bluuebunny/crossref_metadata_2025 huggingface dataset:
Peach Rootstock Performance of BY-520-9 and Lovell in a Peach Tree Short Life Replant Site
Authors: Parker Michael L. , Ritchie Dave , Nyczepir Andy
Published: February 2019

A study was initiated in 1994 to evaluate the performance of the recently released peach rootstock Guardian TM (BY-5209-9), compared to Lovell, the commercial standard in North Carolina. `Redhaven' was the scion for both rootstocks. Guardian&™ is reported to be tolerant to root-knot nematodes and not affected by ring nematodes, which contribute to the incidence of peach tree short life (PTSL). The site of this study has a history of poor peach tree survival. Six-year-old trees were removed because of tree mortality from PTSL in Spring 1993. After tree removal, one-half of each existing row was pre-plant fumigated and trees were replanted over the rows of the previous orchard in Feb. 1994. In Spring 1996, tree mortality for the trees planted on Lovell was 30%, compared to 10% for the trees planted on GuardianTM. Trunk cross-sectional area for trees grown in the fumigated soil was approximately double that of trees grown in the unfumigated soil for both GuardianTM and Lovell. The 1996 fruit crop was eliminated from frost/freeze conditions and 1997 yields will be discussed. In Fall 1996, one-half of the trees were treated with a post-plant nematicide to determine if such treatments are necessary or beneficial with the GuardianTM rootstock.
Inheritance of Leptine Production in Solanum chacoense
Authors: Ronning Catherine M. , Sanford Lind L. , Stommel John R.
Published: February 2019

Colorado Potato Beetle (Leptinotarsa decemlineata Say., CPB) is a destructive pest of the cultivated potato, Solanum tuberosum L. Certain glycoalkaloids in potato leaves are effective deterrents to this insect; however, in tubers these compounds can be toxic to humans. Leptines are foliar-specific glycoalkaloids produced by the related species, S. chacoense. These compounds have been shown to confer resistance to CPB. We are studying the inheritance of leptine production in segregating F1 and F2 populations derived from two S. chacoense accessions, 55-1 and 55-3, which are (respectively) high and low leptine producers. The F1 segregates 1:1 for high (>70% of total glycoalkaloids) and low (<20% of TGA) leptine content. Segregation data from the F1 and F2 populations suggest a twogene model for leptine production: a dominant repressor and a recessive inducer. Using two bulked DNA samples composed of highand low-leptine individuals from the F1 population, we are using various types of molecular markers (RAPDs, SSRs, DS-PCR, and AFLPs) to search for markers linked to leptine production. We have identified a RAPD band that appears to be closely associated with low leptine content and supports the two-gene model. The use of such a marker in a breeding program will facilitate the development of CPB resistant potato varieties.
Inheritance Patterns of Morphological Traits Related to Drought Tolerance in New Guinea Impatiens
Authors: Quene Robert J. , Strefeler Mark S.
Published: February 2019

Three drought-tolerant and four drought-susceptible breeding lines from the Univ. of Minnesota's New Guinea impatiens breeding program were crossed in all combinations (reciprocals and selfs) using a complete diallel crossing scheme. Progeny of each cross were grown using standard cultural practices and data was taken on the morphological traits shown to be related to drought tolerance in previous studies. Data was taken on leaf thickness, leaf width, leaf length, leaf area, and leaf dry weight. From these data the leaf length:width ratio and leaf dry weight/unit area (g·cm–2) were calculated. Mean squares for general and specific combining ability were estimated using Griffing's Model 1, Method 4. Differences between crosses were highly significant (P < 0.001) for all traits examined. Means squares for specific (SCA) and general (GCA) combining ability were significant indicating that both additive and non-additive gene effects are important in the inheritance patterns of these characters. For all traits, GCA was greater than SCA indicating that the additive component had the greatest influence on gain from selection for these traits. These findings agree with other estimates of GCA and SCA for these characters in other crops species. The importance of non-additive effects (SCA) on inheritance of these traits explains why we were able to make rapid improvement in drought tolerance in New Guinea impatiens and the role of additive effects (GCA) on drought tolerance indicates that we can continue to make substantial progress improving drought tolerance in New Guinea impatiens. The impact of these findings on strategies to improve drought tolerance in New Guinea impatiens will be discussed in this presentation.
Distinguishing Poinsettia Cultivars and Evaluating Their Genetic Relationships using DNA Fingerprinting
Authors: Starman Terri Woods , Abbitt Shane
Published: February 2019

The objective was to distinguish between cultivars and evaluate genetic relatedness of poinsettia (Euphorbia pulcherrima) using two methods of DNA fingerprinting—DNA Amplification Fingerprinting (DAF) and Arbitrary Signatures from Amplification Profiles (ASAP). Eleven red poinsettia cultivars were studied, including `Celebrate 2', `Darlyne', `Freedom Red', `Lilo', `Nutcracker Red', `Peterstar Red', `Petoy', `Red Sails', `Supjibi', `V-14 Glory', and `V-17 Angelika'. Amplification was with 10 octamer primers. Gels were visually scored for presence or absence of bands. The 10 primers generated 336 bands. The average number of bands (≈1000 bp) per primer was 34 ranging from 19 to 43. Thirty-one percent of bands were polymorphic and distinguished between each cultivar. The number of unique profiles varied from two to nine. Genetic relationships were evaluated by SAHN cluster analysis based on the distance estimator of Jaccard using the NTSYS-pc program (Numerical taxonomy and multivariate analysis system, version 1.8). The resulting dendrogram closely agreed with known pedigree data. ASAP analysis was used to further assess cultivar identification of two cultivars that were genetically and morphologically similar. Markers were found that separated `Nutcracker Red' and `Peterstar Red'. ASAP analysis separated cultivars within the Freedom series that DAF failed to distinguish. Two cultivars in the Freedom series, `Jingle Bells' and `Marble', were characterized from other cultivars in the series with ASAP.
Regulation of Greenhouse Night Temperature Based on Total Carbohydrate Concentration and Night Length
Authors: Hou Guoqiang , Buxton Jack W.
Published: February 2019

The relationship between initial total non-structural carbohydrate concentration (TNCi) in marigold seedlings, night temperature, and night length were evaluated. Seedlings containing an average of 7.2, 18.1, and 23.5 mg/100 mg dwt of nonstructural carbohydrate (TNC) at sunset were treated with night temperatures of low (10°C), medium (17°C), and high (24°C). Starch and soluble sugars were determined at intervals during the night. TNC concentration at the end of the night is a function of the night temperature, TNCi concentration at sunset, and the night length. A model describing the relationship of these variables and their interactions was derived to estimate TNC concentration at any time during the night. This model when solved for temperature (t) establishes a temperature that will regulate the metabolic rate so the TNC concentration is metabolized efficiently to some minimum concentration by the end of the dark period. t = (–2.93 + 1.14 TNCi + 0.74 T – TNC – 0.48 TNCi * T)/(–0.18 + 0.011 TNCi + 0.04*T), R2 = 0.88**). Thus, by knowing TNCi (possibly by near-infrared spectroscopy), the length of the night, and, assuming some minimum concentration for TNC by the end of the dark period, the night temperature is established.
Polyethylene Mulch, Diurnal and Seasonal Soil Temperatures, and Growth and Productivity of Strawberries in Southern California
Authors: Larson Kirk D.
Published: February 2019

Southern California strawberry growers use clear polyethylene mulch to increase soil warming and promote plant growth and fruiting, but use of clear poly mulch is only feasible when effective preplant soil fumigation controls weeds. In the absence of methyl bromide fumigation, the use of wave-length selective (WLS) or black polyethylene bed mulches may be required for adequate weed suppression, but the influence of these materials on strawberry plant growth and productivity in southern California is not well-documented. We conducted experiments in 1994–95 and 1995–96 to determine the influence of various mulch formulations on soil temperature and growth and productivity of `Chandler' strawberry in Irvine, Calif. Clear poly and a green WLS material (IRT76, AEP Plastics) were compared in both trials; in addition, the 1995–96 trial included a brown WLS material (ALOR, PolyWest, Inc.) and a black poly mulch. For both trials, freshly dug runner plants were established in premulched beds in early October, and soil temperatures were continuously monitored at a 10-cm depth using thermocouples and a recording datalogger. Fruit harvest commenced in December and continued through June. In both years, clear poly mulch resulted in significantly greater soil temperatures, greater December plant diameters, and greater early and total fruit yields than other mulches. In both years, use of clear poly resulted in 12% greater fruit yields than the other three materials. No growth or productivity differences were observed among the WLS and black mulches, although differences were observed in mean soil temperatures.
Comparing Solarization Soil Treatment with Methyl-bromide Soil Fumigation on Strawberries
Authors: Bringhurst Royce S. , Godoy F Jose
Published: February 2019

There is a great deal of interest in the possibility of developing suitable materials or procedures for use in strawberries and other crops in place of methylbromide as a soil fumigant. One such has been soil heating resulting from the bed application of transparent polyethylene. This requires high mid-summer soil temperatures with relatively high soil humidity. We present the results of a solarization experiment. Bed soil temperature were measured regularly at a depth of 12 cm through the 9 weeks of differential treatments. The soil temperature differences were highly significant, averaging ≈7°C higher than the non-solarized treatments. Weed control is one of the results of high interest. The number of weeds were counted twice. The number in the solar plots were not significantly different from the number counted for the methyl-bromide-fumigated plots. Vegetative vigor (asexual response) was also an important measurement. This was measured in two ways: first, the number of runners, and second, the measurement of plant size. The results were identical. The solarized plots and fumigated plots were identical in plant size and identical in runner production, and both were significantly different from the non-solarized and non-fumigated plots. Similar results were obtained for the sexual responses, yield, and fruit size. Solarization should be tested sufficiently in detail as a possible procedure to replace some methyl-bromide fumigation.

The biggest problem may be difficulty getting the temperature high enough to be adequately effective.
E-2-Hexenal Can Both Stimulate and Inhibit Botrytis Growth in Vitro and on Strawberry Fruit in Vivo
Authors: Fallik Elazar , Archbold Douglas D. , Hamilton-Kemp Thomas R.
Published: February 2019

Some plant-derived natural volatile compounds exhibit antifungal properties and may offer a tremendous opportunity to control the causes of postharvest spoilage without affecting fresh produce quality or leaving a residue on the produce. E-2-hexenal has shown significant potential for use as a fumigant for controlling Botrytis cinerea in prior studies. In in vitro studies on the mode of action of E-2-hexenal, mycelial growth and percent spore germination were inversely proportional to concentrations of the compound. Spore germination was found to be more susceptible to the compound then mycelial growth. Much higher concentrations of E-2-hexenal were required to inhibit mycelial growth than spore germination. Lower concentrations of the compound significantly stimulated mycelial growth, especially when the volatile was added 2 days following inoculation. Light microscopy analysis revealed that a high concentration of the volatile damaged fungal cell wall and membranes. Treatment with a high vapor phase level of E-2-hexenal during postharvest storage of strawberry fruit at 2°C prevented botrytis development in a subsequent storage period at 15°C. However, treatment with a low vapor phase level enhanced botrytis development. The implications of these results with respect to the practical use of E-2-hexenal and other natural volatile compounds will be discussed.
Cropping Effects on Flower Development of `Royal Gala' Apple
Authors: Hirst Peter M. , Cashmore Wendy M.
Published: February 2019

Spurs were collected periodically throughout three growing seasons from the 1-year-old section of wood of `Royal Gala' trees growing in New Zealand. Three classes of spurs were sampled: purely vegetative spurs, those that flowered but did not carry fruit, and spurs on which a single fruit was borne. The bourse bud, in which flowers may form for the following year's crop, was dissected and bud appendages classified and counted. In addition, axillary buds from current-season shoots were sampled and dissected. Over the period 50–200 days after full bloom, the number of appendages in buds on vegetative spurs increased from ≈14 to 22, whereas the increase in buds on fruiting spurs was 14 to 20. In contrast, axillary bud appendage numbers increased from ≈11 to 14 over this period. By the end of the growing season, flowers were evident in a high proportion of buds of all classes. The critical appendage number at which the change from a vegetative to floral status became visible was ≈18 for spurs on 1-year-old wood, but 13 for axillary buds. The time at which flowers were able to form varied among years. The degree of flower differentiation that occurred prior to leaf fall was highest in vegetative buds and was reduced by flowering and fruiting, and was lowest in axillary buds.
Effect of Spacing and Rectangularity on Tree Growth, Yield, Light Interception, and Fruit Quality of Y-trellis-trained Apple Trees
Authors: Robinson Terence L.
Published: February 2019

In 1986, an orchard systems trial was planted with `Empire' and `Jonagold' on M.26 rootstock to compare the performance of the Y-trellis training system at a range of spacings and rectangularities. There were four in-row spacings ranging from 90 cm to 3.66 m and four between-row spacings ranging from 3 to 6 m, giving tree densities from 472 trees/ha up to 3588 trees/acre. Rectangularities ranged from 0.83 to 6.67. In several cases, different spacings gave the same tree density, but with different rectangularity. Trees were trained to a Y-shaped trellis with a 60° angle. Scaffold branches were trained to the wires on each side of the Y in a fan-shaped arrangement. At the closest in-row spacing only two scaffolds were allowed per tree, while at the widest in-row spacing up to 12 scaffolds were allowed per tree. At the end of 11 years, tree weight and cumulative yield per tree were negatively correlated to tree density, while light interception and cumulative yield per hectare were positively correlated to tree density. However, the relationship was weakened by differing results with different rectangularities at the same spacing. As rectangularity increased at a given density, tree size, yield, and light interception were reduced. However, at the lower densities, trees failed to completely fill the trellis when rectangularity was low, thus limiting yield per hectare. Fruit red color was reduced at the highest densities and increased with increasing rectangularity.
Morphology of Two-year-old Limb Sections and Mid-season Spur Quality of Four Apple Cultivars on Five Dwarfing Rootstocks
Authors: Erb W. Alan , Ferree David C. , Morrison Frank D. , Pyeatt Mark , Ryer Richard
Published: February 2019

This study was conducted at three locations (Manhattan, Kan.; Wichita, Kan.; Wooster, Ohio) for 3 years (1994–1996). At bloom, 2-year-old limb sections from `Smoothee', `Jonagold', `Empire', and `Rome' on M.9EMLA, Bud 9, Mark, Ottawa 3, or M.26EMLA were evaluated for flowering and vegetative, spurs (5 cm or less), short shoots (5–15 cm) and long shoots (>15 cm). In mid-August, spur quality was estimated by randomly selecting five spurs per cultivar rootstock combination. There were significant location and year differences for all the morphological and spur quality characters measured. Across locations and years, the following characteristics were consistently high for the cultivars listed: stem density of flowering spurs for `Empire'; and leaf area, bud-diameter and average leaf size per spur for `Jonagold'. The most consistently high characteristics across locations and years for the rootstocks were for stem density of flowering spurs for Mark and leaf number, leaf area, bud-diameter, and average leaf size per spur for M.26EMLA. Stem density for flowering short shoots was highest for `Smoothee' and M.9EMLA in Wooster, `Jonagold' and Bud 9 in Wichita and `Rome', `Jonagold', and Bud 9 in Manhattan. Flowering long shoot stem density was highest for `Smoothee', `Jonagold', and M.26EMLA in Wooster, `Smoothee' in Wichita, and `Jonagold' and Ottawa 3 in Manhattan. There were some significant cultivar by rootstock interactions. The most-consistent interactions across locations and years were for stem cross-sectional area, stem length, stem density of flowering spurs, and flowering short shoots and bud-diameter per spur.
Increasing Tree Complexity and Bearing Potential in Young `Fuji' Apple Trees
Authors: Huysamer Marius
Published: February 2019

Under typical South African growing conditions, `Fuji' apple (Malus domestica Borkh.) trees are characterized by strong apical dominance during the first few years after planting. This, together with the current lack of suitable precocious rootstocks and the tip-bearing habit, causes willowy “blind wood” growth with few flowering positions, and delays bearing until the third leaf when a crop of less than 10 tons/hectare can be realized. Promalin (GA4+7 and benzyladenine, Abbott Laboratories) was used in combination with apical meristem defoliation and Agral or Armoblen as surfactant/penetrant to induce sylleptic shoot growth in an effort to increase tree complexity (i.e., branching) without having to resort to pruning, which is dwarfing and delays bearing. The treatments were tested on `Fuji' grafts, 1-year old trees and 2-year old trees in the 1993–1994, 1994–1995, and 1995–1996 seasons, respectively. Concentrations tested were 0, 500, 750, or 1000 ppm, as single or multiple applications in spring. In all trials, randomized, complete block designs were used. Control trees had few, if any, sylleptic shoots or spurs, whereas Promalin in combination with leaf removal or in combination with Armoblen caused significant sylleptic growth to occur. Generally, multiple applications spaced fortnightly, gave best results. Sylleptic shoots were ≈15 cm long, terminated in a reproductive bud, and did not influence the length of the “mother” shoot or the trunk circumference. Based on these results, a combination of multiple applications of 500 ppm Promalin with Armoblen as penetrant, and no leaf removal, is being tested semi-commercially this season.
Foliar Morphology and Anatomy of Hard Maples Vary with Geographic Origin
Authors: Hilaire Rolston St. , Graves William R.
Published: February 2019

Differences in foliar morphology and anatomy of hard maples (Acer saccharum Marsh. and Acer nigrum Michx. f.) may explain contrasting responses to moisture stress of these species. We conducted a 2-year study to examine leaf morphology and anatomy of populations of hard maples indigenous near the 43°N latitude from 94°W longitude in Iowa to the 71°W longitude in Maine. Leaves were collected from shoots exposed to direct solar radiation on multiple trees at each of 24 sites in 1995, and at 36 sites in 1996. Samples collected in 1995 showed stomate frequency on the abaxial leaf surface ranged from 380 to 760 stomata/mm2. Mean guard cell pair width and length were 16 and 17 μm, respectively. Stomate frequency related quadratically to longitude, was greatest for leaves from Iowa, and was negatively correlated with mean annual precipitation of the sample site. Leaf thickness did not vary with longitude and averaged 96 μm. Palisade thickness showed a greater correlation than mesophyll thickness to total leaf thickness. Mesophyll thickness was more highly correlated than palisade thickness to specific leaf mass, which did not vary with longitude and averaged 5.2 mg·cm–2. Analysis of leaves collected over both years showed trichome frequency and lamina area were related quadratically to longitude; the largest and most pubescent laminae were from westerly sites. These studies are being coordinated with greenhouse experiments on responses of seedlings from selected populations to moisture deficits.
Survival and Growth of Amur maackia Seedlings Across North America
Authors: Aiello Anthony S. , Graves William R.
Published: February 2019

Amur maackia (Maackia amurensis Rupr. & Maxim.) has potential for use in small, urban, or cold landscapes. Although Amur maackia is becoming increasingly popular, plants are currently grown from open-pollinated seed populations, and there has been no selection of cultivars. We have addressed the effects of climate on growth and have begun field trials for selection of horticulturally superior genotypes. In May 1995, a field trial near Ames was begun with 337 plants. These were selected from more than 2000 greenhouse-grown seedlings to represent 32 half-sibling seed groups from 16 arboreta across North America. After two growing seasons, the increase in stem length among seed groups ranged from 3% to 75%. Survival rate did not vary with seed group. In a related study, 30 plants from six half-sibling groups have been established at each of 10 sites in the U.S. and four in Canada to assess effects of location on survival and growth. The influence of seed group on survival after 1 year varied with the trial site location. Survival among combinations of half-sibling group and trial location ranged from 0% to 100% (mean = 54%). Half-sibling group and trial location affected growth without interaction. The greatest growth across locations, an 83% increase in stem length, was shown by seeds that originated from a tree at the Arnold Arboretum. At the 14 locations, changes in stem length over half-sibling groups varied from <0% in Ithaca, N.Y., to 179% in Puyallup, Wash.
Low-temperature Tolerance of Testing Woody Ornamental Plants: A Comparison of Ice-seeded vs. Nonseeded Methodologies
Authors: Cappiello Paul E. , Wachter John F. , Libby B.
Published: February 2019

Accurate assessment of the low-temperature tolerance of woody landscape plants is essential to ensure proper siting and use of specific varieties in the landscape. Laboratory determination of lowest survival temperature (LST) has become a popular area of study in recent years, yet there has been no standardization of technique among the many labs conducting this work. One of the major differences in technique employed across the country is the presence or absence of ice seeding of samples prior to the testing procedure. This presentation will present results of a series of studies conducted to determine the need for and efficacy of ice seeding treatments for LST determination in woody plants. A series of four studies was conducted over a 3-year period to test the difference in LST estimation with and without ice seeding. Twenty-two taxa, including both deciduous and evergreen species, were subjected to controlled freezing at ≈4°C/hr. with test samples removed from the freezer every 3°C. Following a 24-hr thaw and 5 to 7 days of incubation at 21°C, 100% RH, stems were sliced longitudinally and visually assessed for damage to vascular tissues. In the majority of cases, ice seeding was determined to have no significant affect on LST determination. In several species (Kalmia latifolia, Vaccinium angustifolium), the introduction of ice seeding into the protocol resulted in greater variation and less distinct determination of LST.
Whole Plant and Histological Analysis of Poinsettia Stem Breakage
Authors: Faust James E. , Will Elizabeth , Duan Xian , Graham Effin T.
Published: February 2019

Poinsettia stem breakage reduces plant quality and marketability. The cultivar `Freedom' is susceptible to stem breakage; however, the severity of stem breakage varies with crop and year. The following four experiments were conducted to determine the factors that influence stem breakage of `Freedom' poinsettias: 1) Cutting Stem Diameter. Cuttings were graded by stem diameter into small (5.0–5.4 mm), medium (6.0–6.7 mm), and large (7.3–8.3 mm) cuttings. 2) Premature Lateral Shoot Development.Small (1- to 3-cm-long) leaves near the shoot tip of the rooted cuttings were excised to remove the lateral shoots from apical dominance prior to pinching, thus causing the lateral shoots to develop prematurely. 3) Container Spacing. The control group was spaced to 35.6 × 35.6 cm at the time of pinching. The plants in one treatment were spaced to 23.1 × 23.1 cm 25 days after pinching, and then spaced to 35.6 × 35.6 cm 11 days later. The plants in a second treatment were grown pot-to-pot for 36 days after pinch, at which time they were spaced to 35.6 × 35.6 cm. 4) Node Number. Plants were pinched to eight nodes, while the control group was pinched to 5 nodes. Tissue development in the stem crotch; i.e., the area of lateral stem attachment to the main stem, was observed by microscopic examination of paraffin-embedded samples from each experiment every 2 weeks until anthesis. Lateral shoot strength was quantified by hanging a plastic beaker from the lateral stem and gradually adding water until stem crotch failure occurred. We observed that stem strength increased as cutting stem diameter increased. Plants pinched to eight nodes produced weaker lateral shoots than those pinched to five nodes. Premature lateral shoot development and container spacing did not affect stem strength.
A Business Study of Michigan Retail Florists
Authors: Collins Carolyn A. , Fails Barbara S.
Published: February 2019

In the spring of 1996, Michigan State Univ. and the Michigan Floral Assn. mailed a comprehensive business survey to all Michigan floral retailers. This was the first nonpartisan study of the retail florist industry in Michigan. Based upon the 183 responses from full-service retail florists (those who deliver and subscribe to a wire service), a profile of the “typical” Michigan florist was constructed. Data presented will include general business operations, such as store floor space and length of time in operation, delivery services, wire service membership, advertising and marketing practices, staffing and wages, and annual profit and loss figures. Results provide a comparative benchmark for common retail florist business practices and can be used to assess the impact certain business operations may have on sales and financial success.
Consumer Preferences for Geranium Flower Color, Leaf Variegation, and Price in Five U.S. Markets
Authors: Behe Bridget , Nelson Robert , Barton Susan , Hall Charles , Turner Steve , Safley Charles
Published: February 2019

Consumers in five U.S. markets evaluated photographs of geranium plants with regard to purchase likelihood. Photographic images were colored electronically to produce uniform geranium plants with five flower colors (pink, white, red, lavender, and blue) and three leaf variegation patterns (dark zone, white zone, and no zonal pattern). Photographs were mounted on cards with five selected price points ranging from ($1.39 to $2.79). We randomly generated an orthogonal array, partial-factorial design for consumers to rate a reduced number of choices. Consumers shopping in cooperating garden centers located in Dallas, Texas; Montgomery, Ala.; Athens, Ga.; Charlotte, N.C.; and Wilmington, Dela., rated 25 photographs on the basis of their likelihood to purchase the plants shown. Conjoint analysis revealed that customers in the Georgia garden center placed the highest proportion of their decision to buy on leaf variegation (29%), while customers in the Alabama outlet placed the most emphasis on price (46% of the decision). Shoppers in Texas valued flower color most highly (58% of their decision to buy). Demographic characteristics and past purchase behavior also varied widely, suggesting diverse marketing strategies for geraniums.
Plant Diversity and Its Effects on Populations of Cucumber Beetles and Their Natural Enemies in a Cucurbit Agroecosystem
Authors: Walker Jason , Caldwell John S. , Jones Robert H.
Published: February 2019

To assess the value of uncultivated vegetation for control of cucumber beetles, populations of striped (Acalymma vittatum Fabr.), spotted (Diabrotica undecimpunctata howardi Barber), and western cucumber beetles (Acalymma trivittatum Mann.) (Coleoptera: Chrysomelidae) and natural enemy Diptera flies (as an indicator of Celatoria spp. parasitoids), Pennsylvania leatherwings (Chauliognathus pennsylvanicus DeGeer) (Coleoptera: Cantharidae), lady beetles (Coleoptera: Coccinellidae), Hymenoptera wasps, and spiders were monitored with sticky traps on 50-m transects running through a field of Cucumis sativa L. `Arkansas Littleleaf' into bordering uncultivated vegetation. Plant species composition was determined in square plots around each sticky trap by estimating total plant cover and height distribution of plants from 0 to 1.0 m. In both years, numbers of cucumber beetles increased and numbers of Diptera decreased towards the crop. These trends increased monthly to peaks in Aug. 1995 (0.3 to 6.0 striped cucumber beetles; 40.0 to 15.3 Diptera) and July in 1996 (0.1 to 7.1 striped cucumber beetles; 46.7 to 15.5 Diptera). Abundance of individual plant species contributed more to maximum R2 regression of insect populations than did measures of plant diversity in sampling squares. Diptera were negatively correlated with sweet-vernal grass (r = –0.65 at 0 m) and wild rose (r = –0.62 at 0.5 m) in 1995, and goldenrod (r = –0.31, –0.59, and –0.53 at 0.5, 0.75, and 1.0 m, respectively) in 1996, but positively correlated with wild violets (Viola spp.) (r = +0.38 at 0 m) in 1996. Cucumber beetles were negatively correlated with wild violets (r = –0.30 at 0 m) and white clover (Trifolium repens) (r = –0.37 at 0 m) in 1996. These results suggest that increasing or decreasing specific plants in uncultivated vegetation might be useful for influencing pest and beneficial insect populations in cucurbit production.
Comparative Accumulation of Carotenoid Content during Vegetative Growth and Postharvest Storage in Four Carrot Genotypes
Authors: Poon W.Y.L. , Goldman I.L.
Published: February 2019

Carotenoids have been shown to be important both nutritionally and medicinally. Carotenoid accumulation was compared during growth and storage of four carrot genotypes: YY y1y1y2y2RPRP, yyY1 Y1Y2Y2 RPRP, YY Y1 Y1Y2Y2 RPRP, and rprp. These genotypes exhibit orange, yellow, white, and pale-orange roots respectively. The orange and pale-orange genotypes are near-isogenic for rp, a gene that reduces total carotenoid content by 93%. Genotypes were grown in replicated field plots during 1996 and stored for 8 months at 4°C. Samples of root tissue were removed at 7-day intervals during vegetative growth and 4-week intervals during the postharvest period. Total carotenoid content were quantified using HPLC and spectrophotometric analyses. Increases in carotenoid content of 119% and 79% in rprp and YY y1y1y2y2RPRP and decreases of 6% and 64% in YYY1 Y1Y2Y2RPRP and yyY1 Y1Y2Y2RPRP, respectively, were measured between 62 and 100 days after planting. At 100 days after planting, YY y1y1y2y2RPRP exhibited 10-fold greater carotenoid content than rprp. Carotenoid content in yyY1 Y1Y2Y2RPRP and YY y1y1y2y2RPRP increased during the first 28 days of storage and decreased subsequently. Meanwhile, rprp began to decrease in carotenoid content at day 14 of storage. HPLC analysis at l = 445 nm revealed two large unique peaks in rprp with elution times of 27 and 28.7 minutes that were of lesser abundance in YY y1y1y2y2RPRP, suggesting that the rate of β- and α-carotene accumulation is not the only difference between YY y1y1y2y2RPRP and rprp.
Plant Regeneration and Genetic Transformation of Brassica campestris ssp. pekinensis via Organogenesis
Authors: Lim Hak Tae , You Y.S. , Park E.J.
Published: February 2019

In order to regenerate explants of Brassica campestris ssp. pekinensis, known to be one of the most difficult crops to regenerate via organogenesis, three different explants, cotyledon, hypocotyl, and leaf, were cultured on MS basal medium supplemented with several plant growth regulators. In the medium containing NAA at 0.5 mg/L and BAP at 3.0 mg/L, the shoot regeneration, when hypocotyl was used as explant, was found to be quite effective. In the case of cotyledon, the most suitable combination of plant growth regulators was NAA at 1.0 mg/L and BAP at 3.0 mg/L. Treatment of AgNO3 (1.0 mg/L) for shoot regeneration gave positive results in general. Zeatin at 2.0 mg/L was very effective in shoot induction of leaf explant, especially when combined with BAP at 2.0 mg/L, NAA at 1.0 mg/L, and AgNO3 at 0.5 mg/L. A system to produce transgenic plants in Brassica spp. has also been developed using hypocotyl and cotyledonary-petiole segments and shoot-tips. An explants from 4-day-old seedlings were inoculated with an Agrobacterium tumefaciens strain containing a disarmed tumor-inducing plasmid pTiT37-SE carrying a chimaeric bacterial gene encoding hygromycin and kanamycin resistance, along with other genes of interests. The explants were co-cultured for 2 to 6 days before transfer to hygromycin and kanamycin selection media. Shoots regenerated directly from the explants in 1 to 4 weeks and were excised, transferred to shoot elongation medium, rooted in root induction medium, and planted in soil. Genetic transformation was confirmed by kanamycin or hygromycin resistance, GUS activities, and Southern blotting.
Utility of DNA Flow Cytometry for Ploidy Determination of Anther-derived Broccoli: Effect of Leaf Age and Sampling Protocols
Authors: Farnham Mark W. , Caniglia Ellis J. , Thomas Claude E.
Published: February 2019

Broccoli (Brassica oleracea L. Italica group) breeders routinely use anther or microspore culture to produce dihaploid (diploid), homozygous lines. During the culture process, polyploidization occurs and diploid regenerants can result. However, polyploidization may not occur at all, or it may involve a tripling or quadrupling of the chromosome complement. Thus, regenerated populations must be screened to identify the diploids that are the regenerants most likely to set seed and serve as inbred lines. DNA flow cytometry has proven a useful procedure for determining ploidy of anther derived regenerants. This study was undertaken to evaluate the effect of leaf age and sampling procedures on ploidy determination via flow cytometry. Anther-derived plants were analyzed at a four- to five-leaf stage (transplant stage) and at time of heading (mature plant stage). In addition, leaves were sampled on a given date and stability of the flow cytometry preparations was evaluated over 7 days. Lastly, the stability of ploidy readings of leaves stored at 4°C was examined over a 7-day period. In only one case out of 123 comparative assays did leaf age affect ploidy determination. For that exception, a haploid at transplant stage was a diploid at the mature plant stage. Flow cytometry preparations and also leaves stored at 4°C gave consistent ploidy determinations up to four days after preparations were made or tissue was refrigerated, respectively. These results indicate that broccoli breeders can make flow cytometry preparations on site and send them offsite for flow cytometry analysis. Alternatively, leaves could be refrigerated, sent offsite, and then prepared and analyzed at another location.
Pawpaw [Asimina triloba (L.) Dunal] Germplasm Evaluation Using RAPD Markers
Authors: Huang Hongwen , Layne Desmond R. , Kubisiak Thomas L.
Published: February 2019

Kentucky State Univ. (KSU) is the national clonal germplasm repository for Asimina species. Previous evaluation of the KSU pawpaw collection using 24 isozyme markers demonstrated that pawpaw has a relatively higher genetic diversity than that noted for other plant species with similar species characteristics (long-lived, woody, perennial, out-crossing, temperate, widespread, etc.). Current evaluation using RAPD markers will provide us with a more-accurate insight into pawpaw genetic diversity and population structure. In a preliminary experiment, one hundred 10-mer primers (OA1-20 through OE1-20, Operon Technologies Inc.) were screened against 32 commercial cultivars or advanced selections. A subset of 24 primers that amplify only the most-informative markers were used for germplasm evaluation. Sixty-eight RAPD markers were identified and used for determining genetic parameters. One-hundred-twenty pawpaw accessions were sampled from the KSU repository for RAPD analysis. These accessions represented nine widely distributed states within pawpaw's native range. RAPD data were subjected to various analyses using the NTSYS-PC computer program (ver. 1.8). Information generated from isozyme and RAPD markers will be used to formulate future germplasm collection strategies from wild populations within the native range. The implications of such information to the genetic enhancement of our repository and establishment of a core collection will be discussed.
Immunolocalization and in Vitro Cryoprotective Activity of PCA60: A Peach Dehydrin
Authors: Wisniewski Michael , Balsamo Ron , Close Tim
Published: February 2019

Cold acclimation in temperate, woody plants is a complex phenomenon that involves distinct changes in gene activity and protein synthesis. In previous research, a 60-kDa protein (PCA60), belonging to the dehydrin family of stress-related proteins, was identified in peach bark, and its corresponding gene (ppdhn1) was cloned and characterized. Presently, we report on the results of immunolocalization studies and in vitro cryoprotection assays. Seasonal collections of current-year stems were embedded in LR White or epoxy resin and sections of bark were probed with either a polyclonal antibody directed against a 15 amino acid sequence consensus region of dehydrins or a polyclonal antibody directed against partially-purified PCA60. In vitro cryoprotection assays utilized lactose dehydrogenase (LDH), a cold-labile enzyme. Immunolocalization at the light level indicated that the dehydrin was confined to the cytoplasm and absent in organelles. This localization was preliminarily confirmed at the ultrastructural level. LDH assays indicated cryoprotective activity in total protein extracts collected from winter bark tissues but completely absent in extracts of summer bark tissues. Preliminary LDH assays utilizing purified PCA60 also demonstrated cryoprotective activity. In general, the data further support a role for dehydrins in cold acclimation of woody plants.
Evaluation of Mechanized Vineyard Production Systems for Barbera (Vitis vinifera L.) Grapevines Grown in the San Joaquin Valley
Authors: Berg G.T. , Striegler R.K.
Published: February 2019

The availability and cost of labor are important concerns for many California wine grape growers. Greater state and federal labor regulations, increased grower liability, increased efforts to control illegal immigration, and mandated increases in the minimum wage are causing growers to investigate production systems that may reduce labor requirements and costs. The purpose of this experiment was to determine the influence of training system and mechanization on vegetative growth, yield, fruit composition, labor requirements, and production costs for wine grapes grown in the San Joaquin Valley of California. Barbera vines grafted on Freedom rootstock were used in the experiment. Treatment variables examined were training system (bilateral cordon, non-positioned vs. bilateral cordon, vertical shoot positioned) and pruning method (hand vs. machine pre-pruning with hand follow-up). The experimental design used was a randomized complete block with data analyzed as a factorial. There were five blocks and all treatment combinations were evaluated. Data were collected during the 1994 and 1995 seasons for vegetative growth, yield, fruit composition, pruning labor requirements, and machinery performance. Few treatment effects were observed on vegetative growth, yield, and fruit composition during the course of this study. When significant differences were noted for these parameters, training system had a greater impact than pruning method. In contrast, labor requirements and production costs displayed a significant response to pruning method. Machine pre-pruning reduced pruning labor requirements from 41 man-hours per acre to 24–28 man-hours per acre per year. Pruning labor requirements were reduced by ≈40% and the costs associated with pruning were reduced by ≈30%.
The Effect of Light and Temperature on the Physiological Status of Bedding Plant Plugs during Short-term Low-temperature Storage
Authors: Papanikou Efstratia , Jennings Paul H.
Published: February 2019

Previous research has shown that low-temperature storage can be used to maintain bedding plants in plug trays when weather conditions in spring make scheduling of transplanting difficult. The objective of this study was to determine what physiological changes occur during the short-term, low-temperature storage of plug seedlings. Plants of two bedding plant species, Geranium and Vinca, were stored at 2, 6, or 10°C and under low light or dark conditions for 4 weeks. Data were collected at three sampling dates (0, 2, or 4 weeks after beginning of storage) and included dry and fresh mass, total leaf area, leaf chlorophyll content and chlorophyll fluorescence as well as electrolyte leakage and soluble sugar content of leaf and root tissue. The parameters will be discussed in relationship to plug seedling survivability, quality, and growth responses under the experimental storage treatments.
Extending Potted Bougainvillea Post-production: NAA, STS, and Ethanol
Authors: Gago Custódia M.L. , Monteiro José A. , Rodrigues Ma Helena M.
Published: February 2019

The effect of NAA [16.5 mg/L or 500 mg/L sprayed once at end-of-production from two different sources: wettable powder (Fruitone) and sodium hydroxide solution (Sigma)], STS (0.5 mM sprayed once at end-of-production and 0.4 mM sprayed every 15 days after bracts started to be apparent) and ethanol 50% (v/v) solution, sprayed twice: at end-of-production and immediately after simulated transport) were tested using two types of completely randomized experiments. At the end-of-production plants were placed for 3 days under simulated transport conditions (171°C, no light) and then placed under interior conditions (211°C and 11 mol·s–1·m–2 of cool-white fluorescent light 12 h/day). Every other day during post-production the number of bracts not completely developed (ED), as well as the number of completely (CD) developed, bracts remaining in the plants were assessed. Among the post-production treatments tested, NAA (500 mg/L) and STS (applications every 15 days during production) + NAA (16.5 mg/L) were the most-efficient treatments. Ethanol and STS (one single application) did not control bract abscission efficiently and did not increase plant longevity. Plants treated with NAA abscise more not completely develop bracts than completely developed bracts. Use of NAA in potted bougainvillea requires fully developed bracts at end-of-production.
Extension of Postharvest Keeping Time of Antirrhinum majus L. Cut Flowers with Hydrogen Peroxide
Authors: Schroeder Kenneth R. , Stimart Dennis P.
Published: February 2019

Three percent hydrogen peroxide (H2O2) was diluted with deionized water (dH2O) to 0.75%, 0.38%, 0.19%, 0.09%, or 0.05% H2O2 plus 1.5% sucrose for use in evaluation of Antirrhinum majus L. (snapdragon) cut flowers. Other vase solutions used as controls included; 300 ppm 8-hydroxyquinoline citrate (8-HQC) plus 1.5% sucrose; dH2O plus 1.5% sucrose; and dH2O. A completely random design with 7 replicationss was used. Flowering stems of three commercial inbreds and one F1 hybrid of snapdragon were cut when the first five basal florets opened. Each stem was placed in an individual glass bottle containing one of the eight different treatments. Flowering stems were discarded when 50% of the open florets wilted, turned brown, or dried. Postharvest life was determined as the number of days from stem cutting to discard. Addition of H2O2 to vase solutions at rates of 0.19 and 0.09% resulted in postharvest life not different from that obtained with 8-HQC plus sucrose. Hydrogen peroxide plus sucrose extended postharvest life of snapdragon cut flowers 6 to 8 days over dH2O and 5 to 7 days over dH2O plus 1.5% sucrose.
Effect of N Source on Photosynthesis and Plant Dry Matter Yield of Tomato
Authors: Whitehead Wayne F. , Singh Bharat P.
Published: February 2019

The objective of this study was to determine if winter legume or grain cover could support net photosynthesis (Pn) and plant dry matter production comparable to recommended rate of synthetic N. The following winter/spring fertility treatments were applied: 1) 0 N winter/0 N spring, 2) 0 N winter/90 kg·ha–1 N spring, 3) 0 N winter/180 kg·ha–1 N spring, 4) 0 N winter+abruzi rye/0 N spring, 5) 0 N winter+hairy vetch/0 N spring, and 6) 0 N winter+crimson clover/0 N spring. `Mountain Pride' tomato was planted in all plots in spring. Plant dry weight and Pn were measured at flowering, fruiting and prior to senescence. The highest Pn (22.78 μmol CO2/m2 per s) and leaf dry weight (115.2 g/plant) were obtained at fruiting, while highest branch dry weight (194.5 g/plant) occurred prior to senescence. There was significant increase in plant dry weight during reproductive growth phase. Tomato plants receiving supplemental N from crimson clover or hairy vetch had Pn and plant dry weight comparable to those receiving synthetic N. The results of this study indicated that legume cover crops were as effective as commercial N fertilizer for supporting photosynthesis and vegetative growth of tomato.
Effect of Antitranspirant and Fertilization on Stomatal Conductance, Transpiration, Mineral Nutrition, and Growth in `Early Girl' Tomato Plants
Authors: Gu Sanliang , Fuchigami Leslie H. , Cheng Lailiang , Guak Sung H. , Shin Charles C.H.
Published: February 2019

Seedling plugs of `Early Girl' tomato plants (Lycopersicon esculentum Mill.) were potted in peatmoss and perlite (60:40% by volume) medium, fertilized with 8, 16, 24, or 32 g NutriCote Total controlled-release fertilizer (type 100, 13N–5.67P–10.79K plus micronutrients) per pot (2.81 l), and treated with 0%, 2.5%, 5%, or 7.5% antitranspirant GLK-8924 solution, at the four true-leaf stage. Plants were tipped at the second inflorescence and laterals were removed upon emergence. Leaf stomatal conductance, transpiration rate, and growth were depressed by GLK-8924. In contrast, higher fertilization rate increased plant growth but leaf stomatal conductance and transpiration rate were not affected until 3 weeks after GLK-8924 treatment. With 24 g NutriCote per pot, lamina N concentration in GLK-8924 treated plants was 12.5-fold of that in untreated plants, regardless of GLK-8924 concentration. Lamina P, K, Fe, and Cu were greater while S, Ca, Mg, Mn, B, and Zn were not affected by GLK-8924. The reduced growth by GLK-8924 may be due to the reduced stomatal conductance while the increased growth by high fertilization may be due to influences on plant nutritional status.