Studies on the differences of single leaf photosynthesis among some rice varieties

水稻和其他谷类作物的产量在很大程度上受到成熟期间光合作用同化的供应的限制。本研究比较了1991 ~ 1992年11个品种、日本东北地区标准品种和选育品系与高产品系抽穗后单叶光合作用（CER）的产量、组成及差异。在抽穗至成熟后期，对主茎旗叶和大分蘖叶片的CER、叶片全氮含量（TNC）和叶绿素含量（CHLC）进行监测。研究结果如下：1。作为本试验材料的欧胡316、欧胡331和山形22由于干物质产量较高，特别是单位面积颖花数较多，产量高于藤森和花野麦，在600 kg/10a和750 kg/10a之间差异较大。采收后随着叶龄的增加，CER、TNC和CHLC逐渐降低，且CER的降低程度大于其他两个因子。如果在抽穗期追肥，则保持较高的CER，特别是在氮肥追肥小区。品种间CER与各生育期和孕穗期叶片TNC和CHLC显著相关，各生育期CER的品种差异与TNC和CHLC密切相关。然而，即使在成熟后期相同的TNC和CHLC水平下进行比较，也可以观察到CER的巨大差异，这被认为是CER品种差异的另一个基础。从这些结果来看，为了阐明相同TNC水平下CER差异的另一个生理基础。必须对更详细的内容进行进一步的研究。

The grain yield of rice, as well as other cereal crops, is limited to a large extent, by the supply of photosyntheses assimilated during the ripening period. In this study, yields, their components and the difference of single leaf photosynthesis (CER) after heading were compared among 11 varieties, the standard varieties in the northeast district of Japan and breeding strains to high yielding varieties, for two years from 1991 to 1992. Furthermore, CER, total nitrogen content in the leaves (TNC) and chlorophyll content (CHLC) were monitored from the heading stage to the late ripening stage on the flag leaves of the main stem and large tillers. The results are as follow:1. The yield of Ohuu 316, Ohuu 331 and Yamagata 22 were higher than that of Fujiminori and Hananomai owing to higher dry matter production and especially more spikelets number per unit area, the large difference in the yield from 600 kg/10a to 750 kg/10a were observed among the varieties, used as this experimental materials.2. CER, TNC and CHLC decreased gradually with increasing in leaf age after antesis to harvesting time and the degree of decrease in CER was greater than other two factors. However, if nitrogen was top- dressed at the heading stage, high CER was maintained, particularly in the nitrogen top-dressed plots.3. CER among varieties were significantly correlated with TNC and CHLC in leaves of various stage and of top-dressed plots, varietal difference in CER at any stage was closely associated with TNC and CHLC. However, the large dispersion were observed in CER even if they were compared under the same TNC and CHLC level at the late ripening stages and this was thought to be another basis for varietal difference in CER.4. From these results, it was suggested that, in order to clarify another physiological basis of the difference in CER under the same TNC level.further studies must be made on more detail.