1992 Volume 61 Issue 4 Pages 576-582
The influences of temperature and photoperiod to phenological development of two spring wheat varieties, early Haruyutaka bred in Hokkaido and late Selpek bred in Germany, were investigated at the field of Agricultural Experimental Farm of Hokkaido University. There were linear relations between the rate of development and temperature through the all of growth phases for both two varieties. In growth phase I and II that is, phases before flag leaf emergence, the rate of development increased as temperature increased, at a larger extent in Haruyutaka than in Selpek. In growth phase IV + V, grain-filling period, the rate of development decreased at low temperature especially in Selpek. The thermal developmental rate, 1/D (T-Ts), is the value of developmental rate, 1/D, divided by temperature, (T-Ts). T and Ts are mean and base temperature, respectively. There were linear relationships between this thermal developmental rate and mean photoperiod in growth phase I and II, indicating photoperiod affected developmental rate more sensitively in Haruyutaka than in Selpek. On the other hand, we compared the calculated results from regression formula for development based on temperature and photoperiod with the observation by field experiment in 1986, 1987 and 1991. The mean difference between observation and calculated results for the whole growing period was only 3.8 days.
