1984 Volume 34 Issue 4 Pages 423-430
Heading responses of barley to temperature and day-length were investigated in order to analyze the physiological characters responsible for early heading in Japanese varieties. Ten varieties were grown under various conditions of temperature (5, 10, 15 and 20%) and day-length (11, 12, 13, 14, 15 and 24hours). When the varieties were grown under a 24-hour day-length regime, heading tirne was accelerated with wihe rise of temperature, regardless of the varieties. There were no appreciable difference in the response to temperature. Varietal differences in heading were observed under short day conditions. When the night temperature was higher than the temperature in the field, heading of earlier varieties was more accelerated. Several materials including early varieties were examined under long day (24 hours) and short day (11 hours) regimes, respectively. The early varieties had generally inherited their insensitivity to short day from the parental varieties or lines. They also showed different responses to both short and long day, due to their adaptation to the producing districts.