Effects of UVB radiation and CO_2 atomosphere on growth of rice (oryza sativa L.).

UVB浓度升高抑制了水稻的分蘖数、生物量、植株长度、光合作用速率和叶绿素含量。大气CO_2浓度升高或暴露于高辐射可见辐射均可减轻UVB的辐射效应。在来自孟加拉和印度尼西亚的5个亚洲水稻生态型(Aus、Aman、Boro、Bulu和Tjeleh)以及日本水稻群和旱稻群中，日本水稻群和Boro生态型抗性较强。在日本旱稻品种中，Sasanishiki对UVB表现出较强的抗性，Norin 1号表现出较低的抗性，尽管这两个品种关系密切。可见，不同品种对UVB的敏感性不同，属于同一生态型和同一类群，水稻对UVB的抗性不仅仅是由于栽培品种的地理环境不同所致。利用Sasanishiki与Nirin 1和F3自交产生的F2代植株对UVB的抗性对水稻生长的影响进行了遗传分析，证明了对UVB的抗性是由隐性多基因控制的。不含UVC的UVB胁迫降低了叶片总氮、可溶性蛋白质和Rubisco的含量，但增加了紫外线吸收物质的积累。品种间对UVB效应的抗性存在差异。Sasanishiki中Rubisco含量的下降幅度较小，而UV吸收化合物积累量的增加幅度较大。因此，品种间对UVB的抗性差异可能是由于受UVB影响而产生的Rubisco含量和UV吸收物质的差异所致。

Elevated unfiltered UVB inhibited tiller number, biomass production, plant length, photosynthetic rate and chlorophyll content in rice. UVB effects were alleviated either by elevated CO_2 atmosphere or by exposure to high irradiance-visible radiation. Among 5 Asian rice ecotypes (aus, aman, boro, bulu and tjeleh) from Bengal and Indonesia and Japanese lowland and upland rice groups, the Japanese lowland rice group and the boro ecotype were more resistant. Among Japanese lowland rice cultivars, Sasanishiki exhibited more resistance to UVB,while Norin 1 showed less resistance, although these two cultivars are closely related. It was evident that various cultivars having different sensitivities to UVB were involved in the same ecotype and the same group, and that the resistance of rice to UVB is not simply due to the difference in the geographical situation where rice cultivars are cultivated. The genetic analysis of resistance to UVB effects on growth of rice using F2 plants generated by reciprocally crossing Sasanishiki and Nirin 1 and F3 lines generated by self-fertilizing F2 plants proved that the resistance to UVB was controlled by recessive polygenes. Elevated UVB containing no UVC reduced total leaf nitrogen, soluble protein and Rubisco, while increased in the accumulation of UV-absorbing compounds. There was a cultivar difference in the resistance to UVB effects. The reduction in Rubisco content was less in Sasanishiki, while the increase in the accumulation of UV-absorbing compounds was greater in Sasanishiki. It was thus suggested that the cultivar difference in the resistance to UVB might be due to the difference between Rubisco content and UV-absorbing compounds as influenced by UVB.