KEEPING QUALITY OF CUT ROSES AS AFFECTED BY HIGH SUPPLEMENTARY IRRADIATION

The rose cultivars 'Kiss', 'Frisco', 'Cardinal', 'Madelon' and 'Jaguar' were grown in a greenhouse under four different levels of supplementary irradiance (130, 190, 250 and 370 mumol m-2 s-1) applied for 20 h day-1. Five times during the production period roses were harvested for the purpose of testing the keeping quality. Vase life and number of days till occurrence of bent neck was about 30% higher when the roses were harvested in June than when they were harvested in November and January. Vase life increased when the supplementary irradiance level increased from 130 to 370 mumol m-2 s-1. The increase in vase life with increase in radiation was most pronounced for 'Cardinal' and 'Madelon'. Significant cultivar differences in vase life and days to leaf drop and bent neck were observed, 'Madelon' had the longest vase life.