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

增强的未过滤UVB抑制水稻分蘖数、生物量、株长、光合速率和叶绿素含量。CO_2浓度升高或暴露于高辐照度-可见光辐射均能减轻UVB的辐射效应。在来自孟加拉和印度尼西亚的5个亚洲水稻生态类型（aus、aman、boro、bulu和tjeleh）和日本低地和高地群体中，日本低地稻群体和boro生态类型的抗性较高。在日本低地水稻品种中，Sasanishiki表现出对UVB的抗性，而Norin 1表现出较低的抗性，尽管这两个品种是密切相关的。由此可见，不同品种对UVB敏感性不同的品种是属于同一生态型和同一类群的，水稻对UVB的抗性并不单纯是由于栽培品种的地理位置不同所致。利用Sasanishiki与Nirin 1杂交的F_2和自交F_2的F_3，对水稻抗UVB效应进行了遗传分析，结果表明，水稻抗UVB受隐性多基因控制。不含UVC的高UVB降低了叶片总氮、可溶性蛋白和Rubisco，而增加了UV吸收化合物的积累。品种间对UVB的抗性存在差异。Rubisco含量的减少在Sasanishiki中较少，而紫外线吸收化合物积累的增加在Sasanishiki中较大。因此，品种间抗UVB的差异可能是由于受UVB影响的Rubisco含量和紫外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.