Effects of solar UVB radiation on growth and yield of rice under outdoor conditions for 2006-2008

Abstract

Supplementary UVB radiation inhibited growth, yield and grain development. One of principal causes of such UVB-induced damage is UVB-induced CPD, and increasing CPD photolyase activity can significantly alleviate UVB-caused growth inhibition. How degree of growth inhibition was caused by UVB in natural sunlight? In this work, effects of solar UVB on growth and yield of rice under outdoor conditions at Miyagi pref. (2006-2008) and Kagoshima pref. (2008) were investigated using UV-resistant Koshihikari and the UV-sensitive chromosomal segment substitution line (SL-229) as experimental plant; chromosomal 10 region, on which CPD photolyase gene located, in SL-229 was homozygous for Kasalath allele, whereas all other chromosomal regions were homozygous for Koshihikari alleles. CPD photolyase activity of Kasalath was lower than that of Koshihikari. The grain size and weight of SL-229 under current outdoor conditions were reduced. These results mean that growth and yield of rice grown under current environmental conditions would be inhibited by UVB in natural sunlight.