Studies on the Growth of Rice Plant Cultivated in Different Seasons. : IV. Estimation of the heading time in early season cultivation of paddy rice

For the purpose to know beforehand the heading date of "early transplanted rice", we investigated the relations among the sowing date, the transplanting date, the heading date and the accumulated air temperature from 1956 to 1961. Thus we found high negative correlations between the time from sowing to heading and the sum of average temperature from the sowing date (or the transplanting date) to a certain date (Fig. 3). Therefore we can estimate exactly the heading date in every year by the sum of average temperatures from the sowing time (or the transplanting date) to a certain date (as an example to the 50th day after sowing) of that year (Fig. 4).