Soybean Responses to to Ultraviolet-B Radiation.

To understand the consequences of rising levels of ultraviolet-B radiation on soybean, an experiment was conducted at five levels of UV-B radiation at optimum water, nutrient and temperature conditions. Plant growth, development and gas exchange parameters were measured and quantified during vegetative period. Among growth and developmental processes, stem elongation rate was the most sensitive process to UV-B followed by leaf area expansion, biomass production and leaf development rate. Stomatal conductance was the most sensitive process among the gas exchange parameters followed by rates of transpiration and photosynthesis. In addition number pods per plant declined linearly with increase in UV-B levels; 30 pods/plant at 0 UV-B to 9 pods/plant at 15 kJ of UV-B. The identified UV-B-specific growth, developmental and physiological responses should be useful in improving soybean responses to changes in UV-B radiation both in the present and future environments.