Response of sunflower cultivars of Iroflor to water deficit stress and methods of biophosphate application in the Miandoab area

In order to evaluate the effect of water stress on sunflower cultivars of Iroflor in different stages of growth and methods of biophosphate consumption, a factorial experiment was conducted in a randomized complete block design with four replications. Water deficit stress in four levels including control (non-stress), stress in vegetative stage, stress in reproduction stage and stress in both vegetative and reproductive stages and application of biofertilizer (Phosphate Fertile 2) in four levels including non use of biofertilizer, seed coated, topdress and and combined application seed coated and topdress. The results showed that water stress and fertilizer stress had significant effect on all traits. However, the interaction was significant only for number of seeds per head, seed yield and oil percentage. The highest traits among levels of water stress were related to control and among the application of biofertilizer belonging to the treatment of combined application seed coated and topdress, which thousand grain weight 74.42 and 67.25 g, head diameter 17.67 and 16.74 cm, biological yield 10596.74 kg. ha-1 and 10165.43 and oil yield 1318.55 and 1216.73 kg. ha-1 respectively. However, the highest number of seeds per head (950.51 number), seed yield (3451.23 kg. ha-1) and oil percent (47.68 %) were obtained in combined treatments of non stress and application seed coated with topdress. The effect of water deficit stress on the reproductive stage was significantly more than the vegetative stage. Biofertilizer treatment as seed coated has no significant difference with combined application seed coated and topdress. Which indicates that biofertilizer (Phosphate Fertile 2) makes better use of seed coated. The result of the experiment showed that with the use of biophosphate to form seed coated achieved optimal yield in sunflower cultivars of Euroflour and under water deficit stress, decreasing the intensity of stress on the traits under study.