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Marco Beyer and Moritz Knoche

We thank Monika Möhler, Kurt Ehm, Wolfgang Meyer, and Erhardt Sonnenkalb for providing fruit samples, Ruth Richter and Matthias Hinz for technical assistance, Stefanie Peschel for useful discussion, Dieter Reese for building experimental equipment

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William R. Graves

Journal Paper no. J-15736 of the Iowa Agriculture and Home Economics Expt. Station, Ames. Project no. 3229. Technical assistance of J. Dieter and K. Lappegard is gratefully acknowledged. The cost of publishing this paper was defrayed in part

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Henry M. Munger

Fruits and vegetables are being recommended more strongly than ever for improving human health, but, in some parts of the world, supplies are inadequate and, even when supplies are abundant, some segments of the population eat far less then recommended amounts. This divergence suggests that careful analysis and multiple approaches are needed to maximize the benefits of horticultural crops to human health. Information about the specific health benefits of certain crops and the value of diversity in the diet to get benefits not yet understood may stimulate increased usage. An attractive, appetizing, and economical supply seems essential, and may require efforts ranging from breeding for resistance, flavor, appearance, and holdability, through production and harvesting methods, to postharvest handling and processing.

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I.L. Goldman

Pigments in orange carrot tissue, such alpha and beta carotene, are important vitamins in the human diet. Previously identified white or nonpigmented carrot roots, such as those from wild carrot and white derivatives of yellow or orange types, are dominant to the production of pigment, which is recessive. A nonpigmented carrot root was discovered during routine propagation of the inbred line W266 in 1992. Subsequent segregation analysis in the F2 and BC1 generations in three genetic backgrounds demonstrated the lack of pigmentation is due to a single recessive gene (reduced-pigment: rp). Total carotenoid content was reduced 92% in the roots of rprp genotypes compared to RPRP genotypes, however there were no differences in carotenoid content in leaves. Plants carrying rprp also exhibit white-speckled leaves during early stages of development, suggesting rp has an effect on leaf chlorophyll content. This character may prove useful in dissecting the complex inheritance of carotenoids in carrot.

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Peter J. Mes*, James R. Myers, and Balz Frei

A nutritional study was initiated to determine which carotenoids found in tomato result in decreased lipid oxidation ex vivo. To compare the carotenoids in a human diet without the use of purified supplements, tomatoes expressing nonfunctional enzymes in the carotenoid pathway were used. Tomato lines carrying the genes t, B, ogc, Del, or r were grown to produce fruit containing with high levels of prolycopene, beta-carotene, lycopene, or delta-carotene respectively, or low total carotenoids in r. Juices were processed from these lines and used in a dietary intervention study. Plasma samples were drawn before and after consumption of each juice. These samples were subjected to a battery of tests to analyze the contribution of carotenoids to the total lipid antioxidant status. Results of these tests are discussed.

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Greg Schlick and David Bubenheim

Chenopodium quinoa is being considered as a “new” crop for Contolled Ecological Life Support Systems(CELSS) due to the unique protein composition and high mineral values of the seeds and leaves. Quinoa is known to have very high protein levels (12-185 reported from field trials), with desirable amino acid proportions, and mineral concentrations suitable for a balanced human diet. Contolled environment, hydroponic culture has increased the nutritional value and has the potential of increasing the yield. Protein and mineral values have increased substantially and will be discussed in more depth. The high concentration of protein, unique amino acid profile, high mineral values, versatility in preparation and the potential for increased yields make quinoa a useful crop for CELSS and long-term space missions

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Mohanjeet S. Brar, Jameel M. Al-Khayri, Teddy E. Morelock, and Edwin J. Anderson

Cowpea (Vigna unguiculata L.) is an important grain legume, which in developing countries provides much of the protein in human diets. A plant regeneration system for cowpea was developed. Cotyledons were initiated on MS medium containing 15 to 35 mg·L-1 benzylaminopurine (BAP) for 5 to 15 days. For shoot regeneration, the explants were transferred to a medium containing 1 mg·L-1 BAP. Regeneration percentage (1% to 11%) and the number of shoots (4 to 12 shoots per explant) were significantly influenced by genotype. The duration of culturing and BAP concentration in the initiation stage significantly affected the regeneration capacity. Explants initiated on 15 mg·L-1 BAP for 5 days resulted in the highest regeneration percentage. Conversely, the highest number of shoots was obtained from explants initiated on 35 mg·L-1 BAP. This is the first report of plant regeneration of U.S. cowpea cultivars.

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Gary Thompson, Russel Tronstad, and Michael Kilby

During the last two decades, per capita consumption of fresh fruit has increased markedly. Although many believe that this increase has been caused by a heightened concern in health and diet, economic analyses indicates that changes in retail prices and increasing per capita incomes adequately explain the increased consumption of fresh fruit. Also, with more single households and women entering the labor force, the convenience factor of focal preparation has likely caused an increase in the consumption of fresh fruit. Substantial substitution between fresh fruit products has occurred: grapes and strawberries have increasingly substituted for citrus fruit, particularly grapefruit. These results suggest that relative prices for fresh fruits, increasing disposable income, and the changing demographic composition of households have prompted observed increases in the per capita consumption of fresh fruit.

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Leslie A. Weston and M.M. Barth

Vegetables provide a major source of essential vitamins such as ascorbic acid and beta carotene and other quality components in the human diet. Postharvest yield and quality of vegetables depend upon genetic, biotic, edaphic, chemic and other factors, as well as combinations of these factors. Successful production, quality and nutritional value of vegetables are related to both primary and secondary metabolic processes occurring during vegetable growth and development. Related research has focused upon cultivar selection, cultural practices used during production, interaction of light and temperature, and use of chemicals for growth regulation, and pest control. We will discuss the effects of genetic, pest, and soil management; crop maturity at harvest; environmental modification; and climatic conditions. Postharvest vegetable quality will be characterized in terms of vitamin content, appearance, yield, and flavor.

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Borut Bohanec, Marijana Jakše, Predrag Šesek, and Michael J. Havey

Bulbous leek-like plants are a poorly defined group usually assigned to the Allium ampeloprasum complex. Studies were initiated to determine the origin of an unusual bulbous accession received in Shanxi province in China, where it was used in diet as garlic but propagated by seeds, and to genetically compare this accession with morphologically similar plants from Europe. Genetic analyses included karyotypes and genomic in situ hybridization, pollination to leek, genome size determination and nuclear rDNA and plastid DNA polymorphisms. Results revealed that this agriculturally interesting accession from China is a so far unknown variant within tetraploid A. ampeloprasum cultivated taxa. We also observed that great-headed garlic did not share derived states in the chloroplast with leek, revealing that this cultivated plant does not possess the cytoplasm of leek or garlic, while its 1C genome size was 17% bigger than those of studied leek and bulbous-leek accessions.