Effect of cytokinin, gibberellin, and nitrogen applications on the growth of eldarica pine seedlings

Abstract

A greenhouse experiment was conducted over a ninety day period to test the effect of different nitrogen fertilizer regimes and several application rates of compounds with gibberellin and cytokinin activity (GA4/7 and BA, respectively) on the growth and development of Pinus brutia var. eldarica. Nitrogen produced no significant effects and this was attributed to its abundance in the potting medium, to begin with. All levels of growth regulators used showed a highly significant effect on vegetative development. A reduction in root collar diameter, shoot elongation, needle nitrogen content and oven-dry weight, was observed, especially when the medium and high hormonal rates were used. Phytotoxicity increased with the increase in concentration of both chemicals. Ba induced a proliferation of adventitious buds along the stem of saplings, but this was accompanied with rapid new top growth and branching at the top only when BA was applied in conjunction with GA4/7.