Interactive Effects of Temperature and Ultraviolet-B Radiation On Corn Growth and Development.

Temperature and ultraviolet-B (UV-B) radiation are projected to increase in the future due to changes projected in climate. A controlled environment study was conducted in sunlit growth chambers to determine the effects of UV-B radiation and temperature on corn growth and development. Plants were grown in the growth chambers at three day/night temperatures (24/16 C, 30/22 C and 36/28 C) and three levels of UV-B radiation (0, 5 and 10 kJ per square meter per day) at each temperature from 9 days of emergence for 38 days under optimum nutrient and water conditions. Changes in plant height, node number, leaf area, and leaf photosynthetic parameters were recorded during the treatment period at weekly intervals. At the end of the treatment period, 47 days after sowing, biomass components of various plant-parts were estimated. Both temperature and UV-B radiation interactively affected growth parameters. Node numbers were significantly affected by temperature, but the effect of UV-B was negligible. The 5 and 10 kJ of UV-B radiation caused 18 and 28% reduction in plant height and 5 and 15% reduction in total biomass, respectively, averaged over the three temperature treatments. The reduction plant height was due to shorter internode lengths rather than fewer nodes as UV-B did not affect leaf addition rates at a given temperature treatment. Similarly, mature leaves were smaller in the UV-B-treated plants compared the control. This resulted in 12 to 15% lower whole plant leaf area in the UV-B treated plants when averaged over the three temperature treatments measured at the end of the experiment. This study suggests a growth- and process-related temperature dependence of sensitivity to UV-B radiation.