Characteristics of Dry Matter Production Process in High Yielding Rice Varieties : III. Comparisons of leaf photosynthesis

[摘要] The difference of dry matter production process among the rice cultivars was previously reported with reference to light intercepting characteristics. This study was conducted to determine if the single leaf photosynthetic characteristics, which affect the dry matter production, were different among the rice cultivars. Leaf apparent photosynthetic rate (APR), diffusive conductance, nitrogen content and chlorophyll content were monitored every ten days from the maximum tillering stage to the harvesting time in the uppermost five leaves on the main stem of two early varieties ; Akihikari (Japanese cultivar) and Nanjing 11 (Chinese cultivar, Indica), and three medium varieties ; Nipponbare, Musasikogane Japanese cultivars) and Milyang 23 (Korean cultivar, Japonica/Indica hybrid). The results obtained were as follows. The maximum APR of the uppermost two leaves in the early varieties was higher than that in the medium varieties. Maximum APR in Akihikari and Milyang 23 was higher as compared with that in Nanjing 11 and that in Nipponbare and Musasikogane, respectively. APR decreased with getting lower in position of leaf on the stem and with increasing in leaf age. Decreasing degree of APR was greater in Nanjing 11 and Milyang 23 than in Akihikari, Nipponbare and Musasikogane, respectively. APR was significantly correlated with nitrogen content (correlation coefficient, r = 0.84), chlorophyll content (r = 0.68) and diffusive conductance (r = 0.90) in the leaves of various positions on the stem and of various ages. However, there was no significant correlation between APR and chlorophyll content above 4 mg dm-2. These relationships were different among the varieties. These results suggested that the lower canopy net assimilation rate in Nanjing 11 as compared with that in Akihikari was mainly owing to the lower leaf photosynthetic rate, but photosynthetic rate hardly affected the difference of canopy dry matter production among the medium varieties.

[学科分类] 农业科学（综合）

[关键词] Ageing;拡散伝導度;Diffusive conductance;乾物生産;High yielding rice variety;個葉光合成速度;Leaf chlorophyll content;多収性水稲品種;Leaf nitrogen content;葉身クロロフィル含量;Single leaf photosynthesis.;葉身窒素含量;老化