LONG-TERM FLOWER PRODUCTION OF A ROSE CROP .2. THE IMPORTANCE OF NEW BASAL-SHOOT FORMATION

The importance of new basal-shoot formation for plant development and flower production of Rosa hybrida 'Motrea' was studied for more than f our years. After one year, new basal-shoot formation was either restri cted or undisturbed. In both treatments, fresh-weight production decre ased after the second year; this is discussed in relation to an increa se in respiration as a result of an increase in stem biomass. Limiting the number of new basal shoots increased flower weight and slightly e nhanced flower production during the second year as compared with leav ing all renewal canes on the plant. In the latter case, the number of basal stems was almost twice as high after three years. New basal shoo ts may compete with existing ones as indicated by the limited diameter increase and the higher mortality rate for old basal shoots in compar ison with the treatment in which basal-shoot formation was restricted. Further, the weight of flowers harvested from new basal shoots was cl early greater than from older shoots. However, restricted basal-shoot growth had hardly any significant effects on the total number of harve sted flowers and average flower weight as compared with the undisturbe d situation. In the fourth year a slightly decreased flower production was observed in the case of restricted basal-shoot formation. It may be concluded that there is no relation between the number of basal sho ots and flower production over a series of years.