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Roy A. Larson

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Roy A. Larson

Plastic products have revolutionized commercial floriculture. Even plastic flowers have caused a new marketing consideration because they are quite competitive with the marketing of live material. Plastic pots are used widely because they are lightweight, attractive, and relatively inexpensive. Plastic flats and trays have been readily accepted by the consumer, and were instrumental in the development of plug culture. Major components of automatic watering systems are made of plastic, and much of the plumbing practiced in commercial floriculture is done with plastic pipe and fittings. Plastic foams are used in floral arrangements, growing media, and propagation cubes or strips. Plastic is used to make steam-sterilization covers, shading material for the manipulation of both light intensity and photoperiod, and mulches or ground covers to help control weeds. Very large quantities of plastic are used in commercial floriculture, and recent landfill restrictions have necessitated procedures for recycling. Recycling procedures are known, but logistics and economics of recycling have not been resolved completely.

Open access

Roy A. Larson

Abstract

Once upon a time, in a far-off land, a member of the genus Gallus was walking through a forest populated with trees of the genus Quercus. Suddenly, something fell and struck this creature on the head. The creature was quite cowardly—you might even call it “chicken”—and it began to run and cry, “The sky is falling, the sky is falling, and I must tell the king”. On the way to the palace, she encountered other feathered members, whose names are really inappropriate to use in a sophisticated presidential address—names such as Henny Penny, Cocky Locky, Goosey Loosey, and Turkey Lurkey—and she told them the news and they joined her in her rush to see the king. They then met a rather devious character, who said he would show them a short-cut to the palace, but he really intended to have a sumptuous dinner of low-cholesterol, low-protein poultry products. Chicken Little forever remained a pessimist and never again went into the oak forest without an umbrella.

Open access

Vincent P. Bonaminio and Roy A. Larson

Abstract

Influence of temperature, media and concentration of ancymidol (α-cyclopropyl-α-[p-methoxyphenyl]-5-pyrimidine-methanol) on the growth and flowering of selected cultivars of Chrysanthemum morifolium were studied. As day/night temperature increased or decreased from 22/18°C length of time required for the plants to come into flower increased. Stem elongation and leaf area decreased while fresh weight increased as temperatures decreased from 30/26° to 18/14°. Ancymidol applied at a concentration of 0.25 mg/pot of aqueous drench was sufficient to control height of plants grown in most media except pine bark humus. Incorporation of river sand, greenhouse soil or Ca(OH)2 into pine bark humus increased ancymidol's effectiveness. Increasing growth regulator concentration also resulted in adequate height control for plants grown in pine bark humus.

Open access

Roy A. Larson and R. Kent Kimmins

Abstract

α-Cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol) applied to inherently tall-growing chrysanthemum cultivars controlled ht at concn of 62 mg/liter (0.06 mg/15 cm pot) when applied as a foliar spray, and 0.12 mg/15 cm pot when applied as a soil drench. An thesis was delayed in plants treated with high concn of the growth retardant but flower size and no., and node no. were unaffected.

Open access

John N. Zacharioudakis and Roy A. Larson

Abstract

2,3-Dihydro-5-6-diphenyl-l,4-oxanthin (UNI-P293), was used to determine its effectiveness as a disbudding agent of Chrysanthemum morifolium cv. May Shoesmith. Concentrations of 0.5, 0.75 and 1.0% were applied on the 18th, 21st and 24th short day (SD). The optimum concentration on the 18th SD was 0.5% and 1.00% on the 21st SD. There was no difference among concentration levels on the 24th SD. Flower size and date of anthesis were not adversely affected when manual disbudding was used as a supplement to chemical treatment, but smaller flowers and delayed anthesis usually occurred when only the chemical was used for disbudding. All treated plants were shorter than untreated plants.

Open access

Amy L. Dosser and Roy A. Larson

Abstract

‘Paul Richter’ tulips were forced in controlled environment chambers at 26/22, 22/18, and 18/14°C day/night temperatures using high and reduced light intensity and short and long daylengths. Photoperiod had no influence on growth or flowering. Reduced light intensity with the coolest temperature treatment significantly increased the forcing period. Increased forcing temperatures had the greatest impact on plant growth, resulting in reduced Plant flower length, and forcing period. In a second experiment, ‘Paul Richter’ was forced in controlled environment chambers under 8 combinations of day/night temperatures from 18 to 26° day and from 14 to 22° night. The warmer day or night temperatures decreased the forcing period. Plant height was increased with increasing day temperatures, but decreased with increasing night temperature. Flower length decreased with increasing day or night temperatures. First internode length was increased with increasing day temperature but decreased with increasing night temperature, with the exception of a slight increase at a day temperature of 18°. Last internode length was increased only slightly with increasing night temperature. Flower longevity and total length were decreased slightly by increased forcing temperatures.

Open access

T. Davis Sydnor and Roy A. Larson

Abstract

Three gibberellins; GA3, GA4, GA7; and abscisic acid (ABA) from the shoot tips of greenhouse grown ‘Gloria’ azaleas, Rhododendron sp.L., were tentatively identified using column chromatography, gas-liquid chromatography, and Rumex leaf senesence bioassay. Growth regulators were quantitatively estimated biweekly from 6 weeks after shoot tip removal until anthesis.

GA3 levels remained nominal for the normal commercial treatment until after plants were returned to 19°C from the 9° cooler. Endogenous GA3 levels then peaked at 0.6 μg/bud at anthesis. GA4 levels remained fairly constant for all treatments and times at 0.1 μg/bud. GA7 levels remained fairly constant below 2 μg/bud except in the cold-treated plants when endogenous GA7 levels peaked at 0.6 μg/bud at the time that plants were removed from the cooler.

ABA levels were similar until 24 wks. from pinch when the levels dropped to undetectable levels in cold-treated plants and increased in treatments not given a cold treatment by peaking at 0.1 μg/bud at 28 wks. from pinch.

Of the commercially available gibberellins that were monitored, GA7 seemed to be the best treatment for chemically overcoming flower bud dormancy in azalea.

Open access

Vincent P. Bonaminio and Roy A. Larson

Abstract

Plants of ‘May Shoesmith’ chrysanthemum (Chrysanthemum morifolium Ramat.) were grown in controlled environment chambers at optimal (16°C) and sup-optimal night temperatures. Reduced night temperatures were imposed for all or part of the night cycle. Number of days to flowering was delayed as night temperature decreased from 16° or as duration of reduced temperature during each diurnal cycle was increased. Compared to plants grown at a continuous 16° night temperature, plants grown at 10° for 9 or 10½ hours each night (with the remaining hours at 16°) had greater stem diameter, were taller and had flowers with greater diameter and fresh weight. Number of nodes was not affected.