THE INFLUENCE OF GROWTH REGULATORS ON SHOOT AND ROOT DEVELOPMENT OF FRUIT TREES
Early application of SADH causes less retardation of shoot growth than treatment applied 2–4 weeks after bloom. The best stage for application is when shoots are 20–25 cm long. It is possible to retard shoot growth without affecting fruit development by treating only the upper parts of the trees. SADH treatment does not alter the periodicity of shoot growth, which is entirely dependent on temperature. The retarding effect starts shortly after application and, for treatments applied in spring or early summer, disappears after 60 days. The growth potential suppressed in the first year will be compensated in the following year by a higher potential, but this may be controlled by pruning in the preceding winter. Shoot retardation increases the ratio of bark + pith to xylem. Shoot retardation caused by SADH does not influence the seasonal periodicity of root development, nor does it appreciably promote root growth, though in relation to shoot growth the root development is greater. Treatments two years in succession have a marked retarding effect on root development, but not in relation to shoot length.
Schumacher, R. (1973). THE INFLUENCE OF GROWTH REGULATORS ON SHOOT AND ROOT DEVELOPMENT OF FRUIT TREES. Acta Hortic. 34, 175-184