Interaction effects of deficit irrigation and row spacing on sunflower (Helianthus annuus L.) growth, seed yield and oil yield

Abstract

Productivity of sunflower is strongly regulated by the availability of water. In order to study the influence of deficit 
irrigation (I1:100% FC, I2 and I3: 75 and 50% FC during stem elongation period, respectively; I4 and I5: 75 and 50% FC at 
flowering stages) and two row spacings (45 - 50 and 75 cm) on growth, yield and oil yield of sunflower, an experiment 
was conducted using a split plot design with three replications in the 2007 - 2008. Results indicated that Maximum 
(374.67 gm-2) and minimum (198.5 gm-2) grain yield was obtained from I1 and I3 treatments. Compared to I1, grain yield 
was reduced significantly under deficit irrigation treatments (I2, I3 and I5). Interaction effects of row spacing and deficit 
irrigation indicated that the highest seed yield (458.0 gm-2) and oil percentage (31.66%) was obtained from I1 and 75 cm 
row spacing. Reduction of grain yield due to deficit irrigation (I4) was not significant (374.6 vs. 340.1 gm-2), compared 
to full irrigation. Therefore, we confirm that irrigation levels significantly affected seed yield and oil percentage. Our 
results indicated that deficit irrigation, during the critical growth period should be avoided.