Submitted to: Journal of Plant Nutrition
Publication Type: Review Article
Publication Acceptance Date: August 5, 2002
Publication Date: January 1, 2003
Citation: Fageria, N.K., Baligar, V.C. 2003. Methodology for evaluation of lowland rice genotypes for nitrogen use efficiency. Journal of Plant Nutrition. 26:1315-1333.
Rice is a staple food for more than 50% of the world's population. Based on land and water management practices, rice ecosystems are mainly divided into lowland, upland, and deep water or floating rice. Most production at the global level comes from lowland or flooded rice systems. In rice growing regions nitrogen is one of the most yield-limiting nutrients for rice production. Use of cultivars or genotypes with high N-use efficiency is a potential strategy reducing the N requirements of crops, lowering the cost of production and reducing the environmental pollution. The objectives of this review paper are to discuss rate and timing of N application, define N-use efficiency, discuss mechanisms involved for genotypic variation in N-use efficiency, and present experimental evidence of genotypic variation in N-use efficiency in lowland rice. Methods and criteria for screening nitrogen-use efficiency are also discussed. Significant variation in N-use efficiency exists in lowland rice genotypes. Nitrogen use efficiency parameters (grain yield per unit of N uptake, grain yield per unit of N applied and recovery of applied N) are useful in differentiating lowland rice genotypes into efficient and inefficient responders to applied N. Such an evaluation could assist in identification of elite genotypes that could be used in breeding programs to produce cultivars with high N-use efficiency that are also capable of producing higher yields.