Abstarct: Abstract Today, plant hormones are considered as one of the effective factors in adapting plants to drought stress. Therefore, in order to determine the response of some agronomic and physiological characteristics of buckwheat (Fagopyrum esculentum Moenc.) to the application of melatonin and spermidine under drought stress conditions, it was carried out. In this research, the quantification of buckwheat seed germination response to temperature was done using non-linear regression models and time-temperature model, in order to test the germination of seeds in the temperature range of 5 to 50 degrees Celsius. Germination was done and acceptable results were obtained by using non-linear regression models (two-piece, tooth-like and beta) and time-temperature model, so that the tooth-like model and temperature of 20 degrees were chosen as the best treatment. In order to investigate the effect of seed pretreatment and seedling foliar spraying with spermidine and melatonin under drought stress conditions, it was carried out in three separate stages in the laboratory, greenhouse and research field of the Faculty of Agriculture and Natural Resources of Shiraz University in the crop year 2018-2019. In the laboratory phase, two separate and simultaneous experiments were conducted in a factorial format (two-factorial) baxsed on a completely random design in four repetitions. Experimental treatments include drought stress at seven levels of zero osmotic potential (control), -0.2, -0.4, -0.6, -0.8, -1 and -1.2 MPa, seed pretreatment with melatonin. in six levels: control (no pretreatment), zero (distilled water), 125, 250, 375 and 500 mM as the second factor and in the second experiment the drought stress factor similar to the previous experiment as the first factor and seed pretreatment with Spermidine at six levels: control (no pretreatment), zero (pretreatment with distilled water), 0.5, 1, 1.5, and 2 mM was used as the second factor. In the next stages, a greenhouse experiment was conducted in a factorial format (three factors) baxsed on a randomized complete block design in three replications. Drought stress as the first factor in the greenhouse at three levels: irrigation at the time of 10% depletion of agricultural capacity (optimal irrigation), irrigation at the time of 40% depletion of agricultural capacity (mild stress) and irrigation at the time of 70% depletion of agricultural capacity (severe stress). , seed pretreatment and seedling foliar spraying were both applied with three levels: control (without pretreatment), spermidine pretreatment (selected level from the laboratory stage) and melatonin pretreatment (selected level from the laboratory stage), and in the final stage And in the field, the experiment was conducted in the form of a factorial split plot baxsed on a randomized complete block design with three repetitions. In the field, the drought stress was at three levels: full irrigation of the field, 8 days of irrigation and 16 days of irrigation, pre-treatment. Both seeds and seedling foliar spraying were applied at three levels: without pre-treatment (control), pre-treatment with spermidine, pre-treatment with melatonin. In the greenhouse and field, seed pre-treatment was done with the best treatment of the laboratory before seed cultivation and foliar spraying with the best selected treatment of the laboratory at the stage of stem development and the beginning of flowering. The results showed that the concentrations of 1.5 spermidine and 375 micromolar melatonin had the highest germination indices. In the greenhouse, experimental treatments showed a significant effect on increasing stomatal conductance, leaf relative humidity, catalase, leaf soluble protein and rutin level. In general, in the greenhouse stage, seed pretreatment and seedling spraying with 375 micromolar melatonin had the greatest effect on drought stress adjustment. baxsed on the results of the field experiments, there was a significant effect on the experimental treatments including the plant growth period, seed filling period and yield components. So that drought stress, especially severe stress, reduced the growth period of the plant, shortened the seed filling period and also reduced the yield of the plant, while spermidine and melatonin treatments showed an increasing effect on these traits and finally the highest seed yield. In control conditions, mild stress and severe stress were obtained with the average of 538.2, 454.4 and 311.1, respectively, at the concentration of 375 μM melatonin with pretreatment and foliar spraying. Therefore, the concentration of 375 micromolar melatonin was chosen as the best experimental treatment for exploitation.