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  • Author or Editor: L. H. Fuchigami x
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Abstract

The effectiveness of (2 chloroethyl)phosphonic acid (ethephon) in inducing defoliation and in delaying spring bud growth of red-osier dogwood was related to the time of application. Plants treated with ethephon before they matured were not effectively defoliated. Mature plants were effectively defoliated and ethephon’s effectiveness increased progressively at subsequent treatment dates. Ethephon treatments applied on September 29, October 6 and 13, delayed spring bud break by 7, 5, and 3 days respectively. Hand defoliation on the same dates induced identical delays in spring growth.

Open Access

Abstract

The title and byline of the paper, The Relationship between Vegetative Maturity and the First Stage of Cold Acclimation by P. C. Nissila and L. H. Fuchigami (J. Amer. Soc. Hort. Sci. 103(6):710-711. 1978), was inadvertently omitted from the table of contents.

Open Access

Abstract

Rooted cuttings of a clonal selection of Salix purpurea L. were grown in perlite, in a warm greenhouse at natural daylengths and irrigated daily with one of 10 different mineral nutrient solutions. Plants from each of the nutrient treatments were hand defoliated at weekly intervals beginning in August to assess the effects of mineral nutrients on vegetative maturity development. Vegetative maturity was quantified the following spring by measuring stem dieback. Plants in some nutrient treatments ceased growing 9 weeks earlier in the autumn, and became vegetatively mature several weeks sooner than plants in other treatments. Specifically, treatments such as the distilled water control and Hoagland solution -N,-P, and -S induced early growth cessation, resulted in less stem growth, and induced early onset of vegetative maturity as evidenced by reduced stem dieback the following spring. Development of vegetative maturity was slower in plants irrigated with complete Hoagland solution or Hoagland solution -Ca, -Mg, and -K, which continued growing until October when natural defoliation and growth cessation occurred on control plants treated with complete Hoagland solution. The study demonstrates that vegetative maturity in S. purpurea can be hastened by witholding N, P, and S.

Open Access

Abstract

Ethylene and ethane production of freeze-stressed rhododendron (Rhododendron sp. ‘Sappho’) leaf disks were compared to visual rating, TTC reduction, and electrolyte leakage as possible means of measuring tissue viability. Ethane production, as caused by freezing temperatures, was highly correlated with visual rating, TTC reduction, and electrical conductivity (r = 0.96, r = −0.81, and r = 0.96, respectively). Ethylene production peaked concurrently with initial stages of visual tissue damage, then decreased as the temperature was lowered until complete death occured. Ethane production and electrolyte leakage peaked coincidentally with the decrease of ethylene. Ethylene:ethane ratios are suggested as a measurement of freeze-induced tissue damage. This study supports the view that ethylene production is related to stress and ethane production to cell death. Chemical names used: 2,3,5-triphenyltetrazolium chloride (TTC).

Open Access

Abstract

Electrical impedance ratios and water contents were measured during the development of vegetative maturity and dormancy in a clone of red-osier dogwood Cornus sericea L.) on plants exposed to 16 hour and 12 hour photoperiods in growth chambers to selectively prevent or induce dormancy. Vegetative maturity was designated as the point at which buds were no longer stimulated to grow following artificial defoliation. After this time the ratio of impedance values obtained from the frequencies 10 kHz:100kHz increased and tissue water decreased. Electrical impedance ratios were more easily measured and showed less variation between plants. We conclude that electrical impedance ratios are a means of identifying the onset of vegetative maturity and dormancy in woody deciduous species.

Open Access

Abstract

Ethylene evolution from excised plant parts was tested as an indicator of stage of seasonal development in red-osier dogwood (Cornus sericea L., syn. C. stolonifera Michx.). A reduction in ethylene production occurs several weeks prior to the time when defoliation can be safely accomplished. This reduction occurs synchronously over the length of the plant, although ethylene production by basipetal tissues prior to the decrease was lower than that by more acropetal tissues. The pattern of change in ethylene production by nodal tissue, which included the axillary buds and about 5 mm of petiole, seemed to be least affected by environmental growing conditions. Ethylene could be used as a predictor for vegetative maturity stage in red-osier dogwood.

Open Access

Abstract

Plants of red-osier dogwood (Cornus sericea L.) treated with 2,4-dichlorophenoxy-acetic acid (2,4-D) or l,1’-dimethyl-4,4’-bipyridium ion (paraquat) after reaching vegetative maturity were much less affected by the herbicides than plants treated earlier. Data support the hypothesis that vegetative maturity is a distinct physiological stage in the development of woody plants, and that inconsistencies in herbicide efficacy can, in part, be explained by this phenomenon.

Open Access

Previously, we reported that plant recovery from “near-lethal” (NL) (sublethal) stresses depended on stage of development and poststress environment (PSE). Dormant red-osier dogwood (Cornus sericea) plants exposed to NL heat, freezing, and hydrogen cyanamide either died or were severely injured when stored at 0C or recovered at 23C and nautral condition. Exposure of dormant stem tissues of red oak (Quercus rubra), paper birch (Betula papyrifera) and European mountain ash (Sorbus aucuparia), to heat stress also resulted in higher ion leakage when they were stored at 0C PSE for 3 weeks. Soaking NL-heat-stressed (49C for 1 hour) stem tissue of red-osier dogwood in double distilled water for 48 hours before incubating at 0C PSE for 2 and 12 weeks resulted in lower ion leakage and 80% tissue survival. NL-stressed tissue had higher sodium and similar potassium leakage at 0C PSE. At 23C, PSE NL stress had no effect on leakage of these specific ion.

Free access

The purpose of this presentation is to discuss the value of identifying growth stages of bud dormancy numerically. The Degree Growth Stage Model (°GS Model) will be used to quantify the annual growth stages and the various developmental stages of endo-, eco-, and paradormancy. The model is divided into 360°GS's, illustrated either as a sine curve or a circle, that serve as a timeline for the cyclical passage of temperate woody plants, through five distinct point events (growth stages). The sine curve illustrates the relative degree of development of the segment events between the point events. This paper will focus on the °GS model as a relative method of quantifying the various segment events and improving our communication of the annual physiological processes of temperate woody plants. In addition, recent evidence on altering dormancy, and its impact on dormancy models, will be presented.

Free access

“Near-lethal” (NL) stresses from varied sources, e. g. NL-heat (47°C-lhr), NL-freeze (-7°C -lhr), and NL-hydrogen cyanamide (0.5-1 M), overcame endo-dormancy in red-osier dogwood (Cornus sericea L.) plants. Near-lethal heat stress applied at early rest (Oct.) had a slight effect on cold acclimation, whereas at late rest (Dec.), NL-stress resulted in the rapid loss of hardiness at warm or natural environment conditions. Recovery of plants from NL-stresses was dependent on the stage of development and temperature. Less dieback occurred with later stage of endo-dormancy, and at warmer temperatures. Dormant plants in October exposed to other NL-stresses, e. g., freezing temperature and hydrogen cyanamide, also caused plant dieback at 0°C and recovered at 23°C post-environment treatment. Conditions that favored recovery also favored production of glutathione.

Free access