LONG-TERM FLOWER PRODUCTION OF A ROSE CROP .1. THE INFLUENCE OF PLANTING SYSTEM AND ROOTSTOCK CLONE

The effect of planting system and rootstock clone on plant development and flower production of R. hybrida 'Motrea' was studied for more tha n four years. Initially rootstock Ludiek gave the highest number of fl owers as compared with the rootstocks Multic and Moonlight. However, t he decline in flower production for 'Ludiek' after two years of cultur e was more severe than for the others. Plants on 'Moonlight' outyielde d those on the other rootstocks during the third and fourth year of cu lture and this result is discussed in relation to their high renewal c ane production. Death of basal shoots during four years of culture was mainly due to competition between numerous shoots. No influence of ro otstocks on the longevity of rose plants could be detected during this period. Comparison of basal-shoot formation during the early period o f plant development in single stemmed plants at double plant density a nd with a two-stemmed planting system at normal plant density showed t hat intra-plant competition between basal shoots was greater than inte r-plant competition. During subsequent years of production no differen ces in basal shoot competition occurred between or within plants, as r eflected in equal total flower fresh weight production, numbers of new basal-shoot formation and numbers of dead basal stems. However, highe r plant density increased the number of harvested flowers and decrease d individual flower weight.