Basal-shoot formation in young rose plants: Effects of bending practices and plant density

To examine the relations between plant architecture and flower production, the effect of bending practices and plant densities on basal-shoot formation was studied in young rose plants. After bending the primary shoot, there was a greater probability for the outgrowth of the two most basal buds. These two buds are already present as secondary buds in the axils of the scales of the axillary bud when used as a cutting for propagation. This probability was even more apparent when bending was delayed. The source capacity of the primary shoot, mainly reflected in the leaf area index (LAI), was determined by date of bending. Delayed bending increased the development rate, diameter, weight and cross sectional area (CSA) of basal shoots per plant. Plant growth rate, expressed as dry-weight increment per day, was positively related with LAI (and thus light interception) during the early phase of basal-shoot formation, although a maximum in plant growth rate was reached when stems were bent 28 d after T-0 (time of bending the primary shoot when the flower petals were reflexing). Sprouting of axillary buds positioned higher on the stem strongly inhibited the outgrowth of basal shoots. Removal of competitive lateral growth increased the number of CSA of basal shoots per plant. Reducing the number of developing basal shoots increased the diameter and weight of the remaining shoots but plant growth rate remained unaltered. The influence of plant density on basal-shoot formation of young rose plants was relatively small. However, numbers and cross sectional areas (CSA) of basal shoots per square metre were positively influenced by increasing plant densities. A general concept on ways to improve plant building of young rose plants, with respect to basal-shoot formation, is discussed. The number, diameter and CSA of basal shoots, expressed per plant or per square metre, could be highly controlled using plant related factors such as the timing of bending the primary shoot, removal of lateral and basal buds and by plant density.