Abstract

Greenhouse grown seedlings of Pinus sylvestris L. (Scots pine) and Pinus nigra Arnold. (Austrian pine) were treated with plant growth regulators in a 1% solution of dimethyl sulfoxide. Benzyladenine (BA) induced branching of seedlings of Scots pine. Both Scots pine and Austrian pine seedlings were reduced in height by BA treatments. The addition of gibberellic acid (GA) to the BA treatments had little effect on branching or seedling height. After a second growth cycle the Scots pine seedlings treated with BA were shorter and had more branches while the Austrian pine seedlings were also shorter without an increase in the number of branches.