Physiological and Molecular Characterization of Three Rice Genotypes with Differential Nitrogen Use Efficiency

Identification and adaptation of rice genotypes with high nitrogen use efficiency (NUE) is a potential approach in optimizing N
requirements, lowering the cost of cultivation and reducing the environmental pollution through the reduction of nitrous oxide
emission in rice. Three rice genotypes differing in their NUE were grown in hydroponics and field conditions and characterized for
physiological, yield parameters and NUE indicators along with expression analysis under low and recommended nitrogen conditions.
Significant variations were observed in 18 physiological, yield parameters and 8 NUE indicators among genotypes confirming the
genotypic variability for the traits under low nitrogen conditions. Reduction of yield related parameters except thousand grain
weight were noted. Correlation analysis of various yield components explains the significance of total biomass for grain yield,
straw yield, N content in grain, straw and nitrogen absorption efficiency. Differential expression of OsNIA2 gene in NUE efficient
genotypes viz., in shoots of GQ25 and ischolar_mains of IR55178 in the present study suggests its possible role in N metabolism and is
encouraging for exploring the possibilities of improving nitrogen use efficiency in rice.