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- Author or Editor: Abraham H. Halevy x
Abstract
Horticulture is not merely the art of growing plants, but that of growing plants for profit. Therefore when we study the effect of an environmental factor or a growing procedure on a horticultural crop, our main criterion is often not growth but a marketable yield.
Experiments aiming to adapt the perennial balloon flower (Platycodon grandiflorus) as a commercial cut flower crop were conducted for 4 years under various growing conditions: four controlled-temperature rooms at two photoperiods in a phytotron, heated and unheated greenhouses, and a saran net-house (15% shade). Best flower yield was obtained following crown cooling for 12 weeks at 2 to 4 °C. Platycodon is a day-neutral plant, but produce more flowering stems under long days. Flower initiation and development is enhanced with increased growing temperature from 17/12 °C (day/night) to 27/22 °C. At very high temperatures (32/24 °C), however, only a few flowers are formed. Best quality stems were produced at 12 to 14 °C night temperature. At higher night temperatures, flowering stems were thin and weak. Gibberellin treatments to the crowns and the plants did not affect flowering time. Chemical name used: gibberellin (GA3).
Abstract
Pot roses (Rosa hyb. cvs. Pink and Orange Margo Koster and Red Garnette) were sprayed with naphthaleneacetic acid (NAA) or 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA) prior to simulated truck shipment which lasted 5 or 6 days to study the effect on flower bud and leaf abscision and on leaf senescence. “Shipment” under refrigerated conditions (1-3°C) prevented bud and leaf abscission. ‘Red Garnette’ and ‘Orange Margo Koster’ had little or no bud and leaf abscission even at a warm “shipping” temperature (20-22°C); however, ‘Pink Margo Koster’ was severely affected. Observations under “home conditions” for 10 days after this warm “shipping temperature” revealed that all 3 cultivars had severe leaf senescence. NAA spray (15 and 30 ppm) severely accelerated leaf abscission and senescence. NAA prevented bud drop, but the buds did not open. PBA (50 ppm) greatly reduced leaf abscission both during “shipment” and in “home conditions”. PBA also prevented bud drop and flowers subsequently opened normally.
Abstract
Splitting and out-rolling of the stem bases in cut flowers of Hippeastrum Xhybridum was prevented by a 1-day-pulse treatment with 0.125 m sucrose. Pulsing also slightly increased vase life and promoted the opening of all the flower buds on the stem.
Abstract
Pulsing gladiolus stems at 21°C with 20% sucrose in combination with AgNO3 before storage of 7 or 10 days resulted in greater floret opening and size than those not pulsed. A silver treatment alone was not effective. The sucrose fulfills the requirements for a carbohydrate source and osmoticum which are necessary for floret growth and development. This treatment with sucrose is recommended prior to shipping or storage of gladiolus for long periods.
Abstract
Flower bud initiation of herbaceous peony (Paeonia L.) may start soon after the current year’s flower anthesis in June; buds continue to develop until the onset of dormancy in the fall. Flower formation, days to harvest, foliage senescence, and dormancy are unaffected by photoperiod. Flower bud dormancy can be broken by storage of dormant plants for a minimum of 4 weeks at 5.6°C after which they may bloom in the greenhouse in 8 to 10 weeks. Increasing storage time to 6 weeks or reducing the temperature to 1° increases the total number of shoots that grow after forcing.
Abstract
Hybrid lisianthus [Eustoma grandiflora (Raf.) Shinn.] was evaluated as cut flower and flowering pot plants. Lisianthus is a day neutral summer blooming plant blooming earlier at high growing temperatures (18°/26°C night/day) than at low temperatures. It is a slow growing plant, requiring about 5 to 6 months from sowing to flowering. Forcing period is about 2 months. Three color variants are available: blue, pink, and white. Only the blue and white are suitable as cut flowers. About 3 cut flower stems are produced per plant in the 1st harvesting cycle, and retaining the plant for a 2nd crop is considered uneconomical. Keeping quality of the cut flowers can be improved by pulsing for 24 hr with a solution containing 5% to 10% sugar, and desirable blue and pink pot plants were obtained by spraying with butanedioic mono-2.2-dimethylhydrazide (daminozide, B-Nine). The white cultivar did not respond to daminozide but did respond to soil application of a-cyclopropyl-a-(p-methyoxyphenyl)-5-pyrimedine methyl (ancymidol). Flowering pot plants should be grown in the greenhouse until about half of the flower buds on the plants open, since buds do not develop properly under home conditions.
Abstract
Direct coating of flowers of carnation (Dianthus caryophyllus L. cv White Sim) with Ag ions by spraying or momentarily dipping flower heads with AgNO3 (50-100 ppm) extended cut flower longevity and counteracted the enhancing effect of ethephon on senescence. Treating stems and leaves similarly had little or no effect. Stem base treatment with 1000 ppm was much less effective than treating the flower directly. Maximum efficiency of the AgNO3 spray was obtained when a period of 2 hours elapsed between the AgNO3 treatment and exposure to ethephon. In spite of the great extension in longevity, silver spray has limited practical use since it causes petal spotting.
Vase life of individual flowers of cut brodiaea (Triteleia laxa Benth.) inflorescences ended 4 days after opening. Best vase life was achieved by harvesting inflorescences 1 to 2 days before anthesis of the first flower and holding them in a vase solution containing 2% sucrose and 200 ppm 8-hydroxyquinoline citrate (HQC). Such inflorescences had a display life of 12 days. Decreasing the pH of the vase solution or pulsing inflorescences with 10% sucrose for 16 hours did not increase their longevity. T. laxa flowers pretreated with 10% sucrose overnight could be stored for up to 2 weeks without significant reduction in vase life.
Experiments to advance early production of herbaceous peony (Paeonia lactiflora Pall.) flowers were conducted over 8 years in the higher elevation, cooler regions of Israel. Anatomical studies during the summer revealed that flower bud initiation of apical buds in the crowns began at the end of July and continued also in lateral buds from mid-August until the plants became dormant in mid-November. Container-grown plants of various cultivars were moved to cold rooms maintained for 10 to 13 weeks at 2 °C, from mid-August to mid-October, then drenched with 250 mL of various concentrations of GA3 and transferred to a greenhouse. The optimal GA3 concentration for flower production was 100 mg·L-1. Plants treated in this way flowered 2-3 months before the natural flowering period. Field-grown plants in uncovered greenhouse structures were exposed to natural winter cold temperatures (0-10 °C), until they had received various chill units according to a “dynamic model” (for details see Erez et al., 1988). The crowns were then drenched with various amounts and concentrations of GA3, and the greenhouses were covered with plastic sheets. The optimal chill units for most cultivars was 40 and the optimal GA3 drench treatment was 250 mL of 100 mg·L-1. Covered and GA3-treated field-grown plants flowered ≈1 month earlier than untreated plants grown in the open field. The GA3 treatment also greatly increased the number of produced flowers.