Media Amendments Research Articles

Organic amendment of commercial culture media for improving control of Rhizoctonia damping-off of cabbage

Rhizoctonia solani AG-4 is an important damping-off pathogen of cabbage. Using a baiting technique, R. solani was recovered from the cabbage seeds buried in nine commercial culture media. The frequency of seed colonization by R. solani varied with medium, ranging from 2.5% in Nev-3 to 30% in Floradur A and SI 2; the seeds were examined after being buried for 48 h. Among the five formulated organic compounds tested as amendment for the commercial BVB No. 4 medium, FBN-5A was most effective in controlling damping-off. Although both rates of FBN- 5A, 0.1% and 0.2%, significantly reduced incidence of damping-off, FBN-5A at 0.1% was the more suitable treatment because it not only reduced the disease incidence, but also enhanced the growth of cabbage. The results were confirmed in a large-scale experiment in a commercial automatic environment-controlled greenhouse. This study suggests that the FBN-5A compound offers potential for commercial use as an organic amendment for the management of Rhizoctonia damping-off of vegetable crops.

Antibiotic amendment for suppression of indigenous microflora in feed sources for an Escherichia coli auxotroph lysine assay.

Growth responses of lysine auxotrophic mutants of Escherichia coli have been used as a measurement of bioavailable lysine in protein sources and animal feeds. Sterilizing feed samples by autoclaving to eliminate non-specific background growth of indigenous feed micro-organisms prior to conducting the bacterial assay may introduce chemical and physical alterations to the feeds, influencing the estimation of available feed lysine. In this study, an antibiotic- and antifungal-supplemented medium was constructed to support growth of an E. coli lysine auxotroph assay organism, and was tested for its ability to repress indigenous bacterial and fungal growth in feed samples. To determine which antibiotics to include, an ampicillin-sensitive E. coli lysine mutant strain (ATCC no. 23812) was screened for antibiotic resistance and transformed with a plasmid carrying an ampicillin resistance gene. Maximum optical density quantitative response of the E. coli auxotroph to lysine was not altered by the antibiotic medium amendments (ampicillin, novobiocin and cycloheximide). Indigenous microfloral growth in a variety of typical animal feeds was suppressed in the presence of the antistatic agents. The estimated lysine recovery was 91.6% and 98.1% when the medium was used in an assay of available lysine in a lysine-supplemented feed. This indicates that the antibiotic-amended basal medium can be used for the E. coli-determined lysine availability of a variety of animal feeds without prior sterilization of the feed sources.

123 The Potential Use of Spent Mushroom Compost as a Soil Amendment for Nursery Crop Production

The use of spent mushroom compost (SMC) as a media amendment for containerized greenhouse and nursery crop production is a promising alternative to disposal of this by-product of mushroom production. Fresh SMC is the compost that is removed from the mushroom house and used without further weathering. The objectives of this study include first, identification of key factors involved its successful use and second demonstration of the effective use of SMC by nurserymen. The plant material used includes both bedding plants and woody perennial species. Results demonstrate that the key factor in the use of SMC for plant production is high soluble salts. Leaching can reduce the high soluble salts. In addition, special consideration should be given to the reduction in potted media volume over time due to composting that continues after the material is removed from mushroom production. SMC as the sole growing media was not as effective as when SMC was amended with a commercial nursery growing mix. Several species were grown in 0%, 25%, 50%, 75%, and 100% mixtures of SMC and a commercial nursery mix. All species grew well in 50% SMC/50% nursery mix.

417 Earthworm Castings as a Media Amendment for Poinsettia Production

An experiment was conducted to determine the effect of earthworm (Eisenia fetida andrei) castings derived from sheep, cow, or horse manures on the growth of poinsettia (Euphorbia pulcherrima `Freedom Red'). Poinsettia cuttings were transplanted to 1-L (15-cm-diameter) plastic pots that were filled with castings:peat moss at 1:0, 1:3, 1:1, 3:1, or 0:1 by volume for each animal manure evaluated. Plants were fertilized using 200 ppm N from a 15-5-25 (N-P2O5-K2O) fertilizer applied with the irrigation water. Total bract area and growth index were greatest in those treatments consisting of 3:1 and 1:1 (castings:peat) from sheep and cow manures, 1:0 (castings:peat) from cow manure and for growth index only, 1:0 (castings:peat) from horse manure. For these two characteristics, 100% sheep manure castings and 100% peatmoss had the lowest values. The time to anthesis was least when poinsettias were grown in 3:1 or 1:1 castings:peat from sheep and cow manures and 1:3, 1:0, or 3:1 from sheep, cow, or horse manure respectively. Anthesis was most delayed when plants were grown in 100% castings from sheep manure.

Revegetation on a Coal Fine Ash Disposal Site in South Africa

AbstractEight medium amendments were conducted on top of a fine ash coal dump (i) to evaluate a few cost‐effective treatments that could determine the minimum fertility status required for the local ash to support the establishment of a viable vegetation cover, and (ii) to select suitable grass species that would establish on the ash and could serve as a foundation for long‐term rehabilitation. Degree and success of grass establishment per medium amelioration treatment is expressed in terms of total biomass, percentage basal cover, and in terms of a condition assessment model. Both the chemical and physical nature of the ash medium before and after amendment was characterized, as were the concentrations of some essential and potentially toxic elements in leaf samples. In terms of medium amelioration 5000 kg ha−1 compost, or 500 kg ha−1 kraal manure or 480 kg 2:3:2 ha−1 proved to be most effective. The grass species that occurred with the highest frequency, irrespective of treatment, were the perennials bermudagrass [Cynodon dactylon (L.) Pers. var. dactylon], weeping lovegrass [Eragrostis curvula (Schrader) Nees], and the annual teff [Eragrostis tef (Zuccagni) Trotter]. Of the potentially toxic extractable metals monitored in the leaves of vegetation on the dump, only Se accumulated to an average level of 4.4 mg kg−1 that could be toxic to livestock.

The Use of Recycled Waste Paper as an Al Source for Blue-flowering Hydrangea

Blue color development in Hydrangea macrophylla is usually accomplished by applying Al as an alum drench. Drenches are applied during forcing 10–14 days after transplanting at a rate of 17,500 mg·L-1. Cultivars Blue Wave and Nikko Blue were used to evaluate if the Al contained in waste paper can provide the necessary Al for blue flower development. Two waste paper forms, pelletized and crumble, were used as surface mulches and as media amendments. The amendments were incorporated into the media at transplanting and mulches were applied either at transplanting or 28 days later. Alum drenching was initiated at transplanting as a control. Leachates were collected weekly using the VTEM. Total Al, electrical conductivity, and pH were determined on all samples. All waste paper treatments resulted in pink flowers in both cultivars. Leachate pH, from plants in this test, was >6.5. Aluminum concentration was greater than the 15 mg·L-1 Al needed for blue color development in flowers, but Al concentration decreased with time. Control of pH at the waste paper surface and in the media is critical for increasing the availability of labile Al for uptake by hydrangea.

Composted Green Waste as a Container Medium Amendment for the Production of Ornamental Plants

Seed germination and crop growth characteristics were determined for Tagetes spp. L. `Lemondrop', marigold; Catharanthus roseus Don. `Little Pinkie', vinca; Petunia hybrida Vilm. `Royalty Cherry', petunia; Dendranthema×grandiflorum (Ramat.) Kitamura `White Diamond', chrysanthemum; Pittosporum tobira Ait. `Wheeleri', sweet mock orange; Photinia ×fraseri Dress., photinia and Juniperus sabina L. `Moon Glow', juniper grown in various size containers containing blends of composted green waste (CGW) and UC Mix. Seed germination, plant height, and stem and root fresh and dry mass were lowest in unamended CGW. For most plants studied, a CGW: UC Mix blend containing at least 25% UC Mix was required for adequate growth and development. Germinating seeds and young seedlings were most adversely affected by unamended CGW. As plants grew and were transplanted into larger containers (10- and 15-cm pots, 530 and 1800 mL), they were better able to grow in media with higher CGW content.

Using granular media amendments to enhance NOM removal

Granular media amendments to slow sand filtration show promise in improving organic precursor removal.Filters amended with anionic resin and granular activated carbon (GAC) achieved significantly higher (>75 percent) removals of organic carbon and trihalomethane formation potential during an 89‐day filter run than any other filter media combination studied. There was no significant difference in removal rate with GAC used as a surface or sublayer amendment. Treatment efficiencies of the aluminum oxide–, anthracite‐, and clinoptilolite‐amended slow rate filters could not be clearly distinguished from conventional slow sand filters with precursor removals <25 percent. Organic precursor removal by slow rate filters was considered a function of both the microbiological maturity and adsorptive capacity of the schmutzdecke and filter bed. Maintenance of elevated removals by resin‐ or GAC‐amended slow sand filters will eventually require the use of deeper amendment layers or frequent replacement or

Suitability of Composted Green Waste for Horticultural Uses

The study was undertaken to determine the physiochemical properties and nutrient supply characteristics of composted green yard and landscape waste (CGW) and to document its performance as a field soil amendment or constituent of potting media. Three CGW samples were collected from each of two composting operations in California from Nov. 1993 to Apr. 1994. Macronutrient content varied widely between operations, and among samples from the same operation, with mean total N, P, and K levels averaging 1.1%, 0.26%, and 0.67%, respectively. Controlled-environment incubation of a moist 1 CGW: 9 soil blend (2 weeks at 30 °C) was conducted to determine net N mineralization from CGW. Despite low C: N ratios (<12), five of six CGW samples showed net immobilization, a characteristic of immature compost. An in-field incubation of soil amended with 1% or 2% CGW (w/w) showed no net N release from CGW over 4 months. In a field trial, bell pepper (Capsicum annuum L.) fruit yield was increased by soil amendment with CGW (17 or 34 t·ha–1) under a low N fertilizer regime (168 kg·ha–1), but was unaffected where sufficient fertilizer N (280 kg·ha–1) was applied. CGW was compared with peat as a constituent of potting media; both were blended 1:1 (v/v) with perlite and used in the production of tomato (Lycopersicon esculentum Mill.) and marigold (Tagetes erecta L.) plants under varying fertigation regimes (constant feed of N at 0, 50, or 100 mg·L–1 as 15N–13P–12K). CGW was equivalent or superior to peat in plant growth; CGW did contribute to crop macronutrient nutrition, but the highest fertigation rate was required for optimum growth.

Rooting and Subsequent Overwinter Survival of Stem Cuttings of Stewartia ovata

Abstract Three experiments were conducted using stem cuttings of Stewartia ovata (Cav.) Weatherby to evaluate: 1) effects of indolebutyric acid (IBA) concentration on percent rooting and rooting index (root system size), 2) influence of N rate and medium amendments (dolomitic lime and/or complete fertilizer) on budbreak prior to overwintering and survival and shoot growth of cuttings following overwintering, and 3) effects of chilling duration on overwinter survival and subsequent shoot growth. Softwood cuttings of S. ovata were taken on June 19 and July 23, 1992, and treated with 0, 1000, 2000, 4000, or 8000 ppm IBA in 50% isopropyl alcohol. Rooting percentages and rooting index were highest for cuttings taken in June and treated with 2000 or 4000 ppm IBA. In the second experiment, cuttings were rooted in pine bark containing three different amendment combinations, and fertilized weekly with either 0, 50, 100, or 200 ppm N following root initiation. Overwinter survival was higher for cuttings rooted in pine bark or pine bark amended with lime, but decreased for cuttings in pine bark amended with lime and a complete fertilizer. Increasing N fertilization up to 200 ppm weekly stimulated budbreak prior to overwintering, resulted in greater shoot growth following overwintering, but had no effect on overwintering survival. In the third experiment, rooted cuttings were subjected to 0, 2, 4, 6, 8, or 10 weeks chilling at 6C (43F). Cuttings chilled for 10 weeks had the highest percent budbreak (survival) and greater overall shoot growth over a 12 week forcing period.

Shredded Waste Tires as a Growing Media Amendment for Production of Flowering Vinca

Catharanthus roseus plants were grown in three media, each containing one of two by-products of shredded waste tires. The media were no. 1) 1 rubber*: 1 peat moss, no. 2) 1 rubber*: 1 vermiculite: 2 peat moss, and no. 3) 2 rubber*: 1 vermiculite: 1 peat moss (by volume) where rubber* indicates either 0.6 cm shredded rubber or a fibrous by-product. Control plants were grown in 1 peatmoss: 1 rockwool and 1 vermiculite: 1 peatmoss (by volume). Catharanthus roseus cv. Peppermint Cooler plants were grown for 7 weeks in 10-cm containers at a commercial Denver-area greenhouse. Data taken included plant heights, plant widths, flowers per stem, and dry weights. Visually, plants grown in the no. 2 mix, with either fiber or 0.6-cm rubber, were similar to the controls and superior to the other two mixes. Ending plant heights were similar among the two controls and no. 2 with fiber and were taller than all other combinations. Flower numbers were greater in the 1 rockwool: 1 peat moss control and no. 2 mix with fiber than any other treatment. The same was true for stem number and dry weight. Results indicate that the no. 2 mix of 1 fiber: 1 vermiculite: 2 peatmoss has potential for container crop production.

Factors contributing to the loss of ethanologenicity of Escherichia coli B recombinants pL0I297 and KO11.

To be economic and to be compatible with modern continuous bioconversion systems, it is imperative that the process organism exhibits an extremely high degree of stability. In the case of ethanol production from lignocellulosic biomass, functional stability of the potential process biocatalyst can be assessed in terms of the capacity to sustain high-performance fermentation during the continuous fermentation of biomass-derived sugars. This investigation employed glucose- or xylose-limited chemostat culture to examine the functional stability of two patented, genetically engineered E. coli-namely E. coli B (ATCC 11303) carrying the Zymomonas genes for pyruvate decarboxylase and alcohol dehydrogenase II on a multicopy plasmid pLOI297 and a chromosomal pet integrant of strain 11303, designated as strain KO11. Both recombinants carry markers for antibiotic resistance and have been reported to exhibit genetic stability in the absence of antibiotic selection. Chemostats were fed with Luria broth (LB) (with 25 g/L sugar) at a dilution rate of 0.14 and 0.07/h when the feed medium was glucose-LB and xylose-LB, respectively. They pH was controlled at 6.3. With glucose, both recombinants exhibited a rapid loss of ethanologenicity even when selection pressure was imposed by the inclusion of antibiotics in the feed medium. With strain KO11, increasing the concentration of chloramphenicol from 40 to 300 mg/L, resulted in a retardation in the rate of loss of ethanologenicity, but it did not prevent it. Under xylose limitation, the plasmid-bearing recombinant appeared to be stabilized by antibiotics, but this did not reflect genetic stability, since the slower-growing revertant was washed out at a dilution rate of 0.07/h. With both recombinants, interpretation of functional stability with xylose was complicated by the inherent ethanologenicity associated with the host culture. Based on an average cost for large bulk quantities of antibiotics at $55/kg and an amendment level of 40 g/m3, the estimated economic impact regarding the potential requirement for operational stabilization by antibiotics in a plant operating in batch mode varied from a maximum of 29 cents/gal of E95 ethanol for antibiotic amendment of all fermentation media to a minimum of 0.45 cents/gal where antibiotics were used exclusively for the preparation of the inocula for every fourth batch fermentation cycle. The high degree of instability observed in these continuous fermentations does not auger well for the proposed potential industrial utility of these patented, genetically engineered constructs for the production of fuel ethanol from biomass and wastes.

CYCLOHEXIMIDE AS A MEDIA AMENDMENT FOR ENUMERATING BACTERIAL POPULATIONS IN ANIMAL FEEDS

The present study was designed to evaluate cycloheximide as a potential media amendment for differential bacterial and fungal enumeration of animal feeds. The objectives of this study were to determine the effect of cycloheximide on bacterial growth rates and to evaluate its efficacy for the reduction of indigenous spreading fungi when enumerating bacterial populations in three types of feeds and after short or long‐term storage. Escherichia coli, Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes and Pseudomonas fluorescens were grown in tryptic soy broth containing cycloheximide to determine its effect on bacterial specific growth rates. Growth rates of B. cereus and S. aureus were significantly decreased by the addition of 600 and 1000 mg/L cycloheximide respectively, but other pure cultures were not significantly influenced by cycloheximide addition. Intrinsic bacterial populations from feed were not significantly affected by cycloheximide additions at concentrations from 10 to 300 mg/L, but the indigenous spreading molds from feeds were significantly decreased by these cycloheximide concentrations and were decreased below detection levels by 300 mg/L of cycloheximide. The addition of 300 mg/L of cycloheximide effectively eliminates fungal growth for accurate enumeration of bacterial populations in feeds.

GROWTH RESPONSE OF SALMONELLA SPP. TO CYCLOHEXIMIDE AMENDMENT IN MEDIA

The present study was designed to evaluate cycloheximide as a potential media amendment to prevent fungal overgrowth on selective media for salmonellae enumeration. The objectives were to determine the effect of cycloheximide on Salmonella spp growth rates and to determine the effect of cycloheximide addition on Salmonella enumeration in selective media. The bacteria tested included two strains of Salmonella typhimurium (NO/NA and LT2) and one strain of Salmonella arizonae. All strains were grown in tryptic soy broth containing cycloheximide to determine the effect of cycloheximide on bacterial specific growth rates. The growth rate of all strains grown in tryptic soy broth were not significantly influenced by addition of cycloheximide at concentrations up to 1,000 mg/L. Growth rates of S. typhimurium NO/NA in minimal media were significantly decreased by addition of cycloheximide aerobically (300 mg/L) and anaerobically (600 mg/L). However, S. typhimurium NO/NA populations on brilliant green agar, MacConkey agar, and from selenite cysteine broth and tetrathionate broth were not affected by cycloheximide additions at concentrations up to 1,000 mg/L. Cycloheximide has potential as a fungistat additive for salmonellae selective media.

Growth of Two Tropical Foliage Plants Using Coir Dust as a Container Medium Amendment

Growth of Ravenea rivularis Jumelle and Perrier (majesty palm) and `Lady Jane' Anthurium Schott was compared in container media, using as a primary organic component sphagnum peat, sedge peat, or coir dust. Growth index and shoot and root dry weights of majesty palm were significantly higher in the coir than the sedge peat medium. Growth index and shoot dry weight were only marginally higher for the anthurium in the coir vs. sedge peat medium, and root dry weights were comparable. Both crops grew equally well in the coir and the sphagnum peat medium. The sedge peat medium had the most air porosity and the least water-holding capacity of the three media at the initiation of the trials, but at termination showed a reversal of these parameters. The coir medium showed the least change in these parameters over 8 months. High-quality coir dust appears to be an acceptable substitute for sphagnum or sedge peat in soilless container media.

Composted Poultry Litter as a Low-cost Media Amendment

The poultry industry is a $1 billion industry in Texas, with most production centered in eastern Texas. The nursery industry is a $600 million industry, with 25% of the producers located in eastern Texas. With hundreds of millions of birds produced each year, and each bird producing ≈2 lb of manure, waste disposal is a growing problem. Composted poultry litter was mixed with composted pine bark to create five media with varying percentages of poultry litter as a component: 0%, 5%, 10%, 20%, and 40%. A randomized complete-block design was used with poultry litter rates as main plots and plant species tested as subplots. Five species included: tomato, marigold, Cortaderia selloana, Asian jasmine, and Salvia leucantha. Prior to planting, all 1-gal containers were leached with 1000 ml of water, the leachate collected, and tested for conductivity. Plant growth measurements to be presented include plant height and dry weight. The results of media and leaf tissue nutrient analysis will be presented.

Shredded Tire Rubber as a Medium Amendment for Container-grown Greenhouse Plants

Media blends containing 25%, 40%, and 50% shredded tire rubber were compared to two commercial media, Baccto Grower's Mix and Ball Peat-Lite Mix, to evaluate its potential as a container medium amendment for container-grown greenhouse plants. Salvia splendens `Red Hot Sally' and Vinca rosea `Cooler Peppermint' grown in 25% rubber were marketable with growth similar to or superior to those grown in the commercial media. Exacum affine `Little Champ', Vinca rosea `Cooler Grape', Tagetes erecta `Discovery Yellow', and Begonia semperflorens `Vodka' grown in 25% rubber were of marginally acceptable quality. Plants grown in 40% or more rubber were shorter and chlorotic compared to those in the commercial media. Exacum affine grown in 40% or more rubber contained high levels of zinc, which may have been linked to the chlorosis and growth reduction. Rubber reduced media water-holding capacity, while cation exchange capacity and pH were not affected.

Using Ground Kenaf Stem Core as a Major Component of Container Media

Results of a series of experiments showed that the ground, noncomposted woody stem core of kenaf (Hibiscus cannabinus L.) can be used successfully as a container medium amendment for producing potted tropical foliage and woody nursery crops. The growth of Brassaia actinophylla Endl., Hibiscus rosa-sinensis L. `Jane Cowl', and Pittosporum tobira (Thunb.) Ait. `Wheeler's Dwarf' in 70% or 80% kenaf (by volume, the balance being peatmoss or perlite or vermiculite and other nutrients) was similar to or greater than growth in two popular commercial mixes. Undesirable shrinkage of certain kenaf-amended media during plant production was reduced greatly by mixing it with at least 30% peatmoss or by using a coarser kenaf grind. As the portion of peatmoss increased from 0% to 30%, noncapillary porosity and water-holding capacity per container increased. A medium consisting of 50% kenaf, 40% peatmoss, and 10% vermiculite held as much water as a commercial medium. However, plants in most kenaf-amended media required more-frequent irrigation than those in the commercial media.

Growth of Chrysanthemum with Ground Automobile Tires Used as a Container Soil Amendment

A study was conducted to determine the potential for using ground automobile tires as a container medium amendment. Rooted cuttings of chrysanthemum [Dendranthema × grandiflorum (Ramat.) Kitamura] were planted in 1.56-liter pots containing 1 sand:2 sawdust (v/v) or media in which coarsely or finely ground particles of rubber substituted for 33%, 67%, or 100% of the sawdust. Amendment with the coarse material decreased total porosity and container capacity and increased air-filled porosity and bulk density relative to the sawdust control. Amending the medium with the fine material did not appreciably alter total porosity, container capacity, or bulk density, but did increase air-filled porosity. Plant height, fresh weight, dry weight, and number of open flowers were reduced significantly in rubber-amended media compared to sawdust controls. Rubber amendment reduced shoot tissue concentrations of N, P, K, Ca, Mg, and Cu, but increased Zn as much as 74-fold over control values. There was no accumulation of other heavy metals (Cd, Cr, Ni, Pb) or Na in the tissue due to rubber amendment. This study demonstrates that ground tires might be used as a component of container media in the production of greenhouse chrysanthemums. However, growth reductions and the potential for Zn toxicity may limit the usefulness of ground tires as a substitute for conventional organic amendments.

GROUND KENAF STEM CORE CAN BE USED SUCCESSFULLY AS A CONTAINER MEDIUM AMENDMENT

The woody stem core of kenaf (Hibiscus cannabinus L.) was ground and used without composting as a container medium amendment for the production of several tropical foliage and nursery species. Media made of various proportions of kenaf and peat moss were amended with micronutrients, gypsum, dolomitic lime stone powder, superphosphate, Osmocote, a wetting agent and a fungicide. Plant growth in these media was compared to that in two widely used commercial media. Brassaia actinophylla in kenaf amended media grew taller and had more leaves, heavier weight, and better root grade than those produced in the two commercial media. Pittosporum tobira plants in kenaf media were taller, wider, and heavier than those grown in the commercial media. Other species tested also responded favorably to media amended with kenaf. Media containing the ground kenaf core tended to maintain the optimum pH better and their leachate samples had lower electrical conductivities than the commercial media. Shrinkage was a problem when 100% fine ground kenaf was used, but this was greatly reduced by adding peat moss or using a coarser grind. Media containing kenaf required more frequent watering than did the commercial media.