Investigation of planting dates and irrigation regimes on physiological traits of two spring sufflower (carthamus tinctorius L.) cultivars

In order to investigation of planting dates and irrigation regimes on physiological traits of two spring sufflower cultivars a field experiment was conducted in 2002.The experimental design was a split-split plot with four replications. Treatments were planting dates as main plots, irrigation regimes as sub-plots and safflower cultivars (Arak-2811, Esfahan Local) as sub-sub plots. The result showed that late planting and low irrigation decrease the physiological traits such as LAI, CGR, and LAR. NAR and LWR were not shown any significant differences between two considered cultivars, because those had similar growth period. Maximum LAI in first planting date and better irrigation was 4.75 and maximum LAI in third planting date and low irrigation was 3.89, which needed 1340 GDD. Highest CGR obtained between 1400-1500 GDD when LAI started to decline.Relative growth rate (RGR) showed net assimilation rate (NAR) also declining trend. NAR also decreased with time. LAR and LWR also showed a declining trend.