Effects of water stress and salicylic acid application on oil yield and some physiological characteristics of sunflower cultivars (Helianthus annuus L.)

A field study was carried out at the Islamic Azad University of Arak in 2010 to find out the effects of salicylic acid and water deficit stress on oil yield and some physiological characteristics of different varieties of sunflower. The experiment was laid out in a factorial split plot based on a randomized complete block design with four replications. Treatments consisted of water stress in three levels (I0:100% of required irrigation water (control)، I1:80% of the amount of irrigation water requirement، I2 = 60 % of the amount of irrigation water requirement] in the main plots، and different varieties of sunflower at three levels V1: Azargol، V2: Allstar and V3: Ariflor) and two levels of salicylic acid (SA0: no salicylic acid and SA1: salicylic acid (sprayed)) in a factorial combination in sub-plots. The results showed that the different levels of water stress and different varieties of sunflower had significant effects (P<0. 01) on traits such as: grain yield، test weight، harvest index، relative water content، water saturation deficit and rate of water loss. In addition، application of salicylic acid had significant effect (P<0. 01) on all measured traits except grain yield. The present study indicated that the Alstar variety exhibited the maximum yield of sunflower oil with an average of 1278 kg ha-1. The application of salicylic acid also resulted in 5. 33% higher oil yield in comparison with treatment of no salicylic acid.