Evaluation of morphological and biochemical traits of safflower (Carthamus tinctorius L.) under drought stress conditions and Foliar application of organic fertilizer

It is very important to find ways to increase the tolerance of plants under drought stress conditions. In order to study the effect of drought stress levels and types of humic fertilizers, amino acid and organic supplements on quantitative and qualitative traits of safflower (Goldasht cultivar), an experiment was conducted as split plots base on randomized complete block design with three replications at the research farm of Zabol University (Chah Nimeh). The main factor of irrigation cut-off levels based on plant growth stages: control (full irrigation), irrigation up to the main stem formation stage and irrigation up to the stage of flowering completion and the secondary factor of five levels of fertilizer treatment: Control (not applicable), amino micropower fertilizer, humic acid, humica and organic supplements in amounts of two per thousand. Maximum plant height (69.76 cm), number of leaves per plant (78.43), number of branches (6.2), oil content (34.2), chlorophyll a, b and carotenoids (11.51, 3.37, 2.40 mg/g fresh weight respectively) was obtained from foliar application treatment with humic acid and complete irrigation. Percentage of changes in plant height (27.7), number of leaves (19.5), number of branches (35.5), petal weight (50), oil content (48), chlorophyll a, b, carotenoids (respectively 33, 38 and 27) under complete irrigation and foliar application of humic acid due to severe stress and non-application of fertilizers. Catalase enzyme activity (97%), peroxidase (99%) and Protein content (62%) increased due to stress and foliar application of humic acid. In general, it seems that foliar application of humic acid compared to other organic fertilizers used in this study can achieve better results under drought stress conditions.