Enzymatic Efficiency and Genotypic Differences for Nitrogen Assimilation in Wheat

Abstract

The present study was conducted to evaluate the potential of nitrogen applied in soil (90, 120 and 150 kg/ha) on activities of nitrogen assimilating enzymes viz. nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) in relation to protein, amino acid and nitrogen content with respect to source-sink relationship (flag leaf and grains) at different developmental stages of six wheat genotypes (PBW 621, PBW 636, PBW 343, PBW 550, HD 2967 and GLU 1356). GLU 1356, HD 2967 and PBW 621 genotypes responded better at suboptimal dose of N (90 and 120 kg/ha N), while PBW 636, PBW 343 and PBW 550 at recommended dose of N. Significant increase in the activities of NR, GS, GOGAT, GOT and GPT was noted under 150 kg/ha N application, which caused an increase in protein and amino acid contents in all the genotypes. Activity pattern of studied enzymes revealed an increasing trend from tillering to anthesis stage and thereafter declined in parallel with decrease in protein and amino acid contents. Conversely, nitrogen and chlorophyll content showed a consistent decline with leaf growth. In crux, sub-optimal N doses had significant influence on nitrogen metabolism especially in GLU 1356 due to high activities of GS and GOGAT. GOT and GPT regulated protein and amino acid biosynthesis. GLU 1356, HD 2967 and PBW 621 were observed as nitrogen efficient genotypes for enhancing wheat crop productivity under low dose of nitrogen to save environment and input cost.