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  • Author or Editor: Michael R. Evans x
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Euphorbia pulcherrima `Freedom' (poinsettia) were grown in coir dust, sphagnum peat, and perlite at the following ratios (respectively) 20:0:80, 40:0:60, 60:0:40, 80:0:20, 0:20:80, 0:40:60, 0:60:40, and 0:80:20 (v/v) substrates. Days to anthesis were not significantly different between substrates. Heights were greater for plants produced in 80% coir compared to plants grown in 80% peat. Overall, plants grown in coir-based substrates were taller than plants grown in peat-based substrates. Plants grown in 60% coir had a greater number of lateral shoots, increased shoot fresh weight and increased bract area compared to plants grown in 60% peat. Overall, plants grown in coir-based substrates had greater shoot fresh weights compared to plants grown in peat-based substrates. Lilium longiflorum `Nellie White' (lily) plants were grown in 40:0:20:40, 0:40:20:40, 0:57:14:28, 0:73:9:18 (v/v sphagnum peat: coir dust: loam: perlite) substrates. As the proportion of coir in the substrate increased, height, and shoot and root fresh weights increased. Nodes to flower, days to flower, and number of flowers were not significantly affected by substrate.

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Euphorbia pulcherrima `Freedom' (poinsettia) and Pelargonium ×hortorum `Pink Elite' (geranium) were grown in 75:25:0, 50:50:0, 27:75:0, 75:0:25 50:0:50, 25:0:75 (v/v sphagnum peat: 0.25-grade rubber: 0.10-grade rubber) substrates or in a 50 sphagnum peat: 30 perlite: 20 loam (v/v) standard greenhouse substrate. Geranium root and shoot fresh weights, height, and number of axillary shoots were reduced when grown in rubber-containing substrates compared to plants grown in the standard control. As the proportion of either grade of rubber increased, root and shoot fresh weights, height, and number of axillary shoots decreased. Flowering in geranium was delayed and the number of inflorescences reduced as the proportion of the 0.10-grade rubber increased. Plants grown in the 0.25-grade rubber failed to flower by the termination of the experiment. Poinsettia plants grown in rubber-containing substrates had reduced shoot fresh weight, height, number of bracts, and bract area compared to plants grown in the standard control. As the proportion of either grade of rubber increased, height, shoot fresh weight, number of bracts, and bract area decreased. Number of axillary branches was reduced in substrates containing 50% and 75% of the 0.10-grade rubber. Days to anthesis was unaffected by substrate.

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Seed of Cucumis sativus and Pelargonium ×hortorum were imbibed for 24 hours in solutions containing 0 (deionized water), 2500, 5000, 10,000, and 20,000 ppm humic acid. Additional treatments included seed which were imbibed in nutrient solutions corresponding to the nutrient content of each humic acid solution as well as an untreated dry control. Percent germination was reduced for geranium seed imbibed in 20,000 ppm humic acid and for cucumber seed imbibed in either 20,000 ppm humic acid or the corresponding nutrient control. Root fresh weights for untreated and water imbibed geranium seed were 0.05 g. Humic acid treatment increased root fresh weights to a maximum of 0.14 g at 5000 and 10,000 ppm. Shoot fresh weights for geranium were 0.12 and 0.10 g for untreated and water imbibed seed, respectively. Humic acid treatment increased shoot fresh weight to a maximum of 0.18 at 2500 ppm. Root fresh weights for cucumber were 0.16 and 0.18 g for untreated and water imbibed seeds, respectively. Humic acid treatment increased root fresh weight to a maximum of 0.33 g at 10,000 ppm. Shoot fresh weights for cucumber were 0.31 and 0.38 g for untreated and water imbibed seed, respectively. Humic acid treatment increased shoot fresh weight to a maximum of 0.43 at 10,000 ppm.

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A series of soilless root substrates was formulated to contain either 20% composted pine bark or perlite and 0%, 10%, 20%, or 30% feather fiber, with the remainder being sphagnum peat. The substrates containing bark or perlite with 0% feather fiber served as the controls for the bark- and perlite-containing substrates respectively. For root substrates containing perlite, the inclusion of feather fiber increased the total pore space compared with the control substrate. For substrates containing bark, the inclusion of 10% or 20% feather fiber increased total pore space, but the inclusion of 30% feather fiber reduced total pore space. For substrates containing perlite, the inclusion of feather fiber increased the air-filled pore space compared with the control, and as the percentage feather fiber increased, air-filled pore space increased. For substrates containing bark, the inclusion of 10% or 20% feather fiber increased air-filled pore space, but air-filled pore space of the substrate containing 30% feather fiber was not different from the control. For all substrates, the inclusion of feather fiber reduced the water-holding capacity, but water-holding capacities for all substrates remained within recommended ranges. The bulk density of feather fiber-containing substrates was not different from the control except for the substrate containing 30% feather fiber with bark, which had a higher bulk density than its control without feather fiber. The difference in physical properties of the 30% feather fiber substrate with bark from its control substrate was attributed to the aggregation of the feather fiber when formulated with composted bark. Aggregation of feather fiber when blended into substrates at levels of 30% or higher would create difficulties in achieving uniform substrates.

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The objective for this research was to evaluate the growth of a long-term crop in biodegradable containers compared with traditional plastic containers using a subirrigation system. Plastic, bioplastic, solid ricehull, slotted ricehull, paper, peat, dairy manure, wood fiber, rice straw, and coconut fiber containers were used to evaluate plant growth of ‘Rainier Purple’ cyclamen (Cyclamen persicum) in ebb-and-flood subirrigation benches. The days to flower ranged from 70 to 79 and there were no significant differences between the plastic containers and the biocontainers. The dry shoot weights ranged from 23.9 to 37.4 g. Plants grown in plastic containers had dry shoot weights of 27.6 g. The dry shoot weight of plants grown in containers composed of wood fiber was 23.9 g and was lower than plants grown in plastic containers. The plants grown in the bioplastic, solid ricehull, slotted ricehull, paper, peat, dairy manure, rice straw, and coconut fiber containers had significantly higher dry shoot weights than plants grown in plastic containers. Dry root weights ranged from 3.0 to 4.0 g. The plants grown in the plastic containers had dry root weights of 3.0 g. Plants grown in paper and wood fiber containers had higher dry root weights than those grown in plastic containers. The only container that negatively affected plant growth was the wood fiber container. Plants preformed the best in solid ricehull, slotted ricehull, and coconut fiber containers based on dry shoot and dry root weights, but all containers were successfully used to produce marketable cyclamen plants.

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Ten substrates were formulated by blending perlite or parboiled fresh rice hulls (PFH) at 20%, 30%, 40%, 50%, or 60% (v/v) with sphagnum peat. After 6 weeks, NH4 + concentrations were not significantly different among substrates containing perlite and those containing equivalent amounts of PFH. Nitrate concentrations were significantly higher in the 40% perlite substrate than in the 40% PFH substrate, but there were no significant differences in NO3 - concentrations among the remaining substrates containing equivalent amounts of PFH or perlite. When tomato (Lycopersicon esculentum Mill.) was grown in the substrates for 5 weeks, tissue N concentrations were not significantly different between equivalent perlite and PFH-containing substrates. Non-parboiled fresh rice hulls produced organically contained a higher number of viable weed seeds than non-parboiled fresh rice hulls produced conventionally. No weed seeds germinated in the PFH. `Better Boy' tomato, `Bonanza Yellow' marigold (Tagetes patula L. French M.), `Orbit Cardinal' geranium (Pelargonium ×hortorum L.H. Bailey), `Cooler Blush' vinca (Catharanthus roseus L.G. Don), `Dazzler Rose Star' impatiens (Impatiens walleriana Hook. f.), and `Bingo Azure' pansy (Viola ×wittrockiana Gams) were grown in sphagnum peat-based substrates containing perlite or PFH at 10%, 15%, 20%, 25%, 30%, 35%, or 40% (v/v). Dry root weights of vinca and geranium were not significantly different among plants grown in the substrates. Tomato plants grown in 10%, 15%, 25%, 30%, and 35% PFH had significantly higher dry root weights than those grown in equivalent perlite-containing substrates. Impatiens grown in 35% PFH had higher dry root weights than those grown in 35% perlite. Marigold grown in 20% perlite had higher dry root weights than those grown in 20% PFH. However, there were no significant differences in impatiens or marigold dry root weights among the remaining substrates containing equivalent amounts of PFH or perlite. Dry root weights of pansy grown in 10%, 20% 25%, 35%, and 40% perlite were not significantly different from those grown in equivalent PFH-containing substrates. Across substrates, root dry weights of impatiens, marigold, and pansy grown in perlite-containing substrates were not significantly different from those grown in PFH-containing substrates. No significant difference in dry shoot weights of vinca, geranium, impatiens, and marigold occurred between equivalent perlite and PFH-containing substrates. Tomato plants grown in 20% to 40% perlite had significantly higher dry shoot weights than those grown in equivalent PFH-containing substrates. However, dry shoot weights of tomato grown in 10% to 15% perlite were not significantly different from those grown in equivalent PFH-containing substrates. Dry shoot weights of pansy grown in 10%, 25%, 30%, 35%, and 40% perlite were not significantly different from those grown in equivalent PFH substrates.

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Helianthus annuus `Big Smile', Tagetes patula 'Bonanza Deep Orange' and Pelargonium × hortorum 'Pinto Rose' seedlings were transplanted into 12 cm (470 ml) pots containing substrates composed of 3 parts (v/v) vermiculite, 3 parts sand and 2 parts perlite. In addition, the substrates contained either 3 parts Florida peat, 3 parts coconut coir (coir), 6 parts coir or 12 parts coir, thus, resulting in 4 substrates. Dolomitic limestone, hydrated limestone, superphosphate, a microelement package and a 14-6.2-11.6 slow release fertilizer were added to the Florida peat-containing substrate. The same materials were added to the coir-containing substrates except that calcium sulfate (gypsum) was used in place of dolomitic and hydrated limestone. All materials were incorporated at rates required to obtain an initial pH of 5.5 to 5.8 and provide equal amounts of calcium, phosphorus and microelements. Data were taken 5 weeks after transplanting. Neither height, shoot fresh weights nor root fresh weights were significantly different between the substrates. Tagetes average heights were between 11.5 and 12.9 cm, while average shoot fresh weights were between 12.6 and 14.7 g and average root fresh weights were between 8.8 and 9.4 g. Helianthus average heights were between 18.4 and 19.9 cm, while average shoot fresh weights were between 29.7 and 31.9 g and average root fresh weights were between 19.6 and 22.3 g. Pelargonium average heights were between 11.9 and 13.4 cm, while average shoot fresh weights were between 13.8 and 15.3 g and average root fresh weights were between 3.4 and 3.7 g.

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The physical properties of new 15.2-cm plastic and comparably sized bioplastic, solid ricehull, slotted ricehull, paper, peat, dairy manure, wood fiber, rice straw, and coconut fiber containers were determined. Additionally, the physical properties of these containers were determined after being used to grow ‘Rainier Purple’ cyclamen (Cyclamen persicum L.) in ebb-and-flood benches for 15 weeks in a greenhouse environment. The punch strength of new coconut fiber containers was the highest of the containers. The used plastic containers had strengths of 228.0, 230.5, and 215.2 N for the bottom, middle, and top zones, respectively. The used peat, dairy manure, and wood fiber containers had strengths of less than 15 N for each zone. Tensile strength of all new containers was 10 kg. The plastic, bioplastic, solid ricehull, slotted ricehull, paper, and coconut fiber containers had used strengths that were similar to plastic containers. Total water used for wood fiber containers was higher than plastic containers. Irrigation intervals for plastic containers were similar to bioplastic, solid ricehull, slotted ricehull, paper, and coconut fiber containers. The irrigation interval for plastic containers was 1.32 days and the wood fiber container had the shortest irrigation interval at 0.61 day. Container absorption for coconut fiber containers was 255 mL and was higher than plastic containers. Wood fiber container absorption was 141 mL and lower than plastic containers. Plastic, bioplastic, solid ricehull, and slotted ricehull containers had no visible algal or fungal growth. The wood fiber containers had 79% of the container walls covered with algae or fungi and the bottom and middle zones had 100% algae or fungi coverage. The bottom zone of rice straw, dairy manure, and peat containers also had 100% algae or fungi coverage. The bioplastic, solid ricehull, and slotted ricehull containers in this study proved to be good substitutes for plastic containers. These containers retained high levels of punch and tensile strength, had no algal and fungal growth, and required a similar amount of solution as the plastic containers to grow a cyclamen crop. The peat, dairy manure, wood fiber, and rice straw containers proved not to be appropriate substitutes for plastic containers because of the low used strengths, high percentage of algal and fungal coverage, and shorter irrigation intervals as compared with plastic containers.

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Ten substrates were formulated by blending perlite or parboiled fresh rice hulls (PBH) to produce root substrates (substrates) that contained either 20%, 30%, 40%, 50%, or 60% (by volume) perlite or PBH, with the remainder being sphagnum peatmoss. All substrates containing PBH had higher total pore space than substrates containing an equivalent amount of perlite. As the percentage perlite increased from 20% to 60%, the total pore space decreased. The total pore space increased as the amount of PBH increased to 50% and then decreased as the amount of PBH increased from 50% to 60%. The air-filled pore space was not different between substrates containing 20% perlite or PBH. However, the air-filled pore space was higher in PBH-containing substrates than in equivalent perlite-containing substrates when the amount of PBH or perlite was at least 40%. As the amount of perlite or PBH was increased, the air-filled pore space increased, but the rate of increase was higher for PBH-containing substrates. The 20% PBH-containing substrate had a higher water-holding capacity than the 20% perlite-containing substrate. However, at 30% or higher PBH, the PBH-containing root substrates had a lower water-holding capacity than equivalent perlite-containing substrates. As the percentage perlite or PBH was increased, the water-holding capacity decreased, but at a higher rate in PBH-containing substrates than in perlite-containing substrates. For all substrates except those containing 40% PBH or perlite, substrates containing PBH had lower bulk densities than equivalent perlite-containing substrates. The differences in bulk densities were not great enough to be of practical significance. Inclusion of PBH in the substrate provided for drainage and air-filled pore space as did perlite. However, less PBH would be required in a substrate to provide the same air-filled pore space as perlite when more than 20% perlite or PBH is used.

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Substrates were formulated by blending parboiled fresh rice (Oryza sativa) hulls (PBH) or perlite with sphagnum peat (peat) to produce root substrates (substrates) that contained 20%, 30%, 40%, 50%, or 60% (by volume) PBH or perlite with the remainder being peat. After 0 (initial mixing), 4, or 8 weeks in a greenhouse environment, samples were taken and pH, electrical conductivity (EC), nitrate (NO3 ), ammonium (NH4 +), phosphorus (P), and potassium (K) were determined. As the amount of PBH or perlite in the substrate was increased, the pH increased. After 0 and 8 weeks, the pH of substrates containing up to 30% PBH or perlite had a similar pH. However, the rate of pH increase at these sampling times was higher than that of perlite so that substrates containing 40% or more PBH had a higher pH than equivalent perlite-containing substrates. At the week 4 sampling period, all substrates containing PBH had a higher pH than equivalent perlite-containing substrates. For all sampling times, the difference in pH between equivalent PBH and perlite-containing substrates was not high enough to be of practical significance. For all sampling times, EC increased as the amount of perlite was increased. Depending upon sampling time, the EC decreased or remained unchanged as the amount of PBH was increased. For all sampling times and substrates, EC was within acceptable ranges for unused substrates. Substrates containing PBH had higher NO3 levels than equivalent perlite-containing substrates. The NH4 + level of the substrates decreased as the amount of PBH or perlite was increased. The levels of NO3 and NH4 + were within acceptable ranges for unused substrates. Substrate P and K increased as the amount of PBH in the substrate was increased, but the concentration of P and K remained unchanged or decreased as the amount of perlite was increased. None of the differences between equivalent PBH and perlite-containing substrates was high enough to be problematic with respect to crop production and all of the chemical parameters were within acceptable ranges for unused root substrates.

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