Effects of terminal water deficit stress and plant density on yield, yield components and some morphological traits of safflower in Jiroft Region, Iran

In order to determine the optimum plant density and evaluate the effect of drought stress on yield and oil content of safflower, an experiment was conducted as a strip plot on the basis of a Randomized Complete Block Design with three replications at Jiroft and Kahnooj Agricultural Research Center, Iran in 2009-2010. The vertical factor was water deficit stress at four levels of irrigation withdrawal before flowering and pollination, at 50% flowering and 100% flowering, and full irrigation (control). The horizontal factor was plant density at four levels of 30, 35, 40 and 45 plants m-2. It was found that drought stress significantly affected seed yield, oil yield, oil percentage, seed number per head and stem diameter at 1% and 1000-seed weight at 5% probability level. The effect of plant density was significant on seed yield, oil yield, head number and floret weight at 5% and on seed number per head and stem diameter at 1% probability level. Out of the studied drought stress levels, the highest seed and oil yield was obtained from control (2634 and 1054 kg ha-1, respectively) and drought stress application at 100% flowering (2389 and 726 kg ha-1, respectively) and the lowest ones from drought stress application before flowering. In addition, as plant density was increased up to 40 plants m-2, seed and oil yields were increased up to 1792 and 801 kg ha-1, respectively and then, started to decrease.