Evaluation of the effects of 6-Benzyl Aminopurine application on safflower cultivars production under drought stress conditions

In order to evaluate the increment possibility of safflower seed yield and oil percentage through the application of cytokinin, a split factorial experiment has been conducted based on randomized complete block design with four replications at the research farm of Agriculture Faculty, the University of Zanjan, during the 2018-2019 and 2019-2020 cropping seasons. In this experiment, irrigation levels include optimal irrigation and drought stress to main plots and safflower cultivars, namely Sina, Faraman, Parnyan, Gholdasht, and Mahaly Esfahan, and three levels of cytokinin (6-Benzyl Aminopurine), including non-application (control), 50, and 75 μM,  have been allocated to subplots as factorial. At the flowering stage, simultaneous with applying drought stress, safflower plants havee been sprayed with 6-Benzyl Aminopurine. Results show that drought stress has decreased yield components, seed yield, biological yield, harvest index, oil percentage, and oil yield and the application of cytokinin minimizes the negative impacts of drought stress, while boosting the above traits. The highest seed yield has been obtained from applying 75 μM of cytokinin, with an increase of 30.7% compared to the control. Also, among the studied cultivars, the Mahaly Esfahan cultivar under optimal irrigation with an average of 36.09% shows a higher oil percentage, compared to other cultivars. Therefore, the use of cytokinin can be suggested as a solution to decrease the negative effects of drought stress and enhance seed yield and oil percentage of safflower under optimal irrigation and drought stress conditions.