Advanced strategies for optimizing soybean seedling growth using plant growth regulators under plug seedling environmental conditions

Soybean ( Glycine max L.) is an important crop that provides food, feed, and industrial products globally. Soybean cultivation in South Korean paddy fields faces challenges due to delayed sowing during the monsoon season, which leads to shortened vegetative growth stages. We evaluated the effects of plant growth regulators (PGRs) on controlling soybean seedling growth and mitigating the impacts of delayed transplanting. Four soybean cultivars were treated with five PGRs and growth parameters such as plant height, stem diameter, and leaf area were measured. Physiological measurements, including Fv/Fm ratio and phytohormone analyses, were conducted to understand the mechanisms underlying PGR-induced growth regulation. The results demonstrated that hexaconazole and diniconazole significantly reduced plant height without negatively affecting leaf area or photosynthetic capacity. These findings suggest that PGRs can improve the flexibility of sowing schedules and stabilize crop production in double-cropping systems. The findings of this study have significant implications for improving soybean production in paddy fields, particularly in the context of climate change, which is expected to increase the frequency of weather events and complicate crop management.