Analysis of the Photosynthetic Characteristics of the High-Yielding Rice Cultivar Takanari

[摘要] It was clarified in a previous paper that higher dry matter production for a newly bred high-yielding rice cultivar, Takanari was mainly due to the higher net assimilation rate (NAR) owing to better light-intercepting characteristics after the panicle formation stage. The CO2 exchange rate, which affects the NAR, was studied using cultivars, Takanari and Nipponbare in this paper. Observations showed that Takanari was remarkably higher in CO2 exchange rate than Nipponbare during diurnal courses, during leaf- senescence or at different leaf positions. These results indicate that the higher NAR for Takanari was due to not only better light-intercepting characteristics but also a higher CO2 exchange rate. Furthermore, the cause why these differences in photosynthesis existed between the two varieties was examined. It was found that the CO2 exchange rates for Takanari maintained a higher level owing to its higher diffusive conductance during diurnal courses, and owing to both its higher diffusive conductance and higher photosynthetic capacity during leaf senescence. Further investigation indicated that the higher photosynthetic capacity for Takanari was mainly owing to a higher apparent carboxylation efficiency and Rubisco content during leaf senescence.

[学科分类] 农业科学（综合）

[关键词] Apparent carboxylation efficiency;イネ;Apparent quantum yield;拡散伝導度;Chlorophyll content;クロロフィル含量;CO2 exchange rate;光合成速度;Diffusive conductance;炭酸固定効率;Photosynthetic capacity;葉肉の光合成活性;Rice;量子収率;Rubisco content;Rubisco含量