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David Creech, Greg Grant and Dawn Parish

The SFA Mast Arboretum began as a landscape plant materials class project on the south side of the Agriculture building in 1985. In 2000, over 20 theme gardens now occupy 18 acres. The garden is computer mapped and an accessioning system is in place. Theme garden developments include daylilies, herbs, a rock garden, a xeriscape, plants for shade, wetland, and bog conditions, a line of vines, an Asian Valley, conifers and hollies, and numerous gardens that trial and display herbaceous perennials. Recent developments include a children's garden and, the biggest project to date, an 8-acre SFA Ruby Mize Azalea garden, with a grand opening in Apr. 2000. Theme gardens are utilized to display collections. Significant assemblages include Rhododendron (400 cultivars and selections), Acer (168 cultivars), Camellia (210 cultivars), Loropetalum (18 taxa), Cephalotaxus (43 taxa), Magnolia (47 taxa), Abelia (37 taxa), Ilex (73 taxa), and others. Plant performance and observational information is recorded. Second author Grant has numerous plant introductions in the past 5 years, many that are well represented in the nursery industry and recognized by TAMU's Coordinated Educational and Marketing Assistance Program (CEMAP) as “Texas Superstar” promotions (trademarked). SFA Mast Arboretum plants are promoted via distributions, trade articles, and the Arboretum's website: www.sfasu.edu/ag/arboretum.

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Allen Owings, Gordon Holcomb, Andrew Bates, Peggy Cox, Stephen Crnko and Anthony Witcher

In 1999, LSU Agricultural Center landscape trials of herbaceous ornamental plants included zinnias, ornamental sweet potatoes, vinca, and perennial verbenas. Based on growth habit, flowering and disease observations from 1999 and previous years, `Homestead Purple', `Tiger Rose', `Rose King', `Taylortown Red', and `Blue Princess' (`Biloxi Blue') are recommended perennial verbena cultivars for Louisiana landscapes. Zinnias evaluated included Zinnia angustifolia and Z. elegans cultivars. `Crystal White', `Profusion Orange', and `Profusion Cherry' (all Z. angustifolia cultivars) were superior landscape performers. Major incidence of bacterial leaf spot was reported on all Z. elegans cultivars in 1999. Over the last several years, the Pacifica series of vinca had significantly improved visual quality ratings in landscape trials when compared to the Heat Wave and Cooler series. In 1999, Mediterranean Deep Rose had visual quality ratings similar to Pacifica but had increased incidence of disease problems. Ornamental sweet potato cultivars recommended for landscape use in Louisiana based on trials in 1999 are `Blackie', `Black Beauty', `Margarite', and `Pink Frost' (`Tricolor'). `Summer Frost' is not recommended.

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Jorge M. Fonseca, James W. Rushing and Robert F. Testin

Fresh-cut watermelon cubes stored at selected temperatures within the range of 1.1 to 14.5 °C had decreasing quality shelf life corresponding with increasing temperature. At lower temperatures there was a random occurrence of chilling injury symptoms in some cubes that was associated with the section of watermelon from which the cubes were cut. Cubes removed from the top side of the intact watermelon fruit were more susceptible to chilling injury than cubes from other sectors of the fruit. Sanitizing cubes with chlorine (40 μL·L–1) or ozone (0.04 μL·L–1) solutions caused an initial reduction in microbial count but during storage the effect diminished and became insignificant compared to controls. Overall quality was lower in cubes receiving aqueous sanitizing treatments, possibly due to mechanical injury occurring during centrifugation to remove excess solution. Overall quality of cubes exposed to UV light (≈250 nm for 1–5 min) was better than cubes receiving aqueous sanitizing treatment. The effectiveness of UV treatment in reducing microbial load was dependent on the amount of cube surface exposed to the light. The results emphasize the importance of preventing microbial contamination during processing of fresh-cut watermelon.

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Kevin A. Lombard, Ellen Peffley, Leslie Thompson, Emmanuel Geoffriau and Jay Morris

The flavonol quercetin has been reported as having many health benefits, including a reduction in the risk of developing cardiovascular disease, stroke, and some types of cancer. The overall content of quercetin in onion was examined in four yellow varieties (`Rio Rita', `RNX 10968', `Predator', and `Tamara') and one red variety purchased at a local grocery store. Each bulb was quartered, with one quarter saved as a control and the other three quarters subjected to three cooking treatments that simulated common domestic processing methods of preparing onion. The treatments included sautéing in sunflower oil for 5 minutes at 93 °C, baking for 15 min. at 176 °C, and boiling for 5 minutes in distilled water. Samples were frozen in liquid nitrogen, ground to a fine powder, blended with 80% EtOH, and filtered for quercetin extraction. The filtrate was then analyzed with a spectrophotometer (uv 374 nm). Quercetin concentrations were obtained in mg quercetin/kg fresh weight of tissue by regressing spectrophotometer readings onto a standard curve. Significant differences between varieties were found when examining fresh samples alone with the red variety containing the highest content of quercetin. Results of cooking showed that sautéing produced an overall 27% gain in quercetin concentration (significantly higher than the fresh control), baking produced an overall 4% gain in concentration (insignificant from the fresh control), while boiling produced an overall 18% loss in quercetin concentration (significantly lower than the fresh control).

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P. Perkins-Veazie, P. Armstrong and J.R Clark

Firmness of blackberries greatly determines shelf life for fresh market. Firmness in blackberries appears to be due to a combination of skin toughness and internal receptacle to permit large sample size measurements. Subjective rating of fruit require consistent evaluation by raters over harvest dates and years, and is subject to fatigue error. The FirmTech2 firmness tester was developed to provide rapid compression measurements and has been successfully used in determining the firmness of cherries and blueberries. Blackberries from a large number of clones ranging in firmness from rock-hard to squishy were measured with the FirmTech2 using a deformation range of 25 to 100 g. Additionally, blackberries were placed in storage at 2, 5, and 2/20 °C to monitor effects of storage temperature on blackberry firmness. Berries were subjectively rated and then placed on the Firmtech for measurements. A comparison of firmness readings for fruit only in the “1” (firm) category was made. Differences found among fruit readings agreed with observed differences in field subjective ratings. Stored fruit that had become soft and mushy could not be statistically differentiated from firmer fruit in quantitative readings. In conclusion, the Firmtech2 allowed rapid evaluation of breeding lines before storage.

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Lianghong Chen, Ajmer S. Bhagsari, Soon O. Park and Sarwan Dhir

This study was carried out to optimize conditions for plant regeneration of sweetpotato [Ipomoea batatas (L.) Lam] using shoot tips, petioles, and leaves of Selection 75-96-1 as explants in Murashige and Skoog (MS) with several growth regulators at different levels. Callus initiation and callus proliferation media were 9.0 μm 2,4-dichlorophenoxyacetic acid (2,4-D) and 9.0 μm 2,4-D + 1.1 μm N 6-benzyladenine (6-BA) in protocol I; 8.1 μm α-naphthaleneacetic acid (NAA) + 1.2 μm kinetin (KIN) and 5.4 μm NAA + 4.6 μm KIN in protocol II; 0.9 μm 2,4-D, and 0.9 μm 2,4-D + 1.2 μm N-isopenylamino purine (2iP) in protocol III; NAA (8.1 μm) + KIN (1.2 μm) and 2,4-D (0.9 μm) + 2ip (1.2 μm) in protocol IV, respectively. In protocol I and II, shoot tip, petiole, and leaf were used, but only petiole and leaf in protocol III and IV. In the protocol I and II, somatic embryos were obtained only from shoot tip explants; in protocol III and IV, only from petioles. The frequencies of somatic embryo development were 33.3% in protocol I, 42.1% in protocol II, 21.2% in protocol III, and 10.3% in protocol IV, respectively. The leaf explants failed to produce somatic embryos in all the experiments. In protocol I, somatic embryogenesis occurred through the well-known sequence of globular-, heart-shaped-, torpedo-, and cotyledon-type embryos. However, in protocol II, the structures resembling plumule and radicle were observed before the emergence of torpedo/cotyledon type embryo clusters. The somatic embryogenesis in protocol III and IV was similar to that in protocol I. Growth regulators influenced somatic embryo development. Further, this study showed that explant resource and growth regulators affected the frequency of plant regeneration in sweetpotato.

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Paul Mangum and Ellen Peffley

(Allium cepa × A. fistulosum) × A. cepa breeding lines have been established to the fourth generation. The aim is to develop an A. cepa-like bulbing onion carrying A. fistulosum genes. Seven populations were characterized for morphological traits and three isozyme markers. Each bulb from the populations was characterized for maturity, soluble solids content, bulb shape, and bulb color. All the populations produced A. cepa-like bulbs. Significant variation was observed within each population for each morphological trait. All the bulbs were screened for the presence of A. cepa and A. fistulosum alleles of alcohol dehydrogenase (Adh-1), esterase (Est), and phosphoglucoisomerase (Pgi-1). Allium cepa Adh-1, Est, and Pgi-1 alleles were observed in all the populations. One population, 951026-8, contained plants heterozygous for A. cepa and A. fistulosum Pgi-1 alleles. Recovery of these fourth generation Allium backcross plants demonstrates introgression of the A. fistulosum genome into an A. cepa-like bulbing onion.

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F.M. Woods, C. Mosjidis, D. Hilmerick, R.C Ebel and B. Wilkins

Strawberry fruit (Fragaria ×ananassa `Chandler') were evaluated at five different stages of growth and development for changes in the senescence process in fruit tissues. Levels of total antioxidant activity, hydrogen peroxide (H2O2), lipid peroxidation product, malondialdehyde, and ethylene production were determined. Total antioxidant activity (TAA) was measured in terms of in situ antioxidants to scavenge the ABTS.superscript +superscript radical cation. With the progression of ripening and senescence, there was a significant decline in TAA that coincided with increased concentration of H2O2, lipid peroxidation and increased production of ethylene. Our results illustrate that the senescence process in strawberry fruit is associated with the decline of TAA and the potential initiation and accumulation of reactive oxygen species. These results are additionally discussed in terms of potential processes associated with abiotic and biotic environmental stresses. Moreover, although strawberry fruit are typically classified as nonclimacteric, this study illustrates that the free radical mediated senescence process is similar to that of climacteric fruits.

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Joseph K. Peterson, Howard F. Harrison and Maurice E. Snook

After removal of the periderm, cortex tissue of the sweetpotato cultivar Regal was collected. Polar extracts of this tissue strongly inhibited germination of proso-millet seed. C18 preparative, step-gradient chromatography (H2O → 100% methanol) gave some 50+ fractions, all of which were assayed for inhibitory properties. Analytical HPLC, using diode array detection and signal processing, showed the presence of chlorogenic, p-coumaric and caffeic acid, scopolin and some unknown phenolic acids. Most fractions were inhibitory to some degree; however, the least polar ones (in 90% and 100% methanol), containing unknown compounds, were most inhibitory. Semi-prep HPLC of these fractions produced eight major peaks (λmax at 210–213 nm, λ2 at 281–284 nm). In our bioassays, the compounds produced 50% inhibition of proso-millet seed germination at ≈60 ppm. It is likely that these compounds contribute significantly to the allelopathic properties of sweetpotato.

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Kenneth A. Sorensen

The 199 sweetpotato growing season was one of extremes: early high temperatures, cool temperatures at planting, drought early and extended, and then hurricane floods. Insect species and population levels were highly variable. Thrips early and armyworms late. Insect control tactics and management strategies were used and include the following. Insect presentations and handouts were made at field days, annual meeting and at several county meetings. A sweetpotato insect field guide was prepared to assist fieldmen with insect scouting. Insect scouting schools were held in several counties to show insects, their damage, and traps to use in detecting their presence and numbers over time. Control studies with insecticide formulations and rates along with timing studies were conducted and prepared for the annual report. Spintor and Admire received registations for worms late and for early season insect control. Aphid vector studies centered on aphid suction traps, yellow sticky traps, and aphid identifications. Foliar and soil insecticides were discussed as to their use and impact. Insecticides of the future were presented and discussed. Cooperative studies and long term plans were discussed.