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  • Author or Editor: Harold F. Wilkins x
  • Journal of the American Society for Horticultural Science x
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Vegetative, single-stem poinsettia plants (Euphorbia pulcherrima Willd. `Gutbier V-14 Glory') were allowed to develop 10, 15, or 20 nodes (nodal groups). Within each nodal group, blades from the same node position were removed, combined into one sample per node, and analyzed for nutrient content. Nutrient concentrations were found to be distributed within the plant in one of three patterns: 1) N, P, and K concentrations were higher in upper than in lower leaves; 2) Ca, Mg, Fe, Mn, and B concentrations were higher in lower than in upper leaves; and 3) Cu and Zn concentrations were higher in upper and lower leaves than in middle leaves. When 10, 15, and 20 noded groups were compared, the distributional patterns were similar, but actual nutrient concentrations between groups differed. Leaf P, Ca, Mg, Fe, Mn, Zn, and B concentrations increased over time. However, concentrations of N, K, and Cu were highest in 43-day-old leaves and lowest in 19-day-old leaves for N and Cu and lowest in 67-day-old leaves for K.

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Poinsettia (Euphorbia pulcherrima Wind. ex. Klotzsch) cultivars were divided into free-branching and restricted-branching groups. Auto and reciprocal grafts were made among three free-branching cultivars, Annette Hegg Brilliant Diamond (BD), Annette Hegg Topwhite (TW), and Annette Hegg Hot Pink (HP), and two restricted-branching cultivars, Eckespoint C-1 Red (CR) and Eckespoint C-1 White (CW). when CR scions were grafted onto BD stocks, vegetative characteristics of branching pattern and leaf morphology of CR plants were altered when compared to the control graft combination CR/CR (scion/stock). Branching pattern was determined by pinching the scion above the 12th node and measuring axillary shoot length, diameter, and node number 30 days later. CR scions grafted onto BD stocks produced a plant very similar to BD plants when axillary shoot length and node number were compared. However, axillary shoot diameter and leaf morphology were intermediate between CR and BD plants. Changes were retained after two generations of serial vegetative propagation and are considered permanent. The reproductive characteristics of anthesis date, bract color, and cyathia cluster diameter were not influenced by the stock. CR/BD plants produced twice as many axillary inflorescences as BD/BD or BD/CR plants, while CR/CR plants did not produce any. All of the free-branching cultivars were able to alter the vegetative characteristics of all of the restricted-branching cultivars.

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The free-branching poinsettia (Euphorbia pulcherrima Willd. ex. Klotzsch) cultivar Annette Hegg Brilliant Diamond (BD) contained a free-branching agent that was graft-transmissible to the restricted-branching cultivar Eckespoint C-1 Red (CR). CR plants were transformed by the agent regardless of whether BD plants were used as scion or stock, indicating that the agent moved basipetally and acropetally through the graft union. The agent was repeatedly transmitted to a CR plant by serial grafting with a free-branching poinsettia plant. A minimum of 10 days contact through grafting was required for BD plants to transmit the agent to CR plants. Percentage of CR plants exhibiting the free-branching characteristic increased from 0% for < 10 days of graft contact with BD plants to 100% after 30 days.

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Abstract

Florida-produced ‘Prize’ azalea plants were shipped to Minnesota with apical floral buds whose individual flowers had styles which had commenced elongating. These plants were ready for rapid forcing if given the traditional 6 weeks at 9°C. However, a single 2000 ppm GA (Pro Gibb3) spray treatment resulted in plants which flowered more rapidly without a traditional cold treatment when forced in a glasshouse under natural daylength (ND) in Minnesota during the spring and summer. Length of the ND in these experiments was considered critical, as plants forced in the spring and summer under an 8-hr short day (SD) treatment did not flower in a uniform manner, or floral abortion occurred in GA treated, uncooled plants forced during the autumn. Under ND conditions, extended to 20-hr by high pressure sodium, cool-white fluorescent or incandescent lamps, plants flowered more rapidly than those plants cooled at 9° for 6 weeks and forced under ND. Uniformity of flowering was enhanced and GA treatment had no effect when 3 weeks of 9° cooling preceded supplemental lighting treatments during autumn forcing. During winter, 20-hr of high pressure sodium + GA treatment or a SD treatment of noncooled plants resulted in more rapid, but similarly uniform flowering, when compared to plants with 6 weeks of cold treatment. These data provide evidence indicating that ‘Prize’ azalea floral buds may not exhibit a physiological dormancy.

Open Access

Abstract

Thirty days of night interruptions (4 to 6 hours) or day extensions (4 to 8 hours) were given using incandescent (I), cool white fluorescent (CWF), and BCJ-ruby incandescent (BCJ) light sources to newly emerged shoots from ‘Nellie White’ lily (Lilium longiflorum) bulbs vernalized (4.4°C) for 0, 1, 3, or 6 weeks.

Regardless of light source a 6 hour night interruption (2200 to 0200) was more effective in accelerating anthesis than day extensions (1600 to 2000 or 0400 to 0800). There were no differences in the dates of anthesis between the light treatments when used as a night interruption with shoots from non-vernalized bulbs. Using partially or non-vernalized bulbs a day extension of CWF light delayed flowering when compared to I or BCJ. This delay by CWF was removed when bulbs were fully vernalized.

Leaf and flower bud number were reduced by bulb vernalization and effective shoot light treatments. Plant height was increased by shoot light treatment and was additive to the bulb temperature effect.

We hypothesize that bulb vernalization and shoot photoperiod treatments lead to rapid flowering through 2 inducing mechanisms. These mechanisms are phytochrome and high energy reaction (HER) systems.

Open Access

Abstract

‘Nellie White’ and ‘Ace’ lily plants from non-vernalized bulbs were placed in growth chambers for temperature and photoperiod treatments at various stages of development.

Under a 16-hour photoperiod, a 21.1°/12.8°C day/night temperature regime was optimal from shoot emergence to flower bud initiation for early flowering and high flower numbers. The increases in the flower numbers were due to the increased number of secondary and tertiary flower buds. Primary buds were constant regardless of temperature and photoperiod treatment. Under a 16-hour photoperiod a night temperature of 7.2° favored secondary bud formation, while a 15.6° night temperature favored tertiary bud formation.

Under a 12-hour photoperiod from floral initiation to visible buds, a 18.3°/15.6°C day/night temperature regime was optimal for early flowering and a minimum loss of flower buds.

Under a 12-hour photoperiod from the visible bud stage to anthesis, a 21.1°/18.3°C day/night temperature regime was optimal for early flowering with the fewest aborted tertiary buds.

Open Access

Abstract

Optimum temperatures for rapid shoot emergence from non-cooled bulbs was a constant 12.8°C with ‘Ace’ and ‘Nellie White’ lilies. Twenty-four hour cycles of 1.7°/12.8°C delayed shoot emergence of both cultivars.

Using 115 days from shoot emergence to flowering as a standard, 6 weeks of 24 hour cyclic temperature treatments of 1.7°/12.8°C produced more flower buds in ‘Ace’ than did 1.7°/7.2° or 7.2°/1.7° treatments. In ‘Nellie White’ constant 1.7°, 1.7°/12.8°, or 12.8°/1.7° temperature treatments produced more flower buds than 1.7°/7.2° or 7.2°/1.7° treatment. Leaf number and plant height were not affected by alternating temperature treatments.

With ‘Nellie White’ an intercalation of 3 weeks at 15.6°C temperature treatment to bulbs after 1, 2, or 3 weeks of 4.4°C increased secondary flower bud (development) when compared to a continuous 4.4°C bulb treatment for 5 or 6 weeks. No differences in days to flower from potting and in plant height were obtained among the various temperature treatments in both ‘Ace’ and ‘Nellie White’. Increases in total flower bud number were due to the increases in the secondary bud number.

Open Access

Abstract

Flowering was accelerated by incandescent light day extensions of 3 minutes of light and 27 minutes of dark or longer light cycles and by 15 minutes of light and 15 minutes of dark cycles when BCJ-ruby incandescent light was given to young shoots from non-vernalized bulbs. If bulbs were vernalized for 3 weeks, cool white fluorescent light accelerated flowering as a day extension. As a night interruption, incandescent, fluorescent or BCJ-ruby incandescent cyclic light treatments accelerated flowering of shoots from vernalized or non-vernalized bulbs.

Day extensions of cyclic fluorescent or BCJ-ruby light treatments of 6 minutes on and 24 off or 3 minutes on and 27 off did not mediate a phytochrome controlled flowering response and along with the fact that there was no photoreversibility between day extensions of incandescent, fluorescent or BCJ-ruby incandescent light, indicate a high energy reaction involvement in the flowering of the lily.

As a night interruption treatment, a phytochrome mediated flowering response was observed with 3 minutes of light on and 27 off or 6 minutes on and 24 off cyclics of fluorescent or BCJ-ruby incandescent light treatments. However, as the light period increased to 15 minutes on and 15 off or under a continuous light cycle, there were no differences in the flowering response between fluorescent or BCJ-ruby incandescent. As night interruptions there was a reversibility response by R — FR, but not by FR — R. This indicated the simultaneous operation of the phytochrome and the high energy reaction.

Open Access

Abstract

Lilium longiflorum cv. Ace and Nellie White shoots from non-vernalized bulbs were intercalated during the 30 long day night-interruption by 10 or 20 natural days. The interrupted long day effect can be summated for early flowering with the same response as that seen under a continuous long day treatment. However, increased total flower numbers were obtained.

Open Access

Abstract

Soil drenches of α-cyclopropyl-α-(p-methyxyphenyl)-5-pyrimidinemethanol (ancymidol) were applied at 3 stages of Lilium longiflorum development. Under a natural photoperiod the internodes of ‘Arai’ lily shoots from vernalized bulbs were reduced by ancymidol without delay of anthesis, but 3 applications reduced flower number and resulted in weak stems. Ancymidol treatments did not delay anthesis of ‘Nellie White’ lilies from non-vernalized bulbs whose shoots were induced to flower by 8 hour long-day photoperiod extensions. However, an apparent interaction occurred between photoperiod and ancymidol as there were increased heights of ‘Nellie White’ lily shoots when treated with ancymidol.

Open Access