The influence of irradiance and water deficit during fruit development on seed dormancy in Datura ferox L.

Summary: The effect on seed dormancy of exposing the mother plants to different environmental conditions was studied in Datura ferox. Reducing incident radiation and withholding water to provoke water stress, during the period from fruit set until seed ripening, caused a decrease in the degree of dormancy of the harvested seeds. A significantly smaller amount of the basic fraction inhibitors was found in the seeds with the lesser degree of dormancy. It is suggested that one of the ways in which the environmental conditions to which the mother plants are exposed can influence seed behaviour is by changing the endogenous inhibitor levels