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- Author or Editor: Daniel J. Cantliffe x
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Seed germination is a critical step to achieve economic success in a transplant operation. Total germination of a seed lot dictates total plant sales by the producer, while uniformity of germination dictates the quality of the transplant crop. Using high vigor seed will help to achieve uniform stands, as well as maximize stands, in the transplant house or field. In order to maintain the highest seed quality, transplant producers should store unused seeds at recommended temperature and relative humidity for the crop species. Methods to promote uniformity and optimum stands under a wide range of conditions include the use of seed priming, film coating with fungicides, and pelleting for ease of planting.
Since the establishment of the land-grant systems in the late 1800s, universities and experiment station systems have sought out and tested vegetable germplasm for its suitability in regional and local areas across the United States. The private seed industry continued to grow, both in number and volume of sales through the early half of the twentieth century. It was during this time that many of the public breeding programs at land-grant universities began corollary plant breeding programs in variety development for vegetables. For many years it was a cooperative coexistence between the private seed industry and the public programs, wherein the seed industry derived much of its germplasm for new variety releases from the public sector. Beginning in the 1970s, the numbers of public breeders began to decline, while the numbers, especially of PhD plant breeders in the private sector, began to proliferate. Throughout this 100-year period university personnel were actively involved in vegetable variety trials, both on main campuses as well as at experiment stations, and in many cases in locales in various counties through cooperative efforts with county agents. Up through this period much credit could be given to individual faculty members for their involvement in such endeavors. In the past 10 to 20 years, many things have changed in university operations and perspectives, namely faculty are only given credit for refereed publications, regardless of the area in which they work. Moreover, they must constantly procure money to support their programs. In the past, vegetable variety testing generally did not lead to refereed publications and was not supported by the industry. Moreover, as previously mentioned many of the public programs in germplasm improvement for vegetables across the United States have ceased, thus ending a direct need for variety testing to support these programs. The critical issue for today's faculty is the relative importance of variety testing and delivering information to the general public versus how they would support such a program and eventually get academic credit for conducting such a program.
For many years, the former Vegetable Crops Department, now the Horticultural Sciences Department, at the University of Florida offered a vegetable crop industries course. This one-credit course is offered each year as a 3- to 5-day field trip into vegetable production areas of Florida in the spring semester during spring break. The intent of the course is to give undergraduate students an extensive on-site evaluation of the application of scientific principles learned in lectures related to Florida's commercial vegetable industry. A new, innovative approach to structuring this course was initiated recently wherein only alumni of the department interacted with the students on all phases of commercial vegetable agriculture in Florida. These alumni had obtained degrees at the BS, MS, or PhD level and represented many professional backgrounds related to producing, handling, and marketing vegetables. Students were exposed to real-life situations and were encouraged to discuss and seek employment opportunities during the farm visitations. Student expenses were offset by donations from the Florida vegetable industry.
Mini or “baby” vegetables have become increasingly popular items for restaurant chefs and retail sales. Squash (Cucurbita pepo) are generally open-field cultivated where climate, insect, and disease pressures create challenging conditions for growers and shippers who produce and market this delicate, immature fruit. In order to overcome these challenges, in Spring 2003 and 2004, 18 squash cultivars, including zucchini, yellow-summer, patty pan/scallop, and cousa types, were grown hydroponically in a passively ventilated greenhouse and compared for yield of “baby”-size fruit. Squash were graded as “baby” when they were less than 4 inches in length for zucchini, yellow-summer, and cousa types and less than 1.5 inches diameter for round and patty pan/scallop types. In both seasons, `Sunburst' (patty pan) produced the greatest number of baby-size fruit per plant, while `Bareket' (green zucchini) produced the least. The zucchini-types produced between 16 and 25 baby-size fruit per plant in 2003. The yellow summer squash-types produced on average 45 baby fruit per plant. The production of the patty pan/scallop types ranged from 50 to 67 baby-size fruit per plant depending on cultivar. The cousa types produced approximately 30 baby-size fruit. Total yields were lower in 2004 due to a shortened season. Squash plants will produce numerous high quality baby-sized fruit when grown hydroponically in a reduced pesticide environment of a greenhouse where they can be harvested, packaged, and distributed to buyers daily. The cultivars Hurricane, Raven, Gold Rush, Goldy, Sunray, Seneca Supreme, Supersett, Butter Scallop, Sunburst, Patty Green Tint, Starship, Magda, and HA-187 could be used for hydroponic baby squash production.
Production and quality of bell pepper (Capsicum annuum) fruit were evaluated in a passively ventilated greenhouse, in soilless media trellised to a “V” system (two-stempruned plants) or the “Spanish” system (nonpruned plants) in flat bags or nursery pot containers; and densities of 1.5, 1.9, 3.0, and 3.8 plants/m2 (0.14, 0.18, 0.28, and 0.35 plants/ft2), in a winter-to-summer-crop in Gainesville, Fla. The trellis systems did not affect total marketable fruit yields but production of extra-large fruit was higher (38%) in non-pruned than in pruned plants. Marketable fruit yields were similar in plants grown in bags and pots, and had positive linear responses to increased plant density. Not pruning reduced by half the percentage of fruit with blossom-end rot. Pruned plants produced 50% fewer flower bud supporting nodes than non-pruned plants but had a greater percentage of fruit set. Regardless of trellis systems, fruit set per plant decreased linearly as plant density increased. Overall, the “Spanish” trellis system at a density of 3.8 plants/m2 resulted in greater yields of extra-large fruit and required 75% less labor than the “V” system to prune and support the plant canopy.
Beit Alpha cucumber (Cucumis sativus) is an exciting new greenhouse crop for production in the southeastern U.S. and Florida. Beit Alpha cucumbers are short, seedless fruit with dark-green skin and an excellent sweet flavor. Beit Alpha-types are the leading cucumber types in the Middle Eastern market and have gained recent popularity in Europe. Beit Alpha cucumbers grown hydroponically under a protected structure have prolific fruit set, yielding more than 60 high-quality fruit per plant during one season. U.S. hydroponic vegetable production is generally associated with structure and irrigation investments which are costly as well as other inputs, such as the media, which must be replaced annually or with each crop. Beit Alpha cucumber `Alexander' was grown in Spring 2001 and 2002 in a passive-ventilated high-roof greenhouse in Gainesville, Fla. Three media types, coarse-grade perlite, medium-grade perlite, and pine bark, were compared for efficiency of growing cucumbers (production and potential costs). During both seasons, fruit yield was the same among media treatments [average of 6 kg (13.2 lb) per plant]. Irrigation requirements were the same for each type of media; however, leachate volume was sometimes greater from pots with pine bark compared to either grade of perlite suggesting a reduced need for irrigation volume when using pine bark. Pine bark is five times less expensive than perlite and was a suitable replacement for perlite in a hydroponic Beit Alpha cucumber production system.
A greenhouse hydroponic system, which uses suspended plastic troughs, was found to be an efficient system for the production of high quality strawberry (Fragaria ×ananassa) plantlets. In this system micropropagated mother plants of `Oso Grande' and `Sweet Charlie' produced an average of 84 and 80 daughters per mother plant, respectively, in 1996, at a plant density of 3 mother plants/ft2 (32 mother plants/m2). Nearly 100% of the plantlets harvested from the system were successfully rooted in plug trays, and showed no symptoms of leaf or crown diseases.
Galia-type muskmelon (Cucumis melo cv. Gal-152) was grown as a fall and spring crop to determine the effect of plant density (1.7, 2.5, 3.3, and 4.1 plants/m2) on yield, fruit quality, plant growth, and economic feasibility for producing the crop in a greenhouse. Plant density had no influence on the early or total number of fruit produced per plant. Marketable yields increased linearly from 11.0 to 20.0 kg·m−2 in fall and from 21.9 to 48.3 kg·m−2 in spring with increasing plant density. Mean fruit size was unaffected by plant density during fall (mean weight, 1.0 kg), but was reduced linearly during spring from 1.8 kg at 1.7 plants/m2 to 1.5 kg at 4.1 plants/m2. Soluble solids content was unaffected by plant density in either fall or spring and averaged 10.1% in both seasons. Number of leaves per plant was unaffected by plant density, but internode length was increased at 4.1 plants/m2 compared with plants from the other densities. Increasing the plant density of ‘Gal-152’ muskmelon grown under protected cultivation led to increased yields in both fall and spring without negatively impacting fruit quality. When the market price is $1.44/kg, increased yields at 3.3 plants/m2 can potentially increase net returns over yields of plants spaced at 2.5 plants/m2 by 25% and nearly double net returns from plants grown at 1.7 plants/m2.
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.