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- Author or Editor: H. F. Wilkins x
Abstract
Irradiating the all-green Chlorophytum comosum Thunb. with incandescent or red cellophane wrapped fluorescent lamps during the night increased the mean number of stolons formed per plant. A night interruption was more effective in stimulating stolon formation than irradiating the plants prior to sunrise or at sunset. There were no significant differences in stolon numbers formed between the two light sources within an irradiation treatment. Less and less time was required between the advent of subsequent stolons under all treatments during the 25 week experiment. Photoperiod treatments had no effect on time from visible stolons to anthesis. Plants in all treatments formed stolons and flowered.
Abstract
‘Ace’ lilies were placed in growth chambers at the visible flower bud stage under a 12-hour photoperiod with all possible day and night temperature combinations of 15.6°, 21.1°, 26.7°, and 32.2°C. At a constant day and night temperature of 15.6°, 21.1°, 26.7°, and 32.2° the time to flowering was 50, 28, 25, and 24 days, respectively. At a day temperature of 21.1°, night temperatures above 21.1° had little effect on flowering, but 15.6° greatly retarded flowering.
Abstract
Lilium longiflorum Thunb. cv. Nellie White bulbs were shipped in 1969, 1970, and 1971 from the west coast to St. Paul by air freight from July to October at 15 day intervals. Bulbs were given 0 or 2 weeks of 10°C, 15.5°C or 21 °C followed by 0 or 6 weeks of 4.5°C. Two weeks exposure to 10°C enhanced shoot emergence and flowering of late-harvested non-cooled bulbs and enhanced flowering of cooled bulbs. Treatments of 15.5°C or 21°C had little influence on shoot emergence and flowering of non-cooled bulbs and delayed flowering of early harvested cooled bulbs. With time and with increased bulb growth the degree of dormancy (delay of emergence) decreased and degree of maturity (enhancement of early flowering by 4.5°) increased.
Abstract
Individual flowers from Rhododendron L. ‘Prize’ inflorescences were used at various stages of development for quantitative analysis of endogenous free abscisic acid (ABA) content by gas-liquid chromatography with electron capture detection. A decrease of endogenous ABA levels was observed in bud scale, petal, and gynoecium tissue during 6 weeks of cold treatment (9°C) given for release of floral bud dormancy. However, plants which received no cold treatment flowered as rapidly as plants exposed to 6 weeks of 9°. Therefore, a relationship between endogenous ABA levels and the capacity of azalea floral buds for continued development after a cold treatment could not be shown. Regression models of endogenous ABA content on respective morphological measurements of flower bud parts were computed to illustrate the relationship between destructive hormonal determinations and defined morphological changes over time.
Abstract
Night irradiation of stock plants and cuttings during the rooting period with red (R) or incandescent (INC) light resulted in statistical differences in rooting of cuttings of chrysanthemum (Chrysanthemum morifolium Ramat. cvs. Bright Golden Anne and Mrs. Roy) but differences were not large enough to be of commercial concern. Rooting was best when stock plants were irradiated with R light and cuttings were subsquently rooted under INC light and poorest when cuttings from INC irradiated stock plants were rooted under R light.
Abstract
Biologically active levels of ethylene were accumulated in flask atmospheres of leaf segments and callus of dahlia cultured in vitro. The ethylene levels were dependent on concentrations of α-naphthaleneacetic acid (NAA) and 6-fur-furylamino purine (kinetin) in the medium. NAA promoted ethylene levels to a greater degree than kinetin. NAA at 1 mg liter, but not 5 or 10 mg liter, interacted with kinetin to stimulate ethylene synthesis. Reducing ethylene concentrations in the flasks by potassium permanganate absorption had no effect on callus formation from leaf tissue.
Abstract
Long photoperiods (either naturally long days or 4-hour night interruptions with low intensity incandescent light) inhibited lateral shoot development and induced early flowering in perpetual flowering carnation (Dianthus caryophyllus). Short photoperiods delayed flowering but enhanced lateral shoot development only when shoots were vegetative. Once a shoot was induced, short photo periods had no influence on time to terminal shoot flower or on subtending vegetative lateral shoot development. Vegetative lateral shoot development was inhibited by night interruption lighting regardless of light source. These data indicate that high flower production in Spring and summer is due to lateral vegetative shoots which begin elongation and growth during the non-flower inductive short days of winter. At higher latitudes low production of flowers may not entirely be due to low photo-synthetic light but to the low number of lateral shoots. This low number of potential flowering shoots is due to highly inductive long days of summer which have caused shoots to flower before subtending lateral shoots can begin growth for future flower production.
Abstract
Alstroemeria L. ‘Regina’ plants grown at 22°C did not flower, regardless of photoperiod treatments. If grown at 13°, plants flowered sooner under long photoperiod treatments than under natural days (ND). Incandescent (Inc) or red light treatments applied as a night interruption (NI) promoted earlier flowering than NI-far-red, ND, or short days (SD). Number of flowering shoots was unaffected by light quality. Plants grown under SD treatments produced the fewest flowering shoots. Flower production was related to early commencement and subsequent duration of the flowering span, as all plants ceased flowering on similar dates. When plants were rotated every 20, 30, or 40 days between SD and NI-Inc light treatments, the days to flower were delayed compared to plants grown continuously (nonrotated) under NI-Inc. Nevertheless, plants which were rotated between the various SD and NI-Inc light treatments flowered sooner than plants under continuous SD. Days to flower were reduced when plants were transferred monthly (December to June) from SD to either ND, 20 hr Inc, or 10 or 20 hr of high-intensity discharge (HID) lights. Flowering was hastened by 20 hr of HID lighting when compared to Inc during the months when the natural photoperiod was less than 12 hr, but had no influence when the 20-HID light treatment commenced after the natural photoperiod was greater than 12 hr. Maintaining plants under SD past January delayed the start of flowering, regardless of subsequent light treatments.
For chrysanthemum [Dendranthema × grandiflorum (Ramat.) Kitamura], the hypothesis that a 12-hr 5C or 13C dark treatment could be used in conjunction with a 12-hr 27, 21, 17, or 13C light treatment for rapid flowering when applied during certain developmental stages was valid. Flowering of `Bright Golden Anne', planted on 23 Sept., was not delayed by 12-hr light/12-hr dark growth chamber treatments of 21/5C or 27/13C (day/night) if treated from planting (P) of the rooted cutting to the start of short days (SD), 3 weeks after start of SD to visible bud (VB) (SD + 3 to VB), or from VB to flower (F) when compared to the glasshouse control plants grown at 21/18C. Plants responded similarly if grown at 13/13C or 21/21C, but flowering was delayed compared to the 17/17C glass house control. Delays were absent, however, when 13/13C was used from P to SD, SD + 3 to VB, or when 17/13 or 21/13C was used from VB to F.
Abstract
Alternanthra amoena Voss, Coleus × hybridus Voss., Hedra helix L., Pelargonium × hortorum Bailey, Peperomia obtusifolia L.,Pilea cadierei Gagnep. & Guillaum, Pilea ‘Moon Valley’ and Pilea involucrata ‘Panamegia’ Sims were grown under normal photoperiods (ND), short photoperiods (SD) and several night lighting regimes using red, incandescent, or far red light. Lateral branching and cutting production was promoted on P. ‘Moon Valley’ under SD while flowering was inhibited. P. ‘Moon Valley’ and P. involucrata flowered under long days. The remaining plant species produced more cuttings under ND or the night lighting treatments when compared to SD. Cycling P. ‘Moon Valley’ and P. involucrata between SD and day continuation red lighting treatments every 20 days significantly increased cutting production on plants compared to plants grown continuously under SD or ND.