The effects of supplementary irrigation on the yield and yield components of three cultivars of sunflower in dry farming

For increasing plant production، an irrigation during the period of plant growth in dry farming is an appropriate technique. For evaluation of supplementary irrigation effects on sunflower (Helianthus annuus L.) yield، a factorial experiment as the base of RCBD (randomized complete block design) in 4 replicates was carried out in dry farming conditions in Kordestan region. Two factors composed of “time of an irrigation” in 3 levels (no irrigation، a supplementary irrigation in flowering and a supplementary irrigation in seeding set stages) and another as “cultivars” in 3 levels (Armavireski، Armavires and Record) were studied. Results indicated that irrigation in flowering stage had a significant effect on yield and other characteristics. The head diameter، seed length and percentage of seeds to shells were significantly affected by “cultivar” and “cultivar * irrigation”. The highest yield of seeds and oil percentage were observed in flowering irrigation (863. 65 kg/ha and 40. 8%/ha respectively). The highest water use efficiency was equal to 1. 34 Kg ha-1mm-1. ‏‏The interaction between cultivars and irrigation time showed that an irrigation in flowering stage caused to produce the highest seed yield (902 kg/ha) in Record cultivar.