To our knowledge, there has not been yet any reported comprehensive study on dormancy, cardinal temperatures, light responses, shading and drought tolerances of this species. Therefore, five separate experiments were conducted. The first experiment (dormancy breaking) was arranged in a factorial arrangement based on completely randomized design with 20 treatments and 3 replications. The treatments were physical seed dormancy breaking (hot water, scarifying by scarifier, H 2 SO 4 , and dimethyl sulfoxide) and physiological seed dormancy breaking (KNO 3 , ethephon, and gibberellin) methods. The highest germination percent was recorded under acid-scarification and GA 3 followed by mechanical scarification and non-scarification under GA 3 , respectively. Seeds under DMSO and hot water treatments did not germinate. In the second study (cardinal temperature estimation), three replicates of seeds were placed in the different germinators with different temperatures (5, 10, 15, 20, 25, 30, 35 and 40 ? C) for two weeks. The base temperature was obtained for D50 using beta (14.50), beta modified (8.89), segmented (15.07), and dent-like (15.51). The models showed an optimum temperature between 33 and 38 ? C for D50. In the third study, the treatments were three drought levels (irrigation after 50 (I 50 ), 70 (I 70 ) and 90% (I 90 ) depletion of the available soil water) and three shading levels (50 (S 50 ) and 80% shading (S 80 ) and full light (S 0 )). The experimental design was a split-block with three replications in which the main plots contained the shading levels and subplots included the irrigation regimes. In this experiment, except Cl b , other photosynthetic pigments content were not significantly affected by shading and drought levels. In parallel with trairation rate, photosynthetic rate was decreased under severe shading but it was not significantly affected by moderate shading. The interaction between shading treatment and irrigation regimes had no marked effects on proline, soluble sugars, anthocyanin, and phenol contents. Shading decreased MDA and H 2 O 2 concentrations, but increased RWC, leaf water potential, Na, Ca, Cu, Fe, Mn, and Zn concentrations. The activities of CAT and POX decreased under both shading treatments. The seed yield of chaste tree was lowest under combined severe drought and shading. The highest leaf essential oil content and yield, and seed essential oil yield were achieved under full light and non-stressed conditions. The highest ?-pinene and caryophyllene contents were recorded in the full light condition under 70% water depletion and the highest ?-terpinyl acetate was observed under 50% shading with 70% water depletion in the leaves. However, seeds had the highest ?-terpinyl acetate and caryophyllene contents under 80% shading with the 50% water depletion condition. In the fourth study, the treatments were similar with third study. In this experiment, under 50% shading, proline, soluble sugars, anthocyanin, MDA, flavonoid and phenol content, and CAT activity were increased under drought stress. The same procedure was observed under full sunlight. Applying of 80% shading increased some photosynthetic traits and leaf essential oil content. Shading decreased root volume and root dry weight. In the fifth study, the treatments were four light quality (Red, blue, white, and red-blue) and three drought levels (irrigation after 50, 70 and 90% depletion of the available soil water). A three replicate completely randomized design was used in this experiment. The red-blue light with 90% soil water depletion caused to the highest essential oil content. The responses of root to combination between light quality and drought were differ from leaves. The highest anthocyanin and proline content, root length, and root dry weight were observed under red light with 70% soil water depletion. GC analysis showed the presence of 25 compounds in chaste tree shoot subjected to different light quality and drought. Red-blue light resulted in a large number production of essential oil compositions. Overall, the results suggest that chaste tree seeds had both mechanical and physiological dormancies that could be broken by combination of GA 3 and sulfuric acid scarification treatments. The beta model because of high calculated R 2 values and low calculated RMSE values was reliable for determining cardinal temperatures. Chaste tree can be planted under 50% shading to cope with drought stress (70% water depletion) and as a result to decrease the amount of needed irrigation water. Red-blue light could be applied to produce some special essential oil compositions in chaste tree. Keywords: Cardinal temperatures, chaste tree, dormancy, drought stress, essential oil, light quality.