Environmental stresses, especially salinity and drought, are effective on seed germination and growth. Materials and Methods: After breaking seed dormancy by simultaneous use of leaching (48 hours) and gibberllic acid (1000 ppm), germination characteristics and seedling growth of Citrullus colocynthis from two ecotypes of Sistan-Baluchestan with six levels of drought (0,-0.3,-0.6,-0.9,-1.2,-1.5 Mpa) and salinity (0, 50, 100, 150, 200, 250 mM) were studied. This experiment was carried out in two

more »

... different factorial experiments using completely randomized design with four replications. Statistical analysis was performed using version 18 of SPSS software and Factorial analysis of variance (general linear model) and mean comparisons were done using Duncan's multiple range test. Results: The results demonstrated that there were significant differences among different levels of drought and salinity in all measured traits (P<0.01) and a significant decrease in seed germination and seedling growth were observed with increasing levels of drought and salinity (P<0.01). The results revealed that there were significant interactions effect between ecotype and different levels of drought as well as salinity (P<0.01), so seed vigor of Zabol' ecotype was higher than that of Saravan. Discussion and Conclusions: This species has acceptable germination at-0.6 Mpa droughts and 50 mM salinity. These issues must be considered in its intense planting in Sistan-Baluchestan province and using of Zabol' ecotype seed is recommended.