Nitrogen Impact on Morpho-physiological Traits and Yield of Indian Mustard (Brassica juncea) Genotypes

摘要

Nitrogen(N)management is crucial in cropping systems,and it is often difficult to strike a balance for normal physiology within human consumption limits.The experiment was conducted on 48 genotypes of Brassica juncea during two crop seasons with two N levels(N deficient(N0)and with fertilization(N100)).Leaf area revealed variability in the light harvesting capacity of genotypes manifested in terms of leaf area index(LAI),chlorophyll,photosynthetic active radiation(PAR)interception which were reduced under N-stress.During crop growth and development,chlorophyll content and LAI were the highest at 90 days after sowing(DAS)whereas PAR interception by the genotypes was the highest at 60 DAS.Critical analysis of photochemical efficiency indicated minor photoinhibition under fertilized conditions as values ranged from 0.708-0.775 with a mean of 0.735.However,under unfertilized conditions(N0),values were much lower(0.677-0.744,mean 0.706)indicating more damage to photosystem Ⅱ(PSⅡ).Photosystem activity(Fv/Fm)of PSII improved by 13.3%and electron transport rate(ETR)by 45.9%with N application.Yielding abilities and performance of MCP632,PBR 357,JT-152-1 and ELM 151 were better under unfertilized condition(N0)and with N-application at 100 kg/ha yield improved though less than 10%in these genotypes.The rest of the genotypes were responsive to N application.