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  • Author or Editor: Michael Evans x
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Aggregates produced from finely ground waste glass [Growstones (GS); Earthstone Corp., Santa Fe, NM] have been proposed to adjust the physical properties of peat-based substrates. The GS had a total pore space (TPS) of 87.4% (by volume), which was higher than that of sphagnum peat and perlite but was similar to that of parboiled fresh rice hulls (PBH). The GS had an air-filled pore space (AFP) of 53.1%, which was higher than that of sphagnum peat and perlite but lower than that of PBH. At 34.3%, GS had a lower water-holding capacity (WHC) than sphagnum peat but a higher WHC than either perlite or PBH. The bulk density of GS was 0.19 g·cm−3 and was not different from that of the perlite but was higher than that of sphagnum peat and PBH. The addition of at least 15% GS to sphagnum peat increased the AFP of the resulting peat-based substrate. Substrates containing 25% or 30% GS had a higher AFP than substrates containing equivalent amounts of perlite but a lower AFP than substrates containing equivalent PBH. Substrates containing 20% or more GS had a higher WHC than equivalent perlite- or PBH-containing substrates. Growth of ‘Cooler Grape’ vinca (Catharanthus roseus), ‘Dazzler Lilac Splash’ impatiens (Impatiens walleriana), and ‘Score Red’ geranium (Pelargonium ×hortorum) was similar for plants grown in GS-containing substrates and those grown in equivalent perlite- and PBH-containing substrates.

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Two grades of ground bovine bone were evaluated as potential alternatives to perlite in horticultural substrates. The bulk density of small and large bone-amended substrates was significantly higher than equivalent perlite-amended substrates. Large and small bone increased the air-filled pore space of sphagnum peat. However, at 10% and 20% (v/v), neither size of bone resulted in as high an air-filled pore space as equivalent amounts of perlite. At 30% and 40%, incorporation of small bone resulted in a similar air-filled pore space as incorporation of equivalent amounts of perlite, and incorporation of large bone resulted in a higher air-filled pore space than incorporation of equivalent amounts of perlite. Water-filled pore space and water-holding capacities of substrates were inversely related to air-filled pore space. When placed in a moist substrate, mineral elements within the bone were able to leach into the substrate over time. Substrates amended with 40% large and small bone had significantly higher concentrations of ammonium (NH4 +), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), and chloride (Cl-) than the 40% perlite-containing substrates. Substrates amended with 40% large bone had similar concentrations of magnesium (Mg), sulfur (S), iron (Fe), and copper (Cu) while substrates amended with 40% small bone had higher levels of these elements than perlite-amended substrates. Substrate concentrations of nitrate (NO3 -), manganese (Mn), zinc (Zn), and boron (B) were not different among the substrates after 4 weeks in the greenhouse. The pH, electrical conductivity (EC) and NH4 + levels of bone-amended substrates increased to levels significantly higher than recommended and resulted in rapid mortality of `Orbit Cardinal' geranium (Pelargonium × hortorum), `Cooler Blush' vinca (Catharanthus roseus), and `Dazzler Rose Star' impatiens (Impatiens walleriana) plants grown in bone-amended substrates. Therefore, ground bovine bone was not a feasible alternative to perlite for use in horticultural substrates.

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Plant growth was evaluated in substrates containing varying proportions of processed poultry feather fiber (feather fiber). `Cooler Blush' vinca (Catharanthus roseus) and `Orbit Cardinal' geranium (Pelargonium × hortorum) dry shoot and dry root weights were not significantly different among plants grown in sphagnum-peat-based and perlite-based substrates containing 0% to 30% feather fiber. `Pineapple Queen' coleus (Coleus blumei) dry shoot weights were not significantly different among plants grown in substrates containing 0% to 50% feather fiber. Coleus dry root weights were not significantly different among the substrates containing 0% to 40% feather fiber. `Better Boy' tomato (Lycopersicon esculentum) dry shoot weights were not significantly different among the substrates containing 0% to 30% feather fiber. Tomato dry root weights were not significantly different among the substrates containing 0% to 30% feather fiber, but tomato grown in substrates containing 40% to 60% feather fiber had significantly lower dry root weights than tomato grown in substrates containing 0% to 30% feather fiber. `Salad Bush' cucumber (Cucumis sativus) dry shoot and dry root weights were not significantly different between plants grown in 0% to 50% feather fiber, but those gown in substrates containing 60% feather fiber had significantly lower dry shoot weights than those grown in substrates containing 0% feather fiber. Dry shoot and root weights of coleus and tomato grown in SB-300 substrate amended with 20% or 30% feather fiber were not significantly different from coleus and tomato grown in SB-300 without feather fiber. Dry shoot and dry root weights of coleus and tomato were significantly lower for plants grown in SB-300 amended with 40% feather fiber than for plants grown in SB-300 without feather fiber. For all species tested, plants grown in substrates containing up to 30% feather fiber were not significantly different from those grown in substrates containing 0% feather fiber and were of marketable qualities.

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Seed of Pelargonium ×hortorum L.H. Bailey `Freckles' (geranium) and Tagetes patula L. `Bonanza' (marigold) were soaked for 12, 24, or 48 h in solutions containing 0 (deionized water), 5000, 10,000, or 15,000 mg·L-1 humic acid (HA) or nutrient controls (NC) containing similar levels of nutrients prior to planting. Soaking in deionized water (DI) and NC treatments had no significant effect on root fresh weight. However, several of the HA treatments increased root fresh weight of marigold seedlings, and all increased geranium root fresh weight. Percentage of germination and shoot fresh weight were not significantly affected by treatment. Seed of Cucumis sativus L. `Salad Bush' (cucumber), Cucurbita pepo L. `Golden Summer Crookneck' (squash), `Freckles' geranium and `Bonanza' marigold were sown into 15-cell plug trays (5 mL volume), and the substrate was drenched with DI, 2500 or 5000 mg·L-1 HA, or 2500 or 5000 mg·L-1 NC. DI and NC treatments did not affect root fresh weight. However, cucumber, squash, and marigold seedlings germinated in substrate drenched with 2500 and 5000 mg·L-1 HA and geranium seedlings germinated in substrate drenched with 2500 mg·L-1 HA had significantly higher root fresh weight than did seedlings from all other treatments. Percentage of germination and shoot fresh weight were not significantly affected by treatment. `Salad Bush' cucumber and `Golden Summer Crookneck' squash seedlings germinated on germination towels soaked with 2500 or 5000 mg·L-1 HA, had significantly higher root fresh weight than did seedlings germinated on towels soaked with DI or NC solutions. Treatment with HA did not affect shoot fresh weight or the number of lateral roots. However, HA treatment increased the total length of lateral roots. The increase in lateral root growth occurred primarily in lateral roots developing from the lower hypocotyl.

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When the substrate surface and drainage holes of feather fiber, peat, and plastic containers were sealed with wax, hyperbolic growth curves were good fits to cumulative water loss on a per container and per cm2 basis, with R 2 values ranging from 0.88 to 0.96. The effect of container type was significant as the differences in asymptotic maximum water loss (max) values for all container pairs were significant at P < 0.05 for both water loss per container and water loss per cm2. The predicted total water loss for peat containers was ≈2.5 times greater than feather containers, and the predicted water loss per cm2 for the peat container was ≈3 times greater than feather containers. Vinca [Catharanthus roseus (L.) G. Don.] `Cooler Blush' and impatiens (Impatiens walleriana Hook f.) `Dazzler Rose Star' plants grown in feather and peat containers required more water and more frequent irrigations than those grown in plastic containers. However, plants grown in feather containers required less water and fewer irrigations than plants grown in peat containers. The surface area of containers covered by algal or fungal growth was significantly higher on peat containers than on feather containers. No fungal or algal growth was observed on plastic containers. Additionally, primarily algae were observed on peat containers whereas most discoloration observed on feather containers was due to fungal growth. Dry feather containers had a higher longitudinal strength than dry plastic containers but a lower longitudinal strength than dry peat containers. Wet feather containers had higher longitudinal strength than wet peat containers but a similar longitudinal strength as wet plastic containers. Dry feather and plastic containers had similar lateral strengths and both had significantly higher lateral strength than dry peat containers. Wet feather containers had significantly lower lateral strength than wet plastic containers but had higher lateral strength than wet peat containers. Dry and wet plastic containers had higher punch strength than wet or dry peat and feather containers. Dry peat containers had significantly higher punch strength than dry feather containers. However, wet feather containers had significantly higher punch strength than wet peat containers. Decomposition of peat and feather containers was significantly affected by container type and the species grown in the container. When planted with tomato (Lycopersicum esculentum L.) `Better Boy', decomposition was not significantly different between the peat and feather containers. However, when vinca and marigold (Tagetes patula L.) `Janie Bright Yellow' were grown in the containers, decomposition was significantly higher for feather containers than for peat containers. Therefore, containers made from processed feather fiber provided a new type of biodegradable container with significantly improved characteristics as compared to peat containers.

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A biodegradable container made from processed waste poultry feathers was developed, and plant growth was evaluated in plastic, peat, and feather containers. Under uniform irrigation and fertilization, dry shoot weights of `Janie Bright Yellow' marigold (Tagetes patula L.), `Cooler Blush' vinca [Catharanthus roseus (L.) G. Don.] and `Orbit Cardinal' geranium (Pelargonium ×hortorum L.H. Bailey) plants grown in feather containers were higher than for those grown in peat containers, but lower than those grown in plastic containers. Container type did not significantly affect dry shoot weights of `Dazzler Rose Star' impatiens (Impatiens walleriana Hook.f.). `Better Boy' tomato (Lycopersicum esculentum L.) dry shoot weights were similar when grown in peat and feather containers. Feather containers were initially hydrophobic, and several irrigation cycles were required before the feather container walls absorbed water. If allowed to dry, feather containers again became hydrophobic and required several irrigations to reabsorb water from the substrate. Peat containers readily absorbed water from the substrate. Substrate in peat containers dried more rapidly than the substrate in feather containers. Plants grown in peat containers often reached the point of incipient wilting between irrigations, whereas plants grown in feather containers did not. This may have been a factor that resulted in higher dry shoot weights of plants grown in feather containers than in peat containers. Tomato plants grown in feather containers had higher tissue N content than those grown in plastic or peat containers. The availability of additional N from the feather container may also have been a factor that resulted in higher dry shoot weights of plants grown in feather containers than in peat ones. Under non-uniform irrigation and fertilization, dry shoot weights of impatiens and vinca grown in feather containers were significantly higher than those of plants grown in plastic or peat containers. When grown under simulated field conditions, geranium dry shoot weights were significantly higher for plants initially grown in feather containers than for those initially grown in peat containers. Container type did not significantly affect dry shoot weights of vinca when grown under simulated field conditions. As roots readily penetrated the walls of both feather and peat containers, dry root weights of vinca and geranium were not significantly affected by container type when grown under simulated field conditions.

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Seedlings of Cucumis sativus (cucumber), Tagetes patula (marigold), Viola tricolor (pansy), Pelargonium × hortorum (geranium), and Impatiens wallerana (impatiens) were germinated on towels soaked with either deionized water, nutrient control solutions, or humic acid solutions. Root fresh weight and root dry weights were higher for all seedlings germinated on towels soaked with humic acid as compared to seedlings germinated on towels soaked with deionized water or nutrient control solutions. Lateral root number and total lateral root length were higher for cucumber, marigold, pansy, and geranium seedlings germinated on towels soaked with humic acid than those germinated on towels soaked with deionized water or nutrient control solutions. Root fresh and dry weights were higher for impatiens, Begonia semperflorens (begonia), marigold, and geranium seedlings germinated in a sphagnum peat: vermiculite (80:20, %v/v) substrate drenched with humic acid as compared to seedlings germinated in substrate drenched with deionized water or nutrient control solutions. Foliar sprays of humic acid also resulted in increased root fresh and dry weights while foliar application of nutrient control solutions either had no effect or reduced root fresh and dry weights.

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A comparison was made of Canadian sphagnum peat (SP) and Philippine coconut (Cocos nucifera L.) coir dust (CD) as growing media components for Dieffenbachia maculata [(Lodd.) G. Don] `Camille' greenhouse production. Three soilless foliage plant growing mixes [Cornell, Hybrid, Univ. of Florida #2 (UF-2)] were prepared using either SP or CD and pine bark (PB), vermiculite (V), and/or perlite (P) in the following ratios (percent by volume): Cornell = 50 CD or SP:25 V:25 P, Hybrid = 40 CD or SP:30 V:30 PB, UF-2 = 50 CD or SP:50 PB. Initial CI concentrations and electrical conductivities were higher for CD-containing media (CDM) than SP-containing media (SPM). At termination, Ca, Mg, and NO3-N concentrations were higher for SPM than CDM. Bulk densities were lower for CDM than SPM for one medium, but not for the others. Water-filled pore space (W-FPS) and water-holding capacity (W-HC) were larger and air-filled pore space (A-FPS) generally was smaller for CDM than SPM. Cornell had the highest W-FPS and W-HC, lowest A-FPS and percentage of large particles, and produced the highest grade and heaviest plants. Plant top grades, fresh mass and overall mass, but not root grades and mass, were higher for CDM than SPM. Plant mass was positively correlated with initial medium W-HC but not with A-FPS. Lower K in mix UF-2 compared to the mixes containing vermiculite may have been partly responsible for the lesser growth in that mix.

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Geranium (Pelargonium ×hortorum L.H. Bailey) `Freckles' and poinsettia (Euphorbia pulcherrima Willd. ex Klotzch) `Freedom' were grown in six peat and shredded-rubber substrates formulated to contain 75:25:0, 50:50:0, 25:75:0, 75:0:25, 50:0:50, 25:0:75 sphagnum peat: fine-grade rubber: coarse-grade rubber (by volume). Additionally, plants were grown in a 50 peat: 30 perlite: 20 loam (by volume) control substrate. Shredded rubber-containing substrates had higher bulk densities, lower total pore space, and higher total solids than the control substrate. Fine rubber-containing substrates had lower air-filled pore space (AFP) and lower water-holding capacities (WHC) than the control substrate. Substrates containing 25% coarse rubber had lower AFP and WHC than the control, but substrates containing 50% and 75% coarse shredded rubber had higher AFP and lower WHC than the control. Shredded rubber-containing substrates had significantly higher levels of Zn than the control substrate. Plants grown in rubber-containing substrates had tissue Zn levels significantly higher than the control and at levels reported to be phytotoxic in other species. Geraniums grown in rubber-containing substrates had lower root and shoot fresh mass, were shorter, and had fewer axillary branches than those grown in the control substrate. Poinsettia plants grown in rubber-containing substrates were shorter, had lower shoot fresh mass, fewer bracts, and lower bract area as compared to plants grown in the control substrate.

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Glycine max (soybean) seed were sown in root substrates composed of 80:0:20 or 0:80:20 coconut coir dust (coir):Sphagnum peat (peat):perlite (v/v) amended with dolomitic limestone to a pH of 5.5. Substrates were inoculated with Phytophthora megasperma races 5 and 25 isolated from soybean and grown in dilute liquid V-8 cultures. Uninoculated controls were included. Containers were watered daily to maintain moisture levels at or near container capacity. The experiment was repeated twice. Plants grown in peat-based root substrates inoculated with P. megasperma suffered 50% to 100% mortality. No plants in coir-based root substrates displayed visually apparent infection symptoms. Soybean seed were also sown in root substrates that contained 0:80:20, 20:60:20, 40:40:20, 60:20:20 or 80:0:20 coir:peat:perlite (v/v). Inoculum of P. megasperma races 1, 5, and 25 was grown on water agar and diluted in deionized water. Solution containing 20,000 colony-forming units (oospores) was mixed into the root substrate of each container. Uninoculated controls were included. As the proportion of coir in the substrate increased, the mortality, the number of plants displaying disease symptoms and the severity of disease symptoms decreased. Plants grown in substrates containing at least 60% coir displayed no visually evident disease symptoms.

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