Effect of sowing dates on grain yield and oil content of spring cultivars of safflower (Carthamus tinctorius L.)

In order to determine sowing date effects on grain yield and oil content of spring safflower cultivars, this study was conducted in Kabootarabad Research Site of Isfahan Agriculture Organization located in east of Isfahan, in 2009. The experimental layout was split plots in a randomized complete block design with three replications. Eight sowing dates (March 5, March 19, April 4, April 20, May 5, May 21, June 5 and June 21) were main plot levels and cultivars Arak-2811, Isfahan-14 and IL-111 were sub-plots. Traits like capitulum number in plant, grain number in capitulum, 1000-grain number, grain yield and oil content were affected by sowing date and decreased with delay in sowing. Cultivar Isfahan-14 produced the most grain yield in second sowing date, whereas Arak-2811 had the least grain yield in eighth sowing date. Adaptation of cultivar Isfahan-14 with regional climatic factors was the reason of its superiority and sowing the spring safflower as soon as possible after freezing risk removal is recommended.