| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1992: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1991: ¥1,400,000 (Direct Cost: ¥1,400,000)
|
|---|
| Research Abstract |
The grain yield of rice, as well as other cereal crops, is limited to a large extent, by the supply of photosyntheses assimilated during the ripening period. In this study, yields, their components and the difference of single leaf photosynthesis (CER) after heading were compared among 11 varieties, the standard varieties in the northeast district of Japan and breeding strains to high yielding varieties, for two years from 1991 to 1992. Furthermore, CER, total nitrogen content in the leaves (TNC) and chlorophyll content (CHLC) were monitored from the heading stage to the late ripening stage on the flag leaves of the main stem and large tillers. The results are as follow:
1. The yield of Ohuu 316, Ohuu 331 and Yamagata 22 were higher than that of Fujiminori and Hananomai owing to higher dry matter production and especially more spikelets number per unit area, the large difference in the yield from 600 kg/10a to 750 kg/10a were observed among the varieties, used as this experimental materials.
2. CER, TNC and CHLC decreased gradually with increasing in leaf age after antesis to harvesting time and the degree of decrease in CER was greater than other two factors. However, if nitrogen was top- dressed at the heading stage, high CER was maintained, particularly in the nitrogen top-dressed plots.
3. CER among varieties were significantly correlated with TNC and CHLC in leaves of various stage and of top-dressed plots, varietal difference in CER at any stage was closely associated with TNC and CHLC. However, the large dispersion were observed in CER even if they were compared under the same TNC and CHLC level at the late ripening stages and this was thought to be another basis for varietal difference in CER.
4. From these results, it was suggested that, in order to clarify another physiological basis of the difference in CER under the same TNC level.further studies must be made on more detail.
|
