Importance of brassinosteroids in activating the antioxidant system and growth in Jatropha curcas L. plants under water deficit

Abstract

Climatic changes and drought reduced plant growth and development. Brassinosteroids act in maintaining turgor and plant growth, increasing tolerance to water stress. The objective of the present study was to identify the effect of brassinosteroids in reducing stresses caused by water deficit in Jatropha curcas L. plants. The study was carried out in a greenhouse at the State University of Goiás, in a completely randomized block design in a factorial 2 × 5 arrangement (plants submitted to five brassinosteroids concentrations (0, 2, 4, 8, 16 mg L-1) and two levels of daily water supply (50% and 100% evapotranspiration) six replications and the plot consisted of one useful plant. A 10 mL volume of the hormone was applied 30 days after emergence and 20 mL at 60 days after emergence, totaling 30 ml. The water deficit was imposed at 70 days after emergence and the evaluations were made at 100 d after emergence. Under water deficit, production increased of reactive substances that damage membranes and proteins, but brassinosteroids played an important role in mitigating the deleterious effects of water deficit on J. curcas plants by acting as an elicitor in activating photoprotection mechanisms that increased vegetative growth and maintained membrane integrity. The antioxidant and growth machinery activation reached maximum points at the 8 mg L-1 brassinosteroids concentration and even higher concentrations