SIGNIFICANCE OF PLANT TYPE AND AGE, SHOOT CHARACTERISTICS AND YIELD ON THE VASE LIFE OF CUT ROSES GROWN IN WINTER

Cvs. Mercedes and Frisco, grafted either on cv. Inermis rootstocks or on own roots, were grown on peat for two successive winter seasons in a greenhouse provided with supplementary lighting (100 mu mol m(-2) s( -1), 20 h day(-1)) after a rest period in December. The vase life of f lowers of the first flush was longer in the second year when the plant s had aged than in the first year. This increase was longer for plants on own roots than for grafted plants. Long stems and large leaf areas of flowering shoots reduced the flower longevity of cv. Mercedes, but not that of cv. Frisco. Even after adjusting for these two variables, the differences between plant type and age still persisted. Yield per plant was not significant for the vase life of either cultivar. A sho rt rest period and pruning thereafter might have stressed the young pl ants of cv. Mercedes, in particular, causing their very short vase lif e.