Effect of drought stress on some morphophysiological traits and yield of safflower (Carthamus tinctorious L.) in response to use of potassium

An experiment has been conducted in the form of split plots in a randomized complete block design with three replications at the Agricultural and Natural Resources Research Institute in Zahak to evaluate the effect of drought stress and potassium application on yield and morphophysiological traits of safflower (Goldasht cultivar) under saline irrigation conditions (EC 6 dS.m-1) in 2018-2019. Drought stress irrigation regimes have been tested at three levels (irrigation after 45% (control), 65%, and 85% of admissible moisture depletion) as the main factor, and potassium fertilizer at four levels (0, 75, 150, and 225 kg.ha-1) as the sub factor. According to the findings, drought stress has reduced plant height, number of heads per plant, number of seeds per head, seed and biological yield, and relative water content. The use of potassium, on the other hand, has increased the above traits greatly. Irrigation after 45% moisture depletion increases seed yield by 42.32%, compared to irrigation after 85% moisture depletion. Interaction of drought stress and potassium has had a significant effect on number of branches per plant, 1000-seed weight, leaf chlorophyll index, soluble carbohydrate content, and seed oil percentage, with the highest amount observed after 45% water drainage and application of 225 kg K ha-1.