryza sativa L.) seeds treated with 24-epibrassinolide / Desempenho fisiológico de sementes de arroz (Oryza sativa L.) tratadas com 24-epibrassinolídeo




The objective of the research was evaluate the importance 24-epibrassinolide in physiological performance of rice seeds, for this two experiments were conducted in laboratory and a greenhouse. The first assessed the performance of different concentrations of 24-epibrassinolide in physiological quality of seeds and seedlings growth in two lots of rice cv. IRGA 422CL. 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 through the tests of germination, the first counting of germination, the speed of germination index, emergency, speed of emergency index, length of shoot and root and fresh and dry mass of shoot and root. Generally in all characteristics determined, concentrations less than or equal to 0.4 μM 24- epibrassinolide produced a positive response in physiological quality seeds of rice cv. IRGA 422CL. The second experiment was conducted with seed rice of two cultivars, BRS Querência, genotype susceptible to salinity and BRS Bojurú, tolerant to salt, in order to determine the effect of the 24-epibrassinolide on the germination, seedling growth, leaf area and concentration of chlorophyll under salt stress condition. Seeds were soaked for two hours in water, 100mM NaCl and solutions of 100 mM NaCl supplemented with 24-epibrassinolide at concentrations of 0.01, 0.1 and 1.0 μM. The viability and vigor of rice seeds of cv. BRS Querência were reduced by salinity and were restored by the application of the 24-epibrassinolide in concentration 1.0 μM. While in cv. BRS Bojurú the vigor was reduced by this concentration. The application of the 24-epibrassinolide in cv. BRS Querência increased the concentration of chlorophyll, leaf area, length of root and shoot, fresh and dry mass of root and shoot, reducing the deleterious effects caused by salinity. However, in cv. BRS Bojurú, tolerant to salinity, the application of the 24-epibrassinolide 0.01 μM reversed or did not affect the characteristics of growth, although, concentrations of 0.1 e 1,0 μM reduced the characteristics of growth, but did not affect the chlorophyll concentration. Based on the results, it can be inferred that the supplementation of saline solution with 24-epibrassinolide improves the quality of seed varieties susceptible to salinity, not acting the same way in more tolerant cultivars.


epibrassinolide fisiologia vegetal brassinosteroids brassinosteróides rice epibrassinolídeo arroz

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