Studies on Meteorological Fluctuation in the Growth of Rice Plants. : V. Regional Differences of Thermo-Sensitivity, Photo-Sensitivity, Basic Vegetative Growth and Factors Determining the Growth Duration of Japanease Varieties.

Abstract

Thermo-sensitivity(X₁), photo-sensitivity(X₂) and basic vegetative growth(X₃) of 70 rice varieties in Japan were obtained by growing plants in growth cabinets under possible 4 combinations of different daylength and temperature : short(SD:10h) or long(LD:14h) daylength and low(LT:20'C) or high(HT:30'C) tempcrature. The X₁, X₂ and X₃ are expressed by n_SDLT-n_SDHT, n_LDLT-n_SDLT and n_SDHT, respectively, where n_SDLT Stands for the number of days from sowing to headlng under 10h and 20 C and so on. Duration (Y) from sowing to heading of the same varieties was examined in a paddy field with three different sowing dates. Multiple correlations between duration(Y) and a set of X₁, X₂ and X₃ of early, medium and late maturing varieties in all sowing dates were highly significant, showing thatvarietal differences in duration(Y) could be largely explained by the combination of the three factors.