Impact of moisture stress and nitrogen on crop growth rate,nitrogen use efficiency,and harvest index of cotton (Gossypium hirsutum L.)

Nitrogen and moisture stress generally modify growth and development of cotton like several other field crops. field experiments were conducted for two years to elucidate the interactive effect of moisture stress (i),nitrogen (n),and genotype (v) on agronomic traits,nitrogen use efficiency (nue) and harvest index (hi) of cotton by using rcbd split-split plot experimental design. four moisture stress treatments (i1: no stress,i2: moisture stress at inter-node elongation stage,i3: moisture stress at vegetative growth stage,and i4: moisture stress at inter-node elongation and vegetative growth stages),three nitrogen levels (50-n1,100-n2,and 150 kg ha-1-n3),and three genotypes of cotton (niab-846-v1,niab-824-v2,and cim-496) were used in this study. moisture stress,nitrogen,and cotton genotypic interaction exhibited significant effect on number of bolls per plant,leaf area duration (lai),crop growth rate (cgr),net assimilation rate (nai),nue,and hi. in all genotypes of cotton,highest cgr,nai,nue,and hi was recorded where irrigation was applied at all growth stages (in no stress treatment) and moisture stress at vegetative growth stage (in treatment where irrigation was withheld at vegetative growth stage) with n dose of 50 kg ha-1 expect in few treatments where 150 kg n ha-1 exhibited greater crop growth rate. during 1st year field experiment highest increase in hi of; niab-846 was 10.46% by i3×n1×v1,niab-824 was 80.62% by i3×n3×v2,and cim-496 was 33.91% by i3×n3×v3. during 2nd year,highest increase in hi was 31.60% in niab-846 (by i3×n3×v1),20.98% in niab-824 (by i1×n1×v2),and 20.10% in cim-496 (by i1×n2×v3). nevertheless,highest nue was achieved in no stress treatment but moisture stress at vegetative growth stage didn’t significantly reduce harvest index and nitrogen use efficiency as compared to no stress (well water) treatment. thus it may be concluded that moisture stress at vegetative growth stage in these cotton genotypes could be applied for saving of irrigation water and nitrogen fertilizer. © 2016,university of agriculture. all rights reserved.