This study was carried out to understand the yield and yield components response of sunflower to conventional and limited irrigation and to determine the irrigation method which gives the greatest production per unit irrigation water in the Ahwaz Plain of Iran. Three irrigation methods i. e. conventional irrigation [CI, both sides (both furrows) of plant row watered; applied 100% of water requirements during the whole season], regulated deficit irrigation [RDI70 and RDI50, both sides of plant row watered; applied 100% of water requirements upto V8 stage (Plant with 8 leaves) then 70 and 50%, respectively, thereafter] and partial root-zone drying [PRID70 and PRD., both sides of plant row alternatively watered; applied 100% of water requirements upto V8 stage (Plant with 8 leaves) then 70 and 50%, respectively, thereafter] with full (about 623 mm) or limited (50 and 70%) irrigation water, were applied to the hybrid Hysun 33 planted on loamy soil. The highest seed yield (6687.7 kg/ha) and oil yield (3553 kg/ha) were obtained from the Cl treatment, and the lowest seed yield was related to PRD50 and RDI50 irrigation treatments (3537.3 and 3615.3 kg/ha, respectively). Also, the lowest oil yield was obtained from the RDI50 and PRID50 irrigation treatments (1464.3 and 1584.7 kg/ha, respectively). A linear relationship was found between irrigation (mm) and seed and oil yield (kg/ha) at 99% level of confidence (R-2=0.99 and R2=0.98, respectively). Seed and oil yield responded linearly to applied water i. e. the seed and oil yield increased as irrigation amount was increased. Therefore, we confirm that CI irrigation treatment is the best choice for maximum yield under the local conditions, but this irrigation scheme must be re-considered in areas where water resources are more limited.
