Abstract
This experiment was conducted to investigate the variation of nitrogen use efficiency, nitrogen uptake efficiency, physiological utilization efficiency and their relationships with growth characteristics in the 28 Korean rice cultivars. Nitrogen use efficiency of 28 rice cultivars was 47.74, nitrogen uptake efficiency was 0.71, and physiological utilization efficiency was 68.76 in average. Nitrogen use efficiency of rice cultivars had low variation ranged from 44.09 to 51.91, but nitrogen uptake efficiency were relatively high variation from 0.51 to 0.90, and physiological utilization efficiency was from 51.71 to 94.26. The high efficient group in nitrogen uptake efficiency whose value was calculated above 0.80 included Daeanbyeo, Seojinbyeo, Ansungbyeo, Dongjinbyeo, and Hwaanbyeo, while the low efficient group with below 0.60 was Kwanganbyeo, Sampyeongbyeo, Soorabyeo, and Hwasungbyeo. Hwasungbyeo, Sampyeongbyeo, Soorabyeo for physiological utilization efficiency were more efficient cultivars, while Daeanbyeo, Seojinbyeo, Ansungbyeo were less efficient cultivars. Nitrogen uptake efficiency had positive correlation coefficients between dry matter weight of plant ($0.842^{**}$), leaf area index ($0.761^{**}$), and leaf nitrogen content ($0.599^{**}$), respectively. Therefore, the dry matter weight of rice plant and leaf area index was important characters to evaluate nitrogen uptake efficiency in rice cultivars. Also, more efficient cultivar in nitrogen uptake had higher chlorophyll meter value, which was appeared dark green color.
