Abstract
In the current study, we used four soybean varieties PK-1029, PK-472, NRC-7, and Hardee to examine the effect of exclusion of solar UV radiation on photosynthetic efficiency and to test possible variety-dependent sensitivity to ambient UV (280-400 nm). Plants that were grown under UV exclusion filters had higher chlorophyll a and b, efficiencies of PSII and more active reaction centers indicated that PSII were substantially affected by solar UV radiation. The significant increase in net photosynthesis was linked to increased stomatal conductance and lower intercellular concentration of CO(2) in UV-excluded plants. The exclusion of solar UV increased seed mass per plant in all soybean varieties as compared to the control; this indicates that ambient UV exclusions boost photosynthetic efficiency and improve soybean yield. The overall cumulative stress response index of four varieties implies that Hardee and PK-472 were more sensitive whereas NRC-7 and PK-1029 were resistant to ambient UV radiations.