Natural dormancy is also called internal dormancy, true dormancy or physiological dormancy. It refers to the stagnation of growth and development determined by internal factors. Even if the external environmental conditions are suitable for growth, the buds can't germinate. Only under certain environmental conditions can the internal dormancy be released and the buds grow normally.
Forced dormancy, also known as external dormancy, is a phenomenon that growth is temporarily stopped due to the stress of unfavorable external environmental conditions. When adversity is relieved, growth can resume again. Such as the roots of deciduous flowers and trees dormant.
In addition, there is another kind of dormancy called related dormancy or mutual inhibition, which means that some buds can't germinate and grow due to the existence of other organs, and are in a dormant state, such as inhibiting the germination of lateral buds due to the effect of apical dominance.
Similar to the growth period, the dormant period is in a relatively stagnant state due to various life activities, and the demand for nutrients is extremely weak, so the supply of nutrients is generally not considered. Moreover, before entering natural dormancy, the nutrient reflux accumulation of plants can fully support the nutrient consumption of plants in dormancy and early germination. However, the level of nutrient reserve during dormancy has a great influence on the ability to resist adversity. Therefore, according to different types of dormancy period, adjusting fertilization strategy and storing nutrients to the maximum extent are the guarantee to spend the dormancy period safely.
Many measures are often taken to adjust the dormancy period in cultivation management.
(1) promotes dormancy
For perennial young flowers and trees or flowers and trees that grow vigorously, it is necessary to promote them to enter dormancy normally, so as to facilitate safe overwintering or summering. Water can be limited in the late growth stage or before dormancy, nitrogen fertilizer can be applied less, or growth inhibitors can be used to inhibit vegetative growth.
(2) Postpone dormancy
Due to some special needs, such as extending the viewing period or changing the flowering period sooner or later, dormancy can be postponed, such as pruning again in summer, applying more nitrogen fertilizer, strengthening watering and lowering the plant temperature in summer.
(3) Prolonging the dormant period
Prolonging the dormancy period can adjust the flowering period appropriately, one is to avoid the harm of adversity, the other is to prolong the ornamental of flowers. The methods adopted include maintaining low temperature environment or high temperature conditions, using hormones, etc. Some researchers also sprayed ferric sulfate during hibernation to prolong hibernation time.