The Breaking of Seed Dormancy

Abstract

Dormancy may be broken as a result of the exposure of the seed to a single factor at the requisite intensity for an appropriate period of time. Germination then follows the breaking of dormancy. Alternatively, dormancy breaking may require or may be accelerated by exposure of the seed to fluctuating conditions, such as diurnal changes of soil temperature or the diurnal cycle of light and darkness. Dormancy may be broken in response to the range of diurnal fluctuations occurring at a particular season of the year, such as spring, or dormancy breaking may result from the seasonal cycle of temperature, as for example in the succession through winter, summer and winter. In a more complex situation, dormancy may be broken as a result of exposure of seeds to two or more distinct factors, such as light and an appropriate temperature range, or to ethylene at an appropriate temperature. Table 6.1 lists the main types of dormancybreaking treatments.