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Open access

T. E. Bilderback, W. C. Fonteno, and D. R. Johnson

Abstract

Equal volumes of peanut hulls, pine bark, and sphagnum peatmoss were combined into 5 media. Particle size distribution, total porosity, air space, easily available water, water buffering capacity, and bulk density were determined for each medium. Top dry weight, root dry weight, and percent growth of Rhododendron indicum (L.) Sweet cv. George L. Taber were measured 14 weeks after potting in 1-liter containers. Peanut hulls increased particle size, total porosity, and air space, and decreased easily available water, water buffering capacity, and bulk density of media. Peatmoss generally reduced total porosity and air space and increased easily available water, water buffering capacity, and bulk density regardless of other component combinations. Top dry weight, root dry weight, and percent growth were greater in peanut hull-containing media. Addition of peatmoss to the container media tended to produce less growth.

Free access

Jesse R Quarrels and Steven E. Newman

A study was conducted to determine the effects of pine bark grind size and pine bark levels on the activity of two growth regulators on poinsettia Two bark grinds (≤ 6 mm and >10 mm) were used with four media combinations within each grind: vermiculite:bark:peat moss at 2:0:3, 2:1:2, 2:2:1, and 2:3:0 (by volume). Two growth regulators, paclobutrazol and uniconazole, were applied at 0, 0.125, and 0.250 mg/15 cm container in 250 ml water. Two poinsettia cultivars, `Freedom' and `Gutbier V-14 Glory', were planted September 2, 1993, pinched September 16, and growth regulators applied September 30. There were five single plant replications for each treatment. Stem length and bract area were effected by bark grind, bark level, growth regulator, and growth regulator rate. Plants treated with uniconazole had the shortest stems and the least bract area. Plants grown in the smaller grind and at higher bark levels were less effected. Plants treated with paclobutrazol had longer stems than those treated with uniconazole.

Open access

F. A. Pokorny and B. K. Henny

Abstract

Volume of loose media was determined accurately by a devised mechanical method and used for bulk density (BD) calculations. BD associated with increasing percentages of pine bark and/or sand potting media were plotted. Linear increase in BD associated with increasing percentage of sand in the medium was used to predict the percentage by volume of sand and/or bark in an unknown mixture of the two components. The technique should be useful in synthesis studies utilizing pine bark and sand as medium components.

Free access

Susan H. Butler and Bradford Bearce

Rosa × hybrida 'Samantha' plants were planted in pots of three soilless and two soil-containing media. Soilless media consisted of coal bottom ash and composted hardwood bark in 1:1, 2:1, and 3:1 ratios. Soil-containing media were equal parts soil, peat, and coal bottom ash; and a control of equal parts soil, peat, and sand. Half the pots of each media were treated with a cover crop of Hordeum vulgare L. 'Barsoy' to simulate weathering and incorporate additional organic matter prior to planting the roses. Physical and chemical properties of all five original media were examined, and production indices of two harvests were measured; including stem length, flower bud diameter, fresh weight, days to harvest and average number of blooms per plant. Results to date indicate satisfactory growth in all treatments. The three soilless treatments have produced more stems with larger flower bud diameters and shorter days-to-harvest than the soil-containing treatments. However, the fertilization, and electrical conductivity of all treatments remains below normal. Moisture retention data also show the soil-containing treatments to have higher container capacity and easily available water. Cover-cropped plants also had shorter days-to-harvest, but in one of two harvests produced flower buds of smaller diameter.

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James S. Owen Jr., Stuart L. Warren, Ted E. Bilderback, and Joseph P. Albano

The physical and chemical properties of pine bark yield low water and nutrient efficiency; consequently, an engineered substrate altering the substrate properties may allow greater water and nutrient retention. Past research has focused on controlling the quantity and rate of water and nutrient inputs. In this study, pine bark was amended at 8% (by volume) with a Georgiana palygorksite-bentonite blended industrial mineral aggregate with a particle size of 850 μm-4.75 mm or 300 μm-710 μm to improve water and nutrient efficiency. Each particle size was pretreated at temperatures of ≈140 °C (pasteurized) or ≈390 °C (calcined). The study was a 2 (particle size) × 2 (heat pretreatment) factorial in a randomized complete-block design with four replications. The control was a pine bark substrate amended with 11% sand (by volume). Containers (14 L) were topdressed with 17–5–12 controlled release fertilizer. A 0.2 leaching fraction was maintained by biweekly monitoring container influent from spray stakes and effluent volume measured daily. An aliquot of the daily collected effluent was analyzed for phosphorus (P). After 112 days, tops and roots were harvested, dried, and weighed for dry weight comparisons. Compared to pine bark amended with sand the 300 μm-710 μm particle size mineral decreased mean daily water application by ≈0.4 L/day per container. The calcined mineral reduced P leaching by ≈10 mg of P per container or 60% over the course of the study compared to pine bark: sand. Top and root dry weights were unaffected. These results suggest 300 μm–710 μm calcined mineral provided the most significant decreases in water use and P leaching while growing an equivalent plant.

Free access

John D. Lea-Cox and I.E. Smith

Pine bark and peat-based substrates have been shown to have low-phosphorus (P) fixation capacity and high leach-potential, similar to that occurring in high-organic soils lacking in inorganic colloids. A long-term greenhouse experiment was conducted where three rootstock species of varying growth rate, Citrus jambhiri Lush.(RL), Citrus reshni Hort. ex Tan. (CM), and Poncirus trifoliata L. × Citrus sinensis L. (Osbeck) (CC), were grown in 3-L containers in composted pine bark, amended with three forms of P. Two slowly soluble forms (Calmafos and MagAmp) and soluble single superphosphate were incorporated at 0 (control), 200, 400, and 800 g P/m3, in a completely randomized block design (n = six plants). A split fertigation treatment of P at 50 mg·L–1 vs. No P was superimposed on the design (n = 3). Despite significant (P > 0.01) differences in P availability in the substrate after 380 days, particularly between liquid P (μ = 65 mg·L–1) vs. no liquid P (μ = 15 mg·L–1), differences in leaf analysis of seedlings after 235 days showed little significance (2.2 vs. 2.7 mg·g–1). To avoid excessive leaching of P from pine bark substrates, it therefore appears that slow-release forms of P are adequate to maintain relatively high growth rates of citrus stock without supplemental P fertigation.

Free access

Santakumari Mane and James A. Turner

Eight different peat-based or peat: bark-based potting media were evaluated for their wetting performance when treated with the media wetting agent AquaGro 2000 (2–5 oz/yd3). Upon initial irrigation, no differences in wetting uniformity were observed in seven of the eight test media regardless of their media wetting agent treatments. In four media, water retention was reduced by media wetting agent treatment, however, uniform distribution of water was achieved. AquaGro 2000 improved uniformity of initial wetting in one medium in which the initial moisture content was 6.5%. Uniformity of wetting and water retention improved with increasing wetting agent rate. All media were allowed to air dry and then were re-irrigated. Wetting agent-treated media rewet uniformly, while rewetting varied greatly in untreated media (7.5%–82.5%). Less than 50% of the mass of untreated media wet subsequent to drying. Those portions of the untreated media that did wet retained up to three times more water per unit volume compared to AquaGro 2000-treated media. AquaGro 2000 enhanced uniformity of rewetting, reduced water logging, and improved drainage at all rates (2–5 oz/yd3) tested. Media composition (peat vs. peat: bark did not affect wetting agent efficacy.

Open access

Dale M. Maronek, James W. Hendrix, and Jennifer Kiernan

Abstract

Plants of southern magnolia (Magnolia grandiflora L.) and ‘Bar Harbor’ juniper (Juniperus horizontalis Moench) were grown in a composted hardwood bark: expanded shale medium in 7.6 cm square containers in a greenhouse. All plants received either a low rate (1.1 kg/m3) or the manufacturer's recommended rate (4.5 kg/m3) of 18N-6P-12K slow-release fertilizer, and half the plants received inoculum of Glomus fasciculatus. After 6 months, height of magnolia plants inoculated with G. fasciculatus was nearly twice that of uninoculated plants, and the height difference between the two groups of plants increased with time. In contrast, plants of ‘Bar Harbor’ juniper demonstrated little or no growth response to infection with the mycorrhizal fungus. Fertilization of magnolia plants at the recommended rate as compared with ¼ that rate did not inhibit the degree of mycorrhizal infection of roots. Roots of inoculated ‘Bar Harbor’ juniper plants were heavily infected at both fertilizer rates, but the degree of infection was significantly greater at the lower fertilizer rate.

Free access

Larry J. Shoemake and Michael A. Arnold

Zea mays L. and Taxodium distichum L. seedlings were grown for 35 days in sand or 3:1 milled pine bark:sand media in 0.7 liter containers. Containers were painted on interior surfaces with 100 g Cu(OH)2/liter or 200 g Cu(OH)2/liter latex carrier (Spin Out™) or not. Five seedlings of each treatment combination were watered daily from 9.5 liter reservoirs with 100 ml of recycled fertilizer (20N-8.7P -16.6K. pH 6.0) solution initially containing 0.036 mg Cu/liter. Fertilizer solutions containing 0.036, 5, 10, 100, or 1000 mg Cu/liter were used to develop toxicity response curves with additional seedlings. Growth of both species in both media was increased by Spin Out treatments. Soluble Cu content of the recycled solution from Spin Out treated containers increased slightly (<1.2 mg/liter) during the experiment. Soluble Cu in leachate from Cu-treated containers ranged from 0.2 to 5 mg/liter with sand and from 0.30 to 1.2 mg/liter with bark. Soluble Cu in leachatc from non-treated containers ranged from 0.02 to 0.40 mg/liter with sand and 0.10 to 0.86 mg/liter for bark media.

Free access

M.J. Havey and O.H. Bark

Open-pollinated (OP) onion (Allium cepa L.) cultivars are primarily in normal (N) fertile cytoplasm; however, specific cultivars possess both N and sterile (S) cytoplasm or are exclusively in S cytoplasm. It is unclear whether the presence of S cytoplasm in OP cultivars is due to ancient or recent introduction or both. Restriction-enzyme analysis of the chloroplast DNA established that S cytoplasm has been introgressed into OP onion cultivars since its discovery in 1925. `Valencia Grano' (released in 1927), `New Mexico Early Grano' (1931), `Texas Early Grano (TEG) 502' (1947), and `Temprana' (1979) are in N cytoplasm; S cytoplasm was introduced into the population `TEG 502 PRR', and subsequent selections (`NuMex BR1' and `NuMex Sunlite') are in S cytoplasm. The inbred `TEG 951 C' and `Texas Grano 1015Y' possess a mixture of N and S cytoplasm and, because these two onions originated from self-pollinations of single plants, bulb or seed mixtures or both must have occurred.