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Abstract

Carbon-nitrogen relationships and pH of 2 milled hardwood bark-amended media were influenced similarly by 3 N sources, (NH₄)₂SO₄, NH₄NO₃, and Ca(NO₃)₂ incorporated at 0, 0.89 and 1.78 kg/m³ prior to composting. Nitrogen source did not affect overall growth; however dry weight and growth index of Cotoneaster dammeri Schneid cv. Royal Beauty increased with increasing N rate. Source and rate of N had little effect on the foliar analysis, and all values were within the acceptable range for woody ornamentals.

Abstract

Rewetting of gasifier residue (GR) at 0% of container capacity was greater than milled pine bark (B) or Canadian sphagnum peat moss (P). The percentage of container capacity necessary to obtain 80% rewetting of GR was substantially lower than for either P or B (5%, 23%, and 25%, respectively). Neither the rewetting of B, P, or GR at 0% of container capacity, nor the percentage of container capacity necessary to produce 80% rewetting of these media were affected by Aqua-Gro wetting agent (WA). Addition of GR in excess of 75% substantially increased the percentage of rewetting of both B and P.

Abstract

This paper describes a system for predicting container mixture physical and chemical properties from component properties. An additive model is presented that assumes that a mixture property is the weighted sum of the properties contributed by the individual components. To test this hypothesis, 24 combinations of sandy loam soil (Typic Xerothent), sand (Typic Xeropsamment), bark, and perlite were tested for bulk density, total and air-filled porosities, container capacity, available water, saturated hydraulic conductivity, pH, and cation exchange capacity. The measured experimental data were compared with values predicted from the additive model. Measured and predicted values were in good agreement for most properties, except saturated hydraulic conductivity and air-filled porosity for mixtures with low total porosity. Application of the same approach also worked well for previously published data.

Seasonal changes in cold tolerance and proteins were studied in the leaves of sibling deciduous and evergreen peach [Prunus persica (L.) Batsch]. Freezing tolerance [defined as the subzero temperature at which 50% injury occurred (LT₅₀)] was assessed using electrolyte leakage. Proteins were separated by sodium dodecyl sulfate polyacrylamide-gel electrophoresis. Electroblots were probed with anti-dehydrin and anti-19-kD peach bark storage protein (BSP) antibodies. Leaf LT₅₀ decreased successively from -5.8 °C on 18 Aug. to -10.3 °C in the evergreen genotype and from -7.0 °C to -15.0 °C in the deciduous genotype by 14 Oct. Protein profiles and immunoblots indicated the accumulation of a 60- and 30-kD protein during cold acclimation in the leaves of deciduous trees; however, levels of these proteins did not change significantly in the evergreen trees. Immunoblots indicate that the 60-kD protein is a dehydrin-like protein. Gel-electrophoresis and immunoblots also indicated that the 19-kD BSP progressively disappeared from summer through fall in leaves of deciduous peach but accumulated to a high level in bark tissues. A similar inverse relationship was not evident in evergreen peach.

Container-grown Viburnum plicatum var. tomentosum `Mariesii' were planted in tilled beds and tilled beds amended with aged pine bark. After transplanting, plants were fertilized at three different rates: no fertilizer, 18.4 g of N m^-2, and 36.8 g of N m^-2. A 31 day drought was begun 73 days after planting. Fertilization of tilled plots induced ammonium toxicity, which caused a linear reduction in leaf area, shoot dry weight, and root dry weight. Fertilization of amended plots had no effect on shoot growth but reduced mot growth by 54%; thus, amendments ameliorated ammonium toxicity. Between 10 and 28 days after beginning the drought, plants in unfertilized-amended plots maintained higher relative leaf water contents (RLWC) and relative leaf expansion rates (RLER) than plants in unfertilized-tilled plots. Amendment induced nitrogen deficiencies contributed to the increased drought tolerance of plants from unfertilized-amended plots. Since fertilized plants developed symptoms of ammonium toxicity, we were unable to determine if increasing fertility would counteract the drought tolerance conferred by pine bark soil amendments.

Deciduous fruit trees undergo endo-dormancy during fall at which time they also attain maximum cold hardiness (CH). Because these two processes occur simultaneously it is difficult to study them independently. We have been able to overcome this limitation with the use of genetically related (sibling) deciduous and evergreen peach trees. Using this system we conducted a time course study to characterize the seasonal fluctuations in CH and proteins in bark and xylem tissues. Cold hardiness (LT₅₀) was assessed using electrolyte leakage method. Polypeptides were separated using SDS-PAGE. The data indicated that 1) CH of bark increased from -5°C (in August) to -49°C (in January) and from -3°C to -22°C for deciduous and evergreen trees, respectively. In January, under favorable conditions, evergreen trees were actively growing. 2) CH of xylem successively increased from -11°C to -36°C in deciduous trees and from -7°C to -16°C (in November) in evergreen trees and then plateaued. 3) LT₅₀ of xylem in both genotypes closely approximated the mid-point of low temperature exotherms determined by differential thermal analysis. 4) As CH increased several qualitative and quantitative differences in polypeptides were noted between two genotypes. These changes during cold acclimation will be compared with those during de-acclimation.

The objective of this study was to determine the influences of 8 commercial media, 4 peat-based and 4 pine bark-based, on the effects of uniconazole applied as a media drench to `Gutbier V-14 Glory' poinsettias. The peat-based media were Baccto Grower's Mix, Baccto High Porosity Professional, Baccto High Porosity Professional with Bacctite, and Baccto Rockwool Mix. The pine bark-based media were Metro 300, 360, 500, and 700. Uniconazole was applied to plants grown in each media at 5 rates (0, 2, 4, 6, and 8 mg · 15 cm por¹).

Uniconazole effectively reduced plant height and width, bract dry weight, and bract number in all media. Plants grown in the Metro products, however, tended to be larger than those grown in the Baccto products. Bract size and number, plant weight, width and height were greatest in Metro 360. The rockwool mix produced the smallest plants. Plants grown in the peat-based media were more sensitive to uniconazole drenches. Plants grown in Metro 360 were the least sensitive to uniconazole drenches.

Abstract

‘Red Prince Delicious’/East Mailing (EM) VII trees were grown in sand culture and fertilized with a complete nutrient solution containing 0.5, 5.0 or 50.0 ppm Mn. ⁵⁴Mn was supplied to provide the same specific activity in all treatments. Autoradiographs showed “islands” of radioactivity in bark patches from all treatments 2½ months after initiation of the experiment. These “islands” disappeared after 8 months in the 0.5 ppm treatment, and after 10 months in the 5.0 ppm treatment, but continued to exist in bark patches from the 50.0 ppm treatment through the last sampling at 15½ months. Typical, and some aberrant, symptoms of IBN first appeared after 5½ months in the 50.0 ppm treatment. Pimples occurred at sites where autoradiographs indicated Mn concentrations. As the pimple stage of IBN progressed to necrotic lesions, radioactivity was concentrated around the periphery of the lesions. Data is presented which suggests that, as Mn supply is increased, alteration of mechanisms for regulating uptake and distribution of Mn occurs.

Abstract

Hardwood bark, amended with either urea (CO(NH₂)₂) or ammonium nitrate (NH₄NO₃) was composted in 210 liter drums at 10 to 40°C or heated to 55°. In the supplemental heat composted (SHC) bark amended with CO(NH₂)₂, pH increased to 6.8 to 7.4 within the first week. Bark amended with CO(NH₂)₂ generated more heat than bark amended with NH₄NO₃. Phenolic content decreased (as indicated by the Folin-Ciocalteu (F-C) method), and germination percentage of Lactuca sativa L. cv. Grand Rapids seed in water extracts of bark samples increased with time. Additions of polyvinylpyrrolidone (PVP) to extracts decreased phenolic content and increased the percentage of seed germination. Plant growth assays using Chrysanthemum × morifolium Ramat ‘Bright Golden Anne’ revealed a possible N deficiency in SHC NH₄NO₃ treated bark. Plants grown in SHC CO(NH₂)₂ amended bark did not have as severe a N deficiency. As time of composting increased, naturally composted (NC) bark treated with either N source gave plant growth comparable to that of the control plants grown in a medium of peat:perlite:vermiculite:soil (3:2:2:1 v/v).

Abstract

The phellogen of cultivated apple, sweet cherry, and peach trees was wounded at regular intervals beginning in early May and ending in late Aug. 1983. Bark tissue supporting the wounds was excised, sectioned, treated with phloroglucinol + HCl, and examined under a bright field to determine the extent of lignification. The same sections were examined under ultraviolet epi-illumination to determine the extent of suberin deposition in the boundary zone tissue formed from cells present at the time of wounding. Mean daily temperature, time post-wounding, and accumulated degree days (base = −5°, 0°, 5°, and 10°C) were used to predict the percentage of wounds lignified and suberized. A segmented quadratic equation incorporating accumulated degree days (base = 0°) was the best model for predicting lignification for the 3 species and for suberin deposition in peach and sweet cherry.