Differences in dry matter production and ecophysiological characteristics between soybean cultivars, Enrei and Tachinagaha

Abstract

The soybean cultivar, Tachinagaha, could attain a higher grain yield than Enrei because of higher dry matter production after flowering. The crop growth rate during ripening was clearly high in Tachinagaha because of high net assimilation rates compared with Enrei. No difference in the light extinction coefficient of the whole canopy was observed between the two cultivars, but it was far smaller in the upper layer of the canopy in Tachinagaha than in Enrei, especially at midday. The leaf photosynthetic rates in Tachinagaha were high compared with Enrei. The degradation of leaf color and the decrease in the number of living leaves with ripening slowed in Tachinagaha compared with Enrei. These results indicated that the higher leaf photosynthetic rate because of slow senescence might contribute to the higher NAR in Tachinagaha as well as improved light intercepting characteristics of the upper layer in the canopy.