Indices de Maturité
Roses are harvested at different levels of maturity, depending on marketing and cultivar. For long-distance transport or storage, roses should usually be harvested with some of the sepals reflexed. Flowers harvested before the sepals reflex may fail to open or may be more susceptible to a bent neck. Fast-opening roses, like some yellows and whites, should be harvested just before the sepals start to separate from the bud. The marketing life of roses harvested later will be reduced unless extra care is taken with their postharvest handling. Harvesting is most convenient using shears provided with auxiliary jaws to hold the bloom after harvest. The cut is normally made so as to leave 2 five-foliate leaves below the cut. When stem length is an important consideration, the cut may be made ‘below Roses should be purchased and sold by cultivar name. Avoid blooms that are already open – flowers should normally have some or all of their sepals (the green protective ‘leaves’ at the base of the flower) folded back, but the petals should not have started unfolding. Brown spots or patches on the outer petals may be an indication of Botrytis infection.
Grading and Bunching. Objective grading is based on stem length; subjective grading is based on flower maturity, stem straightness, stem caliper, and quality of flower and foliage. Defects on the outer "guard" petals are not normally a cause for down-grading, because these petals are removed by the retail florist. Leaves and thorns may be removed manually or mechanically if desired. This operation has little effect on vase life if flowers are placed in an effective preservative. The number of stems per bunch, and bunch pattern (single layer, staggered two-layer) depends on market preferences.
Manipulation et stockage post-récolte
Roses should be stored, dry, at 0-1°C. Roses intended for long-term storage should be packed in polyethylene-lined cartons and pre-cooled. They may be held for up to 2 weeks in dry storage if the temperature is maintained steady and close to the freezing point.
Some cultivars are ethylene sensitive. Treat with 1-MCP or STS if they are being distributed through the mass markets, especially if being shipped through distribution centers, and also treat to prevent the effects of the ethylene prior to dry storage.
Rose bunches are routinely sleeved in plastic, waxed paper, or soft corrugated card sleeves. The ‘spiral’ bunch used by many off-shore producers increases the difficulty of pre-cooling the flowers, and the opportunity for condensation collecting on the outer petals. Botrytis infection is a common result of the presence of free moisture on the petals of cut roses.
Removal of those leaves and thorns below the water line should not reduce vase life if the stems are placed into a preservative solution. The fungus Botrytis represents a major problem for roses. Symptoms of Botrytis infection include brown blotches on petals and gray, fuzzy growth on leaves, stems or flowers. Postharvest fungicide dip can be helpful - use only registered products according to label instructions. Petal blackening on some red cultivars is due to the growing conditions, and cannot be corrected at wholesale or retail levels.
Rosa cvs. hybrids. The rose undoubtedly remains the queen of cut flowers. The historical association of this flower with romance and beauty ensures that roses will continue to be a highly desired cut flower in the future. Properly handled, most commercial-cut roses will easily last in the vase for 10 days. Unfortunately, many consumers consider roses to have a very short vase life. This is partly because poor water uptake by certain cultivars of purchased roses all too often results in the symptom called "bent neck" in which the flower neck wilts and the bud fails to open. We also have found that many commercial cultivars are quite sensitive to ethylene gas. The cut flower industry has an important stake in overcoming the poor postharvest reputation of cut roses. All that is required is proper postharvest care for those cultivars susceptible to the bent neck, and appropriate pre-treatment of those that are sensitive to ethylene, especially if they are to be sold in supermarkets or other ethylene-polluted areas.