Effects of nitrogen topdressing at the neck-node differentiation stage on rice [Oryza sativa] yield in warmer regions of Japan
1997
Ida, R. (Tottori-ken. Government Office (Japan))
Effects of nitrogen topdressing on young seedlings and yield-determining factors of brown rice were studied with the aim of developing an efficient method of applying nitrogen fertilizer to achieve greater grain production. It was found that there is a limit to increasing the number of spikelets just by increasing the number of panicles when the number of spikelets reached 31,000 m(-2). This is due to a decrease in the number of spikelets per panicle. The decrease of spikelet numbers per panicle was caused because of fewer differentiated secondary rachis-branch numbers, and not by the degeneration of rachis-branches nor that of spikelets. A significant positive correlation was observed between the rate of nitrogen absorption by rice plant during vegetative-lag phase and the number of differentiated secondary rachis-branches, which is closely related to the number of spikelets per panicle. The rate of nitrogen absorption during vegetative-lag phase was found to be determined by nitrogen absorption during the approximately 7-day period from neck-node differentiation stage to early spikelets differentiation stage
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