Morphological and physiological responses of nine southern US rice cultivars differing in their tolerance to enhanced ultraviolet-B radiation

The impact of climatic change on crop production is a major global concern. One of the climatic factors, ultraviolet-B radiation (UV-B; 280-320 nm), which is increasing as a result of depletion of the global stratospheric ozone layer, can alter crop productivity. As the initial step in development of UV-B tolerant rice cultivars for the southern U.S., in this study we screened popular southern U.S. rice cultivars for variation in tolerance to elevated UV-B radiation with respect to morphological, phenological and physiological parameters. Plants grown in the greenhouse at the Texas AgriLife Research and Extension Center in Beaumont, Texas. U.S. were exposed to 0, 8 or 16 kJ m(-2) day(-1) UV-B radiation for 90 days. Our results showed differences among southern US rice cultivars in response to UV-B treatments with respect to leaf photosynthetic rate (P), leaf phenolic concentration, pollen germination (PG), spikelet fertility (SF), leaf number, leaf area, and yield. For most of the cultivars, plants exposed to enhanced UV-B radiation showed decreased P-n, PG, SF and yield and increased spikelet abortion and leaf phenolic concentration compared to the plants grown in a UV-B-free environment. In this study, cultivar 'Clearfield XL729' performed better than the other cultivars under enhanced UV-B radiation. (C) 2010 Elsevier B.V. All rights reserved.