Effects of Plant Growth Regulators, Nitrogen Fertilization, and Irrigation on Eldarica Pine Seedlings

Abstract

Effects of applications of cytokinin-like and gibberellic growth regulators, nitrogen fertilizer, and irrigation on the development of containerized eldarica pine (Pinus brutia var. eldarica) seedlings was studied in a greenhouse for 13 weeks. All concentrations of growth regulators reduced nitrogen content of needles and dry weight of shoots; importantly, medium and high concentrations also adversely affected root collar diameter growth and shoot elongation. Nitrogen fertilization alone was not significant in its effect on seedling development, due probably to the nitrogen-rich nature of the potting medium. It is suggested that contentration is a critical factor when applying growth regulators, as phytotoxicity of seedlings can result at high rates.