Growth characteristics of submerged hill-seeded rice (Oryza sativa L.) in warmer regions of Japan - Improvement of growth and yield by basal application of controlled release fertilizer at a later growth stage [Japanese]

摘要

It has been reported that hili-seeded rice, using a newly developed "Shooting hill-seeder", shows high lodging resistance and ripening ability in the warmer regions of Japan. It suggests possibility for an increase in yield by increasing the number of spikelets through an improvement of the nitrogen uptake pattern. We examined the effects of a basal application with the controlled release fertilizer appearing at a later growth stage (CFL) on the growth and yield. Hill seeded rice under conventional fertilization showed vigorous early growth and advanced maximum-tillering stage compared with transplanted rice. These changes in growth caused yield reduction by a decrease in the total number of spikelets through a decrease in nitrogen uptake at the vegetative lag phase (VLP). On the other hand, the slower early growth rate and shorter VLP caused by the CFL application resulted in the increase in nitrogen absorption during VLP. The improvement of nitrogen uptake contributed to the increase in yield, which is equivalent to that of transplanted rice, through an increase in the total number of spikelets. Furthermore, under this type of fertilizer application, adverse effects on the lodging resistance and the nitrogen content of brown rice were not observed. These results suggest that the basal application of CFL as an improvement of fertilization would contribute to stabilize the submerged direct-seeded rice both in yield and quality.