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  • Author or Editor: John A. Biernbaum x
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Medium CO2 and O2 partial pressures were measured at three locations [3.8 (top layer), 7.5 (middle layer), and 10.3 (bottom layer) cm below the rim] in 15-cm-tall pots containing flowering chrysanthemums [Dendranthem×grandiflorum (Ramat.) Kitamura] grown in one of three root media. Average ambient medium CO2 and O2 partial pressures were 63 Pa and 21 kPa, respectively, and were similar in the three sampled layers in root media with an average moisture content of 50% to 60% of container capacity. Within 10 minutes after a drip-irrigation application of well water containing a titratable alkalinity to pH 4.5 of 320 mg CaCO3/liter, the partial pressure of medium CO2 increased to ≤1600 Pa and medium O2 decreased to 20.5 kPa in the top and middle layers of the pot. With subirrigation, medium CO2 partial pressures increased to ≤170 Pa and medium O2 remained at 21 kPa. When reverse-osmosis purified water (titratable alkalinity to pH 4.5 of <20 mg CaCO3/liter) was used instead of well water, the large increase in medium CO2 did not occur, indicating that the bicarbonate alkalinity in the irrigation water was the source of CO2. The high medium CO2 partial pressure measured after irrigation was not persistent; within 180 minutes, it returned to levels averaging 45% higher (100 Pa) than that measured before the irrigation. Medium O2 also had returned to ambient levels 180 minutes after the irrigation.

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Chemical analyses of 4306 randomly selected greenhouse water samples for 1995 from the United States and Canada were obtained from four analytical laboratories and graphically characterized using a distribution analysis. For pH, electro-conductivity (EC), and nutrient concentrations, a mean and median value and the percentage of samples with concentrations above or below those generally considered acceptable are presented for all samples and the 10 leading states in floricultural production. The median nutrient concentrations were more representative of the type of water found throughout the United States and Canada than that of the mean values because of the unequal distribution of the data. The overall median water source had a pH of 7.1; an EC of 0.4 dS·m−1; an alkalinity of CaCO3 at 130 mg·L−1; (in mg·L−1) 40 Ca, 11 Mg, 8 SO4−S, 13 Na, 14 Cl, 0.02 B, and <0.01 F; a Ca: Mg ratio of 3.2, and a sodium adsorption ratio (SAR) of 0.7. The information presented characterizes irrigation water and may assist in developing more refined fertilizer recommendations for greenhouse crop production.

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Two experiments were run to validate a “Nitrogen Calcium Carbonate Equivalence (CCE)” model that predicts potential fertilizer basicity or acidity based on nitrogen (N) form and concentration for floriculture crops grown with water-soluble fertilizer in containers with minimal leaching. In one experiment, nine bedding plant species were grown for 28 days in a peat-based substrate using one of three nutrient solutions (FS) composed of three commercially available water-soluble fertilizers that varied in ammonium to nitrate (NH4 +:NO3 ) ratio (40:60, 25:75, or 4:96) mixed with well water with 130 mg·L−1 calcium carbonate (CaCO3) alkalinity. Both the ammonium-nitrogen (NH4-N) content of the FS and plant species affected substrate pH. Predicted acidity or basicity of the FS for Impatiens walleriana Hook.f. (impatiens), Petunia ×hybrida E. Vilm. (petunia), and Pelargonium hortorum L.H. Bailey (pelargonium) from the Nitrogen CCE model was similar to observed pH change with an adjusted R 2 of 0.849. In a second experiment, water alkalinity (0 or 135.5 mg·L−1 CaCO3), NH4 +:NO3 ratio (75:25 or 3:97), and N concentration (50, 100, or 200 mg·L−1 N) in the FS were varied with impatiens. As predicted by the N CCE model, substrate pH decreased as NH4 + concentration increased and alkalinity decreased with an adjusted R 2 of 0.763. Results provide confidence in the N CCE model as a tool for fertilizer selection to maintain stable substrate pH over time. The limited scope of these experiments emphasizes the need for more research on plant species effects on substrate pH and interactions with other factors such as residual limestone and substrate components to predict pH dynamics of containerized plants over time.

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Abstract

Inconsistent yield increases in the United States have prevented recommending triacontanol (TRIA) for commercial application. Based on tests over several years, TRIA is recommended for use on many vegetable and agronomic crops in most provinces in the People's Republic of China. Their formulations were shown either to be less effective or no better than the colloidal dispersion developed by the Procter and Gamble Co. TRIA dispersions passed through 2 standard field sprayers and 3 of 5 experimental small-plot sprayers lost at least 37 % of their activity as measured by the increase in maize (Zea mays L.) seedling growth. Hexane extracts of water passed through sprayers and polyvinyl chloride (PVC) tubing contained more than 5 μg/liter of di-(2-ethyl)hexyl phthalate. This phthalate ester, as well as other phthalates, decreased activity of both the colloidal dispersion and emulsion formulations of TRIA at phthalate concentrations of 5 μg/liter or more. Phthalate esters are common in the environment, including water of developed countries, and are important constituents of the PVC tubing used on most American field and small-plot sprayers. Sprayers equipped with other types of hoses did not inactivate TRIA as measured by the growth of maize seedlings.

Open Access

Abstract

The yield response of crops to triacontanol (TRIA) applied as a colloidal dispersion was tested with 13 crop species in 45 field experiments over a 3-year period. Foliar application of TRIA resulted in treatment effects with 11 of the 13 crops and in 30 of the 45 experiments. The average yield increase was 14% with the optimum TRIA concentration in tests where yield was significantly increased, and was 5% over all 45 experiments. In seven experiments, significant yield decreases averaging 10% were measured with TRIA concentrations that increased crop yield of the same species in other tests. The most effective TRIA concentrations generally were 0.1 to 1.0 μg·liter−1. No particular stage of crop development for treatment was optimal for all crops. Based on the results of these studies, TRIA cannot be recommended for commercial application to crops in Michigan or similar environments. Chemical names used: 1-triacontanol (triacontanol).

Open Access

Two surveys were conducted to determine characteristics important in containerized edible flowers that could be sold in retail outlets. Self-selected participants at Bloomfest at Cobo Hall, Detroit, were assigned to one group that rated the importance of attributes such as color of pansy (Viola ×wittrockiana Gams. `Accord Banner Clear Mixture'), color combinations, container size, and price. Participants assigned to a second group rated color, color combinations, and container size. Flower color was allocated the most points in the purchasing decision (63% for the first group and 95% for the second), with a mixture of all three colors (blue, yellow, and orange) being the most desirable. Responses were subjected to Cluster Analysis (SPSS Inc., Chicago), which resulted in the formation of three distinct groups. The groups were labeled “Likely Buyer” (those who had eaten and purchased edible flowers before and rated characteristics of edible flowers favorably); “Unlikely Consumer” (those who had eaten edible flowers before and had rated characteristics of edible flowers unfavorably); and “Persuadable Garnishers” (those who had not eaten edible flowers before, but were very likely to purchase edible flowers for a meal's garnish).

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Two surveys were conducted to assess consumer and professional chefs' perceptions of three edible-flower species. Our objectives were to determine opinions, preferences, and uses of Viola tricolor L. `Helen Mount' (viola), Borago officinalis L. (borage), and Tropaeolum majus L. `Jewel Mix' (nasturtium). Flowers were grown using certifiable organic methods and chosen to reflect a variety of flower tastes, textures, and appearances. We quantified three attributes (taste, fragrance, and visual appeal) with a total of seven semantic, differential scales adapted from a scaling authority. The attributes were rated as: visual—“appealing”, “desirable,” and “very interested in tasting”; fragrance—“appealing” and “pleasant”; and taste—“tasty” and “desirable”. Garden Day participants were self-selected to evaluate and taste flowers from a consumer perspective. When asked to rate the three species on visual appeal and desire, no less than 76% of consumers awarded all flowers an acceptable rating. We found similar results when consumers answered questions regarding the taste of two of the three species. Results from this study support our hypothesis that customers would rate edible flower attributes highly and would be likely to purchase and serve the three species tested. Members of the Michigan Chefs de Cuisine Association participated in a similar survey. At least 66% of these chefs rated the three visual attributes and two fragrance attributes of viola and nasturtium acceptable. Chefs' ratings of the fragrance of borage as “appealing” and “pleasant” were higher than those of consumers, but the ratings were still low, 21% and 25%, respectively. Unlike consumers, chefs' ratings of the taste of viola as “appealing” and “desirable” were low (29% and 36%, respectively). We found some minor differences in ratings when groups were compared, using demographic variables as a basis for segmentation, indicating a homogenous marketing strategy may be employed.

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Do consumers prefer certain combinations of edible-flower species and colors over other assortments? Two hundred and sixteen people were self-selected for a survey at a Michigan flower show to rate 15 photographs of edible flowers arranged in 0.24-L, clear, plastic containers. Each container had either an individual species or combinations of Viola tricolor L. `Helen Mount' (viola), Borago officinalis L. (borage), and Tropaeolum majus L. `Jewel Mix' and `Tip Top Apricot' (nasturtium). To determine what color(s) of nasturtium participants would prefer, containers held either orange and crimson, peach and cream, or a combination of all four flower colors. Participants rated photographs using a semantic differential on a 7-point Likert scale (7 being the highest rating) based on their likelihood to purchase each container of edible flowers to serve to family and friends in a meal. Participants were asked an additional 21 questions regarding their attitudes about edible flowers, gardening habits, dining habits, and several demographic questions. Responses were subjected to conjoint analysis (SPSS Inc., Chicago). The addition of other species to nasturtium (viola, borage, viola, and borage) had a greater relative importance (53%) than the color of the nasturtium (47%). A mixture of all four nasturtium colors (peach, cream, orange, and crimson) was awarded the highest utility (0.091). Peach and cream nasturtiums or containers that did not contain any nasturtium flowers at all were least preferred (-0.070 and -0.083 utilities, respectively). Mean ratings that participants assigned to containers of edible flowers supported these utilities. The container assigned the highest mean rating included nasturtiums of all four colors, yet 66% were unlikely to purchase any container with 10% insect damage. Differences in preferences were noted using selected demographic characteristics such as age, gender, and income.

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A small suction lysimeter tube (SLT) was used to extract media solution samples for twelve pot plant species in peat-based media subirrigated with 50, 100, or 200 mg · liter-1 N and K2O. Media samples from different pots were also tested using the saturated media extract (SME) procedure. Sample solution pH, EC, NO3 --N and K+ were measured with Cardy flat electrode meters. Averaged over crops, solution pH was similar for SLT and SME (after extraction) at each N concentration. The mean (12 crops × 3 reps at each N level) SME and SLT solution EC and K+ concentrations were similar for samples collected from the 50 and 100 mg · liter-1 N treatments. NO3 --N values were lower with the SLT than SME method at 50 mg·liter-1 N. SLT levels for EC, NO3 --N, and K+ were 27, 39, and 24% higher than SME values for samples collected from the 200 mg·liter-1 N treatments. Sample variation between replicates and between methods for the single pot samples was unacceptable. More testing is needed with SME and SLT samples from the same pot and composite samples from several pots, but SLT sampling is fast, nondestructive, simple, and economical at $6-7 per tube.

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The rhizon soil solution sampler (RSSS) currently is being used for in situ extraction of the soil solution for nutrient analysis of mineral soils used to produce field-grown crops. In this study, laboratory and greenhouse experiments were conducted to test the effectiveness of the RSSS for in situ solution extraction from soilless container root media and to compare an RSSS extraction method for measuring root-medium pH, electrical conductivity (EC), and NO3-N and K concentrations with that measured with the saturated media extract (SME) method. A near 1:1 correlation was found between the pH, EC, and NO3-N and K concentrations measured in the extracted solution of the RSSS and SME method in media without plants and in media from ten species grown using three water-soluble fertilizer concentrations applied by subirrigation. More testing is needed with the RSSS, perhaps using composite samples form several pots for analysis. The RSSS shows promise for nutrient extraction in container-grown crops because it is fast, nondestructive, simple, economical, and has minimal effect on the nutritional status of the medium in the pot.

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