Plant bioregulator enhances agronomic traits and physiological quality of soybean seed

Abstract

To explore the maximum productive potential of soybean crops, several strategies can be adopted, such as the use of plant bioregulators. In this context, the application of nutritional products as well as plant growth regulators constitutes an important approach to optimize flower retention and, consequently, reduce the abortion of reproductive structures. In addition, these practices contribute to maintaining the physiological quality of seeds. Given the above, the objective of this study was to obtain information on flower retention and soybean grain yield, as well as to evaluate the physiological quality of seeds subjected to the application of different products. Field and laboratory experiments were conducted. In the field, treatments were arranged in a randomized complete block design, in a 3 × 10 factorial scheme (three soybean cultivars and 10 products), with six replications. Each plot consisted of four rows of five meters. In the third row of each plot, six plants were selected, from which aborted reproductive structures were collected using a field-built device called a “floral receptacle.” Yield traits, percentage of flower retention, and yield components were evaluated. In the laboratory experiments, a completely randomized design was adopted, with four replications. Three experiments were conducted using different soybean cultivars, evaluating nutritional products and plant growth regulators. Electrical conductivity and tetrazolium tests were performed on freshly harvested seeds, and emergence speed index (ESI), germination, and accelerated aging were evaluated in freshly harvested seeds and in seeds stored for three and six months. In general, the application of plant bioregulators influenced flower retention and the agronomic performance of soybean, with responses depending on the cultivar. However, the magnitude and direction of the responses were strongly modulated by unpredictable environmental factors. Furthermore, the results indicate that the application of plant bioregulators affects the physiological quality of soybean seeds; however, the response depends on the cultivar, the product, and the storage period. Nevertheless, these treatments did not show consistent effects on seed storability, indicating that their application does not provide protection against deterioration during storage.