Nitrogen utilization efficiency variability in genotypes of Indian mustard (Brassica juncea) under contrasting N supply

Abstract

Identifying genotypes of high nitrogen utilization efficiency (NUtE) under contrasting N supply is a way of improving N economy of Indian mustard (Brassica juncea Czern &; Coss) under different soil fertility. A field experiment was conducted with 22 Indian mustard genotypes grown under normal and limited N supply conditions to investigate the genotypic variations of NUtE. The genotypes ranking to NUtE was different under normal and limited N supply, however, seven genotypes (RH 1222-28, RH 1301, RH 1117, RH 601, RH 1053, NRCDR 2, RH 1441) were identified as N-responder under normal N supply, and N-efficient under limited N supply. The lowest seed yield reduction (<20%) under limited N supply was recorded in RH 601 (15%), RH 1301 (17%), RH 1215 (17%), and DRMRIJ 31 (18%) compared to normal N supply. Among these genotypes, DRMRIJ 31 and RH 1215 were the highest seed yielder (>3.0 t/ha) under normal N supply and RH 601 (>2 t/ha) under limited N supply. The linear regression analysis showed significant and positive relationship between N uptake and seed yield. Whereas, N uptake and utilization efficiency showed negative trend and decreased with increase in N uptake beyond 120?kg N/ha under normal N supply, and 60?kg N/ha under limited N supply. NUtE was positively correlated with seed yield under both normal as well as limited N supply. These results may be used to identify the key associated traits, and to isolate target genes for developing varieties/hybrids to harness better N economy.