On Dry Matter Production and Efficiency for Solar Energy Utilization by Rice Population in Warmer Region of Japan

Abstract

"Maximal Growth Rate Experiment" was conducted using rice variety Hoyoku at Kyushu Agricultural Experiment Station from 1967 to 1971. The results obtained are as follows. 1. High positive correlation was observed between the amount of solar radiation and CGR during the period from 6 to 3 weeks before heading. With the increase of solar radiation CGR increased much at the early stage of the growth, but not so much at the later stage of the growth (Fig. 1). 2. Mean temperature was positively correlated with CGR at the early stage of the growth and negatively at the later stage of the growth (Fig. 2). 3. The significant positive partial correlation was found between the amount of increase in leaf area and temperature during the period from transplanting time to 6 weeks before heading, and between the amount of increase in leaf area and solar radiation during the period from 6 to 3 weeks before heading (Table 2). 4. The efficiency for solar energy utilization of whole growing duration was higher in normal season culture than in early planting culture (Table 4). 5. The efficiency for solar energy utilization after heading had a tendency to become lower as temperature became higher (Fig. 7).