北限地帯における水稲の生産生態に関する研究 : 第1報 乾物生産過程の解析

抄録

The productivity of rice plants growing the north-marginal area in Japan was studied. In the present paper, varietal differences in dry matter production was discussed mainly using 8 varieties in 1982 and 11 varieties in 1983 (Table 1). The results obtained were summarized as follows; 1. Daily solar radiation and accumulated daily mean temperature from June 1 to September 30 were 417.8 cal/cm²/day and 2168°C in 1982, and 358.8 cal/cm²/day and 1897°C in 1983 (Fig.1). 2. The average value among varieties of the maximum dry weight was 1152.7 g/m² in 1982 and 1021.2g/m² in 1983 (Fig.2). 3. The average value among varieties of CGR during the whole growth period was 9.9g/m²/day in 1982 and 7.6g/m²/day in 1983. The average value of LAImax. was 3.3m²/m². field in 1982 and 3.2m²/m². field in 1983. The average value of the efficiency for solar energy utilization (Eu) during the whole growth period was 0.86% in 1982 and 0.79% in 1983. The average value of the efficiency for solar energy conversion (Ec) during the whole growth period was 2.3% in 1982 and 2.2% in 1983 (Table 2, Fig.4). 4. Relative light intensity at the bottom of the canopy (logarithmic scale) decreased linearly with increasing LAI. The regression value (light diminution coefficient, K') was varied among varieties (Fig.5). 5. Dry matter production (ΔW) can be expressed by the following equation, ΔW = LAD × ΔTS × MEi/LAD × ΔW/ΔIS where LAD is leaf area duration, ΔTS is accumulated solar radiation, MEi is mean value of the efficiency for intercepting solar radiation, ΔIS is accumulated solar radiation intercepted by the canopy. 6. To clarify the relative contribution of LAD, K', Ec and ΔTS to ΔW, the multiple regression analysis was used. Ninety six percent of the variation among varieties and years in ΔW were accounted by these 4 factors. The ratios of standard partial regression coefficients of LAD, K', Ec and ΔTS were 47:30:20:3 before full heading stage, but 14:18:46:22 after full heading stage (Table 3).