Abstract:

【Objective】 The goal of this research was to analyze the characteristics of nitrogen uptake and distribution in conventional indica rice cultivars with large sink potential(SP). 【Method】 Eighty-eight and 122 conventional indica rice cultivars were solution-cultured in 2001 and 2002, respectively. Dry matter weight (including root system, culm and sheath, leaves, panicle), nitrogen content in different organs, yield and its components were measured. The tested rice cultivars were classified into 6 types (i.e. A, B, C, D, E and F, A was the lowest, and F was the highest) based on their SP level by the MinSSw method, to study their difference in nitrogen uptake and distribution. 【Result】 Difference of SP of the cultivars used in this study was very large, the averages of SP in different types were 426.37, 642.53,770.96, 903.73, 1064.32, 1213.90 g?m-2 in 2001, and 359.36, 574.11, 764.98, 962.43, 1200.11, 1455.59 g?m-2 in 2002, respectively; in large SP types of indica rice, N content (%) at heading stage was higher, while that decreased more during grain filling period. Cultivars with large SP were characterized by higher N accumulation during grain filling period and at mature stage, lower rate of N distributed in root, leaf, culm, and sheath and higher translocation rate from leaf, culm and sheath to panicle. N accumulation was significantly influenced by growth duration and N uptake intensity, but the effect of N uptake intensity on N accumulation was more important than growth duration. Enhancing N accumulation and rate of nitrogen translocation in culm, sheath and leaf during the grain-filling stage could improve SP. 【Conclusion】 Cultivars with large SP were characterized by higher N accumulation during grain filling period and at mature stage, lower rate of N distributed in vegetative organs and higher translocation rate from leaf, culm and sheath to panicle.

Key words: conventional indica rice, cultivars, sink potential, nitrogen uptake, nitrogen distribution