The relationships between the growth index, the yield, the number of panicles per m2, and the lodging degree of the early-season culture of Oryza sativa L. 'Koshihikari' in Sizuoka prefecture [Japan]

1) We have investigated the growth index values in order to diagnose the growing Process and to get the target yield (54, 57, 60kg a level) of the early-season culture of Oryza sativa L. 'Kosihikari' in Sizuoka Pref. 2) The average DVI (DeVelopmental Index) at each cultivation stages of 1993 - 1996 was DVI=0.37 at the drying starting stage, DVI=0.64 at the drying finishing stage and DVI=0.74 at the panicle formation stage. These average DVIs were temporarily designated as peculiar DVI at each cultivation stages. 3) The numbers of panicles per square meter corresponding to each yield level were calculated from the yield with a quadratic equation. They varied from year to year. Namely, the number of panicles per mi was 23,900-30,900) to 54kg/a yield level, 26,300 - 34,900) to 57kg/a yield level panicles, and 32,000 - 40,400 to 60 kg/a yield level, respectively. 4) The relation of growth index with the yield, the number of panicles per square meter, and the lodging degree was investigated. As a result, it was suggested that the growth index should be designated as plant length (cm) A-stem number (number/square meter). 5) The relationship between the yield and growth index(plant length A-stem number) was shown with a quadratic equation. The ranges of the growth index value with this quadratic equations were searched. They were not shown clearly. 6) The relation between growth index (plant length A-stem number) and the number of panicles per m2 was shown with a simple equation. The growth index value for the target yield from the necessary number of panicles per au was cleared. Namely, in a case of the 54 and 57 kg/a level, the growth index value was especially high in 1995, and stable in 1993, 1994, and 1996. In the case of the 54 kg/a level, the averages of the value in 1993, 1994, and 1996 were 11.1 (A-10-(3)) at DVI 0.37, 24.1 at DVI=0.64, and 24.1 at DVI=0.74