Gerbera, Transvaal daisy
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Description / Shipment / Storage / Risk factors
Scientific Name and Introduction
Gerbera jamesonii and hybrids. Cut gerbera flowers, known for their remarkable variety in coloration and form, are an increasingly important part of the florists’ palette. Their postharvest life can be substantial if they are given proper postharvest conditions, but they are sensitive to gravity, to light, and to bacterial contamination of the vase solution. Originally spelled “Gerberia,” the genus was named after Traug Gerber, a German naturalist.
Quality Characteristics and Criteria
Most gerbera varieties should be harvested when the two outer rows of disk florets have begun to open, but some cultivars can be harvested later, particularly those types that close at night. Flowers are harvested by twisting the stems off near the point of attachment to the rhizome; this is thought to encourage subsequent flower production. If flower stems are pulled from the ground, immediately cut 10 cm from the bottom to remove the ‘woody’ base of the stem, which does not draw water readily. Place soon after harvest in a solution containing 40 ppm hypochlorite. Make sure that at least one or two rows of disk flowers (tubular flowers in the centre of the head) are showing pollen. If stems were pulled from the ground, cut 10 cm off the bottom to remove the woody portion and improve water uptake. With well over 300 cultivars in commerce that vary greatly in vase-life, it is important that florists order gerberas by cultivar name. Unfortunately, the large number of cultivars makes it difficult to learn the names of better cultivars.
Grading and Bunching
Maturity, freedom from defects, and stem length, strength and straightness are important quality criteria for gerberas. Some producers bunch the flowers, but most pack them individually. Some producers place each flower into a firm plastic sleeve, and may insert the stem into a plastic tube to reduce stem bending.
Gerberas are unaffected by exposure to ethylene.
Present industry practice is to place cut gerbera stems in a 40 ppm sodium hypochlorite solution immediately after harvest to improve vase-life. A rapid pulse treatment with 100 ppm silver nitrate is sufficient to greatly alleviate postharvest problems with gerbera cultivars that are relatively short-lived. The silver nitrate presumably guards against bacterial contamination of the stem and vase water. After the dip, rinse the flowers in good quality water. This treatment causes only minimum phytotoxicity (brown damage to the stem). The use of 6% sugar + 200 ppm 8-HQC as a preservative has shown to be of some benefit but can cause stem elongation during storage and may reduce overall flower quality.
Gerberas should be stored at 0°C to 1ºC; the widely-held opinion that gerberas are sensitive to chilling injury has not been scientifically substantiated. Generally, gerberas should not be stored longer than 1 week; even this short storage period can reduce subsequent vase-life.
Most commonly, producers pack individual flowers horizontally in shallow cardboard containers especially designed to support gerberas. Flower stems are passed through slits in the bottom of a cardboard tray so that the flower heads face up showing their colours while the stems pass under the box. Several rows of flowers can be arranged in each box. The boxes are then hung so that the stems dangle downward and can be placed in a re-hydration solution (hypochlorite is most commonly used). Afterward, two trays of flowers are packed horizontally into a fibreboard box in such a way that the flowers are facing upward and easily seen, while the stems are underneath the flower cards.
Stem bending is primarily in response to gravity, and is greatly reduced if flowers are held at the proper storage temperature. One of the major problems in postharvest handling of these flowers is their tendency to 'conk,' which is folding of the stem 10 to 15 cm below the flower head, resulting in an unmarketable flower. This bending has been variously attributed to harvesting of the flower before the stem has hardened sufficiently, and/or microbial plugging of the stem and subsequent water stress. The tendency to conk varies with variety and also varies throughout the year for any given variety. Be sure to enhance water uptake by keeping holding solutions and buckets clean and including hypochlorite in the water. Since more water is lost through the flower stem (scape) than through the flower petals, the scapes should be handled with as much care as the flowers themselves. Hang flower heads through a meshed support or shipping tray when first hydrating to keep stems straight.
BMT De Beer’s Consolidated Manual on (Dutch) Flower Bulbs, cut flowers/greens and potted plants