| Summary: | Pine seedlings were cultivated in Ingestad nutrient solution containing potassium as KCl on a 16-hr day, under light intensity of about 4000 lx and temperature of about 23° C. K+ used in a concentration of 50 ppm exerted a most pronounced positive effect on the growth of seedlings. After 4 months it was found that potassium used in this concentration increased elongation of hypocotyls, shoots, roots, primary and secondary needles as well as fresh weight and dry matter of tissues. In leafy shoots K+ increased the level of free gibberelirns (GAs) and auxins and decreased the amount of bound GAs and an ABA-like inhibitor. In the roots K+ nutrition increased the amount of free GAs and of the growth inhibitor and decreased the level of bound GAs and auxins. No evident influence of K+ on the level of cytokinins in plant tissues was stated.
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