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  • Author or Editor: L.E. Hinesley x
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Harvested eastern redcedar (Juniperus virginiana L.) Christmas trees coated with combinations of latex-based green colorant and needle sticker were observed for 2 weeks at 20C. Green colorant reduced drying rates and helped maintain a better water status following dehydration. Even though these materials improve postharvest water relations, their primary value with respect to marketing and use of eastern redcedar Christmas trees is to impart a better color and/or mask the prickliness of juvenile foliage.

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Branches of Fraser fir [Abies fraseri (Pursh) Poir.] and eastern white pine (Pinus strobus L.) were subjected to various temperatures, vapor pressure deficits (VPD), and light regimes in controlled-environment chambers. Drying rates, based on measurements of needle water potential (ψ), were accelerated by increasing VPD, high temperature, and light. Fraser fir and white pine dried to – 4.0 MPa and – 3.0 MPa, respectively, in about the same time. The relationship of moisture content (MC) to ψ was linear for Fraser fir, quadratic for white pine. The MC of Fraser fir at – 4.0 MPa was also a linear function of VPD during drying. Water loss was greatest early in the drying cycle, and high temperature (25C) promoted rapid drying, even at low VPD.

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Several floral and tree preservatives were evaluated to determine their effect on postharvest needle retention of Fraser fir [Abies fraseri (Pursh) Poir.], an important Christmas tree species. Clorox (sodium hypochlorite) and aspirin (salicylic acid) caused massive needle loss, and three of the six commercial additives increased needle loss significantly, No treatment was better than water alone.

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Cut branches of Fraser fir [Abies fraseri (Pursh) Poir.] were subjected to solutions with different molarity, pH, and solutes. Citrate-phosphate and Na-phosphate buffers induced heavy needle loss at concentrations as low as 10 mm, whereas needle loss was negligible for MES buffer, sucrose solutions, and distilled water. Needle drop increased in response to higher solute concentration and/or greater duration of exposure. Needle loss was almost 100% at pH 3.0 and 9.0, but minimal at pH 6.0 and 7.0. Chemical name used: 2-(N-morpholino) ethanesulfonic acid (MES).

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Red- and purple-leafed seedlings and clonal material selected for superior color and growth under northern climatic conditions may exhibit progressive color loss and reduced growth rates when exposed to the hot summers and high night temperatures of more southern climates. Studies were conducted to characterize the color loss associated with red-leafed seedlings of Acer palmatum Thunb. (Japanese maple), and to determine to what extent night temperatures affect the dark respiration, growth, and anthocyanin expression of A. palmatum `Bloodgood'. The percentage of seedlings within each of five color classes was determined for five dates from spring to early fall. Significant shifts in class distribution occurred on every evaluation date tested. The class changes contributing the most to these shifts varied with age of leaf material and date. Dark respiration rates increased by 0.09 mg CO2/g leaf dry weight per hour for every 1C rise in temperature, regardless of exposure duration. Dark respiration rates of 0.69 and 1.73 mg CO2/g per hour were found at 14 and 26C, respectively. The greatest amount of growth occurred during weeks 6 through 8 at a night temperature of 14C. Plant growth during this period increased by an average 51%, compared to that at warmer night temperatures. Ultimately, total plant growth at 14C decreased 7%, 19%, and 32% as night temperatures increased from 18 to 22 to 26C. Leaf redness index values at 14 or 18C were from two to seven times greater than those at warmer night temperatures.

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Current-year shoots of Fraser fir [Abies fraseri (Pursh) Poir.] were sampled in Christmas tree plantations in western North Carolina. Needles were sampled at five positions on each shoot: 0% (proximal end), 25%, 50%, 75%, and 100% (distal end). At each position, needles were collected in a tight left-hand spiral beginning on the abaxial side (bottom) and ending on the adaxial side (top). Length, width, thickness, dry weight, and projected surface area were determined for each needle. Specific area (one-sided) averaged 45 cm2·g-1 and increased from the shoot base to the tip. On individual shoots, needle dimensions were maximal at the middle (50% position). Within sample positions, needle dimensions increased from the adaxial to the abaxial side. Needle length, weight, and area differed more than width or thickness by position. Needle surface area per centimeter of shoot was relatively stable. Regression models using shoot length, diameter, needle density, and average needle length or weight yielded good estimates of total foliage area and weight.

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Abstract

Stem cuttings of Fraser fir [Abies fraseri (Pursh) Poir.] were used in 3 studies to examine rooting and visible terminal bud activity as influenced by cutting length (10 to 26 cm), type of cutting (laterals vs. terminals) and genotype. Pronounced genotypic variation was observed for percentage of rooting as well as number and length of roots. Trees which rooted in high percentages produced the greatest number and length of roots. Cutting length did not affect percentage of rooting. Long cuttings exhibited less visible bud activity and produced the greatest number of roots. Lateral cuttings exhibited a higher percentage of rooting than terminals, particularly without treatment with indolebutyric acid (IBA), and also displayed greater visible terminal bud activity.

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Cones of two provenances (Wayne Co., N.C., And Escambia Co., Ala.) of Atlantic white cedar [Chamaecyparis thyoides (L.) B. S. P.], were collected Fall 1994. Cones were dried for 2 months, followed by seed extraction and storage at 4°C for 6 months. Seeds were graded and stratified (moist-prechilled) for 0, 30, 60, or 90 days. Following stratification, seeds were placed at 25°C or 8/16 hour thermoperiods of 25°/15°C or 30°/20°C with daily photoperiods at each temperature of 0, 1/2, 1, 2, 4, 8, 12, or 24 h. At the conclusion of a 30-day germination period, the Alabama provenance exhibited greater germination than the North Carolina provenance for all treatments (74% vs. 46%). There were no significant differences between 25°/15°C and 30°/20°C with regard to total percent germination for both provenances. Germination was lowest at 25°C for each provenance. In some cases, however, there were no significant differences in germination of the North Carolina provenance when stratified for 60 or 90 days and germinated at 30/20°C or 25°C (61% vs. 63%). There was a highly significant quadratic response to stratification for cumulative percent germination for both provenances. The North Carolina provenance required 90 days stratification to maximize germination (66%) in contrast to the Alabama provenance, which only needed 30 days (80%). Seeds of both provenances did not exhibit an obligate light requirement. However, photoperiods ≥1/2 h increased germination greatly over seeds in darkness (29% vs. 62%).

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Foliar raffinose and sucrose concentrations in eastern white pine (Pinus strobus L.), eastern redcedar (Juniperus virginiana L.), Leyland cypress (×Cupressocyparis leylandii Dallim.), and Virginia pine (Pinus virginiana L.) were measured monthly over 2 years. During cold weather, foliage of white pine and redcedar contained higher concentrations of raffinose and sucrose than did Leyland cypress and Virginia pine. Rafflnose concentrations were highest during winter and were best correlated with the frequency of occurrence of daily minima ≤ 1.7C during the 30 days before sampling. Sucrose concentrations, which also reached maximum levels during the winter, were best correlated with the frequency of occurrence of daily minima ≤ 7.2C in the prior 30 days. Sucrose concentrations were relatively high during fall and spring. Raffinose and sucrose concentrations increased in response to recurring low temperature, with correlations highest for raffinose.

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