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Abstract

Freeze-damaged ‘Marsh’ grapefruit (Citrus paradisi Macf.) and ‘Pineapple’ orange [Citrus sinensis (L.) Osbeck] fruit were sealed in polyethylene shrink film and stored for 6 weeks at 15°C in an attempt to prevent segment dehydration. Although the film greatly restricted water loss from the fruit, segment dehydration was similar to that observed for waxed fruit. During dehydration of freeze-damaged segments of ‘Valencia’ orange fruit, the relative water content of the adjacent mesocarp tissue increased. However, no differences were found in the soluble carbohydrate levels in mesocarp tissue adjacent to damaged and undamaged segments. The results indicate that the mesocarp tissue is not only in the pathway of water loss from free-damaged citrus fruit, but also accumulates water from damaged tissues. Furthermore, segment tissue membranes and walls appear to be differentially permeable to sugars and water.

Open Access

`Cheyenne', `Mohawk', `Pawnee', and `Osage' grown in different locations in the United States were analyzed for fatty acid composition. The effect of heat units accumulated 12 weeks prior to shuck split were studied. Growing area affected the fatty acid profile for all cultivars. `Cheyenne' and `Mohawk' showed a positive correlation between heat units and oleic/linoleic acid ratios (r = 0.905 and r = 0.720 respectively), a positive correlation between heat units and oleic acid content (r = 0.863 and r = 0.773 respectively), and a negative correlation between heat units and linoleic acid content (r = -0.871 and r = -0.792 respectively). However, no correlation was obtained between heat units and the fatty acid profiles for `Osage' and `Pawnee'.

Free access

Shearing is an important cultural practice for maintaining plant size and appearance during nursery crop production. However, oakleaf hydrangea (Hydrangea quercifolia) is susceptible to dieback after shearing. The objective of this study was to determine whether foliar or substrate surface applications of ancymidol or uniconazole can reduce plant growth of oakleaf hydrangea similar to pinching, which was used to simulate shearing. ‘Alice’ or ‘Pee Wee’ oakleaf hydrangea plants were treated in 2002 or 2006, respectively, with ancymidol or uniconazole as a substrate surface application at 0, 1, 2, or 4 ppm; ancymidol as a foliar application at 0, 25, 50, or 100 ppm; or uniconazole as a foliar application at 0, 12.5, 25, or 50 ppm. Both cultivars received the same plant growth regulator treatments in 2012, and a pinched control was included in the 2012 experiment. Ancymidol and uniconazole had limited and inconsistent effects on growth of ‘Alice’ and ‘Pee Wee’ plants regardless of application method. Uniconazole was more effective at controlling growth of ‘Alice’ in 2002 when the study was conducted from October through December than in 2012 when the study was conducted during a more typical growing season of May through September. Plants treated with either ancymidol or uniconazole by either application method usually grew more during the first 2 weeks after application than those that were pinched. During the remainder of the growing season, little difference in growth between pinched plants and growth regulator-treated plants occurred. At harvest in 2012, pinched ‘Alice’ plants had more leaves but a smaller leaf area per leaf than plants treated with growth regulators resulting in no difference in total leaf area or in leaf, shoot, or root dry weight among the treatments. ‘Pee Wee’ treated with uniconazole using either application method or uniconazole as a foliar application had fewer leaves than pinched plants.

Full access

Southern Nevada Master Gardeners (MGs) donate 50 hours annually to educational and service projects. These volunteers respond to community needs by developing and staffing horticultural projects under UNCE supervision. In Las Vegas, 20 such projects exist. Some are more energy and information intensive than others. Mojave Guides are docents at the Desert Demonstration Garden, a part of the Las Vegas Springs Preserve, not Extension. They commit to a shift at the garden, providing information to visitors. While they are directly supervised by garden staff, the hours they contribute are Master Gardener hours. These volunteers receive training in desert flora from gardens staff and participate in seminars on selected topics. The MG Orchard Team operates a teaching orchard at the Center for Urban Water Conservation in North Las Vegas. These volunteers maintain hundreds of fruit trees and grape vines. They receive training on topics related to fruit trees and orchard management. This project began in 1996. Since 2002, they have been formalizing their organization using the logic model and SWOT analysis. Many members work weekly at the orchard and take the produce to a local farmers market. This raises funds for the orchard and is an opportunity to teach the community about desert horticulture. Project PLANT volunteers work at the Red Rock National Recreation Area visitor center and grounds. They are docents who also learn about and maintain the native plants there, and prevent infestations of invasive weeds which threaten the area. Their monthly meetings include training on topics related to the project. These projects are successful because of the MGs themselves. They grew out of interest and continue because the volunteers have drawn commitment from others.

Free access

`Stuart' pecans were harvested as soon as shucks would split in the fall of 1989 and 45 kg inshell samples were placed in 30 × 30 × 105 cm drying bins. The nuts were dried at air volumes of either 0, 1.27, 1.56, 1.84, or 2.12 m3/min down to 4% moisture. Air temperature in the drying bins was maintained at uniform 35°C with the exception of the 0 air volume treatment which was allowed to dry at room temperature. Four random samples of each treatment were held in frozen storage awaiting fatty acid analysis. Palmitic, stearic, oleic, linoleic, and linolinic fatty acids were separated in a 183 cm × 3 mm packed column using a 10% Silar 10C phase on a Gas Chrom QII, 100/120. The samples dried with a air volume of 1.27 m3/min retained a significantly higher oleic acid content than the 0 and 2.12 m3/min drying volumes. The 1.27 m3/min volume retained 64.55 % oleic acid compared with 61.37'% for the 0 velocity sample and 59.61% for 2.12 m3/min treatment. The more desirable oleic/linoleic ratio of 2.24 was found in the 1.27 m3/min sample compared to a 1.78 ratio in the 2.12 m3/min sample. Increased volume of air in the drying bins was thus deleterious to these samples because of the loss of monounsaturated fatty acid.

Free access

The phloem mobility of boron (B) in plants varies dramatically among species. Variations in phloem B mobility occur as a consequence of the presence of sugar alcohols (polyols) in some species but not in others, and these differences in phloem B mobility profoundly affect the expression of B toxicity symptoms. Twenty-four species including common ornamental species varying in sugar alcohol content, were selected to test their response to B toxicity. Species that do not produce sugar alcohols exhibited previously described B toxicity symptoms that include accumulation of high concentrations of B in, and burning of, the tip and margin of old leaves. In the sugar-alcohol-producing species these symptoms were absent, and B toxicity was expressed as meristematic dieback and an accumulation of B in apical tissues. These symptoms have not previously been associated with B toxicity in these species and hence may have been frequently misdiagnosed.

Free access

Previous work in this lab has shown that drying temperatures above 35°C will cause excessive loss of the kernel's natural light color and less oleic (18:1) oxidation to linoleic (18:2) fatty acid. The former is undesirable because of poor consumer appeal and the latter is desirable because of superiority of oleic acid in reducing low density lipoprotein in the blood plasma of consumers and a longer shelf life. The drying temperature of 35°C and an air volume of 45 CFM was superior in 1989 to 75 CFM at the same temperature and an air dried control. Lower air volumes in 1990 proved to be no better than 45 CFM at 35°C The best compromise drying regime was determined to be 45 CFM at 35°C.

Free access

The pawpaw [Asimina triloba (L.) Dunal] is a native plant found mainly in the southeastern and eastern United States, and its fruit has great potential as a new high-value crop in these regions. Although there are ≈45 named pawpaw cultivars, breeding for improvement of specific traits, such as fruit size and quality, is desirable. Our long-term goal is to utilize molecular marker systems to identify markers that can be used for germplasm diversity analyses and for the construction of a molecular genetic map, where markers are correlated with desirable pawpaw traits. The objective of this study was to identify random amplified polymorphic DNA (RAPD) markers that segregate in a simple Mendelian fashion in a controlled A. triloba cross. DNA was extracted from young leaves collected from field-planted parents and 20 progeny of the cross 1-7 × 2-54. The DNA extraction method used gave acceptable yields of ≈7 μg·g-1 of leaf tissue. Additionally, sample 260/280 ratios were ≈1.4, which indicated that the DNA was of high enough purity to be subjected to the RAPD methodology. Screening of 10-base oligonucleotide RAPD primers with template DNA from the parents and progeny of the cross has begun. We have identified two markers using Operon primer B-07 at 1.1 and 0.9 kb that segregate in a simple Mendelian fashion in progeny of the 1-7 × 2-54 cross. Other primers and controlled crosses will also be screened.

Free access