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

升高的未过滤UVB抑制水稻分蘖数、生物量、植株长度、光合速率和叶绿素含量。通过提高二氧化碳浓度或暴露于高辐照度-可见辐射来减轻UVB的影响。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）以及日本低地和高地水稻类群中，日本低地水稻类群和boro生态型的抗性较强。在日本的低海拔水稻品种中，Sasanishiki对UVB的抗性较强，而Norin 1抗性较弱，尽管这两个品种是亲缘关系较近的品种。可见，在同一生态型和同一类群中存在着对UVB具有不同敏感性的不同品种，水稻对UVB的抗性并不仅仅是由于栽培品种地理环境的差异造成的。利用Sasanishiki与自交F2植株产生的Nirin 1和F3杂交产生的F2植株对UVB抗性的遗传分析表明，对UVB的抗性是由隐性多基因控制的。不含UVC的UVB升高可降低叶片总氮、可溶性蛋白和Rubisco，增加吸收紫外线的化合物的积累。不同品种对UVB的抗性存在差异。Rubisco含量的减少在三石木中较少，而紫外吸收化合物积累的增加在三石木中较大。因此，品种间抗中波紫外线的差异可能是由于受中波紫外线影响的Rubisco含量和吸收中波紫外线的化合物存在差异。

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.