|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1992 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1991 : ¥1,700,000 (Direct Cost : ¥1,700,000)
About 4.5 leaf-aged rice seedlings of different ecotype and plant type cultivars with almost same heading time were transplanted in ca. 1/1000a pot with one seedling per hill. And primary tillers developed from base to the 5th(T1), 8th(T2) or 11th(T3) node on the main stem were removed to clarify the effects of tillering position on the grain productivity in rice tillers of different order and position on the main stem. The results were summarized as follows:
1.First tillering date of T1,T2 and T3-plot corresponded to the beginning active and final to maximum tillering stage of non-treated(C) plot, respectively.
2.The lower the nodal position on the main stem was, the higher the panicle weight in all plots, mainly due to the difference of panicle number. Both of the total panicle and average a panicle weight at the same position on the main stem was higher in order of T3>T2>T1>C-plot. And also the average of a panicle weight was higher in tillering order and marked decrease of a panicle weight by ascending the nodal position was found in higher order tillers.
3.Although the number of maximum tillers and panicles were lower in order of T1<T2<T3<C-plot, the average of a panicle weight showed reverse response to the removal of lower tillers. But great varietal difference was found in the increment of a panicle weight by the treatment, that is, increasing rate was higher in panicle number type than panicle weight type cultivars. Consequently, panicle weight per hill, namely yield, of the former type cultivars did not change or rather increase, but decrease in case of the latter type cultivars by the treatment. And this yield in-crease was closely related to the period of vegetative growth, that is, days from tiller appearance to heading, so the highest effect was obtained in the early planting in normal season culture.