Physiological, phenometric and productive changes in soybean crop due to the use of kinetin

Abstract

A fast growth in the use of substances that increase soybean yield through physiological or morphological changes, such as cytokinin, has taken place in recent years. This study aimed at assessing the effect of the application time of cytokinin as kinetin on soybean crops. The experiment was carried out under field conditions, using four treatments (control and kinetin at the vegetative stages V₄, V₆ and V₄ + V₆), with five replications, in completely randomized blocks. Physiological (nitrate reductase and peroxidase activity, H₂O₂ content and lipid peroxidation) and phenometric parameters (leaf and root dry mass), as well as yield, were evaluated. The application of kinetin at V₄, V₆ or V₄ + V₆ increased the activity of the nitrate reductase enzyme and reduced stress (evaluated via lipid peroxidation and hydrogen peroxide content), in addition to raising the dry matter content. All these characteristics resulted in increased yield. However, the most significant effects were caused by the application of kinetin at V₆, which increased yield  in 20 %, in relation to the control.