Morpho-physiological and biochemical characterization of maize genotypes under nitrogen stress conditions

Forty maize inbred lines were assessed at seedling, vegetative and flowering plant growth stages for nitrogen use efficiency under nitrogen sufficient and deficient soil conditions. Significant variations were observed in the morpho-physiological and agronomical traits. Inbred lines were classified into two major clusters based on the response of morphological and physiological traits to nitrogen limiting conditions. Cluster 1(C1) I included DMI 4, DMI 5, DMI 22, DMI 27 and DMI 56 inbred lines-derived from the drought or thermal tolerant parents HKI335 and LM17 with less reduction in growth-related parameters as compared to cluster CII inbred lines, which were derived from sensitive genotypes MGUD22 and HKI1015wg8. The enzymatic activities of nitrate reductase (NR) and glutamine synthetase (GS) were observed to be more critical for screening in the early growth stage. The identified inbred lines have the potential for developing maize hybrids with improved nitrogen use efficiency.