Soybean plants architeture and plant growth regulators application

Abstract

Treatment with plant growth regulators was studied in soybean plants (Glycine max (L.) Merrill cv. BRS-184) to assess the leaf chlorophyll content, the branching number and the height of the pods. The experiment has been carried out in the greenhouse of the Department of Botany, Bioscience Institute, São Paulo State University – UNESP, Botucatu, SP, Brazil. The experimental design was completely randomized with three replications and eight treatments: control; GA₃ 100 mg L^-1; BAP 100 mg L^-1; IBA 100 mg L^-1; Stimulate,sup>® (IBA + GA₃ + kinetin) 20 mL L^-1; mepiquat chloride 100 mg L^-1; mepiquat chloride 100 mg L^-1 + BAP 100 mg L^-1 + IBA 100 mg L^-1 and ethephon 600 mg L^-1. The treatments were applied three times every 30 days during the plant cycle and six evaluations have been made every 13 days. The treatments with BAP, ethephon and mepiquat chloride + IBA + BAP maintained the high chlorophyll content until the end of the plant cycle. The height of the plants treated with ethephon was lower than the control and all treatments, excepting the treatment with GA₃. The number of plant branches was incremented by the ethephon treatment and the height of the first pod was the lowest in this treatment and the highest in the treatment with GA3. The treatment of soybean plants with ethephon can be recommended on soybean, which promoted the formation of plants with the ideal architecture for mechanical harvesting.