Evaluation of Water Stress Effect on Growth and Yield of Spring Safflower

To evaluate the effect of water stress on growth and grain yield of spring safflower (Carthamus tinctorious L.) at reproductive stage, an experiment as a split plot on the frame of randomized complete block design with three replications was performed in Bu-Ali Sina university research field in spring season of 1391. Water stress as the main factor consisted of three irrigation levels such as normal irrigation, no irrigation from %50 flowering stage (flowering stress) and no irrigation from start of the seeding stage (seeding stress) were placed in main plots, and six cultivars of safflower including PI, local Ajabshir, Mec11, Faraman, Zarghan6 and Sina as the second factor were compared in three levels of irrigation treatments. Results indicated that water stress caused a significant reduction in all traits except of number of lateral stem, plant height, number of heads per plant and harvest index. The most effect of water stress on the studied characters was observed at the flowering stage. Water stress at flowering and seeding stages also caused 59/81 and 29/80 percent reduction in seed yield compared to control (non stress). At the flowering stage, reduction of seed yield and oil yield was due to reduction in the number of seeds in head, 1000 seed weight, and at the seeding stage was because of decrease in 1000 seed weight. Sina and local Ajabshir had maximum and minimum seed yield and oil yield, respectively at the flowering and seeding stages.