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 nSDLT-nSDHT, nLDLT-nSDLT and nSDHT, respectively, where nSDLT 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.