effect of water stress and plant density on growth and seed yield of safflower

in order to evaluate the effect of water stress and plant density on growth and seed yield of safflower, a study was conducted during 2009 growing season at agricultural college of shiraz university. the experimental design was split plot based on randomized complete block design with three replications. the treatments were deficit irrigation (100, 75, and 50% of field capacity-fc) as main plot and safflower density cultivar sina in four levels (5, 10, 15 and 20 cm plant spacing) as sub plot. results indicated that by increased plant spacing, seed yield decreased significantly. maximum (351.03 g m-2) and minimum (222.95 gm-2) seed yields were recorded at 5 and 20 cm plant spacing, respectively. with reduction of irrigation from 75 to 50% fc, seed yield was significantly reduced up to 63% (from 368.83 to 134.10 g m-2). among yield components, number of head seeds number per head and seed weight were significantly decreased. plant height and seed oil percentage was also significantly reduced as a result of water stress and reduction of plant density. it is concluded the optimal safflower seed yield can be achieved by applying 75%fc deficit irrigation and 10 cm plant spacing that were(33 plant m-2).