ASSOCIATION BETWEEN BRANCHING IN MAIDEN APPLE TREES AND LEVELS OF ENDOGENOUS AUXINS

Shoot tips of the poorly branched Tydeman's Early had a higher concentration of auxin-like substances than those of the freely branching Cox's Orange Pippin. A comparison of maiden trees of Cox on MM.106 which are branched, with trees on M.27 which are dwarf and unbranched, showed a higher concentration of auxin-like substances in shoot tips of the latter. Shoot tips of trees induced to branch by treatment with a branch-inducing agent (NC 9634) contained very low levels of auxin-like substances for approximately two weeks after treatment. The level of gibberellins in the shoot tips was unaffected by this treatment.