Foliar application of a biostimulant-effect growth regulator on soybean plant architecture

Abstract

Application of a biostimulant-effect growth regulator (BGR) can modify soybean plant architecture by stimulating branching and enhancing phenotypic plasticity under low plant densities. This study sought to evaluate changes in soybean plant architecture and grain yield in response to the application of a BGR containing auxin, cytokinin, and molybdenum under different plant densities. The experiment included 10 treatments arranged in a 2 × 5 factorial design comprising two BGR treatments (with and without BGR at the V3 growth stage) and five plant densities (155, 200, 244, 288, and 333 thousand plants ha-1). The evaluated traits were stem diameter, first pod insertion and plant height, number of branches per plant, number of grains per square meter, percentage of grains produced on branches, grain weight per plant, one hundred-grain weight, and grain yield. BGR application minimally alters soybean plant architecture, with no increase in the number of lateral branches, but rather an increase in yield. The greatest changes in plant architecture resulted from variation in plant density. Soybean exhibited high phenotypic plasticity across the range of plant densities evaluated, with no significant effect of plant density on grain yield.