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Alicia Sanchez-Escarcega and George C. Elliott

Growth inhibition has been observed with plants grown in potting media containing compost. The objective of this study was to determine if \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{2}^{-}\) \end{document} toxicity or N immobilization might be involved. Two potting media were blended from aged pinebark, vermiculite, sphagnum peat, and compost, along with a control medium without compost, and cropped with Dendranthema ×grandiflorum `Bravo'. Pots were fertilized weekly with a 15N–1.1P–12.5K soluble fertilizer at 24 mM N. Plants were harvested and media samples were collected at intervals. Saturated media extracts (SME) were prepared immediately. Separate samples were incubated at 25C for 4 days following addition of 2.5 mmol urea-N/cm3. In SME of one compost-containing medium, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{2}^{-}\) \end{document} was present at 0.25 ± 0.03 mM 2 weeks after transplant, and at progressively lower concentrations thereafter. In incubated samples of the same medium, accumulation of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{2}^{-}\) \end{document} was observed after 3 weeks of cropping, with peak accumulation of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(0.7{\pm}0.32{\ }{\mu}{\ }\mathrm{mol}\mathrm{NO}_{2}^{-}{/}\mathrm{cm}^{3}\) \end{document} after 9 weeks of cropping. Nitrite was scarcely detectable in other media. Some indication of N immobilization was obtained, as NH+ 4levels decreased during incubation without any increase in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}, and \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document} present at the beginning of incubation disappeared during incubation. In this study, significant effects of media on plant growth were not related to differences in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{2}^{-}\) \end{document} accumulation or N immobilization. However, subsequent studies appear to have established such a relationship.

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Fred D. Rauch and Paul K. Murakami

Several trials have been conducted to determine the optimum amendment level for the production of container foliage plants in a 1:1, V:V, peat:perlite potting mix.

Experiments with various controlled-release fertilizers have shown superior growth and quality with resin coated products in an artificial mix. This appears to correspond to the nitrogen source with those containing nitrate and ammonium nitrogen giving better results than those with other nitrogen sources, such as IBDU or urea.

Trials with variable rates of dolomitic lime resulted in better or equal growth and quality of a variety of foliage plants without added lime even at pH levels of 4.0.

These results suggest the recommendations for the production of container plants in mixes without soil need to be reviewed and perhaps revised.

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Mark A. Nash, Tim P. Brubaker, and Billy W. Hipp

Expanded shale and peat moss were mixed in 5 ratios and evaluated as potting media for Petunia and Impatiens. Two grades of shale (coarse and fine) were used. Bulk density increased linearly with increasing shale whereas total pore space and container capacity increased linearly with increasing peat. Air space of peat-fine shale was consistently lower than that of peat-coarse shale when the peat/shale ratio was the same. Container capacity of peat-fine shale was consistently higher than that of peat-coarse shale when the peat/shale ratio was the same. Growth and quality of both bedding plants increased quadratically with increasing peat in peat-coarse shale and increased linearly with increasing peat in peat-fine shale. Highest growth and quality of both plants were found in peat-coarse shale media with at least 50% peat and in peat-fine shale media with at least 75% peat.

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George C. Elliott and Harvey J. Lang

Fungicides were applied at label rates to two commercial soilless potting media in which Iris siberica L. crowns had been potted and were subsequently grown under greenhouse conditions. Effects of fungicides on urea hydrolysis were inconsistent and generally insignificant. Ammonium oxidation was inhibited to varying degrees by Truban, Benlate, Banol, and Subdue. In a subsequent experiment, the same fungicides were added to cropped samples of the same media in vitro, followed 12 hours later by a solution containing urea and ammonium. Urea hydrolysis was essentially unaffected by fungicide treatments. Subsequent oxidation of ammonium was inhibited by Truban and Banol only in one medium. Transient accumulation of nitrite was inhibited by Truban but stimulated by Benlate in both media. When added to pure cultures of Nitrosomonas europea and Nitrobacter agilis, Truban completely inhibited oxidation of ammonium and nitrite. Benlate partially inhibited oxidation of ammonium and nitrite, while Subdue and Banal partially inhibited oxidation of ammonium but not nitrite. Chemical names used: [Methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate] (benomyl); N- (2,6-dimethylphenyl) -N- (methoxyacetyl)alanine methyl ester (metalaxyl); [2-chloro-6-(trichloromethyl)pyridine (nitrapyrin); 5-Ethoxy-3-(trichloromethyl)-1,2,4-thiadiazole (ethazol); Propyl[3-(dimethylamino)propyl]carbamate monohydrochloride (propamocarb).

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Muhammad Mumtaz Khan*, Muhammad Azam Khan, Muhammad Asif Ali, and Hasnain Raza

Six-week-old rough lemon (Citrus jambhiri L.) seedlings uniform in size were transplanted from nursery to pots filled with peat, spent compost of mushroom and leaf manure used at different proportions with soil, sand and farm yard manure and grown in green house environment. Initial physical and chemical analysis of media indicated that electric conductivity (EC), total porosity, bulk density, moisture percentage, available nitrogen, phosphorus and potassium are more suitable for citrus plant growth and development than other media of different compositions. Peat + sand (1:1) had pH 6.7 which is optimum for growth of citrus nursery. After every four weeks plant length, stem diameter, number of leaves and leaf area were measured. Leaf analysis for N, P, K and mortality percentage was measured at the end of the experiment. Peat + sand (1:1) produced highest percentage of transplant success, plant height, stem diameter, and number of leaves as compared to all other treatments tested. At initial stage peat + sand (1:1) gave the highest results in relation to leaf area, but at the end of experiment it was observed that treatment with silt + spent compost (button) + spent compost (oyster) (1:1:1), produced maximum leaf area with lush green leaves however, mortality rate was very high. This study suggests that peat + sand (1:1) may serve as a standard medium for the container grown citrus nursery.

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Andrew Koeser, Gary Kling, Candice Miller, and Daniel Warnock

purchasing considerations—including price and carbon footprint. These findings have led researchers to state that consumers are more interested in making the pots sustainable than the plants themselves ( Yue et al., 2011 ). Despite this consumer interest

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Sven E. Svenson

Shoot and root growth responses of `Cunningham's White' rhododendron (Rhododendron x) was studied when grown in black plastic or molded fiber pots treated with copper hydroxide, or not treated. Containers of two sizes were studied, and the influence of pot type on substrate temperature was recorded. Rhododendron shoot height and dry weight was not influenced by pot volume, pot type, or copper treatment at 49, 131, or 362 d after potting. Rhododendron shoots were larger when grown in 3.8-L (trade 2-gal) pots compared to 2.8-L (trade 1-gal) pots, or when grown in 3.8-L fiber pots compared to 3.8-L plastic pots, both 131 and 362 d after potting. Copper treatment did not influence shoot size. Copper treatment reduced the amount of circling or matted roots at the container-substrate interface for both plastic and fiber pots, but there was better control of root growth in 3.8-L pots compared to 2.8-L pots. Substrate average minimum temperatures were warmer, and average maximum temperatures were cooler when pots were located near the center of the growing block compared to the southwest corner ofthe growing block. Substrate average maximum temperatures were cooler in fiber pots compared to plastic pots, but only when pots were located on the southwest corner of the growing block.

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Shravan K. Dasoju and Brian E. Whipker

Drench applications of plant growth retardant paclobutrazol were applied at 2, 4, 8, 16, or 32 mg a.i./pot, plus an untreated control to pot sunflowers (Helianthus annuus cv. `Pacino') to determine its effect as a chemical height control. All paclobutrazol concentrations applied significantly reduced plant height by »27% when compared to the untreated control, but excessively short plants were observed at 16 and 32 mg a.i./pot. Plant diameter was also significantly decreased by »16% at 2 and 4 mg a.i./pot of paclobutrazol, when compared to the untreated control. Flower diameter decreased by »4% at 2 and 4 mg a.i./pot of paclobutrazol, but only concentrations ≥4 mg a.i./pot were significantly different from the untreated control. Paclobutrazol concentrations had no effect on days from potting to flowering. Drench concentrations of 2 and 4 mg a.i./pot of paclobutrozol produced optimum height control in relation to 16.5-cm-diameter pot size used.

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Kathryn Wimberley and Dr. Pat Williams

Kentucky West Nursery Cooperative, producers of pot-in-pot trees, needed recommendations on slow-release fertilizer applications due to regional environmental influences affecting production. Murray State University established a pot-in-pot tree nursery to research these influences in 2004. Two different fertilizer applications in three different treatments were tested on one-year old bare-root whips of Acer rubrum `Red Sunset' and `Autumn Blaze'. These trees were planted in 100% pine bark in 15-gallon pots and placed in the sockets with a complete random split-block design. Drip irrigation by spray stakes watered each pot. Nursery floor was kept clean by landscape fabric. New growth was pruned as needed to keep the trees within nursery standards. Tree calipers were measured on 1 Apr. and 1 Dec. 2004 at the beginning and end of growth. Leaves for chlorophyll readings were randomly selected to measure nitrogen uptake in late summer. Measurements were analyzed by SAS 9.1 and results found no significant differences among the treatments either in caliper increase or in chlorophyll levels (SAS, 2002). This experiment recommends a treatment using one application of slow-release fertilizer, versus split or additional applications, provides equal, quality growth of Acer rubrum `Autumn Blaze' and `Red Sunset'. The information gathered will direct fertilizer applications for KWNC and reduce their labor costs.

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Sven E. Svenson and Diane L. Johnston

Stem tip cuttings of Evolvulus glomeratus Nees & Mart., E. tenuis Nees & Mart., Lantana camara L. `Dallas Red,' and L. montevidensis Briq. `Alba' were rooted for 6 weeks in 57-mm-diameter (150 ml) square pots. Before rooting, interior surfaces of half of the pots were treated with 100 g Cu(OH)2/liter, while remaining pots were left untreated. Elongation of adventitious roots stopped when root tips came in contact with a Cu(OH)2-treated surface. Cupric hydroxide treatment reduced total root length and the length of the longest root for all four species, but did not influence root, shoot, or total plant weight. One month after transplanting to 150-mm-diameter (1.2 liter) hanging baskets, plants moved from Cu(OH)2-treated pots had more flowers than those transplanted from nontreated pots. Applying Cu(OH)2 to interior surfaces of pots used for propagation prevented root deformation, reduced root length, and increased flowering following transplanting.