Effect of deficit irrigation on seed yield and yield components of sunflower (Helianthus annuus L.) hybrids

This experiment was conducted to evaluate the effect of deficit irrigation on seed yield and its components of sunflower hybrids, and also identify tolerant hybrids. Twelve sunflower hybrids; Farrokh, Shams, Ghasem, Barzegar, G5 ×43, G6×43, Hysun25, Hysun36, Azargol, Sumbro, Euroflor and Sirena were evaluated under three irrigation treatments; normal irrigation (60 mm), mild drought stress (120 mm) and severe drought stress (180 mm) evaportation from Class A Pan, using split plot arrangements in randomized complete block design with three replications in Islamabad Gharb research station, Iran in 2012 and 2013 cropping seasons. Irrigation treatments were assigned to main plots, and sunflower hybrids were randomized in sub plots. Results of combined analysis of variance showed that irrigation treatments had significant effect on growth duration, stem diameter, head diameter, seed per head, 1000 seed weight and seed yield, but had no significanteffect on seed oil content. Sunflower hybrids were significantly difference for growth duration, 1000 seed weight and seed yield. Interaction effect sunflower hybrid×irrigation was not significant for any of measured traits. Mean comparison showed that seed yield of sunflower hybrids was more affected by irrigation treatments than other traits, as average seed yield in normal irrigation, mild drought stress and severe drought stress were 4470, 3637 and 2832 kg ha-1, respectively. Reduction in seed yield was due to cumulative reduction in yield components such as head diameter, seed per head and 1000 seed weight. Sunflower hybrids were also different for growth duration, plant height, non-filled seed, head diameter, seed per head and 1000 seed weight. Barzegar and Sumbro hybrids had the highest and lowest seed yield (4091 and 3362 kg.ha-1, respecrively) and the the highest seed oil content was obtaind in Hysun36 hybrid (45.6%). The results showed that Barzegar hybrid had the higher seed yield in both full irrigation and deficit irrigation conditions, therefore it can be recommended to be grown under these conditions.