Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 53 3 2022 09 23 Effects of cytokinin application on the photoassimilate partitioning and oil percentage in safflower cultivar under drought stress condition Effects of cytokinin application on the photoassimilate partitioning and oil percentage in safflower cultivar under drought stress condition 249 261 91637 10.22059/ijfcs.2021.324063.654827 FA Leyli Golchin Department of Plant Production and Genetics, Agriculture Faculty, University of Zanjan, Iran. Afshin Tavakoli Department of Plant Production and Genetics, Agriculture Faculty, University of Zanjan, Iran. 0000-0003-3585-6768 Ehsan Mohsenifard Department of Plant Production and Genetics, Agriculture Faculty, University of Zanjan, Iran. Journal Article 2021 05 23 In order to evaluate the possibility of partitioning photoassimilate improvement and increasing the percentage of safflower seed oil by cytokinin application, a split plot factorial experiment was conducted based on a randomized complete block design with four replications at the research farm of Agriculture Faculty, University of Zanjan, Iran, during 2018-2019 and 2019-2020 growing seasons. In this experiment, irrigation levels included optimal irrigation (-0.4MP) and drought stress (-2 MP) were the main plots and safflower cultivars (i.e Sina, Faraman, Parnyan, Gholdasht and Mahaly Esfahan), and three levels of cytokinin, (i. e no- application (control), 50 and 75 μM) were subplots. Drought stress started at flowering stage and cytokinin spray and drought stress were performed simultaneously. The results showed that drought stress increased the remobilization efficiency (42.75%) and contribution of stem reserves to grain yield (26%) and decreased the grain yield (26.8%) and seed oil percentage (10.6%). Under drought stress condition, Mahally Esfahan cultivar had the highest oil percentage with an average of 35.42% and an increase in the transfer efficiency of stem reserves to grain (52.7%). Cytokinin application minimized the negative effects of drought stress and improved traits such as stem efficiency in grain transfer, grain yield and oil percentage in the studied cultivars. The highest percentage of seed oil was obtained by 75 μM cytokinin application (with an average of 33.38%) compared to the control treatment. Therefore, cytokinin application can be suggested to reduce the negative effects of drought stress, increase photosynthetic partitioning material and of safflower seed oil percentage.<br /><br />, 50 and 75 μM were allocated to subplots as factorial. At the flowering stage, simultaneously with drought stress safflower plants were sprayed with cytokinin.The results showed that drought stress increased the allocation ،transfer efficiency of stem reserves to grain, decrease grain yield and oil percentage. Under drought stress conditions Mahally Esfahan cultivar had the highest oil percentage with an average of 35.42% and an increase in transfer efficiency of stem reserves to grain 52.7 percent. The application of cytokinin minimized the negative effects of drought stress and improvement in the above traits. The highest oil percentage was obtained by application of 75 μM of cytokinin with an increase of 10% oil percentage compared to the control. Therefore, the application of 75 μM BAP can be suggested as a solution to reduce the negative effects of drought stress, increase photoassimilate partitioning and safflower seed under optimal irrigation and drought stress conditions. In order to evaluate the possibility of partitioning photoassimilate improvement and increasing the percentage of safflower seed oil by cytokinin application, a split plot factorial experiment was conducted based on a randomized complete block design with four replications at the research farm of Agriculture Faculty, University of Zanjan, Iran, during 2018-2019 and 2019-2020 growing seasons. In this experiment, irrigation levels included optimal irrigation (-0.4MP) and drought stress (-2 MP) were the main plots and safflower cultivars (i.e Sina, Faraman, Parnyan, Gholdasht and Mahaly Esfahan), and three levels of cytokinin, (i. e no- application (control), 50 and 75 μM) were subplots. Drought stress started at flowering stage and cytokinin spray and drought stress were performed simultaneously. The results showed that drought stress increased the remobilization efficiency (42.75%) and contribution of stem reserves to grain yield (26%) and decreased the grain yield (26.8%) and seed oil percentage (10.6%). Under drought stress condition, Mahally Esfahan cultivar had the highest oil percentage with an average of 35.42% and an increase in the transfer efficiency of stem reserves to grain (52.7%). Cytokinin application minimized the negative effects of drought stress and improved traits such as stem efficiency in grain transfer, grain yield and oil percentage in the studied cultivars. The highest percentage of seed oil was obtained by 75 μM cytokinin application (with an average of 33.38%) compared to the control treatment. Therefore, cytokinin application can be suggested to reduce the negative effects of drought stress, increase photosynthetic partitioning material and of safflower seed oil percentage.<br /><br />, 50 and 75 μM were allocated to subplots as factorial. At the flowering stage, simultaneously with drought stress safflower plants were sprayed with cytokinin.The results showed that drought stress increased the allocation ،transfer efficiency of stem reserves to grain, decrease grain yield and oil percentage. Under drought stress conditions Mahally Esfahan cultivar had the highest oil percentage with an average of 35.42% and an increase in transfer efficiency of stem reserves to grain 52.7 percent. The application of cytokinin minimized the negative effects of drought stress and improvement in the above traits. The highest oil percentage was obtained by application of 75 μM of cytokinin with an increase of 10% oil percentage compared to the control. Therefore, the application of 75 μM BAP can be suggested as a solution to reduce the negative effects of drought stress, increase photoassimilate partitioning and safflower seed under optimal irrigation and drought stress conditions. https://ijfcs.ut.ac.ir/article_91637_9eeb3f3e5c71e45bdb37dcf1af09c76d.pdf