벼에서 생리적 질소이용효율의 품종간 변이와 농업형질과의 관계

Genotypic Variation of Physiological Nitrogen Use Efficiency and its Relationship with Agronomic Characters in Rice

This study was carried out to evaluate the variation of physiological nitrogen use efficiency (PNUE=grains yield/total nitrogen content of shoot)) in rice varieties under different nitrogen (N) fertilizer levels, and to investigate the relationship of PNUE with agronomic characters in order to obtain the basic information for breeding lines of high PNUE. PNUE of rice varieties ranged from 24.5 to 64.4 and from 40.6 to 84.0 under medium N and non N fertilizer levels, respectively. PNUE was significantly higher in improved varieties than in unimproved local varieties, and was not different among varietal groups such as indica, temperate japonica, and tropical japonica. PNUE was significantly correlated with harvest index, grain yield and number of grains per panicle, and was directly contributed by grain yield based on path analysis in both N fertilizer levels. PNUE was the highest in non N fertilizer level, and decreased by the increment of N fertilizer levels. Under heavy input of N fertilizer of 30 kg/10a, varietal difference became negligible. There was no difference in PNUE among F3 lines derived from F2 by selection for grain yield, indicating that direction selection for PNUE should be needed in breeding program for high PNUE.