investigation of dormancy and the effect of some environmental factors on germination of junglerice (echinochloa colona (l.) link.) seeds

junglerice, c4 plant and thermo-live of poaceae family, is one of the most serious grass weed in the tropics and subtropics. to determine methods for breaking dormancy, characterizing cardinal temperatures and investigating the effect of salinity and drought on junglerice seeds germination four separate experiments were conducted in the laboratory. results showed that the junglerice seed dormancy is physical and 10 minutes treated with sulfuric acid (95-97%) is the good way to break dormancy. germination was occurred in temperature range 10 to 45 °c. based on the results of the five parameters beta model, cardinal temperatures (minimum, optimum and maximum), were determined 3.7, 3.28, and 46 °c, respectively. junglerice tolerance to salinity was high, hence the concentrations of 223 and 400 mm nacl, were 50 and 9% germination, respectively. it was very sensitive to drought, so with exposing to the concentrations of -0.43 and -0.6 mpa showed 50 and 0 germination percent, respectively. due to germination in wide range of constant temperatures, it could be concluded that it is likely that it could be invasive to other regions, especially tropics and subtropics. apparently, it able to compete with crop in the saline and wet conditions. although, due to the low germination percent in recovery test after salinity treatments, its invasion will be difficult in saline areas.