Effect of Transplanting Time on Growth of Rice Cultivar "Kinuhikari"in Kagawa Prefecture : Temperature effect on time of appearance of the first tiller, heading and maturation

[摘要] This experiment was carried out in order to examine the influence of transplanting time on the growth of rice plants in Kagawa Prefecture, Japan. A rice cultivar, Kinuhikari, was transplanted at 3-4 different times from 1992 to 1995. The number of days required for first tiller appearance(DFTA), the number of days from transplanting to heading time (DTH) and the number of days from heading to maturation(DHM) were investigated in relation to temperature.The relation between DFTA(Y1) and the mean temperature for 5 days after transplanting(X1) was expressed by means of the following equation;Y1=197.35×e<:0.170>l:X1···(1) According to this equation, the estimated DFTA was prolonged abruptly and required more than 12 days when (X1)was below 16∼17°C.This temperature corresponded to that of the second five days of May in Kagawa Prefecture.Similarly, DTH(Y2)was expressed by the mean temperature for 30 days after transplanting(X2)and DFTA(X3);Y2=-2.56X2+0.76X3+118.86···(2) DHM(Y3)was expressed by the mean temperature for 30 days after heading(X4)as follow;Y3=-2.1X4+89.2···(3) Therefore, we estimated that the safe transplanting time in Kagawa Prefecture is during the second five days of May.Also, heading time and maturation can easily be estimated by equations(2) and (3), respectively.

[学科分类] 农业科学（综合）

[关键词] Heading time;移植時期;Kinuhikari;キヌヒカリ;Mean temperature;出穂期;Number of days from heading time to maturation;出穂迄日数;Number of days from transplanting to heading time;初発分げつ迄日数;Number of days required for first tiller appearance;水稲;Rice;登熟日数;Transplanting time.;平均気温.