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Climate control is an important aspect of greenhouse crop management. Shading is one popular method for reducing excess solar heat radiation and high air temperatures in the greenhouse during the summer season. A new innovative technology has recently been developed and is based on the injection of liquid foam between the double layers of polyethylene of the greenhouse roof. The foam can be used as a shading method during the warm days of the summer. This is the first investigation into the effect of shading using the liquid foam technology on greenhouse and plant microclimates. Our research was conducted over 2 years in two different areas of Canada. Experimental greenhouses were retrofitted with the new technology. Tomato (Solanum lycopersicum) and sweet pepper (Capsicum annuum) were transplanted. Two shading strategies were used: 1) comparison of a conventional nonmovable shading curtain to the liquid foam shading system and application of liquid foam shading based only on outside global solar radiation; and 2) application of foam shading based on both outside global solar radiation and greenhouse air temperature. Data on the greenhouse microclimate (global solar radiation, air temperature, and relative humidity), the canopy microclimate (leaf and bottom fruit temperatures), and ventilation (opening/closing) were recorded. Our study showed that the retractable liquid foam technology improved greenhouse climate. Under some conditions (very sunny and hot days), a large difference in air temperature (up to 6 °C) was noted between the unshaded and shaded greenhouses as a result of liquid foam application (40% to 65% shading). Foam shading also increased relative humidity by 5% to 12%. Furthermore, bottom fruit temperatures stayed cooler 3 h after shading treatment was stopped. As well, a reduction in ventilation needs was observed with liquid foam shading.

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This study was conducted to compare different formulations of a slow-release fertilizer with a conventional fertilizer program to determine their impact on yield and growth of bell pepper (Capsicum annuum). Two formulations of a methylene-urea slow-release fertilizer (Nitamin®) were evaluated on drip-fertigated and plastic-mulched bell peppers during 2006 in the eastern coastal plain and western Appalachian mountains of North Carolina. Liquid slow-release formulations were applied the first 6 or 9 weeks of the growing season and a dry formulation was banded at planting. Treatments were compared with the extension-recommended rate of 200 lb/acre nitrogen (N) (NC-200) and a high-input fertilizer rate of 300 lb/acre N (HI-300) from calcium nitrate injected in 12 weekly applications of drip irrigation. Irrigation was applied twice per week. The slow-release granular formulation at 200 lb/acre N produced the highest marketable yield and better canopy quality in eastern soil. Early marketable yield for this treatment accounted for 46% of the total yield. All slow-release treatments had higher N use efficiency (NUE) values than NC-200 and HI-300 in the eastern study. In loam soil (western study), pepper yield was statistically similar among treatments. Lower rates (150 lb/acre N) of slow-release fertilizer performed as well as NC-200 and HI-300 for marketable yield. Low rates (150 lb/acre N) of one of the liquid formulations performed better in total and marketable NUE than NC-200 and HI-300 in Fletcher, North Carolina. Liquid and dry formulations of slow-release fertilizer showed a potential to be used on bell pepper production across the state at reduced N rates, with greater impact on yield in coarse-textured soils found predominantly in the eastern coastal plain region.

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Composts made from organic wastes have the potential to substitute for peat and bark as components of container growth substrates. Composts for this research were produced in small-scale aerobic bins using biosolids blended with construction debris, storm debris, or horse waste in a 1:3 (v:v ratio). The composts were screened and blended 1:1 (v:v) with douglas fir (Pseudotsuga menziesii) bark to produce substrates. They were compared with a peat–perlite control substrate, a biosolids blend control substrate, and substrates made from a commercial biosolids compost mixed 1:1 with bark and from fiber from an anaerobic digester (dairy manure and food waste) mixed 1:1 with bark. Chemical and physical properties of the substrates were measured before transplanting, and growth, quality, and leaf color of ‘Little Hero Flame’ marigold (Tagetes patula) and ‘Golden California Wonder’ bell pepper (Capsicum annuum) were measured in a replicated greenhouse study comparing the substrates at two rates of nitrogen (N) application. The experimental biosolids composts-bark substrates performed similar to the peat–perlite and biosolids blend controls for growing marigold and pepper. The commercial biosolids compost mixed with bark did not perform as well as the experimental substrates or the controls. Digester fiber-bark was intermediate between commercial biosolids compost-bark and other treatments. Higher N rates improved plant growth and quality across all container substrates in pepper, but had fewer significant effects on marigold. Experimental substrates were coarser texture than the peat–perlite or biosolids blend controls, resulting in higher aeration porosity (AP) and lower water-holding capacity (WHC), but performed well nonetheless under the drip irrigation used in this study. Using locally sourced organic waste materials as container substrates can help capture value from organic wastes and contribute to the sustainability of nursery production practices.

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A field study was conducted in 2010 and 2011 to determine the suitability of Earth-Kind® production principles for home vegetable gardening. Earth-Kind® production encourages water and energy conservation, and reduction of fertilizer and pesticide use. Seven vegetable cultivars [Sweet Banana and bell pepper (Capsicum annuum); Celebrity and Juliet tomato (Solanum lycopersicum); Spacemaster cucumber (Cucumis sativus); Ichiban eggplant (Solanum melongena); Spineless Beauty zucchini (Cucurbita pepo)] were grown in mushroom compost (MC) or city compost (CC). Both composts were incorporated preplant into the soil with shredded wood mulch placed over them. In each year, nitrogen (N) fertilizer (15.5N–0P–0K from calcium nitrate) was applied preplant to CC plots to bring initial soil fertility levels similar to MC plots. No additional fertilizer was applied during the growing season. Drip irrigation was supplemented weekly. One application each of neem oil and pyrethrin (organic insecticides) and chlorothalonil (synthetic fungicide) was applied before harvest in 2010, but none was applied in 2011. Results indicated that Earth-Kind® technique could be effectively implemented in a home vegetable garden. MC is better suited for Earth-Kind® vegetable production than CC for some vegetables. Banana pepper, bell pepper, and zucchini had twice the yield in MC plots when compared with CC plots. No yield differences (P > 0.05) were observed between composts for tomato, eggplant, or cucumber. With proper irrigation and soil preparation practices such as addition of compost and mulch, Earth-Kind® vegetable gardening techniques can be used for selected vegetable crops without additional N fertilizer or pesticides. Furthermore, Earth-Kind® vegetable gardening can be successful as long as the home gardener understands that low yields may result from using this production method. However, often the home gardener is more concerned about producing vegetables using sustainable, environmentally friendly methods than maximizing yields.

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Nitrogen (N) use efficiency (NUE) of crops is examined by taking into account both plant N uptake efficiency, focusing on the recovery of fertilizer-N, and the utilization efficiency of the absorbed N. The latter is further analyzed as the overall effect of the absorbed N on crop leaf area, light absorption, photosynthesis, crop growth, biomass partitioning, and yield. The main sources of variation for the NUE of crops are considered, and several of them are discussed based on results from field experiments carried out at the University of Perugia (central Italy) between 1991 and 2008 on sweet pepper (Capsicum annuum), lettuce (Lactuca sativa), and processing tomato (Solanum lycopersicum). More specifically, the effects of species, cultivar, fertilizer-N rate, form and application method (mineral and organic fertilization, green manuring, fertigation frequency), and sink limitation are reported. Implications for residual N in the soil and leaching risks are also discussed. The fertilizer-N rate is the main factor affecting crop NUE for a given irrigation management and rainfall regime. Indeed, avoiding over fertilization is the first and primary means to match a high use efficiency and economic return of fertilizer-N with limited environmental risks from nitrate leaching. The form and application method of fertilizer-N also may affect the NUE, especially in the case of limiting or overabundant N supply. Particularly, high fertigation frequency increased the recovery of fertilizer-N by the crop. It is suggested that species-specific curves for critical N concentration (i.e., the minimum N concentration that allows the maximum growth) can be the reference to calibrate the quick tests used to guide dynamic fertilization management, which is essential to achieve both the optimal crop N nutritional status and the maximum NUE.

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The increase in U.S. demand for colored bell peppers (Capsicum annuum) has been satisfied with increased supplies from imports and increased domestic production. Greenhouse-grown peppers of red, orange, and yellow colors were imported during the period 1993–2002 at wholesale fruit market prices that were three to five times greater than field-grown fruits. With high market prices and a suitable environment for growing colored peppers under inexpensive greenhouse structures [<$40/m2 ($3.7/ft2)], up to 14 ha (34.6 acres) of greenhouses produced bell peppers in Florida in the year 2002. To estimate the profitability of a bell pepper greenhouse enterprise, a budget analysis was used to calculate the returns to capital and management. Production costs of greenhouse-grown peppers were estimated assuming the use of current technology applied in commercial greenhouse crops in Florida and in experimental crops at the University of Florida. Production assumptions included a crop of nonpruned plants grown in soilless media in a highroof polyethylene-covered greenhouse [0.78 ha (1.927 acres)] located in north-central Florida. For a fruit yield of 13 kg·m–2 (2.7 lb/ft2), the total cost of production was $41.09/m2 ($3.82/ft2), the estimated return was $17.89/m2 ($1.66/ft2), and the return over investment was 17.1%. A sensitivity analysis indicated that fruit yields should be greater than 7.8 kg·m–2 (1.60 lb/ft2) in order to generate positive returns based on a season average wholesale fruit price of $5.29/kg ($2.40/lb). For this price, a range of possible fruit yields [5–17 kg·m–2 (1.0–3.5 lb/ft2)] led to returns ranging from –$9.52 to 30.84/m2 (–$0.88 to 2.87/ft2), respectively. The estimates indicate that production of greenhouse-grown peppers could represent a viable vegetable production alternative for Florida growers.

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Vegetables are grown throughout the U.S. on various soil types and in various climates. Irrigation is essential to supplement rainfall in all areas to minimize plant water stress. In the U.S., irrigated vegetable production accounts for about 1.9 million ha or 7.5% of the irrigated area. California, Florida, Idaho, Washington, Texas, Nebraska, Oregon, Wisconsin, and Arizona account for 80% of the U.S. production of irrigated vegetables. In the U.S., surface and subsurface (seepage) irrigation systems were used initially and are currently used on 45% of all irrigated crops with a water use efficiency of 33%. Sprinkler or overhead irrigation systems were developed in the 1940s and are currently used extensively throughout the vegetable industry. Sprinkler systems are used on 50% of the irrigated crop land and have a water use efficiency of 75%. In the late 1960s, microirrigation (drip or trickle) systems were developed and have slowly replaced many of the sprinkler and some of the seepage systems. Microirrigation is currently used on 5% of irrigated crops. This highly efficient water system (90% to 95%) is widely used on high value vegetables, particularly polyethylene-mulched tomato (Lycopersicon esculentum), pepper (Capsicum annuum), eggplant (Solanum melongena), strawberry (Fragaria ×ananassa), and cucurbits. Some advantages of drip irrigation over sprinkler include reduced water use, ability to apply fertilizer with the irrigation, precise water distribution, reduced foliar diseases, and the ability to electronically schedule irrigation on large areas with relatively smaller pumps. Drip systems also can be used as subsurface drip systems placed at a depth of 60 to 90 cm. These systems are managed to control the water table, similar to that accomplished with subsurface irrigation systems, but with much greater water use efficiency. Future irrigation concerns include continued availability of water for agriculture, management of nutrients to minimize leaching, and continued development of cultural practices that maximize crop production and water use efficiency.

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In the southwestern U.S. growing region, which includes southern New Mexico, west Texas, and southeastern Arizona, mechanical harvest of chile peppers (Capsicum annuum) is increasing because of the high cost of hand labor. Mechanical harvesters have been developed, but there is limited information on the performance of chile cultivars when machine harvested. Four red chile pepper cultivars (New Mexico 6-4, Sonora, B-18, and B-58) were grown in a farmer's field near Las Cruces, N.M., and harvested in October 2000 using a double-helix-type harvester. Ethephon was applied 3 weeks before harvest at 1.5 pt/acre (1.75 L·ha-1) to promote uniform ripening. Ethephon caused fruit of `B-18' and `B-58' to drop before harvest, thereby affecting yield results. Treatment with ethylene-releasing compounds is not recommended for these cultivars. `Sonora' and `New Mexico 6-4'dropped much less fruit than `B-18' and `B-58' after the ethephon treatment. Dry weight marketable yield ranged from 1419 to 2589 lb/acre (1590.5 to 2901.8 kg·ha-1), and total yield potential (discounting dropped fruit) ranged from about 2500 to 3100 lb/acre (2802.1 to 3474.6 kg·ha-1), depending on cultivar. Harvest efficiencies of 73% to 83% were observed among the cultivars. Trash content of the harvested chile varied from 25% to 42% of dry weight. Trash was predominantly diseased and off-color fruit, leaves, and small stems. Trash content was highest for `Sonora'. `New Mexico 6-4' had the greatest marketable yield and harvest efficiency among the cultivars evaluated in this study.

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Biochar, a carbon-rich material derived from the pyrolysis of organic matter, exhibits beneficial chemical and physical properties when added to a soilless medium. Research on the use of biochar to improve plant productivity and growth has increased over the past decade, and has focused on using biochar as an alternative to sphagnum peatmoss. However, little work has been done to determine whether biochar can be used to partially replace commercially available sphagnum peatmoss–based greenhouse medium in vegetable transplant production. This study investigated the potential for supplementing a greenhouse growing medium with biochar for ‘Paladin’ pepper (Capsicum annuum) transplant production. Biochar was added to a soilless mix at rates of 0%, 20%, 40%, 60%, or 80% (by weight). Pepper seedlings were grown for 56 days in 50-, 72-, or 98-cell transplant trays at each of the five levels of biochar concentration. Germination increased in the 50- and 72- cell trays with 20%, 40%, and 60% biochar; however, biochar had no effect on germination in the 98-cell tray. Seedling height and dry weight decreased as biochar concentration and cell number increased. Seedling stem diameter also decreased with increasing cell number and biochar concentration. Leaf SPAD readings (indirect measurement of chlorophyll) decreased with increasing biochar rate. Medium pH increased with increasing biochar application rates. Higher rates of biochar (60% and 80%) increased pH well beyond 7.0 and negatively affected transplant growth. Overall results indicate positive effect of biochar in sphagnum peatmoss–based growing mix on seedling growth characteristics; although higher biochar concentrations could negatively affect seedling growth. Biochar can successfully replace up to 40% of sphagnum peatmoss–based growing medium and serve as a sustainable alternative medium in vegetable transplant production.

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We evaluated emerging biopolymer horticultural products that provide fertilizer nutrients to plants (fertilizing biocontainers, pelletized biopolymer fertilizer, and biopolymer fertilizer spikes) for their effectiveness during greenhouse production and garden growth of floriculture crops, and during postproduction culture of container ornamentals. Greenhouse experiments (in 4.5-inch containers) and garden trials were performed with tomato (Solanum lycopersicum), pepper (Capsicum annuum), petunia (Petunia ×hybrida), and marigold (Tagetes patula). Postproduction experiments were performed with 12-inch hanging baskets containing lobelia (Lobelia erinus), trailing petunia (Calibrachoa ×hybrida), and petunia, and with 13-inch patio planters containing zonal geranium (Pelargonium ×hortorum), spikes (Cordyline indivisa), bidens (Bidens ferulifolia), and trailing petunia. Although slightly less effective than synthetic controlled-release fertilizer (CRF), all three nutrient-containing biopolymer horticultural products were sufficient and suitable for providing fertilizer nutrients to plants grown in containers and in garden soil. Results of the postproduction experiment provided proof-of-concept for the effectiveness and potential of biopolymer fertilizer spikes as a sustainable method for providing fertilizer nutrients to containerized plants. The current formulation of pelletized biopolymer fertilizer was somewhat more effective for vegetable crops (pepper and tomato) than for floriculture crops (marigold and petunia). For plants produced in 4.5-inch containers, the combination of the fertilizing biocontainer with no additional fertilizer in the greenhouse, then burying the fertilizing container beneath the plant to degrade and provide nutrients in the garden was very effective. Biopolymer horticultural products represent a promising alternative to petroleum-based plastic containers and synthetic fertilizers. Adoption of some or all of these technologies could improve the environmental sustainability of the horticulture industry without reducing productivity or efficiency, and without increasing labor intensity.

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