An experiment on summer sunflower (Helianthus annuus L.) was conducted duri
ng 1994-96 with 4 irrigation levels based on the ratio of irrigation water
depth : cumulative pan evaporation (IW : CPE) and 4 nitrogen levels in Biha
r. The results showed that seed yield increased significantly at IW : CPE r
atio of 0.8 (1.49 tonnes/ha) with 6 cm depth comprising of 6 irrigation. Bu
t water-use efficiency was higher at 0.6 ratio with 4 irrigation. Response
to nitrogen was recorded only up to 40 kg N/ha. Plant height, dry-matter/pl
ant and capitulum diameter were maximum at 0.8 IW : CPE ratio. But 1000-see
d weight increased only at IW : CPE of 0.6 and 40 kg N/ha. Total nitrogen u
ptake and net return were also highest at 0.8 IW : CPE ratio and 40 kg N/ha
. Soil-moisture depletion was higher from 0-60 m layer with 4-6 irrigation,
whereas relative depletion in lower soil profile (60-90 cm) was more in ra
infed control.