Importance of brassinosteroids for mitigating water stress in sorghum

Abstract

The objective of the present study was to assess the mitigating effect of brassinosteroids on water stress caused by different water supplies (water deficit and excess water) in sorghum. The experiment was conducted at the experimental farm of the State University of Goias, South Campus, in Ipameri, GO, Brazil. A completely randomized design was used, in a 2×5 factorial arrangement with 4 replications. The plants were grown under five water supplies (25%, 50%, 100%, 200%, and 400% of the evapotranspiration) and treatments with and without brassinosteroid (0.1 mg L-1) application at 30.0 mL plant-1, carried out in three moments (at 45, 47, and 49 days after emergence). The tests conducted in pots limited the root system growth by the volume of the container, but despite these conditions, sorghum plants treated with brassinosteroids presented higher root system development and plant height, denoting that the brassinosteroids have the potential for mitigation of water deficit at field level. The main mechanism of tolerance to drought of sorghum is its high stomatal sensitivity, which rapidly reduces transpiration and minimizes the plant dehydration under water deficit