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Greenhouse-Grown Bell Pepper Production

The Tomato Magazine
August 2006

Bell pepper growers in Florida, and perhaps other areas of the country, have a viable alternative to growing them in the field. During the 2002-2003 growing season, 17,800 acres of bell peppers were planted and mostly green bell pepper fruits (mature but unripe stage of fruit development) were harvested from these field crops. Colored bell pepper fruits (ripe) attract market values that are three to five times greater than green fruits, but high fruit quality and yield of colored fruits are difficult to obtain in open field environments.

High-quality colored bell peppers can, however, be produced year round and especially during the high-priced off seasons, in protected environments such as high passively ventilated greenhouses. Fruits can be harvested with red, orange, or yellow color depending on the pepper cultivar used. Indeed, essentially all of the high-quality and high-value colored bell peppers imported to the United States are grown in greenhouses. In Florida, a small number of growers already produce high-quality colored fruits in an area of about 45 acres.

During the past six years, University of Florida scientists at the Protected Agriculture Project, lead by Daniel J. Cantliffe, have been examining the production of greenhouse-grown peppers in Florida (http://www.hos.ufl.edu/protectedag/). Scientists Elio Jovicich, Daniel J. Cantliffe, John J. VanSickle, Lance S. Osborne, Nicole L. Shaw, Peter J. Stoffella, Steven A. Sargent, and Margaret L. Smither-Kopperl examined the production of greenhouse-grown peppers in Florida.

“The initial impetus for this research was to explore which greenhouse and management practices for pepper would work best in Florida,” says Jovicich. “We wanted to adapt what other countries were using and found that greenhouse roofs needed to be high to provide ventilation and allow cooling, shade systems and supplemental fuel heating were needed, and fertigation could be done in containerized plants filled with low-cost soilless media.”

In the U. S., the consumption of high-quality red, orange, and yellow bell peppers (Capsicum annuum) has been increasing dramatically the past decade. To satisfy consumer demand, Mexico, The Netherlands, Canada, Israel and Spain export high-quality greenhouse-grown peppers into the United States. In Florida, high market prices, consumer demand, and a suitable environment for growing colored peppers under protected agriculture have encouraged greenhouse growers to consider the economic viability of this crop.

The impending ban on methyl bromide, along with greater demand for high-quality colored peppers, may give growers a reason to consider growing peppers in greenhouses. Other pressures include urban sprawl and subsequent high prices for arable land. For the past five years, pepper ranked first in production area in Florida’s total greenhouse area dedicated to vegetable crops (followed by tomato, cucumber, and lettuce).

Jovicich, VanSickle, Cantliffe and Stoffella simulated a full production of greenhouse-grown peppers under a passively ventilated structure in Florida using management practices necessary to successfully grow peppers and turn a profit. The estimates indicate that production of greenhouse-grown peppers could represent a viable vegetable production alternative for Florida growers and possibly for growers in other regions of the United States.

A greenhouse production system of peppers greatly differs from the traditional field pepper cultivation system where plants are grown on polyethylene-mulched beds and with drip irrigation. In greenhouses, high fruit yield and quality are produced in a small area during an extended growing season. Moreover, soil sterilization is not needed, and water and nutrients that drain from the bottom of the plant containers can be recycled. The enclosed environment also makes the use of biological control practices for pest management more effective than in open fields, actually allowing the production of fruits that are pesticide-free.

Marketable fruit yields will vary with greenhouse location, growing season, plant density, trellis system, cultivar, irrigation, and fertilizer management. Current marketable yields of 1.6 to 3.0 lb. per square foot and potential yields of 4 lb. per square foot can be obtained in Florida in passively ventilated greenhouses with low use of heating fuel. “However, because of the higher costs involved with greenhouse growing systems compared to growing in the open field, greenhouse growers have to manage their crops to maximize fruit yield and quality while minimizing production costs per unit of greenhouse floor area,” says Jovicich.

Greenhouse Structures
In Florida, there is currently a trend towards using high-roof, passively ventilated greenhouse structures (13 foot or more to the roof gutter) for protected vegetable production.
The greenhouses are covered with polyethylene, which is replaced every three to four years. The side walls and roof vents can be covered with insect screens to restrict the entrance of pest insects and to keep beneficial insects, such as bumblebees, within the greenhouse.

“ These high-roof greenhouse designs are less expensive and more suited for use in regions with subtropical and tropical climates than structures covered with glass or polycarbonate,” says Jovicich. “Costs of passively ventilated greenhouses can range as much as 80 percent less per square foot than the types of greenhouses that seek maximum climate control.” Greenhouses with passive ventilation and heating provide a level of climate control that enables plants to survive and produce at economically sufficient yields.

Sweet pepper cultivars most commonly used in greenhouse production are hybrids that have bell-shaped or blocky-type fruits with red, orange, or yellow color when mature.

“Cultivars should be selected for a grower’s ability to market them, as well as pest and disease resistance or tolerance, low susceptibility to fruit disorders, and yield and quality performance,” says Jovicich. Some of the commonly used cultivars are Parker, Triple 4, Cubico, and Lorca for red, Kelvin for yellow, and Neibla and Emily for orange fruits. However, new pepper cultivars for greenhouse production are introduced by seed companies every year.

In a pepper cultivar trial conducted in a passively ventilated greenhouse in Gainesville, Florida, the total marketable yield was acceptable for 23 cultivars tested when grown and harvested during the winter months in north central Florida, according to a study by Shaw and Cantliffe in 2002. The red and yellow cultivars produced fruit yields of 1.8 to 2.2 lb. per square foot and the orange cultivars had yields of 1.4 to 2 lb. per square foot. When comparing cultivars for those with the highest yield and fruit quality characteristics with low amounts of culls or other disorders, the best red cultivars in the study were Lorca, Torkal, Triple 4, and Zambra; yellow cultivars were Pekin, Kelvin, Neibla, Bossanova, and Taranto; and orange cultivars were Paramo, Lion, and Boogie.

Growing Seasons
The most common greenhouse pepper production season extends from mid-July or early August to May. Long crops of up to 300 days are transplanted during the second or third week of July with a first harvest around the middle of October, ending in late May. Depending on fruit prices and on the quantity and quality of the fruits harvested, production may be extended until June.

High temperatures and humidity during July and August adversely affect production but are good for young plant growth. With some cultivars, percentages of unmarketable fruits increase during the late spring mainly due to a higher incidence of blossom-end rot and fruit cracking. Fruit set can also be low during the summer due to high rates of flower abortion under high temperatures. Air ventilation and shade materials for 30 percent shade help reduce high temperatures during the late spring, summer, and early fall. Currently, water misting is being evaluated as a cooling system for plants transplanted in the summer. Cold weather during winter can also adversely affect the set of marketable fruits due to poor pollination and delay maturation and earliness in production. “In central and northern Florida, optimum daytime temperatures required for pepper production can easily be achieved in winter while optimum night temperatures cannot, and therefore, heating during the night is necessary to increase fruit yield and improve fruit quality,” says Jovicich.

Soilless Culture Systems
Greenhouse pepper crops in Florida are grown in soilless culture. Methyl bromide is not needed since problems with soil-borne diseases and insect and nematode pests are avoided. The plants are grown in containers filled with soilless media, such as perlite, pine bark, or peat mixes. The media can be reused for two or three crops if disease contamination does not occur. The containers used are nursery pots (three and four gallons) with one plant per pot. Another planting scheme uses flat polyethylene bags that are three foot long (five gallons) with three to four plants per bag. The plant containers can be aligned in single or double rows, one next to the other, and can lead to plant population densities of 0.27 to 0.36 plants per square foot.

In local trials with greenhouse-grown peppers, fruit yields from plants grown in three-gallon pots or five-gallon flat bags have been similar. Also, similar marketable fruit yields were harvested from plants grown in various substrates, such as perlite, pine bark or peat-perlite mixes. “Pine bark, milled and sieved to particle sizes smaller than one square inch, have shown to be a promising medium in Florida because of its low cost, availability, lack of phytotoxicity and excellence as a plant production media,” says Jovicich.

Irrigation and Fertilization
Pepper plants in soilless culture are fertigated frequently with a complete nutrient solution. Nutrient solution concentrations are similar to those used for tomatoes grown in soilless culture. The concentrations of most of the nutrients required by pepper plants in larger quantities are increased with plant growth. For example, in the irrigation solution used with soilless culture, the concentration of nutrients in parts per million (ppm) can be N:70, P:50, K:119, Ca:110, Mg:40, and S:55, starting when transplanting the seedlings.
In plants at full production, the nutrient concentration levels can reach N:160, P:50, K:200, Ca:190, Mg:48, and S:65 ppm, respectively.

At the time of transplanting, seedlings can be irrigated about 10 times a day and deliver about 1.3 fluid ounces per irrigation event. As plants grow and season temperatures rise, irrigation frequency and volume per irrigation event can be increased up to 40 times a day and deliver about 2.5 fluid ounces per irrigation event.

Systems for recycling the fertigation solution are available and provide a more sustainable use of water and nutrients. “With these ‘closed’ irrigation systems, the solution that drains from the pots is sanitized and then the pH and EC are corrected to meet the plant needs. Subsequently, the nutrient solution can be recycled on the same pepper crop,” says Jovicich.

Transplanting, Pruning, and Training
Transplanting of plants is also a bit different in greenhouse production. Frequent irrigation and high levels of salt deposits near the cotyledonary node level can promote localized epidermal injuries on a swollen stem base and fungal infection can lead to basal stem rots and sudden plant wilts. To avoid injuries to the plant stem below the cotyledonary leaves, seedlings should be transplanted into the soilless culture substrate to the depth of the first leaf node. To reduce creating a humid environment at the base of the stem, irrigation emitters that are placed near the seedling stems at transplanting can be gradually moved back two to three inches from the base of the pepper plants over a three-week period.

Greenhouse pepper cultivars generally have an indeterminate pattern of growth. Because the plants can grow up to six foot tall during a growing season of 250 days, they need to be supported vertically. Pepper plants can be trellised to the Dutch “V” system or to the “Spanish” system. The “V” system consists of forming a plant with two main stems by removing one of the two shoots developed on each node and leaving one or more adjacent leaves per node. The pairs of stems are kept vertically by the use of hanging twines that wind around the stems as they grow.

In the “Spanish” trellis system, the plant canopy is allowed to grow without pruning. The plants are vertically supported by a structure of poles and horizontal twines extended on both sides of the plant rows. Labor requirement for the “Spanish” system is reduced minimally by 75 percent of the labor used compared with the “V” trellis system. In a study where the two trellis systems were compared, the percentage of fruits with blossom-end rot at the end of the spring was lower in the non-pruned plants.

While pepper plants are self-pollinated, the use of bumblebees inside the greenhouse help to ensure the set of high-quality fruits, especially during the cool season when pollen viability is lower. “Although one bumblebee hive (containing 60 bees) per 16,000 square feet might seem costly to the grower, pollination done by workers would be less efficient and much more expensive,” says Jovicich. “The hive should be placed under a shade in summer and in the sun in winter and isolated from ants. The hives should contain a supplement food for the bees during periods of low abundance of flowers because over-visited flowers may lead to fruits with cork-like spots at the blossom-end.”

Harvesting and Packing to Maintain Postharvest Fruit Quality
Throughout the harvest season, pepper fruits ripen in flushes or waves of production. Under warm environments, fruits can be picked once or twice a week at close to full color. Nonmarketable fruits should be removed from the plants as soon as they are observed. Clipped peduncles keep a better appearance during shipping and handling and cause fewer injuries to adjacent peppers.

Marketable fruits are graded by diameter, and fruits with greater size bring higher prices. Fruit grades can follow the USDA standards for field-grown peppers or classifications based on diameter ranges similar to greenhouse peppers imported from Holland (extra-large, diameter more than 3.3 inches; large, 3 to 3.2 inches; medium, 2.5 to 2.9 inches; and small, 2.2 to 2.3 inches).

Peppers should not be submerged in water during the transfer to the packing line since water can easily infiltrate the hollow pod and cause postharvest decay. The use of overhead spray with clean water and brush rollers works well for washing.

Pepper fruit respiration can be delayed by quickly cooling the product to the lowest safe temperature of 48 to 50° F and 90 to 95 percent relative humidity, resulting in a postharvest life of two to three weeks. Rapid cooling of harvested sweet peppers is essential in reducing marketing losses. Forced-air cooling is the preferred method.
Pre-cooling within a few hours of harvest and storage in a high relative humidity will minimize weight loss and shrivel symptoms, and maintain firmness. Waxing provides some surface lubrication, which reduces chafing in transit. Water loss can also be limited by packing cooled peppers into cartons with moisture-retentive liners or into perforated polyethylene bags.

Pests and Diseases
Pests are reduced but not eliminated in screened greenhouse structures. Transplants must be free of pests and weeds must not be present inside the greenhouse. “The major arthropod pests observed in greenhouse peppers in Florida are broad mite (Polyphagotarsonemus latus), two-spotted mite (Tetranychus urticaae), western flower thrips (Frankliniella occidentalis), melon thrips (Thrips palmi), green peach aphid (Myzus persicae), melon or cotton aphid (Aphis gossypii), silverleaf or sweet potato whitefly (Bemisia agentifolii), pepper weevil (Anthonomus eugenii), fungus gnats (Bradysia spp.), and several lepidopterous pests.”

Fungal diseases that may be present are powdery mildew (Leveillula taurica) and Fusarium (Fusarium oxysporum and F. solani).

Insecticides are available to control insect and mite pests. However, many chemicals negatively affect bumblebees, beneficial organisms, and the pepper plant itself. Some products, such as soaps, oils, and sulfur, are often phytotoxic to pepper plants in the greenhouse.

Biological control practices used in other regions and crop systems are being evaluated by researchers in the Protected Agriculture Project at the University of Florida and at the Mid-Florida Research and Education Center.

Compared to the use of pesticides, with biological control, insects do not develop the resistance that they do to certain insecticides. Also, restricted reentry period to the greenhouse due to the use of insecticides are eliminated, the environment for workers is safer, and harvest products can be labeled “pesticide free,” which may bring higher prices and/or increase consumer demand. The use of biological controls will require that the crop is scouted frequently to determine presence and to estimate population densities of crop damaging pests and their natural enemies.

The production of greenhouse-grown peppers represents an alternative crop in Florida, and ongoing research by the Protected Agriculture Project continues on greenhouse-grown peppers on production systems, fruit quality, cultivars, nutrient and water management, integrated pest and disease management, postharvest, and marketing.

© 2006 Columbia Publishing

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