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X.E. Yang, X.X. Long, W.Z. Ni, and E.W. Stover

Vegetables play an important role in the human diet, and production in suburban areas has increased as populations have become more urbanized. However, heavy metal pollution of soils has enhanced in such areas, and metal accumulation in vegetables may pose a human health risk when consumed. Zinc is an essential micronutrient for plants and humans, but it is toxic to plants and humans at high levels. Although a maximum Zn tolerance for human health has been established for edible parts of vegetables (20 mg/kg DW), little information is available for predicting vegetable Zn concentration based on soil and water Zn levels. The objectives of this study were to determine the critical Zn concentrations in nutrition solution and soil to reach maximum Zn tolerance concentrations in Chinese cabbage, bok choy, and celery. Five Zn levels were used for both solution and soil culture experiments, with three replicates of each. Shoot growth was significantly inhibited at Zn concentrations above 50 mg/L in nutrition solution and above 180 mg/kg in soil. The sensitivity of crops to zinc toxicity, in term of shoot and root growth, decreased in the order: celery > Chinese cabbage > bok choy. Zinc accumulation in shoots and edible parts varied with Zn supply levels and type of vegetables. A negative correlation was noted between Zn accumulation and dry matter yields, with r-squared values of 0.980** for nutrient solution and 0.960* for soil culture. Zinc concentrations in shoots or edible vegetable parts were below 20 mg/kg (human health threshold) when they were grown at DTPA extractable Zn in the soil less than 75, 100, and 175 mg/kg for bok choy, celery, and Chinese cabbage, respectively.

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Allison E. Stewart, Debra J. Carpenter, Vincent R. Pantalone, and Carl E. Sams

Consumer interest in Edamame (edible soybean) is increasing due to reported health benefits associated with diets high in soy. The purpose of this study was to compare four varieties of edible soybean grown at four plant spacings on three planting dates. The lines were grown at the Plateau Research and Education Center in Crossville, Tenn. They were analyzed for horticultural traits and isoflavone content. All lines were at the R6 stage. Fresh weight of pods, weight of 200 pods per plot, the number of seeds per 200 pods, and the weight of 100 seeds were recorded from two-row plots (6.10 m x 1.52 m). A significant (P < 0.001) difference was found for fresh weight among planting dates. The May planting had the highest mean fresh weight (3118 g/plot), followed by the June (3068 g/plot) and July (2131 g/plot) dates. The weight per 100 seeds was significantly different (P < 0.001) for planting date and genotype. May seed weight was highest at 49 g, followed by June at 45 g, and July at 42 g per 100 seeds. `Gardensoy-43' was the highest-yielding variety, with a mean of 3253 g/plot. It was followed by `TN00-60' and `TN03-349', with mean fresh weights of 2730 and 2723 g/plot, respectively. The line `TN5601T' had the lowest mean fresh weight of 2389 g/plot. Both fresh weight (P < 0.001) and weight per 100 seeds (P < 0.05) were significantly different among plant spacings. Twenty-six plants per meter within rows yielded the highest total fresh weight per plot (3071 g), but had the lowest mean weight per 100 seeds (43 g). Spacing three plants per meter within rows resulted in the highest weight per 100 seeds (48 g), but the lowest fresh weight per plot (2122 g). Isoflavone content will be measured for each variety, planting date, and spacing.

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Geoffrey Meru and Cecilia McGregor

Egusi watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai subsp. mucosospermus var. egusi (C. Jeffrey) Mansf.] is known for its distinctive fleshy-pericarp seed phenotype and high seed oil percentage (SOP). The seed is part of the daily diet in West Africa where it is used in soups and stews or processed for cooking oil. Genetic mapping studies have revealed that most of the variation in SOP between egusi and normal, non-egusi seed is explained by the egusi (eg) locus, which is also associated with the unique seed phenotype. However, variation in SOP is also observed within egusi and normal seed types although the basis of this variation remains to be elucidated. A high correlation between kernel percentage (KP) and SOP has been observed in watermelon and other crops, and recent data also suggest an association between seed size and SOP in watermelon. The aim of this study was to elucidate the relationship among SOP, KP, and seed size traits in watermelon and to identify quantitative trait loci (QTL) associated with the latter traits to facilitate marker-assisted selection (MAS) for traits correlated with SOP. KP showed a significant (α = 0.05) positive correlation with SOP in both egusi and normal seed types, whereas seed size traits showed significant negative correlations with SOP. QTL associated with KP and seed size traits in normal seed were colocalized with a previously mapped locus for SOP on linkage group (LG) 2, but in egusi seed, a QTL explaining 33% of phenotypic variation in KP was localized on LG 7. The results of this study show that SOP in watermelon is correlated with KP and seed size, but KP is associated with different loci in normal and egusi seed phenotypes.

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Oleg Daugovish and Michi Yamomoto

California leads national strawberry fruit production with annual value in Ventura County alone near $300 million. Bird damage to fruit routinely accounts for 3–5% losses and may exceed 50% in some fields. Conventional bird control tools have limited or no effect on fruit damage and may contribute to noise pollution. A four-site study at Oxnard, Calif., from Jan. to Apr. 2005 (highest value fresh market season) showed that release of Peregrine, Saker, or Barbary falcons in combination with helium balloon launching (site 4) in response to fruit damage reduced fruit damage from 80–90% to 15–20% after 1 week. When fruit damage increased again (>20%) a repeated 1-week daily program completely reduced fruit damage during the rest of the season. Falconry alone at site 2 (near man-made structures) for two consecutive days reduced fruit damage from 70–80% to 10–20%, however, at site 3, near giant reed, three weeks of daily releases did not eliminate the damage, but confined it to the strawberry beds adjacent to reed shelter (reducing overall damage from 100% to 25–50%). High frequency of release is likely unfeasible and destruction of shelter habitat may be justified. Falconry alone before damage occurrence (site 1) seemed to prevent fruit damage; however, lack of birds and fruit damage before, during, and after releases made it difficult to draw conclusions about the success of the preventive program. In April, no fruit damage occurred even during bird presence suggesting the change in their diet. The study showed that seed-eating birds were the main pests at Oxnard, Calif., and that trained falcons can disperse them, thus, reducing fruit damage. The success of falconry was site-specific and depended on proximity of suitable habitat and availability of food sources for pest birds.

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Alexandra B. Napier, Kevin M. Crosby, and Soon O. Park

Muskmelons (Cucumis melo L.) play an important role in the American diet. Ranked as one of the top 10 most-consumed fruits by the USDA, cantaloupe melons have the highest amount of beta-carotene of all the ranked fruits. Beta-carotene, also called pro-Vitamin A, is an essential nutrient required for eye health, and may have the potential, as an antioxidant to reduce the risks associated with cancer, heart disease, and other illnesses. Breeding melons with increased levels of beta-carotene will benefit consumer health. Research has found phytonutrients are most bioavailable when consumed in their fresh form, rather than as vitamin supplements. The high level of beta-carotene found in some melons has a genotypic component, which may be exploited to breed melons high in beta-carotene. Molecular markers and marker-assisted selection (MAS) can be used to increase the efficacy of the breeding process, while lowering breeding costs. An F2 population was created using `Sunrise', the female parent, containing no beta-carotene crossed with `TAM Uvalde', a high beta-carotene variety. A field population consisting of 115 F2 individuals and a greenhouse population containing 90 F2 individuals were grown. The resulting fruit were screened phenotypically and ranked according to beta-carotene content. Chisquare values fit the previously reported model of a single dominant gene for presence of beta-carotene (orange-flesh) vs. absence (green or white flesh). A continuous distribution of beta-carotene concentrations from high to low suggested quantitative inheritance for this trait. Two eight-plant DNA bulks composed of either high or low beta-carotene F2 individuals were screened for polymorphic molecular markers using the amplified fragment-length polymorphism technique.

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Everardo Zamora, Santiago Ayala, Cosme Guerrero, Damian Martínez, and Francisco Rivas

The pod cactus (Opuntia sp.), a tender stem, has been consumed by Mexican people for centuries either as a fresh or boiled vegetable. Traditionally, Southern Mexico people consume this tender pod cactus in several traditional Mexican dishes. During recent years, an increase in nopalitos consumption by Sonoran people has been observed. People interested in a disciplined diet or people troubled with high cholesterol desire this peculiar vegetable. In Hermosillo, Mexico, people buy nopalitos in small plastic bags packages a pound of small cutting of tender pods from local supermarkets and mobile sellers. Usually, a nopalitos bag pound price is a range of $1.00 to $1.2 U.S. dollars in Hermosillo. Nopalitos production in Sonora, Mexico, is a seasonal. Nopalitos harvesting starts in early April and runs through late October. Because low temperatures start in late October, and continue during the winter season, there is no nopalitos production in Sonora. Hense, Sonoran producers are considerig building high tunnels, to provide more temperature control and to produce nopalitos during the winter. Most growers are low-income people that produce nopalitos in home gardens. This activity allows low-income growers to have nopalitos during most of the year, except during the winter. The current growing area production of 240 acres (170 ha) of tender pod cactus was recorded during 2005 in Sonora, of which a half is cultivated in home gardens. A potential yield production of nopalitos in Sonora is about of 40 tons per acre of tender pod cactus. In comparison to other crops, nopalitos production is a good alternative for small growers.

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Chieri Kubota, Cynthia A. Thomson, Min Wu, and Jamal Javanmardi

Plants produce various phytochemicals that are of nutritional and medicinal value to humans. Phytochemicals having antioxidant capacity are drawing increased interest from consumers. Population studies among Americans have consistently demonstrated inadequate consumption of fruit and vegetables. Improving intake of fruit and vegetables has been a major public health effort for many years with minimal success. Given this, it seems opportunistic to consider other approaches to enhance the nutritional quality of the American diet. One plausible approach is the development of fresh produce containing a greater concentration of phytochemicals known to improve health, thus while consuming fewer servings of produce, Americans would still have significant exposure to health-promoting food constituents. Controlled environments provide a unique opportunity to modify the concentrations of selected phytochemicals in fruit and vegetables, yet practical information is limited regarding methods effective in optimizing antioxidant capacity. Our research at the University of Arizona Controlled Environment Agriculture Program has shown that application of moderate salt stress to tomato plants can enhance lycopene and potentially other antioxidant concentrations in fruit. The increase in lycopene in response to salt stress in the tomato fruit was shown to be cultivar specific, varying from 34% to 85%. Although the specific biological mechanisms involved in increasing fruit lycopene deposition has not been clearly elucidated, evidence suggests that increasing antioxidant concentrations is a primary physiological response of the plant to the salt stress. Another experiment showed that low temperature during postharvest increased antioxidant capacity of tomato fruit while it maintained the lycopene concentration. More detailed study in this area is needed including accumulation of antioxidant phytochemicals as affected by environmental conditions during the cultivation and the postharvest.

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Manuel C. Palada, Thomas J. Kalb, and Thomas A. Lumpkin

AVRDC–The World Vegetable Center was established in 1971 as a not-for-profit international agricultural research institute whose mission is to reduce malnutrition and poverty among the poor through vegetable research and development. Over the past 30 years, AVRDC has developed a vast array of international public goods. The Center plays an essential role in bringing international and interdisciplinary teams together to develop technologies, empower farmers, and address major vegetable-related issues in the developing world. In its unique role, AVRDC functions as a catalyst to 1) build international and interdisciplinary coalitions that engage in vegetable and nutrition issues; 2) generate and disseminate improved germplasm and technologies that address economic and nutritional needs of the poor; 3) collect, characterize, and conserve vegetable germplasm resources for worldwide use; and 4) provide globally accessible, user-friendly, science-based, appropriate technology. In enhancing and promoting vegetable production and consumption in developing world, AVRDC's research programs contribute to increased productivity of the vegetable sector, equity in economic development in favor of rural and urban poor, healthy and more diversified diets for low-income families, environmentally friendly and safe production of vegetables, and improved sustainability of cropping systems. Recent achievements at AVRDC that greatly impact tropical horticulture in the developing world include virus-resistant tomatoes raising farmers income, hybrid sweet pepper breaking the yield barrier in the tropics, flood-resistant chili peppers opening new market opportunities, broccoli varieties for monsoon season, pesticide-free eggplant and leafy vegetable production systems and fertilizer systems that protect the environment. Beyond vegetable crops, AVRDC is playing an important role in expanding and promoting research and development efforts for high value horticultural crops, including fruit, ornamentals, and medicinal plants through its new Global Horticulture Initiative. AVRDC believes that horticulture crop production provides jobs and is an engine for economic growth. The important role AVRDC–The World Vegetable Center plays in developing and promoting tropical horticultural crops is discussed in this paper.

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Penelope Perkins-Veazie*, J.K. Collins, and Warren Roberts

Watermelons contain the carotenoids b-carotene, phytofluene, lycopene, and lutein. These carotenoids play an important role in plant oxidative protection and may serve to protect humans against oxidative assaults. Of the carotenoids, lycopene is the predominant pigment in red-fleshed melons (30-130 μg·g-1), b-carotene is present in small amounts (1-14 μg·g-1), and other carotenoids are present in minute amounts (1-3 μg·g-1). Seventy varieties were screened for lycopene content using scanning colorimetry, spectrophotometry, and HPLC techniques, and grouped as low, medium, high, or very high in lycopene. Pink-fleshed heirloom varieties such as Sweet Princess and Black Diamond contained low amounts of lycopene (<40 μg·g-1). A number of seeded and seedless varieties had medium amounts of lycopene (40-60 μg·g-1). Varieties in the high category (60-80 μg·g-1) were primarily seedless types, although `Dixie Lee', an open-pollinated, seeded variety had 69 μg·g-1, indicating that high lycopene content is not restricted to hybrid or seedless melon germplasm. Six selections were found to be very high in lycopene (>80 μg·g-1), including the minimelon Hazera 6008 (Extazy). Total carotenoids and carotenoid profiles were determined by HPLC for 23 varieties in 2003. Both seeded and seedless type melons had varieties high in bcarotene, lycopene, and total carotenoids. These results indicate that commercial watermelon varieties have a wide range in lycopene and b-carotene content, and that most commercially important varieties are high in lycopene and total carotenoids, providing important sources of phytonutrients to the human diet.

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Roseann Leiner, Abraham Smyth, Rudy Candler, and Patricia S. Holloway*

Berries and vegetables can be sources of beneficial phytochemicals that may have antioxidant activity in the human diet. Information on type and quantity of phytochemicals may open new crop opportunities for berries and vegetables harvested in Alaska. A method was developed for detecting ascorbic acid and eight phenolic acids on an HPLC instrument using a reverse phase Merck Chromolith C18 column. The method used UV absorbance detection at 280nm to separate a standard solution of the following nine phytochemicals: ascorbic acid, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, p-hydroxyphenylacetic acid, caffeic acid, syringic acid, p-coumaric acid and ferulic acid. The mobile phase was a mixture (3.5% to 14% gradient) of organic solvent (5 parts acetonitrile: 2 parts methanol) and aqueous solvent (2 mmol aqueous trifluoroacetic acid - TFA) at a flow rate of 2 mL/min. In 2003, over 60 samples of berries and 60 samples of baby greens were extracted and analyzed. Plant samples were extracted by blending 10-20g of frozen plant tissue with 5 parts TFA. The extracts were centrifuged, diluted 4:1 and filtered (0.2 μm). Chromatograms from HPLC analysis for all samples were complex in peak size and number. Chromatograms for six extracts of high bush cranberries, Viburnum edule, exhibited intense peaks that indicate the presence of caffeic acid, based on retention times. Chromatograms for seven extracts of rose hips, Rosa acicularis, exhibited peaks that indicate the presence of ascorbic acid, based on retention times. Gallic acid and p-hydroxybenzoic acid are apparent minor components in the leaves of some baby greens. This research will continue in 2004 with more plant samples and further method development for detection of other phytochemicals.