Evaluation of Germination of Safflower Seed (Carthamus tinctorius L.) Faraman Cultivar, Under Water Deficite Stress and Determination of Cardinal Germination Temperatures

Safflower (Carthamus tinctorius L.) is an important industrial plant, which classified in the category of oil plants. The tolerance of plants to drought is different, as well as Plants have different temperature and water requirements, and understanding this requirement helps them survive and reproduce. Therefore, the purpose of this study was to evaluate the germination characteristics of safflower seeds at different temperatures and humidity and the adaptation power of this plant under these conditions. For this purpose, germination of safflower seed (Faraman cultivar) was investigated in incubator at constant temperatures of 5, 10, 15, 20, 25, 30, 35 and 40 ° C. in this study, 3 regression model including, Beta model, Dent like model and segmented model were used to determine cardinal safflower temperatures. Then, to investigate germination and seedling growth response of Carthamus tinctorius toward different levels of Water Deficite Stress at an optimum temperature, another test was conducted. in this experiment, seed germination was assessed in six levels of Water Deficite Stress with the osmotic potential of 0, -3, - 5, -7 and -9 bar (in temperatures of 20 ° C). Based on Beta model, Dent like model and segmented model, the cardinal temperatures of Carthamus tinctorius seeds germination including, (Tbase, Topt and Tmax) were: (4.6, 4.1, 4.1), (22.02, 20 – 24.3, 22.5) and (43.3, 50.3, 50.3) °C, respectively.