CHOICE OF SUBSTRATE AND FERTILIZATION STRATEGY TO GREENHOUSE GROWN CLOUDBERRY (RUBUS CHAMAEMORUS L.)

Cloudberry, Rubus chamaemorus L. (Rosaceae) a circumpolar, dioecious, perennial herb naturally occurring in ombrotrophic sphagnum bogs has been suggested as a future greenhouse crop. The purpose of the present investigation was to examine the prospects of production of cloudberry under greenhouse conditions. We therefore studied physical and chemical qualities of natural cloudberry stands in order to select an appropriate growing medium for indoor cultivation. Peat (H₂) from a recently opened bog was found to correspond best to the natural conditions when compared to two commercial growing media (K-soil; rhododendron soil). In order to secure structure stability different nitrogen forms (nitrate, ammonium, urea) were tested for fertilization regime; a commercial fertilizer (Superba Red) was used for the control treatment. Our results indicate that addition of urea and ammonium as nitrogen form kept the pH at an appropriate level in the substrate solution during the observation period. However, the concentration of readily available nutrients differed significantly between the control treatment and the treatments including different nitrogen forms. Plant development was comparable in all the different treatments.