USO DE BIOESTIMULANTE ASSOCIADO A REDUÇÃO DE POTASSIO EM SOJA

Abstract

The use of biostimulants can promote several benefits to plants, such as hormonal balance, resulting in gains in productivity and product quality. Thus, the objective of this research was to evaluate production and productivity components of soybean grains as a function of the use of biostimulants and potassium reduction. The experimental design used was randomized blocks in a 2 x 5 factorial scheme with ten treatments and four replications, totaling 40 plots. The treatments resulted from the combination of potassium and biostimulants. Potassium was applied as topdressing, at the full dose (100 kg K2O ha-1) and half the dose. The biostimulants (B) were composed of: B1 = Bacillus licheniformis, B2 = solution containing auxin, gibberellin and cytokinin, B3 = B. pumillus + B. subtilus + B. velezensis and B4 = B. pumillus + B. subtilus + B. amyloliquefaciens, in addition to the control. NR and MSF were influenced by all biostimulants used, promoting gains of 19.9% and 13.2%, respectively, when compared to the control. For the variables NVP, NGP, and MGP, only biostimulant B3 promoted gains, reaching values of 16.8%, 12.1%, and 15.5%, respectively. For MMG, in addition to B3, B4 was also efficient in promoting higher yield for this characteristic, with an average increase of 2.6%. With half the K dose, B3 favored plant height, and B3 and B4 favored stem dry mass. Treatment B3, with half the K dose, promoted a 4.0% gain in soybean grain productivity, reaching 6207 kg ha-1, when compared to the control. It was concluded that the use of half the K dose, when associated with the treatment containing Bacillus pumillus + B. subtilus + B. velezensis, is sufficient to promote higher grain yields. Keywords: Bacillus spp., phytohormones, Glycine max, growth regulators.