Abstract
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 CIM496 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.
