Effect of atrazine anti-transpiration application on improving physiological traits, yield and yield components of safflower under rainfed condition

In order to possibility of improving physiological traits, yield and yield components of safflower (Carthamus tinctorius cv. sina) by anti-transpiration application in rainfed condition, a research was carried out in factorial based on randomized complete block design (RCDB) with three replications in Miyaneh region (East Azarbaijan province - Iran) in 2011. The treatments antitranspirant rate were zero (control), 80, 120 and 160 g a.i.ha-1. The antitranspirant application time was at elongation, flowering and seed filling stages. The results showed that there were significant differences between treatments in all studied traits. Applying atrazine at 80 and 120 g a.i.ha-1 specially in flowering stage by providing plant favorite conditions such as reducing canopy temperature, increasing photosynthesis and chlorophyll content, improved yield and yield components comparing to rainfed stressed condition. Applying atrazine at 160 g a.i.ha-1 did not improve growth but acted as a growth inhibitor. The highest and lowest number of prolific capitol, number of seed in capitol and also grain yield were obtained at 120 g a.i.ha-1 in flowering time and 160 g a.i.ha-1 in elongation time, respectively.