Search Results

You are looking at 31 - 40 of 61 items for

  • Author or Editor: Michael R. Evans x
Clear All Modify Search

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, 4, or 8 weeks in a greenhouse environment, samples were taken and calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and boron (B) were determined. At all sampling times, substrates containing PBH had higher Ca concentrations than perlite-containing substrates. At all sampling times, Ca concentration decreased as the amount of perlite or PBH was increased, but the Ca concentration decreased at a higher rate in perlite-containing substrates than in PBH-containing substrates. After 0 weeks, perlite-containing substrates had higher Mg concentrations than equivalent PBH-containing substrates, but the opposite was true after 4 weeks. After 8 weeks, perlite- and PBH-containing substrates had similar concentrations of Mg. At all times, Mg concentration decreased as the amount of perlite or PBH was increased. Perlite substrates had higher concentrations of Fe than equivalent PBH substrates, and as the amount of perlite or PBH was increased, the amount of Fe decreased. PBH-containing substrates had higher concentrations of Mn than equivalent perlite-containing substrates, and as the amount of PBH was increased, the amount of Mn increased. Cu concentrations were significantly affected by sampling time, but at all sampling times, PBH-containing substrates had similar or higher Cu concentrations than equivalent perlite-containing substrates. Perlite substrates had higher concentrations of Zn than equivalent PBH substrates, and as the amount of perlite was increased, the amount of Zn increased. S and B were not significantly affected by substrate component or time. Secondary macro- and microelement concentrations of all substrates were within recommended levels for greenhouse crops except for Mn. Mn concentrations were within recommended ranges at up to 50% PBH. In most cases, PBH would be used at levels lower than 50%, but in cases where more than 50% PBH were used in the substrate, proper pH management may be important to prevent excessive Mn availability.

Full access

A top coat is a lightweight substrate component used in seed germination. The seeds are typically placed on a substrate such as peat and then the seeds are covered with a layer of the top coating substrate. The top coat serves to maintain adequate moisture around the seeds and to exclude light. Vermiculite and cork granulates (1 mm) were used as top coat substrates for seed germination to determine if cork granulates could be successfully used as an alternative to vermiculite. The cork granulates had a bulk density of 0.16 g·cm−3, which was higher than that of vermiculite that had a bulk density of 0.12 g·cm−3 . Cork granulates had an air-filled pore space of 22.7% (v/v), which was higher than vermiculite which was 13.2%. The water-holding capacity of vermiculite was 63.4% (v/v), which was higher than that of cork granulates that was 35.1%. Seeds of ‘Rutgers Select’ tomato (Solanum lycopersicum), ‘Dazzler Lilac Splash’ impatiens (Impatiens walleriana), ‘Orbital Cardinal Red’ geranium (Pelargonium ×hortorum), ‘Better Belle’ pepper (Capsicum annuum), and ‘Cooler Grape’ vinca (Catharanthus roseus) were placed on top of peat and covered with a 4-mm top coating of either vermiculite or cork granulates. For tomato, impatiens, and vinca, days to germination were similar between seeds germinated using vermiculite and granulated cork as a top coat. Days to germination of geranium and pepper were significantly different with geranium and pepper seeds coated with cork granulates germinating 0.7 and 1.5 days earlier than those coated with vermiculite. For tomato, impatiens, and geranium, the number of seeds germinating per plug tray was similar between the top coats. Number of seeds germinating per tray for pepper and vinca were significantly different. Pepper had an average of 2.8 more seeds germinating per tray, and vinca had an average of 2.4 more seeds germinating per tray if seeds were germinated using granulated cork vs. vermiculite. For all species, dry shoot and dry root weights were similar for seedlings germinated using cork and vermiculite top coats.

Full access

Abstract

Gaillardia × grandiflora Van Houtte ‘Dazzler’ and ‘Goblin’ were induced to flower under long days. Applications of GA4+7 (GA) substituted for long days and promoted flowering under short days in the same amount of time required by untreated, photoperiodically induced plants. Although cultivar and photoperiod dependent, GA also increased scape length and reduced scape caliper, flower head diameter and ray floret number. Leaf production was accelerated by several weekly applications of GA.

Open Access

Growth of Pythium aphanidermatum, Pythium ultimum, Pythium irregulare, Phytophthora nicoctianae, Phytophthora cinnomomi, Fusarium oxysporum, Rhizoctonia solani and Thielaviopsis basicoli was inhibited in vitro when grown in a clarified V-8 nutrient solution containing 10% garlic extract. After exposure to 10% garlic extract for 3 days, all fungi and fungal-like organisms failed to grow after being washed and transferred to fresh cornmeal agar nutrient medium without garlic extract. When Sphagnum peat was inoculated with P. aphanidermatum and drenched with solutions containing varying concentrations of garlic extract, a single drench of 35% garlic extract or two drenches of 15% garlic extract were required to rid the substrate of viable P. aphanidermatum. In sand, a single application of 25% garlic extract or two applications of 10% garlic extract were required to rid the sand of viable P. aphanidermatum Thus, Sphagnum peat appeared to partially inactivate the components in garlic and did so to a greater extent than sand. Therefore, efficacy of garlic extract as a soil drench fungicide will be affected by the type of substrate or soil to which the garlic extract is applied.

Free access

Ground fresh rice (Oryza sativa) hull materials were produced by grinding whole fresh rice hulls and passing the resulting product through a 1-, 2-, 4- or 6-mm-diameter screen to produce a total of four ground rice products (RH1, RH2, RH4, and RH6, respectively). The physical properties and water release characteristics of sphagnum peatmoss (peat) and the four ground rice hull products were evaluated. All of the ground rice hull products had a higher bulk density (Bd) than peat, and as the grind size of the rice hull particle decreased, Bd increased. Peat had a higher total pore space (TPS) than all of the ground rice hull products except for RH6. As grind size decreased, the TPS decreased. Peat had a lower air-filled pore space (AFP) than all of the ground rice hull products and as the grind size of the rice hull products decreased, AFP decreased. Peat had a higher water holding capacity (WHC) than all of the ground rice hull products. Grind sizes RH4 and RH6 had similar WHC, whereas RH1 and RH2 had a higher WHC than RH4 and RH6. Peat, RH4, and RH6 had similar available water content (AVW), whereas RH2 had higher AVW than these materials and RH1 had the highest AVW. However, peat had the lowest AVW and easily available water (EAW) as a percentage of the WHC. The ground rice hull products RH1 and RH2 had the highest AVW and EAW of the components tested. Peat had the highest water content at container capacity. As pressure was increased from 1 to 5 kPa, peat released water more slowly than any of the ground rice hull products. The RH1 and RH2 ground hull products released water at a significantly higher rate than peat, but RH4 and RH6 released the most water over these pressures. For all rice hull products, most water was released between 1 and 2 kPa pressure. The rice hull products RH1 and RH2 had physical properties that were within recommended ranges and were most similar to those of peat.

Full access

The vertical dry strength of rice hull containers was the highest of all containers tested. Plastic containers and paper containers had similar vertical dry strengths. Containers composed of 80% cedar fiber and 20% peat (Fertil), composted dairy manure (Cowpot), and peat had lower dry vertical dry strengths than the aforementioned containers but had higher vertical dry strengths than those composed of bioplastic (OP47), coconut fiber, and rice straw. Rice hull containers and paper containers had the highest lateral dry strengths. Rice straw, Cowpot, and plastic containers had similar dry lateral strengths, which were significantly higher than those of OP47, Fertil, coconut fiber, and peat containers. Highest dry punch strengths occurred with traditional plastic and Cowpot containers, while the lowest dry punch strengths occurred with OP47, Fertil, coconut fiber, peat, and rice straw containers. Plastic, rice hull, and paper containers had the highest wet vertical and lateral strengths. Plastic containers had the highest wet punch strength, while Fertil, Cowpot, and peat containers had the lowest wet punch strengths. When saturated substrate was placed into containers and the substrate surface and drainage holes were sealed with wax, plastic, OP47, and rice hull containers had the lowest rates of water loss per unit of container surface area, while peat, Fertil, and rice straw containers had the highest rates of water loss per unit of container surface area. The amounts of water required to produce a geranium (Pelargonium ×hortorum) crop were significantly higher and the average irrigation intervals were shorter for peat, Fertil, coconut fiber, Cowpot, and rice straw containers than for traditional plastic containers. The amounts of water required to produce a geranium crop and the average irrigation intervals were similar among plastic, rice hull, and OP47 containers. Algal and fungal coverage on the outside container walls averaged 47% and 26% for peat and Fertil containers, respectively, and was higher than for all other containers tested, which had 4% or less algal and fungal coverage. After 8 weeks in the field, Cowpot containers had decomposed 62% and 48% in the Pennsylvania and Louisiana locations, respectively. Peat, rice straw, and Fertil containers decomposed 32%, 28%, and 24%, respectively, in Pennsylvania, and 10%, 9%, and 2%, respectively, in Louisiana. Coconut fiber containers had the lowest level of decomposition at 4% and 1.5% in Pennsylvania and Louisiana, respectively.

Full access

Pythium aphanidermatum, Pythium irregulare, Pythium ultimum, Phytophthora cinnomomi, Phytophthora nicotianae, Rhizoctonia solani, Fusarium oxysporum, and Thielaviopsis basicoli grew and eventually covered petri plates containing a nutrient solution alone, but they failed to grow in nutrient solutions containing 10% or higher levels of garlic extract or a fungicide control. When plugs containing the fungal organisms exposed to 10% garlic (Allium sativum) extract solution for 48 h were washed and transferred to fresh cornmeal agar (CMA) growth medium, only F. oxysporum displayed growth. However, growth of F. oxysporum was limited to no greater than 2 mm from the original inoculum plug. After a single application of a solution containing at least 35% garlic extract or two applications containing 25%, viable P. aphanidermatum could not be recovered from a peat-based root substrate. By contrast, after a single application of a solution containing 25% garlic extract or two applications of 10%, we were unable to recover viable P. aphanidermatum from a sand substrate. When peat treated with increasing concentrations of garlic extract was placed on CMA inoculated with P. aphanidermatum, the first visual sign of a zone of inhibition occurred for peat saturated with 30% garlic extract solution and the zone increased as the garlic extract concentration increased. By contrast, when sand treated with increasing concentrations of garlic extract was placed on CMA inoculated with P. aphanidermatum, the first visual sign of a zone of inhibition occurred when saturated with 10% garlic extract solution. Therefore, the garlic extract was found to be fungicidal against a broad range of soilborne fungal organisms, but the concentration required to kill the organisms varied depending on root substrate.

Full access

The use of biochar as a soil amendment has fostered much attention in recent years due to its potential of improving the chemical, physical, and biological properties of agricultural soils and/or soilless substrates. The objective of this study was to evaluate the chemical properties of feedstocks, common in the southeast United States, and their resulting biochar products (after being torrefied) and determine if the chemical properties were within suitable ranges for growers to use the biochar products as root substrate components. Poultry litter biochar produced at 400 °C for 2 hours had a higher total phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), chloride (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), sodium (Na), and zinc (Zn) concentration than biochar made using the same process with mixed hard wood species, miscanthus (Miscanthus capensis), cotton (Gossypium hirsutum) gin trash, switchgrass (Panicum virgatum), rice (Oryza sativa) hull, and pine (Pinus sp.) shavings feedstocks. The pH of the biochar products ranged from 4.6 for pine shaving biochar to 9.3 for miscanthus biochar. The electrical conductivity (EC) ranged from 0.1 dS·m−1 for mixed hardwood biochar to 30.3 dS·m−1 for poultry litter biochar. The cation exchange capacity (CEC) of the biochar products ranged from a low of 0.09 meq/g for mixed hardwood biochar to a high of 19.0 meq/g for poultry litter biochar. The water-extractable nitrate, P, K, Ca, Mg, sulfate, boron, Cl, Cu, Fe, Mo, Na, and Zn were higher in poultry litter biochar than in all of the other types of biochar. The high EC and mineral element concentration of the poultry litter biochar would prevent its use in root substrates except in very small amounts. In addition, the high degree of variability in chemical properties among all of the biochar products would require users to know the specific properties of any biochar product they used in a soil or soilless substrate. Modifications to traditional limestone additions and fertility programs may also need to be tested and monitored to compensate for the biochar pH and mineral nutrient availability. Users should be aware that biochar products made from different feedstocks can have very different chemical properties even if the same process was used to manufacture them.

Full access

Physical properties differed significantly among five Philippine-produced coconut (Cocos nucifera L.) coir dust sources. Bulk densities ranged from 0.04 to 0.08 g·cm–3. Air-filled pore space, water-filled pore space, and total pore space ranged from 9.5% to 12.6%, 73.0% to 80.0%, and 85.5% to 89.5% (v/v), respectively. Total solids accounted for 10.5% to 14.5% of total volume, and water-holding capacities ranged from 750% to 1100% of dry weight. Significant differences existed in particle size distribution, with the largest differences occurring for particle sizes <8.0 mm and 0.25 to 0.50 mm in diameter. Chemical properties were determined for 12 sources from the Philippines, Sri Lanka, or Indonesia. The pH and electrical conductivities ranged from 5.6 to 6.9 and 0.3 to 2.9 mS·cm–1, respectively, and were significantly different among sources. No significant differences occurred among samples with respect to Fe, Mn, Zn, B, Cu, NH4-N, and Mg concentrations. Coir dust samples contained Fe, Mn, Zn, B, and Cu at 0.01 to 0.07 mg·L–1. The levels of NH4-N and Mg were 0.1 to 0.2 and 1.0 to 7.4 mg·L–1, respectively. Significant differences occurred between sources for Ca, Na, and NO3-N, with levels (mg·L–1) ranging from 1.0 to 24.3, from 22.3 to 88.3, and from 0.4 to 7.0, respectively. The widest ranges occurred in K (19 to 948 mg·L–1) and Cl (26 to 1636 mg·L–1). Sources differed with respect to cation exchange capacities, with values ranging from 38.9 to 60.0 meq/100 g.

Free access

Rooted cuttings of 22 different Euphorbia pulcherrima Willd. ex Klotzsch cultivars were grown in root substrate inoculated with 0, 5000,15,000, and 30,000 oospores of Pyuthium ultimum Trow per 10-cm containers. The root substrate was a mixture of 50% peat, 30% perlite, and 20% soil, adjusted to a pH 5.5. Plants were grown in a greenhouse with a temperature range of 15-32 °C, and were fertilized daily with 200 ppm N (Excel 15-5-15, Scotts Co. Marietta, Ga). After 8 weeks, roots were rated for disease incidence and root fresh and dry weights were determined. The data were analyzed using ANOVA with six blocks in a 22 × 4 factorial design, linear regression, and cluster analysis. Significant differences among the responses of the cultivars were found. The slopes of the regression equations, using the log10 of the inoculum level for the X axis, were more positive for disease incidence and more negative for fresh and dry root weights in the more susceptble cultivars. The cultivars were separated, by the cluster analysis, into three groups, less susceptible, moderately susceptible, and highly susceptible. Cultivars Marblestar and Galaxy Red were representative of less susceptible, `Pepride' and `Jolly Red' were representative of moderately susceptible, and `Snowcap' and `Success' were representative of highly susceptible cultivars.

Free access