Effect of cell size and cytokinins on growth of petunia plants

Annual floral plant crops are produced in cells or pots of various sizes. Varying container size alters the volume which plant roots can explore, which in turn affect plant growth. This work assesed the effect of the initial container size on growth of Petunia x hibrida cv Dream Mix, supplemented with cytokinins after potting. Seedlings obtained in trays of 90 or 288 cells, were transplanted to 11 pots. They were then supplemented with 6-bencyladenine (BA). The assay consisted of 4 treatments: two container sizes by two BA conditions (with and without). Cell size conditioned growth above ground and below ground; growth rate and shoot/root ratios decreased (p<0.001) as cell size decreased. At the end of the assay, branching differences on plants supplemented with BA were highly significant (p<0.001; 14.7 versus 6.9) with respect to those without BA. This occurred independently of cell size the plant came from. Final weight and growth rate of potted plants, coming from trays of 288 cells, were smaller than those coining from trays of 90 cells. Cell size employed in early growth stages conditioned size and final quality of petunia plants. Supplementation with BA allows obtaining better developed, greater size plants.