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- Author or Editor: H. B. Tukey Jr. x
Abstract
Urban Horticulture is a new area of scientific horticulture concerned with functional uses of plants to maintain and improve urban environments. “Functional uses” means that plants are used not only for beauty and ornamentation, but also as screens against wind, headlights, and unpleasant views, to influence climate, perhaps to reduce noise and combat forms of air pollution, for essential food and variation in human diet, and to improve the human psyche in densely populated areas. The constituent audiences for urban horticulture are people who utilize plants, primarily in landscape situations, including landscape maintenance and parks personnel, landscape architects, arborists, highway planters, nursery contractors, members of plant societies, and amateur horticulturists.
Abstract
The founding and early administration of the American Society for Horticultural Science was led by those concerned primarily with pomology and to a lesser extent vegetable crops, and these two areas of horticulture dominated Society meetings for half a century. Reports of research with ornamental crops, including both floriculture and nursery plants, did not appear on programs or in the Proceedings for many years, despite the interest of L. H. Bailey, first president of the Society. Bailey mentioned the virtues of floriculture and landscape gardening in his first presidential address (1) and later the “growing taste for ornamental planting” in America (2). Speakers at early meetings summarized research on nursery crops in Europe (16), the benefits of plant exploration in China, and the need for a coordinated effort in establishing a system of plant introduction (2), but it was not until 1913 that Blake's report (3) on roses appeared, the first paper about a floricultural crop. Woody plants were first discussed in 1925-26 (11, 17, 25); but it was not until 1930, 27 years after the founding of the Society, that papers related to nursery plants appeared with any frequency. Thus, the early history in ASHS of growth and development of woody landscape plants is sparse, although at the same time bulletins were being published at several experiment stations and scientists in Europe were publishing regularly.
Abstract
We often use the noun “ornamentals” to describe plants used in landscapes, around homes and other buildings, in parks and public gardens, and along streets and highways. However, “ornamentals” can be perceived quite differently by others outside our profession and with serious consequences.
Abstract
Abscisic acid (ABA) content of Euonymus alatus leaves increased in response to increasing moisture stress. In excised leaves, ABA content rose rapidly following loss of 7-10% of the initial fresh weight In intact plants, the ABA increase was triggered at a xylem pressure potential of −10 to −12 bars. Non-misted Euonymus plants contained significantly greater amounts of ABA than misted plants; however, xylem pressure potentials of the misted and non-misted plants did not differ. Thus, leaching of ABA, rather than reduced moisture stress, is apparently the cause of decreased ABA content of misted Euonymus, as previously proposed.
Abstract
Onset of rest, anthocyanin development, and leaf senescence and abscission were delayed in Euonymus alatus Sieb. ‘Compactus’ grown under intermittent mist. Leaf and bud tissues of misted plants contained less extractable abscisic acid (ABA) than did leaves and buds of non-misted plants. Mist leached endogenous and applied ABA from Euonymus leaves. Application of synthetic racemic ABA to growing Euonymus plants hastened onset of rest and increased anthocyanin development. This suggests that the observed responses of Euonymus to intermittent mist may be due to leaching of endogenous ABA.
Abstract
Rhododendron cuttings absorbed Ν and P from intermittent nutrient mist during propagation; there was no net uptake of K, Mg, or Ca. However, the foliage was injured and rooting was inhibited at all concentrations of nutrient mist. Cultivars differed in sensitivity to nutrient mist. ‘Gloria’ cuttings did not root under distilled water mist and developed symptoms resembling Κ deficiency. Azaleas have low nutritional requirements and nutrient mist during propagation was of no benefit.
Abstract
Leaves of Betula alleghaniensis Britt. (yellow birch) and Phaseolus vulgaris L cv. Red Kidney (bean) were examined microscopically during development and after exposure to simulated rain of pH 5.5, 4.3, 3.2, and 2.8. Yellow birch leaves attained maximal leaf area, midvein length, and cuticle thickness at 21 days. Trichomes were either long, unicellular, or multicellular with caplike head and stalk. Epicuticular wax was a bumpy and amorphous layer. The 2nd trifoliolate leaf of red kidney bean attained maximal leaf area, midvein length, and cuticle thickness when the 3rd trifoliolate leaf was expanding. Trichomes present were long, with a unicellular head and a multicellular base; long, unicellular, and terminally hooked; and small and multicellular. Epicuticular wax was present as small irregular flakes. After 2 days of pH 2.8 and 4 days of pH 3.2 simulated acid rain, round yellow and small tan lesions appeared on birch and bean leaves, respectively. Most injury occurred on or between small veins. Most trichome types were uninjured. Lesions formed as a result of collapsed epidermal and highly plasmolyzed palisade cells. The cuticle was still present over injured epidermal cells and epicuticular waxes were unchanged. There was no statistical difference in mean cuticle thickness due to pH of simulated rain.
Abstract
Rooted cuttings of Pilea cadierei Gagnep. & Guillaum., Chrysanthemum morifolium Ramat. cv. Giant #4 Indianapolis White, Hedera helix L. cv. Thorndale, Pachysandra terminalis Siebold & Zucc. and young plants of Juniperus chinensis L. cv. Mint Julep and Ligustrum X vicaryi were exposed for 3 weeks to either water mist or mist to which a complete all soluble fertilizer (23N-8P-14K) was added; roots and root medium were protected from the mist. The N, P and usually K content of all plants increased after foliar application of nutrients. Pilea, pachysandra and Hedera increased in height, dry weight, and number of lateral breaks; privet increased in height and overall greening of the foliage occurred. The optimum concentration of foliar-applied nutrients was 600 ppm for Pilea, 750 ppm for Hedera and pachysandra and 300 ppm for Ligustrum; higher concentrations caused foliage injury. Injury occurred to chrysanthemum and juniper at all concentrations studied. Cuticle thickness and plant tolerance to foliar nutrition were not correlated.
Abstract
Solution pH differentially affected the foliar absorption of phosphorus compounds by Chrysanthemum morifolium Ramat cv. Giant #4 Indianapolis White. All phosphates were absorbed readily at pH 2, which was accompanied by necrosis of the treated area of the leaf. Maximum absorption occurred with Na phosphate at pH 3-6, K phosphate at pH 7-10, and NH4 phosphate at all pH values (3-10), whereas Ca phosphate was not readily absorbed. The results could be explained by pH dictating the phosphate form present in solution; solubility, moisture retention, and crystallization on the leaf surface of the predominant phosphate salt were the factors determining the degree of absorption.
Abstract
Foliar absorption of RbCl, RbNO3 and Rb2SO4 by Chrysanthemum morifolium Ramat. cv. Giant No. 4 Indianapolis White was greatest at pH 2, at which there was considerable leaf damage, but changed little at pH 3-10. Absorption of RbCl was greater than RbNO3 or Rb2SO4 regardless of pH. Absorption of Rb and phosphate as Rb phosphate was minimal at pH 3-6, but was greatly increased at pH 7-10. These results may be explained by the degree of drying and crystallization of the applied compounds on the leaf surface.