Seed yield and oil content of some sunflower (Helianthus annuus L.) hybrids irrigated at different growth stages
This research was carried out to determine the effects of irrigation applied at different growth stages on yield, yield components and oil content of sunflower during 2002 and 2003. Sunflower cultivars Sanbro, Tarsan-1018 and Ozdemirbey were used as materials in the experiment which was designed in a split plot of randomized complete blocks with three replications. Seven irrigation schedules; I0 = nonirrigated (control), I1 = irrigation at vegetative stage, I2 = irrigation at heading stage, I3 = irrigation at flowering stage, I4 = I1 + I3 (two irrigations) I5 = I1 + I2 + I3 (three irrigations) and I6 = I1 + I2 + I3 + irrigation at milking stage were applied. According to the results of the research, plant height and head diameter by cultivars and irrigations ranged between 106 to 183 cm and 12.5 to 19.3 cm, respectively. Irrigations at all growth stages increased seed yield by 43.1% in 2002 and 77.2% in 2003. The results revealed that three irrigations should be scheduled at vegetative, bud formation and flowering stages. Under severe conditions of water scarcity, it would be better if irrigation is applied at flowering stage.
Key words: Sunflower, irrigation, yield, oil ratio.