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C.L. Boehm, I.K. Lee, G. Jung, H.C. Harrison, J. Nienhuis, M. Sass, and Moore Hall

Random amplified polymorphic DNA (RAPD) may have utility as genetic markers facilitating selection in ginseng crop improvement. This experiment determined chemical buffer and root tissue-type combinations that yield repeatable bands. The results allow further experiments using RAPD markers for estimating the genetic distance between ginseng landraces, selection for crop improvement, and extensive fingerprinting for use in determining the origin of tissue samples. This experiment determined mean band yields for all combinations of dry, fresh, and powdered root with cetyltrimethylammonium bromide, potassium/sodium ethyl xanthogenate, and urea buffers. The buffers were applied in replication to the tissue-types with other extraction protocol factors constant. Replications were amplified four times with four different primers using constant PCR and agarose gel electrophoretic protocols. Distinct bands were counted in each replication, and the summation of the replication repeats considered an observation. Least squares means for several response variables were analyzed. The most significant difference found was between buffers. The buffers ctab and urea were productive, and the pex was not. Significant difference was found when buffers were crossed with tissue. The applications of urea to fresh root, ctab to dry root, urea to dry root, and ctab to powdered root were productive. Based on these results we conclude 1) urea and ctab are productive when applied to all tissue-types, 2) dry root, which is easily collected and stored, yields sufficient DNA for analysis, and 3) powdered root, often the form of commercial products that might be tested for genetic origin, will yield sufficient DNA for analysis.

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Richard S. Buker*, Jackie K. Burns, and Fritz M. Roka

Continuous canopy shakers (CCS) were developed in the late 90's and have been used to commercially harvest citrus in Florida. A viable mechanical harvester in Florida must be able to selectively remove mature `Valencia' fruit. A study was conducted to evaluate the effect of operating conditions on mature and immature fruit removal during the 2003 harvest season. The study was conducted in the southern flat woods and northern ridge areas. The study treatments were completely random and replicated four times. The CCS treatments were 145, 215, 230, and 245 cycles per minute (cpm) and a hand picked control. The harvest occurred on 17 and 19 June at the southern and northern sites, respectively. Mature fruit removal linearly increased from 95.7% to 97.9% between 145 and 245 cpm, respectively. Varying the operating ranges significantly influenced mature fruit removal in the southern flat woods site. The trees at the southern site were taller (>4m), and had a larger crop load. At the northern ridge site where trees were smaller, varying the CCS operating ranges did not significantly influence mature fruit removal. Immature fruit removal was influenced by the operating ranges. Immature fruit removal was increased at least 22% over hand picked controls. The results were interpreted to indicate the frequency of CCS is dependent on tree size. The initial selectivity of the CCS was not equal to hand picking.

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Esmaeil Fallahi and John K. Fellman

Effects of three times and five rates of urea application on productivity, tree growth, soil nitrate movement, nutrient partitioning, and postharvest fruit quality of `Redspur Delicious' apple on M.7 rootstock over several years were studied. Time of application did not have significant effects on most fruit quality factors or yield. However, significant differences were observed for quality and yield measurements among different quantities of N. Fruit firmness decreased with every increment in N increase. Trees with N at 0.045 kg/tree had lower yield and higher fruit firmness than those with higher quantities of N. Fruit weight and color decreased with each increment increase in the quantity of N. Trees with N at 0.045 and 0.18 kg/tree had significantly better (more red) color and lower fruit N and leaf N than those with higher quantities of N. Bud tissue nutrients were affected by quantity of N application. Fruit from trees with N at <0.18 kg/tree had lower soluble solids. High N increased fruit ethylene and respiration. Nitrogen application affected 2-methyl butyl acetate of fruit. Monitoring nitrate movement through the soil showed that application of N at >0.45 kg/tree, particularly in fall resulted in excess levels of nitrate, increasing the possibility of underground water contamination. Applying N at ≤0.32 kg/tree did not result in excess soil nitrate at 1.52-m depth.

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Amanda Bayer, John Ruter, and Marc W. van Iersel

Excessive irrigation and leaching are of increasing concern in container plant production. It can also necessitate multiple fertilizer applications, which is costly for growers. Our objective was to determine whether fertilizer and irrigation water can be applied more efficiently to reduce leachate volume and nutrient content without negatively impacting aboveground growth of Gardenia jasminoides ‘MAGDA I’. Plants were fertilized with one of three rates of a controlled-release fertilizer (subplots) (Florikan 18–6–8, 9–10 month release; 18.0N–2.6P–6.6K) [100 (40 g/plant), 50 (20 g/plant), and 25% of bag rate (10 g/plant)] and grown in 5.4-L containers outside for 137 days. Soil moisture sensor-controlled, automated irrigation was used to provide plants with one of four irrigation volumes (whole plots) (66, 100, 132, or 165 mL) at each irrigation event. All plants were irrigated when the control treatment (66 mL irrigation volume, 100% fertilizer treatment) reached a volumetric water content (VWC) of 0.35 m3·m−3. Plants in the different irrigation treatments were irrigated for 2, 3, 4, or 5 minutes, thus applying 66, 100, 132, or 165 mL/plant in the different irrigation treatments. Fertilizer rate had a greater effect on aboveground growth than irrigation volume with the 25% fertilizer rate resulting in significantly lower shoot dry weight (18.7 g/plant) than the 50% and 100% rates (25.3 and 27.3 g/plant respectively). Growth index was also lowest in the 25% fertilizer rate. Leachate volume varied greatly during the growing season due to rainfall and irrigation volume effects on leachate were most evident during the third, eighth, and ninth biweekly leachate collections, during which there was minimal or no rainfall. For these collections the control treatment of 66 mL resulted in minimal leachate (less than 130 mL over the 2-week leachate collection period), whereas leachate volume increased with increasing irrigation volumes. Pore water electrical conductivity (EC), leachate EC, NO3-N content, and PO4-P content were all highest with the 100% fertilizer rate, with the 66 mL irrigation treatment having the highest leachate EC for all fertilizer treatments. Cumulative leachate volumes for the 66 and 100 mL irrigation treatments were unaffected by fertilizer rate, whereas the 132 and 165 mL had greater leaching at the 25% fertilizer rate. Lower irrigation volumes resulted in reduced water and nutrient leaching and higher leachate EC. The higher leachate EC was the result of higher concentration of nutrients in less volume of leachate. The results of this study suggest that a combination of reduced fertilizer rates (up to 50%) and more efficient irrigation can be used to produce salable plants with reduced leaching and thus less environmental impact.

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Antonio Figueira and Jules Janick

In vitro culture of axillary cotyledonary shoots of Theobroma cacao L. (cacao) under increasing CO2 concentration from ambient to 24,000 ppm (culture tube levels) significantly increased total shoot elongation, number of leaves, leaf area per explant, and shoot dry and fresh weight. Although light was necessary for the CO2 response, the effect of various photon fluxes was not significant for the measured growth parameters. Net photosynthesis estimated on the basis of CO2 depletion in culture tubes increased 3.5 times from 463 to 2639 ppm CO2, and increased 1.5 times from 2639 to 14,849 ppm CO2, but declined from 14,849 to 24,015 ppm CO2. Ethylene concentration in culture vessels increased under enriched CO2 conditions. Depletion of nutrients (fructose, K, Ca, Mg, and P) from the medium was increased under enriched CO2 conditions.

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Esmaeil Fallahi, Brenda R. Simons, John K. Fellman, and W.M. Colt

Influence of different quantity and timing of nitrogen application on various physiological aspects of `Redspur Delicious' apple, including nutritional partitioning, bud initiation, fruit set, yield, fruit quality and nitrate movement in the soil were studied over several growing seasons. Urea at the rates of: 40.2 Kg/ha; 160.8 Kg/ha; 281.3 g/ha; 401.9 Kg/ha; 522.4 K /ha were applied. Each rate of urea was applied: all at full bloom; half at full bloom and half at late spring; or all in fall. In 1993, time of application did not influence yield, fruit weight, color or soluble solids at harvest. Trees that received 401.9 and with 522.4 Kg/ha had higher yield than those with other quantities. Trees with 160.8 and 281.3 Kg/ha had higher yield than trees with 40.2 Kg/ha. Fruit weight in all quantities, except that of 522.4 Kg/ha, were similar. Fruit weight of trees with 522.4 K /ha was reduced. Fruit color was reduced as N quantities increased. Trees with 40.2 Kg/ha N had lower soluble solids than all other quantities. A high level of N increased ethylene and respiration in the fruit. Thus, if the poor color of fruit is due to high nitrogen, a long delay in harvest to improve the color could lead to an over ripe fruit. A preliminary test did not indicate harmful levels of nitrates movement in the soil.

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Shangchun Hu, Gail Hansen, and Paul Monaghan

Stormwater ponds are widely used in urban developments to control and clean stormwater and add aesthetic appeal to the landscape. This dual function of residential stormwater systems can create conditions at odds for the optimal performance of either function. This investigation sought to discover connections between aesthetics, plants, design, maintenance, and municipal codes as a means to improve water quality and stormwater pond appearance. To establish the connections between visual quality and environmental function, we conducted five focus groups, four interviews with landscape professionals, and reviewed regulatory codes for 46 municipalities. We concluded that homeowner preferences and the social influence of neighbors were closely linked to design, codes, and management issues. Insights gained include the shared social value of wildlife viewing and aesthetic preferences for diverse, but maintained shoreline planting.

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Jerry C. Leyte and Charles F. Forney

Forced-air cooling rates of highbush blueberries (Vaccinium corymbosum L.) packaged in 6-oz (177-mL) or 1-pt (473-mL) clamshell containers were affected by positions of vent holes in corrugated flats. Most rapid cooling occurred in flats with vents across the top of the flat. Additional vents aligned in front of clamshells resulted in more rapid and uniform cooling than vents placed between clamshells. Vent holes in the bottom of flats had no effect on cooling rates. Clamshells cooled more slowly in the front of the pallet where cold air entered than in the back of the pallet where cold air exited. Fruit in 6-oz clamshells cooled faster than fruit in 1-pt clamshells.

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Jonathan M. Frantz and Cary A. Mitchell

A major source of power consumption in controlled-environment crop production is plant-growth lighting. Methods developed to minimize this source of power consumption will reduce the negative environmental impact of crop production through more-efficient management of non-renewable resources. One such method uses “intracanopy lighting,” in which the plants are allowed to grow through multiple levels of low-intensity lamps to irradiate the understory that normally is shaded when traditional overhead lighting is used. Early results with cowpea (Vigna unguiculata L. Walp `IT87D-941-1') indicate a significant reduction in net power consumption within a given growth area or volume while enhancing the harvest index (HI = percent edible biomass). Incorporation of mylar reflectors and manipulation of lamp geometries for more-efficient use of available photosynthetically active radiation, while maintaining low power consumption are the focus of present experiments. Photosynthetic rates by leaves of different ages and positions within the canopy are measured as a way of determining lighting efficiency. The productivity parameters HI, edible yield rate (EYR = gDW × m–2 × day–1), yield efficiency rate (YER = gDW edible × m–2 × day–1 [gDW non-edible]-1), energy conversion efficiency (ECE = EYR × [kW·h]–1), and energy partition efficiency (EPE = YER × [kW·h]–1) express the costs of edible biomass production in terms of the spatial, temporal, energetic, and non-edible biomass penalties. [Research supported in part by NASA grant NAGW-2329.]

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Anita N. Azarenko, Annie Chozinski, Sarah F. McDonald*, Thomas A. Forge, and Timothy Righetti

Information about the use of alternative management practices (AOFMP) in perennial systems to manage soil biota and influence the uptake of nutrients is limited. The objectives of this study are to evaluate AOFMP on soil quality, focussing on soil biology, and on nitrogen uptake efficiency. Research plots are located in Lewis-Brown Farm (LB), Corvallis, OR (`Fuji' apple trees) and Mid-Columbia Ag. Research & Extension Cent. (HR), Hood River, OR (`Red Delicious' apple trees). Main plot treatments were weed control methods: herbicide or cultivation. Sub plot treatments were soil amendments: no amendment, bark mulch (BM), compost, and green vetch/barley mulch (VB). A split-plot completely randomized design with 3 replications was used. Depleted NH3 SO4 was applied to single-tree replicates at bud break in 2001, 2002, and 2003. Compost amended plots contained more fungivorous nematodes than other treatments, although this difference was not significant at LB. At both sites there was a significant interaction between main and sub plot treatments in the number of bacterivores. At LB, the interaction between main and sub plot treatments affected the number of enrichment opportunists and the F-ratio was affected by amendment. At HR, the structural index was also affected by amendment. Compost resulted in the most diverse populations. Soil respiration rates in compost and BM plots were consistently higher than in unamended and VB treated plots. Soil P, pH, and organic matter content were increased by compost amendment and bulk density was decreased. At HR mid-season leaves, fruit, and first year growth from compost treated plots contained the least nitrogen derived from fertilizer, followed by bark mulch. The highest nitrogen derived from fertilizer was in unamended plots.