ABSTRACT
This chapter shows that what is known about growth regulators in relation to the physiological processes of dormancy, cold hardiness, and water deficits in tree species. It reviews the known roles of growth regulators on stem elongation, cambial activity, root growth and tree form in order to provide a basis for considering their potential uses for manipulating these processes. Some of the plant growth regulators, most notably the auxins, can be used in forest practice as herbicides. The correlative inhibition of lateral buds and shoots by the apical shoot was one of the first physiological processes to be recognized as linking the control of growth in one part of a plant to a hormone produced in another part. Conifers exhibit juvenile phases for leaf morphology, ability to be propagated vegetatively, rapidity of growth, apical form, and ability to flower. It is now apparent that a large number of conifers will flower in response to exogenous application of gibberellins.
