6Novoa R, Loomis R S. Nitrogen and plant production. Plant and Soil, 1981,58 : 177 - 204
7Cassman K G, Peng S, Olk D C ,et al. Opportunities for increased nitrogen use efficiency from improved resource management in irrigated rice systems. Field Crops Research,1998,56:7 -38
8Fageria N K, Baligar V C. Methodology for evaluation of lowland rice genotypes for nitrogen use efficiency. Journal of Plant Nutrition,2003,26 : 1 315 - 1 333
9Dobermann A. Nitrogen use efficiency-state of the art. Paper of the IFA International Workshop on Enhanced-Efficiency Fertilizers. Frankfurt, Germany. 2005
10Cassman K G, Dobermann A, Wahers D T. Agroecosystems, nitrogen-use efficiency, and nitrogen management. Ambio, 2002, 31:132 - 140
