Effect of Plant Growth Regulators on Regulating of the Expression of Genes Encoding Seed Traits in Soybean (Glycine max L.)

• Ghofran Mohammed Abbass 1, Ayoob Obaid Alfalahi,2

  Author

This study was conducted to investigate the efficacy of plant growth regulators (PGRs) and their application stages in regulating the expression of genes encoding seed traits in soybean. The field experiment evaluated three selected PGRs—Gibberellic acid (GA), Abscisic acid (ABA), and Brassinolide (BR)—applied at a concentration of 100 mg L⁻¹ across four distinct growth stages: the late vegetative stage (V3), flowering (R1), pod setting (R3), and seed filling (R6). The treatments were arranged in a factorial experiment using a Randomized Complete Block Design (RCBD) with three replications.

​The study evaluated the efficacy of these factors in regulating the expression levels of the GmCKX3 and GmCIF1 genes, which are responsible for seed traits. The results revealed a significant down-regulation of gene expression levels influenced by the PGRs and application stages, with the BR treatment and the V3 stage exhibiting the most pronounced effects. Regarding phenotypic traits, foliar application of GA and BR significantly increased the 100-seed weight, reaching 13.46 g and 13.11 g, respectively, whereas the ABA treatment recorded the lowest average (11.85 g). Among the application stages, the V3 stage achieved the highest 100-seed weight average of 13.29 g. Furthermore, BR application led to a significant reduction in the percentage of severely wrinkled seeds (9.17%) while simultaneously increasing the percentage of non-wrinkled seeds (78.50%). This improvement positively reflected on the total seed yield, which peaked under the BR treatment (4.376 t ha⁻¹) and the V3 application stage (4.170 t ha⁻¹).

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