Efeitos do 24-epibrassinolídeo na atenuação do déficit hídrico na fase de crescimento vegetativo na cultura da soja

Abstract

Soybean (Glycine max (L.) Merrill) is a crop of great economic importance, used for human and animal food. The water deficit is the main limiting factor for the productivity of this crop in the world. Alternatives to minimize the impacts of water deficit on plants involve the application of plant bioregulators, among which Brassinosteroids stand out. For this reason, this work aimed to evaluate the application of 24-Epibrassinolide in the attenuation of water stress in the vegetative growth phase in the soybean crop. The cultivar used was IMA 84114 RR, the experiment was carried out in a 2x2 factorial scheme with eight replications. The treatments consisted of two water conditions (control and water deficit) combined or not with the application of 24-Epibrassinolide (24-EBR), which was applied at a concentration of 0.1 mg/L, which were carried out on the leaves of thirds middle and upper part of the plant, at intervals of 5 days. The maximum period of water deficit was determined by the wilting of soybean plants, which determined the moment of rehydration. Water stress caused reductions in plant height, stem diameter, leaf area, stem dry matter, root dry matter, leaf dry matter and total dry matter, but the treatments that received the application of 24-EBR showed an increase in average of these variables. The maximum quantum yield of PSII (Fv/Fm) of plants under water deficit without the application of 24-EBR was lower than the plants that received the application of 24-EBR under the same water condition, these results indicate that 24-Epibrassinolide have a positive effect on plants subjected to water deficit, and can be used to mitigate water stress.