Folia Horticulturae

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Effects of gibberellic acid and different levels of nitrogen and potassium on the growth of Juniperus communis ‘Suecica’

Mieczysław Grzesik*, Marten Joustra**

**Research Institute of Pomology and Floriculture
**Waryńskiego 14, 96-100 Skierniewice, Poland
**Research Station for Nursery Stock and Urban Greenery
**Boskoop, The Netherlands

The effect of treatment with GA3 at a concentration of 400 ppm applied at the initiation of new growth of when new shoots were 7 cm long was studied together with that of four nutritional levels and ratios of N-P-K; 3-1-3; 4.5-1-3; 6-1-3; 4.5-1-4.5 on the outdoor growth of Juniperus communis ‘Suecica’ plants.

The application of GA3 resulted in taller plants and longer new shoots than without its application. Treatment during new shoot growth gave a greater elongation of shoots than earlier treatment. An increase in the nitrogen and potassium dose did not affect the growth of the treated plants, but slightly improved that of untreated ones. The plants treated with GA3 assimilated more macroelements than the untreated plants.

Grzesik M., Joustra M., 1991. Effects of gibberellic acid and different levels of nitrogen and potassium on the growth of Juniperus communis ‘Suecica’. Folia Horticulturae III/1: 61-66.