[Effects of enhanced ultraviolet-B radiation on growth development and yield formation in rice (Oryza sativa L.)].

Effect of enhanced ultraviolet-B radiation (280-320 nm) on growth, development and yield formation in the three rice cultivars (Oryza sativa L.) under pot conditions were investigated. The results showed that enhanced ultraviolet-B radiation decreased rice height, tiller number, total leaf area and biomass, but the inhibitory rate varied in different cultivars and developmental stages. Plant height was decreased by 9.4%-12.2% in seedling stage, plant shoot and root of dry matter were decreased by 45.3%-59.8% and 54.9%-59.0% respectively in tillering period. The leaf emergence delayed, resulting in delayed time of flowering in Shanyou 63, Nanchuan and IR65600-85 by 2d, 3d and 7d, prolonged total growth period by 3d, 4d and 9d. Net photosynthesis rate of Shanyou 63, Nanchuan and IR65600-85 were decreased by 11.9%, 12.8% and 29.7%, respectively. Attributed to decreased contents of chlorophyll a, b, carotenoid and induction kinetics parameters of Fv, Fv/Fm and Fv/Fo. Effective panicle per plant, total grain number per panicle, filled grain rate and 1000-grain weight were decreased by enhanced UV-B radiation. Consequently the grain yields were reduced by 25.2%-31.1%.