落花生の開花におよぼす気温の影響

抄録

This study consists of two experiments. The first experiment was performed in the growth cabinet illuminated by YOKO lamps (Toshiba D-400) with a day length of 12 hours and with relative humidity of 70%. The mean air temperatures were maintained at 20°C (day and night temperature ; 25°C and 15°C), 25°C (30°C and 20°C) and 30°C (35°C and 25°C), using three varieties of peanut plants, namely Chiba-handachi(large seed, semi-erect type), Java no. 13 (small seed, erect type) and Chiba no. 43 (large seed, runner type) as materials. In the second experiment, the effective heat summations required for the first flowering were calculated from the data on flowering of the plants sowed at the different times. 1. As air temperature became higher, the days required for the first flowering became shorter and the increasing rate of the dry matter and the leaf emergence rate on the main stem were promoted more remarkably. But the promoting rate of temperature on flowering in the case that air temperature was raised from 25°C to 30°C was less as compared with that in the case from 20°C to 25°C. 2. Regardless of air temperature, a turning point of the leaf emergence rate on the main stem was found at the time of the fourth leaf emergence, including the three varieties used. 3. The number of the leaves on the main stem and the dry matter weight at the time of the first flowering of plants grown at air temperature of 30°C were more than those of plants grown at 20°C or 25°C. 4. The number of the leaves on the main stem, the dry matter at the first flowering time and the days required for the flowering after sowing of Java no. 13 were less than those of Chiba-handachi and Chiba no. 43. 5. It is assumed that the flower bud of peanut plants is formed at earlier stage after germination when cultured at higher air temperature. So it seems quite reasonable to assume that air temperature has a direct effect on flowering. 6. The effective heat summation required for the flrst flowering which was obtained by integrating a daily mean temperature over 12°C, was 417.3±12.8°C and showed the least variation among the peanut plants sowed at the different times.