Effect of applied growth regulators and cultural treatments on flowering and shoot growth of Pinustabulaeformis

Abstract

Fourteen treatments expected to promote and regulate flowering were administered to 7-year-old seedlings of Chinese pine (Pinustabulaeformis Carr.), and three were administered to 11-year-old grafted propagules. The cultural treatments, including root pruning, stem girdling, polyethylene mulching, and injection of gibberellin A3 (GA3) significantly increased male cone bud production of the young seedlings. For female flowering, however, only GA4 injection, alone and in combination with root pruning, had a statistically significant positive effect. N6-benzyladenine (BA) injection significantly decreased both male and female cone-bud production. There was no synergistic effect between the cultural and the hormonal treatments on flowering of the seedlings. Treatments with naphthaleneacetic acid dramatically enhanced male cone bud production of the grafted propagules, but did so at the expense of female cone bud production. The hormonal treatments (GA3, GA4, and BA injection) all promoted vegetative shoot growth of the treated seedlings. The cultural treatments generally inhibited shoot length growth and had no significant effect on diameter growth.