Analysis of the photosynthetic characteristics of the high-yielding rice cultivar Takanari.

摘要

The CO2 exchange rate, which affects the net assimilation rate (NAR), was studied in rice cv. Takanari (high yielding) and Nipponbare. Takanari was remarkably higher in CO2 exchange rate than Nipponbare during diurnal courses, during leaf senescenceor at different leaf positions. It was suggested that the higher NAR for Takanari was due to not only better light-intercepting characteristics but also a higher CO2 exchange rate. The reasons for these differences in photosynthesis between the 2 cultivars were examined. It was found that the CO2 exchange rates for Takanari maintained a higher level due to its higher diffusive conductance during diurnal courses, and due to both its higher diffusive conductance and higher photosynthetic capacity duringleaf senescence. Further investigation indicated that the higher photosynthetic capacity for Takanari was mainly due to a higher apparent carboxylation efficiency and ribulose-bisphosphate carboxylase content during leaf senescence.