Correlation of the Weight of Brown Rice per Panicle with the Vertical Distribution of Leaf Area and the Nitrogen Content of Leaves on the Tillers at Each Nodal Position and Nodal Order in Rice Canopy

Abstract

The vertical distributions of leaf area and nitrogen content of leaves per leaf area were examined in the tillers at each nodal position and nodal order in rice canopy to clarify the factors that cause the difference in the weight of brown rice per panicle among the tillers at different nodal positions and orders. The tillers bearing heavy brown rice had many spikelets per panicle without reduction in the number rate of brown rice (>1.9 mm) to unhulled rice and thousand-grain weight. They also had a large leaf area without a significant difference in leaf area per spikelet. In addition, they had many leaves with a high nitrogen content per leaf area in the upper layer of rice canopy where the relative irradiance was high. These results suggest that the difference in the vertical distributions of leaf area and the nitrogen content of leaves per leaf area among the tillers after heading time in the rice canopy causes the difference in the weight of brown rice per panicle among the tillers at different nodal positions and nodal orders in the rice canopy.