The yields of the paddy rice (y) in the warmer districts in Japan are mainly proportional to the sunshine-duration (s) in autumn, but are increased or decreased according to the air-temperature (t) in summer; the optimum temperature (t0) averaged in summer is about 27.2°C, and the yields are poor in both cases of cooler summer and too hot summer.
The above relation are expressed by the following equations. See Figs. 2 and 3.
y(KAN/TAN)=10.1+0.27s+31.87e-4.36(t-27.19)2
or y(%)=9.0+0.21s+25.41e-4.32(t-27.2)2
(note) KAN/TAN≅3.75kg/1000m2
