Enhancement in Biomass and Yield of Soybean Var: JS-71-05 After Exclusion of Solar UV Components

A field experiment was conducted to assess the effects of excluding solar UV-B (280–315 nm) and UV-A (315–400 nm) radiation on the growth, physiology, and yield of soybean (Glycine max L. Merrill var. JS-7105). Plants were cultivated under open-field conditions using a specially designed UV-exclusion setup with selective filters that blocked either UV-B (<315 nm) or both UV-A and UV-B (<400 nm) components of the solar spectrum. Control plants were grown under filters that transmitted ambient solar UV radiation. Exclusion of UV-B and UV-A/B led to significant improvements in vegetative growth parameters, including plant height, internodal length, and leaf area. Biomass accumulation was enhanced, as reflected in increased fresh and dry weights. The maximum quantum efficiency of Photosystem II (Fv/Fm), measured in dark-adapted leaves, was also significantly improved under UV exclusion, indicating reduced photoinhibition. Levels of UV-absorbing substances (UAS) in the unifoliate leaves decreased by approximately 33% in UV-excluded plants compared to controls, suggesting lower UV-induced stress. Total soluble protein content increased, and SDS-PAGE analysis revealed a more intense 53 kDa protein band corresponding to the large subunit of Rubisco, indicating improved photosynthetic protein expression under UV exclusion. Yield parameters were markedly improved under UV exclusion. The number of seeds per plant increased by approximately 46% under -UV-B and 43% under -UV-A/B conditions. The 100-seed weight increased by 42% and 91% under -UV-B and -UV-A/B, respectively. Harvest index and pod number also showed significant enhancement. These findings demonstrate that ambient solar UV-B and UV-A negatively affect soybean growth and productivity by impairing photosystem II efficiency and Rubisco expression. Exclusion of these components enhances physiological performance and yield, suggesting that natural UV radiation is a limiting factor in soybean cultivation. However, the practicality and economic viability of implementing UV-exclusion strategies at a field scale require further investigation.