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Monica Ozores-Hampton and Thomas A. Obreza

In 1997, 24.7 million t of solid waste were produced in Florida (about 4.3 kg per person per day). If all biodegradable material was composted, 12.4 million t of compost would be produced annually. If this compost was used as a soil amendment in fruit and vegetable production, knowledge of its N mineralization rate would be important to determine the application rate. We measured the field N mineralization of four commercial Florida composts mixed with sandy soil (dry weight rate): Jacksonville (yard trimming compost, 127 t•ha-1), Sumter (municipal solid waste compost, 67 t•ha-1), and Nocatee and Palm Beach (yard trimming and biosolids composts, 63 and 56 t•ha-1). The control treatment was unamended soil. Open-top, 20-cm long PVC columns were filled with soil/compost mixtures and fitted at the bottom with a trap containing cation and anion exchange resin to capture leaching NO3 and NH4-N. The columns were buried in the soil at ground level and incubated in situ for 45 and 90 days in the spring. The resin was extracted with 1 N KCl and the mass of NO3-N and NH4-N adsorbed was determined. A similar procedure measured the NO3-N and NH4-N left in the soil/compost mixture. After 90 days in the field, net N immobilization was observed with Nocatee (-4.3%), Sumter (-3.0%), and Jacksonville (-1.3%) composts, while N mineralized (6.4%) from Palm Beach compost. Where N immobilization occurred, composts had initial C: N greater than 20: 1 and N concentration <1.6%. Mineralization occurred where compost had C: N ratio lower than 20: 1 and N concentration greater than 1.6%.

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Iwanka Kozarewa, Daniel J. Cantliffe, Russell T. Nagata and Peter J. Stoffella

1 Present address: Umeå Plant Science Center, Umeå, SE 901 87, Sweden. 2 To whom reprint requests should be addressed: Fax: 352-392-9905. Email: djc@mail.ifas.ufl.edu . 3 Everglades Research and Education Center, 3200 East Palm Beach Road, Belle

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Alan W. Meerow

Coir is the name given to the fibrous material that constitutes the thick mesocarp of the coconut fruit (Cocos nucifera L.). The long fibers of coir are extracted from the coconut husk and utilized in the manufacture of various products. The short fibers and dust (“pith”) left behind have accumulated as a waste product. Coir pith is light to dark brown in color and consists primarily of particles in the size range 0.2-2.0 mm (75-90%). In composition, it is 65-70% lignin and 20-30% cellulose. To date, few replicated tests have assessed the performance of coir pith as a plant growth medium. From April, 1993 to April, 1994, four ornamental crops (pentas, ixora, anthurium and majesty palm) were grown in container media that differed only in the peat fraction (40%), either sphagnum, Florida (sedge) peat, or coir pith. On the basis of plant growth parameters, coir pith was superior to sedge peat as a medium component (though only marginally for the anthurium) and at least equal to sphagnum peat. In addition to physical qualities equal to or better than sphagnum peat, coir decomposes more slowly than either sedge or sphagnum peat, withstands compression better and is easier to wet than peat. There are also no ecological drawbacks to the use of coir -- a waste product -- relative to the harvest of peat from wetland ecosystems.

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Henrique Mayer, Adrian Hunsberger and Marguerite Beckford

Miami-Dade County Extension, with the participation of University of Florida faculty and other speakers, created a Certified Course in Horticulture in 2005. The intended audience is landscape maintenance and installation personnel, tree trimming employees, home gardeners, city and parks employees, and others who want horticultural knowledge. The goal of the program was to educate the participants in basic horticultural practices such as: plant selection and installation—including palms and turf; plant propagation; landscape design; pruning; irrigation; fertilization; pest control, and related topics. The class was limited to 60 participants due to space constraints. The response surpassed all expectations with 58 people completing the course and 40 passing the final exam. Eight months after the end of the program, a follow-up telephone survey was conducted with 24 participants. The results reflect that a high percentage of the participants are still using the correct landscape techniques. In order to reach as many people as possible a video or CD with the entire course is going to be prepared.

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Monica L. Elliott and Timothy K. Broschat

A commercially available microbial inoculant (Plant Growth Activator Plus) that contains 50 microorganisms, primarily bacteria, was evaluated in a soilless container substrate to determine its effects on root bacterial populations and growth response of container-grown plants at three fertilizer rates. The tropical ornamental plants included hibiscus (Hibiscus rosa-sinensis `Double Red'), spathiphyllum (Spathiphyllum `Green Velvet') and areca palm (Dypsis lutescens). The bacterial groups enumerated were fluorescent pseudomonads, actinomycetes, heat-tolerant bacteria, and total aerobic bacteria. Analysis of the inoculant before its use determined that fluorescent pseudomonads claimed to be in the inoculant were not viable. The plant variables measured were plant color rating, shoot dry weight and root dry weight. Only hibiscus shoot dry weight and color rating increased in response to the addition of the inoculant to the substrate. Hibiscus roots also had a significant increase in the populations of fluores-cent pseudomonads and heat-tolerant bacteria. From a commercial production point of view, increasing fertilizer rates in the substrate provided a stronger response in hibiscus than did addition of the microbial inoculant. Furthermore, use of the inoculant in this substrate did not compensate for reduced fertilizer inputs.

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Melinda S. Conner and Gerald Klingaman

Studies were undertaken to compare plant growth and water use in a new commercially produced media that contained a hydrophilic polymer combined with a traditional peat-lite media. Rooted cuttings of nephytis, spathiphyllum, parlor palm, pothos, corn plant, `Dallas' fern, and gold dust dracaena were planted into 15cm plastic pots containing either a peat-lite media or the media with hydrophilic polymer. Both mediums were amended with 2.4 kg/m3 gypsum and then treatments of 0, 1.5, or 3 kg/m3 of dolomitic limestone were added. Plant height, width, growth index, top fresh weight and dry weight were measured. Preliminary tests indicated that the media with the hydrophilic polymer performed better with slow-release fertilizer than a constant liquid fertilization program. Plant growth appeared to be optimum at the 0 or 1.5 kg/m3 rate of dolomite. Plants grown in the media with the hydrophilic polymer produced plants of comparable quality to those in the peat-lite media.

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Darrin Parmenter, Russell Nagata, Kent Cushman and Nancy Roe

Recently, an increasing number of restaurants in Palm Beach County, Florida, have been requesting squash (Cucurbita pepo) flowers from local vegetable growers. Typically, current field-grown squash cultivars produce a higher ratio of female to male flowers, with the emphasis on fruit production. However, a market for squash blossoms indicates a need for cultivars that produce higher numbers of consistently developing male flowers throughout the growing season. In order to evaluate male squash blossom production, 10 squash cultivars, including yellow-summer, zucchini, round, and scallop-types, and one compact-type pumpkin, were field-grown during the 2005–06 growing season. The average number of male flowers per plant by week was recorded for 7 weeks, starting when the first male flowers were identified within the entire trial. In addition to blossom counts, flower traits, such as bell height, depth, volume, and weight were also recorded. Preliminary results from the 2005 season indicate that the commercial yellow-summer squash cultivars, Mulitpik and Early Prolific Straightneck, and the zucchini cultivars, Jaguar and Raven, produced fewer male flowers on a week-by-week and total basis. The cultivar, White Bush Scallop, produced significantly more male flowers then any other entry, with an average of 9.8 male flowers per plant per week. Little or no difference was seen in bell height and depth among the 11 cultivars; however, two cultivars, Costa Romanesque and Hybrid Pam (compact pumpkin type) had significantly greater bell volumes and weights, indicating a much larger blossom size.

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Bijan Dehgan, Joseph E. Durando and Thomas H. Yeager

Cycas revoluta, an important ornamental palm-like plant of warmer regions of the world, often exhibits a foliar chlorotic/necrotic dieback in landscapes. Despite a weak correlation (r2 ≤ 0.28) of percent symptoms with soil nutrient levels or pH, symptom severity was correlated more notably (r2=0.49) with Mn and had even a higher correlation (r2 = 0.61) with the Fe : Mn ratio. Anatomical examination of chlorotic leaflets indicated an accumulation of tanniniferous cells but did not provide direct evidence of Mn deficiency. Although field surveys indicated a link between low Mn levels and Fe : Mn ratio in the plant and appearance of the disorder, the manifestation of symptoms could not be directly correlated with any edaphic factors. However, identical symptoms were induced in young plants by withholding Mn in a solution culture experiment. Application of chelated Mn on expanding leaves alleviated the disorder, but only for the current growth flush. Irrigation frequency in concert with other cultural practices probably are more responsible for development of symptoms than actual soil Mn inadequacy. In consideration of acute susceptibility of cycads to micronutrient deficiencies, plants should be supplied with a complete micronutrient fertilizer during growth in containers and before field planting.

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Robert F. Bevacqua

The introduction of horticulture to the Hawaiian Islands by Polynesian voyagers in AD 300 represents the culmination of eastward voyages of discovery by navigators whose origins were in southeastern Asia and who dispersed an important assemblage of horticultural crops through the Pacific islands. Archaeological, botanical, and linguistic evidence has been used to establish that these voyagers, using double-hulled sailing canoes, transported 27 horticultural plants with them in their voyage of discovery of the Hawaiian Islands. This assemblage included banana, coconut palm, sweetpotato, yam, breadfruit, and taro. The introduction of these plants had a dramatic and damaging impact on the island ecosystem. Many native species of plants and birds became extinct as the settlers used fire as a tool in clearing land for the planting of the introduced plants. A complex civilization developed based on the production of horticultural crops. The staple of food for this society was taro or kalo. The corm or underground portion was mashed with water and eaten as a paste called poi. Large, irrigated, terrace systems were developed for taro production. The most enduring achievement of the Polynesian navigators who explored and colonized the Hawaiian Islands was the dispersal of an assemblage of horticultural plants that transformed the natural environment of both Hawaii and much of the world's tropical regions.

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J. Benton Storey

Tropical horticultural crops can be the spark that builds student interest in horticulture. They are a refreshing alternative to the temperate crops that most of our curricula are necessarily built around. Students who become familiar with production problems and opportunities between 30° north and south latitudes are better equipped to compete in the world economy. HORT 423 covers tropical ecology, soils, atmosphere, and many major crops. Beverage crops studied are cacao, coffee, and tea. Fruit and nut crops include bananas, mango, papaya, pineapple, dates, oil palm, coconut, macadamia, cashew, and Brazil nuts. Spices such as vanilla, black pepper, allspice, nutmeg, mace, cinnamon, cassia, and cloves are studied. Subsistence crops such as cassava, yam, taro, pigeon peas, chick peas, vegetable soy beans, and black beans round out an exciting semester that draws students. HORT 423 is a 3-hour-per-week lecture demonstration course supplemented with slides from the tropical countries. Many students simultaneously enroll in a 1-hour HORT 400 course that is taught during the 1-week spring break in a tropical country. Recent trips have been two each to Costa Rica and Guatemala. These study trips are gaining in popularity. For more information about HORT 423 consult the world wide web at http://http.tamu.edu:8000/~c963/a/h423main.html.