Effects of withholding irrigation and foliar application of zinc and manganese on fatty acid composition and seed oil content in winter safflower.

Experiment was conducted in 2001 –2002 and 2002 –2003 crop years in Esfahan, Iran. The experimental design was the split factorial in a randomized complete block with three replications. Four drought stresses (S1= full irrigation, S2= withholding irrigation in vegetative growth stage, S3= withholding irrigation in flowering stage, and S4= withholding irrigation in seed filling stage) were randomized to the main plot units and 12 treatments from combination levels of three cultivars (C1= Zarghan 279, C2= Varamin 295 and C3= LRV 5151) and four foliar applications (F1= no foliar application, F2=foliar application of water, F3 = foliar application of Zinc Sulfate (3000 ppm) and F4=foliar application of manganese sulfate (3000 ppm)) were randomized to the subplot units. After seed harvest, oil yield and percent of seed oil were measured and fatty acid profiles of oil were determined by GC. Results presented that in S3 and C1 and C3 cultivars manganese foliar application significantly increased oil percent. In S4 oil percent and yield were increased in C1 and C3 cultivars with both zinc and manganese foliar applications. In some interaction levels zinc and manganese foliar applications significantly increased palmitic and oleic acids whereas these foliar applications decreased linoleic acid percent. Generally, drought stress during flowering stage imposed the most damage to oil percent and yield and also decreased linoleic acid content and increased stearic and oleic acid content, so flowering stage is more sensitive to drought than vegetative or grain filling stages and foliar application of zinc and manganese can compensate the negative effects of drought on safflower.