bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Ethanol on Membrane Integrity and Enzyme Expression in Chilled Cucumber Seedlings
Authors: Boyd Windy , Jennings Paul H.
Published: February 2019

Previous experiments have shown that chilling-stressed cucumber seedlings treated with ethanol have greater chilling tolerance when compared to untreated seedlings. To determine whether this increased chilling tolerance would diminish with time after treatment, cucumber seedlings were treated with ethanol and placed at chilling temperatures for 0, 2, 4, 6, or 8 hours after ethanol treatment. Ethanol-induced chilling tolerance declined as the time interval between treatment and chilling exposure increased. A second ethanol treatment was given 3 hours after the first treatment in an attempt to extend the enhanced chilling tolerance response. Ethanol has been reported to function as an anesthetic in some systems, interacting with cellular membranes. To determine the effect of ethanol and chilling on membrane integrity, a malondialdehyde assay was used. Since chilling stress effects may result from accumulation of active oxygen species, the activity of one radical scavenging enzyme (catalase) has been assayed. Ethanol treatment resulted in a rapid increase in catalase activity, and was associated with increased chilling tolerance. The effect of a second ethanol treatment will be discussed as related to induced chilling tolerance, membrane effects, and catalase activity.
Effects of Cold and Photoperiod on Flowering of Several Herbaceous Perennial Species
Authors: Runkle Erik S. , Heins Royal D. , Cameron Arthur C. , Carlson William H.
Published: February 2019

Thirty herbaceous perennial species were treated at 5°C for 0 or 15 weeks. Critical photoperiods for flower initiation and development with and without a cold treatment were determined. Photoperiods were 10, 12, 13, 14, 16, or 24 hours of continuous light or 9 hours plus a 4-hour night interruption. Continuous photo-periodic treatments consisted of 9-hour natural days extended with light from incandescent lamps. Species were categorized into nine response types based on the effects of cold and photoperiod on flowering. Plants had three flowering responses to cold treatment: obligate, facultative, or none. The perennials were obligate long-day, facultative long-day, or day-neutral plants. For example, Campanula carpatica `Blue Clips' had no response to cold and was an obligate long-day plant requiring photoperiods of 16 hours or longer or night interruption for flowering. Rudbeckia fulgida `Goldsturm' had a facultative response to cold and required photoperiods of 14 hours or longer or night interruption for flowering. Veronica longifolia `Sunny Border Blue' had an obligate cold requirement and was day-neutral. Some species responded differently to photoperiod before and after cold. Leucanthemum ×superbum `Snow Cap' flowered as an obligate long-day plant without cold and as a facultative long-day plant after cold. Response categories are discussed.
Cross-pollination within Pecan Orchards
Authors: Wood Bruce W.
Published: February 2019

Pecan is wind pollinated, exhibits heterodichogamy and are either protandrous (I) or protogynous (II). Orchards are typically established using two complimentary flowering types but with no further scrutiny as to the degree of compatibility of these two types. Additionally, orchards are sometime established with a very low frequency of pollinator. An evaluation of several orchards revealed that yield losses are due to poor pollination is likely common. Data indicate that trees beyond about 46 m (150 feet) from a complementary pollinator exhibit substantial reductions in fruit-set; therefore, large block-type plantings are disadvantaged. Flowering data over several years show that Type I and Type II cultivars are often functionally noncomplementary, suggesting that pecan cultivars should also be identified with a seasonal identification (i.e., early, mid, and late). Data also indicate that dichogamy patterns substantially change as trees age or with abnormally warm or cool springs; hence, pollination patterns will vary depending upon orchard age. Data indicate that orchards should be comprised of 3+ cultivars. RAPD-DNA analysis of “hooked-nuts” indicates that this trait is not reliable as an indicator of selfing.
Benzyladenine and Daminozide Sprays Applied after Initial Anthesis Affect Bract Necrosis in Poinsettia
Authors: McAvoy Richard , Bible Bernard
Published: February 2019

Bract necrosis (BN) in poinsettia is thought to be caused by a localized calcium deficiency in the margins of bracts. Both calcium and silicate sprays can suppress the post-anthesis development of BN if applied repeatedly during bract development. However, studies conducted in 1993 and 1994, with BN-susceptible scions (`Supjibi') grafted onto either `Supjibi' rootstock or the BN-resistant `Annette Hegg Dark Red' (AHDR) rootstock, failed to support the calcium hypothesis. In these studies, higher calcium concentrations were found in the margins of `Supjibi' bracts on `Supjibi' rootstock, then in `Supjibi' bracts on `AHDR' rootstock, even thought the incidence of BN was highest on plants with `Supjibi' rootstock. These studies suggested that non-nutritional factors (possibly hormonal factors) may play a role in BN. In 1995, `Supjibi' plants were produced in the greenhouse, and at initial anthesis, were sprayed once with either deionized (DI) water, benzyladenine (BA) (100 ppm), or daminozide (2000 ppm). At initial anthesis, plants in all treatment groups showed a low level of BN (0.75% of bracts with symptoms). Four weeks after initial anthesis, 18.5% of bracts on DI water sprayed plants and 38.7% of bracts on daminozide treated plants had developed BN; but BA treated plants developed BN on only 1% of bracts. At final harvest (38 days after treatments were applied), BN was evident on 3.4% of BA-treated bracts, 28.7% of DI-treated bracts, and 46.3% of daminozide-sprayed bracts.
Shoot Proliferation of Gardenia jasminoides in Vitro Culture
Authors: Al-Juboory Karim H.
Published: February 2019

Shoot proliferation of Gardenia jasminoides was achieved from cultured shoot tips on Nitsch and Nitsch medium supplemented with different levels (0.0–0.6 mg·L–1) of zeatin, BAP, BA, TDZ, and kinetin. Zeatin proved to be the most effective cytokinin for stimulating shoot proliferation. Shoot length obtained with zeatin was shorter than with other cytokinins and shoot leaves were narrower. Shoot tips were cultured on Nitsch and Nitsch medium supplemented with BA at 4.0 mg·L–1 combined with IAA at 0.0–0.2 mg·L–1. The results indicated that BA at 4.0 mg·L–1 with 0.1 IAA produced greater shoot proliferation. Plantlets regenerated in vitro were then transferred to a mixture of 1 peat: 1 perlite: 1 soil and acclimatized for potting. Our results show that micropropagation of Gardenia has high potential for use in commercial industry.
Asymbiotic in Vitro Propagation of Temperate Terrestrial Orchids (Orchidaceae)
Authors: Szendrák Erika , Read Paul E.
Published: February 2019

The temperate native terrestrial orchids are endangered species. Their propagation from seeds poses specific problems. It is well known that orchid seeds are devoid of endosperm and in nature they need microscopic fungi in a symbiotic relationship for germination. We developed a successful asymbiotic in vitro culture method for germinating seeds of several temperate orchid species and for maintaining the cultures of young plantlets. The medium used for both germination and seedling culture was a modified FAST medium. Seeds were surface-disinfested for 10 minutes in a 10% calcium hypochlorite solution. After sowing, the cultures were kept under dark condition at 10–12°C for 4 weeks. After that the cultures remained in the dark, but the temperature was raised to 25–26°C until germination occurred. Thereafter cultures required alternating seasonal temperatures: 25–26°C from the beginning of April to the end of September and 17–19°C from October to March. For the development of the young plantlets natural dispersed light and prevailing day-length was favorable. After 2 years of aseptic culture they were suitable for transfer ex vitro. Different stages of seed germination and plant development were observed using a scanning electron microscope and will be included in this presentation. Further observation of the effects of different environmental factors is currently under investigation.
Effect of Season, Cultivar, Location, and Storage Regime on Kernel Color in Pecans
Authors: Grauke L.J. , Thompson T.E. , Young E.F.
Published: February 2019

The Munsell system of color notation was used to study differences in kernel color arising between four pecan cultivars (`Cheyenne', `Choctaw', `Western', and `Wichita') grown at four locations (Tulare, Calif., and Brownwood, Crystal City and El Paso, Texas) during two seasons (1987 and 1988) and were stored under different temperatures (ambient and frozen). The hue, value, and chroma of pecan kernels varied significantly in the 2 years of the test. Kernels collected in 1987 were more yellow and lighter and had greater color saturation than kernels collected in 1988. Cultivars differed in hue, value, and chroma at the initial color determination. `Cheyenne' kernels were the most yellow (hue of 18.8) and were the lightest (value of 6.4) of any cultivars tested. `Wichita' kernels were more intensely colored (chroma of 4.7) than `Cheyenne' or `Choctaw' kernels. Kernels from pecan trees in El Paso were more yellow than those from other locations and were lighter than kernels from either Brownwood or Tulare, Calif. Kernels evaluated after being frozen 6 or 12 months could be distinguished from fresh kernels on the basis of hue. Frozen samples were more red than fresh kernels. Kernels frozen 12 months were less intensely colored than fresh kernels or those frozen only 6 months. There was a significant linear relationship between time in the freezer and each color attribute. Hue and chroma were negatively correlated with storage time, while value was positively correlated.
Nitrogen Fertilization Management for Bell Pepper (Capsicum annuum L.)
Authors: Shaw Nicole L. , Hochmuth George J. , Sargent Steven A. , Hanlon Ed A.
Published: February 2019

`Camelot' bell pepper was grown in a N fertigation study on sandy soil using polyethylene-mulched and fumigated beds. Portions of N (0%, 33%, 67%, 100% of total season N) were applied at bed formation. The remaining N was injected weekly into the drip irrigation system. Total N application treatments were 64, 128, 192, and 256 kg·ha–1. Early and total-season marketable fruit yields increased linearly with N rate. Preplant fertilizer proportion did not influence early yields, but late and total-season marketable fruit yields decreased linearly as preplant fertilizer proportion increased. Petiole sap NO3-N concentration increased with increasing N rates, but decreased linearly as preplant fertilizer proportion increased. Petiole sap NO3-N concentrations fell below critical levels for all N rates and preplant fertilizer proportions early in the season. Whole-leaf N concentrations were higher than critical values (>40 g·kg–1) throughout the season. Preplant fertilizer proportion had a significant linear effect on whole-leaf N concentrations for all sampling periods. Petiole sap was better correlated to yield data than whole-leaf N.
Production Characteristics of High-quality Single-stem Roses
Authors: Anderson Robert G.
Published: February 2019

Commercial-quality cut roses were produced in a single-stem production system from single node cuttings. About 1800 rose cuttings in seven sequential crops were identified from 7500 cuttings grown from Feb. through May, 1995. More than 70% of the cut stems harvested from these cuttings were 46 to 75 cm long. Longer stem roses had significantly more nodes and grew from lower, older nodes than shorter rose stems. Longer stem roses required significantly more days to flower harvest because the number of days to axillary bud break was longer than for shorter rose stems. The number of days for rooting, days from axillary bud break to visible bud, and days from visible bud to flower harvest were similar in longer and shorter rose stems. Axillary buds began to grow before rooting in shorter stems and began to grow a mean of 8 days after rooting in the longest rose stems.
Growth and Flowering of Interspecific Hybrids of Sri Lankan Exacum species (Gentianaceae): A Challenge in Domestication
Authors: Anon Kelly M. , Craig Richard
Published: February 2019

Interspecific hybrids of Exacum species (Gentianaceae) endemic to Sri Lanka possess excellent qualities for domestication as a new floriculture crop. The exact mode of floral induction and development responses are unknown, impeding the introduction of this potential crop. The interspecific hybrids evaluated are the result of controlled cross pollinations of E. macranthum. Arn. ex Griseb., E. trinervium (L.) Druce ssp. trinervium, and E. trinervium ssp. ritigalensis. (Willis) Cramer. The hybrids exhibit great genetic variability for horticultural traits. In addition, two growth and flowering patterns exist within the Penn State germplasm. Continuous-flowering genotypes flower throughout the year but more profusely and rapidly under late spring and summer conditions. In contrast, periodic-flowering genotypes exhibit two distinct seasonal habits. Under winter conditions, these accessions have a rosetted habit, much secondary branching, and few or no flowers. In summer conditions, they break their apical dominance, bolt, and produce flowers. As members of the Gentianaceae, Exacum hybrids produce an elegant blue flower with a striking yellow eye and bottle-shaped anthers. We evaluated the growth and flowering responses of Exacum interspecific hybrid accessions to photoperiod and irradiance. Accessions were evaluated under greenhouse conditions for floral production, rate of floral development, and growth characteristics. For the 20 accessions evaluated, supplemental irradiance under winter conditions resulted in greater floral production and much greater shoot and root mass accumulation. Little height and branching response occurred with supplemental irradiance. Of the 15 accessions evaluated under four photoperiod regimes, flowering and growth responses to photoperiod occurred under summer conditions but not in winter. An interaction among season, accession, and photoperiod revealed the complexity of Exacum germplasm and environmental responses.
Influence of Stock Plant Photoperiod on Cutting Production and Rooting
Authors: Koreman Paul , Cameron Art , Heins Royal , Carlson William
Published: February 2019

Five vegetatively propagated perennial species that received 0 or 15 weeks of cold treatment were placed under seven photoperiods (10-, 12-, 13-, 14-, 16-, 24-, and 4-hour night interruption). Cuttings were harvested every 3 weeks, and their number and total fresh weight were recorded. Cutting bases were dipped in a 1200 ppm IBA solution for 5 seconds, stuck in perlite, and placed under mist for 3 weeks. Results varied by species. Stock plants of Achillea `Moonshine' produced the most cuttings under a 12-hour photoperiod. Noncold treated Coreopsis verticillata `Moonbeam' only produced cuttings under photoperiods longer than or equal to 14 hours. Cold treated `Moonbeam' produced cuttings under all photoperiods in the first flush. Eighty percent of cuttings from the first flush of Phlox paniculata `Eva Cullum' rooted when taken from plants growing under the 10-hour photoperiod, but only 1.2 cuttings per plant were harvested; 2.5 cuttings per plant were taken from Phlox grown under the 24-h photoperiod, but only 20% rooted. Only stock plants of Sedum `Autumn Joy' receiving a 14-hour photoperiod produced significant numbers of vegetative shoots. Cutting production and rooting of Veronica `Sunny Border Blue' was not affected by photoperiod.
GA4+7 Plus Benzyladenine Reduce Leaf Yellowing of Greenhouse Easter Lillies
Authors: Heins Royal D. , Wallace Thomas F. , Han Susan S.
Published: February 2019

Chlorosis of Easter lily (Lilium longiflorum) lower leaves causes significant economic loss. Lily plants growing in 15-cm pots were sprayed 30, 60, or 90 days after emergence or at 60 and 90 days after emergence with 25 to 100 ppm each of benzyladenine and GA4+7 from Promalin (Abbott Chemical Co.) and were grown pot-to-pot until flower. Chlorotic leaf count at flower decreased as Promalin concentration increased; plants sprayed at 60 days had the smallest chlorotic leaf count. Chlorotic leaves at flower varied from 28% for control plants to 10% for plants sprayed with 100 ppm at 60 days and from 36% to 17% 3 weeks later, respectively. The Promalin sprays promoted significant stem elongation, but differences in height at flower were only 2 cm. Plants sprayed with 100 ppm at 30 days averaged one deformed flower per plant; plants sprayed at 60 days and 60 and 90 days averaged 0.0 and 0.1 deformed flower per plant, respectively. Additional trials in which only the lower part of the plant was sprayed prevented any chlorotic leaves without any significant effect on final height or flower bud quality.
Sensory and Chemical Analyses of Tomato Flavor
Authors: Ke Dangyang , Boersig Michael
Published: February 2019

Consumer acceptance of sensory quality was significantly correlated (P = 0.05) with overall eating quality of tomatoes (Lycopersicon esculentum Mill.) determined by a trained taste panel. The overall eating quality was partitioned into three flavor components (sweetness, sourness, and aroma) and internal texture. Relationships between the sensory flavor components and concentrations of several chemical compounds were analyzed in tomatoes of eleven varieties within a range of acceptable texture. Sweetness was significantly correlated with total sugar concentration and overall flavor at P = 0.01 and 0.001. High concentrations of two ketone volatiles (6-methyl-5-hepten-2-one and 1-penten-3-one) were significantly correlated with aroma and overall flavor at P = 0.05 to 0.001. This study indicates that positive tomato flavor may be characterized by high sweetness, moderate acidity, and high concentrations of certain ketone volatiles.
The Role of Desiccation in the Manifestation of Chilling Injury in Cucumber Fruit
Authors: Purvis A.C.
Published: February 2019

It has long been observed that chilling injury of warm-season fruit and vegetables during postharvest storage as well as during early seedling growth can be mitigated by maintaining high relative humidities during the exposure to low temperatures. A strong correlation between transpiration rates and chilling injury was observed among the fruit of several PI lines of greenhouse-type and field-type Cucumis sativus L. differing in their susceptibility to chilling injury. Transpiration rates and chilling injury of the F1s from crosses between resistant and susceptible lines were intermediate. Immature fruit lost moisture at faster rates and chill injured more severely than mature fruit of the same genotype. Coatings, applied as postharvest treatments to the fruit either reduced or increased chilling injury depending on the concentration applied and whether or not they retarded or enhanced moisture loss during low temperature storage. Fruit coated with surfactant-based waxes lost more moisture and developed more chilling injury than uncoated fruit or fruit coated with carnauba wax or polyethylene emulsions. The causal relationship between transpiration at low temperatures and chilling injury is not known, primarily because the precise mechanism of chilling injury has not been unequivocally delineated. The manifestation of chilling injury, however, occurs concomitantly with an increase in respiratory rate. We have postulated that chilling injury is caused by active oxygen species generated when the mitochondrial electron transport chain is impaired. In studies with germinating seed, desiccation injury was associated with free radicals generated by mitochondria. Thus, desiccation at low temperatures may intensify respiratory activity resulting in the generation of oxygen free radicals and extensive peroxidative damage to cellular membranes and enzymes.
Microbial Population Reduction on Cantaloupe Destined for the Minimally Processed Market Using Vapor Hydrogen Peroxide or SO
Authors: Simmons Gilbert F. , Rij Roger , Smilanick Joseph L. , John Shama
Published: February 2019

Refrigerated fresh-cut fruit and vegetables are the most rapidly expanding area in produce sales. Shelf life for minimally processed produce depends on natural product senescence or spoilage organism decay. Shelf life limits, near-aseptic cutting facilities, refrigerated transportation, and refrigerated storage make it possible to ship precut cantaloupe coast to coast on a year-round basis. Thorough cantaloupe surface disinfection reduces potential spoilage organisms and harmful pathogens. We compared using vapor hydrogen peroxide and sulfur dioxide to the current practice of hypochlorite (HOCL) washing to reduce cantaloupe microbial load. After treatment, cantaloupe were stored in unsealed polyethylene bags at 2.2°C for 4 weeks. The HOCL treated fruit were scrubbed and soaked for 5 minutes in a commercial HOCL solution. After 4 weeks, the HOCL washed fruit had reduced visible molds compared to controls. Cantaloupes fumigated for 60 minutes with 5000 or 10,000 ppm sulfur dioxide developed sunken lesions but no significant decay after 4 weeks storage. Cantaloupes, treated 60 minutes with 3 mg·L–1 volume vapor hydrogen peroxide, did not show injury or significant decay after 4 weeks storage. Sulfur dioxide and vapor hydrogen peroxide show promise as alternatives to HOCL.
A Linkage Map and QTL Analysis using RAPD Markers in a Narrow Cross in Cucumber (Cucumis sativus L.)
Authors: Serquen Felix C. , Bacher J. , Staub J.
Published: February 2019

Linkage maps in cucumber have been constructed in broad and narrow genetic base populations, using mostly RFLPs. RAPD markers are believed to be more advantageous than RFLPs for mapping in narrow crosses. An F3 population derived from F2 intercrossing cucumber inbred lines (G421 and H19) was used to construct a linkage map and to perform QTL analysis for horticultural traits recorded in two locations. One hundred three F3 families were used for mapping purpose. The parents were screened using ≈1500 primers yielding 80 RAPD markers that exhibited expected 3:1 Mendelian segregation. Additionally, female sex expression (F), little leaf (l), and determinate (de) loci also were evaluated in the segregating population. The linkage analysis and mapping was performed with MAPMAKER software, using a LOD score of 3.0 and recombination frequency of 0.40. QTL analysis was performed using one-way analysis of variance (ANOVA) and MAPMAKER/QTL. The linkage map integrates 83 map-points assembled into nine linkage groups. F and de loci mapped to linkage group `B', and the l locus was placed on linkage group `D'. The total map length is 628 cM, with an average distance between loci of 8.4 cM. Results from using one-way ANOVA and MAPMAKER/QTL had a good agreement for most QTL detected. Some QTL were location specific. Across locations four, one and three QTL were detected for sex expression, mainstem length, and number of laterals, respectively.
Episodic Growth and Shoot Differentiation in Apple (Malus ×domestica Borkh.)
Authors: Crabbe Jacques J.
Published: February 2019

The flushing behavior of shoot growth and its consequences on shoot differentiation are important features in fruit tree development, with regard to flowering ability. In this respect, two different approaches were applied to young `M26' apple trees. First, poorly branched 2-year-old trees were headed back, either in the second-year or in the first-year wood, at different times from right before to 6 weeks after budbreak. Early pruning resulted in rapid and prolonged regrowth, with a final very similar shaping of the tree to that of the intact controls. Late pruning, in contrast, leads to a two-step reaction (late spring and summer flushes), sometimes stronger on 2-year-old than on 1-year-old wood. In a second experiment, buds and young shoots were sampled on pruned trees in locations where they could be supposed to remain short shoots or grow long, with one or two flushes. They were weighed, their leaves and internodes measured, and the plastochron evaluated. During budbreak and the first month afterwards, shoot differentiation appears achieved. The primary difference between long and short shoot types does not consist in faster internode elongation but, rather, in faster production (reduced plastochron) of larger leaves.
Stimulation of Citrus Pitting by Wax Application and High-temperature Storage
Authors: Petracek Peter D.
Published: February 2019

A peel disorder of white grapefruit that has caused substantial losses over the past several seasons was examined. This disorder, which has been identified also in Fallglo and reported for oranges and other grapefruit varieties, is characterized by scattered clusters of pits and is caused by the collapse of oil glands. Applying commonly used waxes and subsequent high-temperature storage (15°C or higher) triggered pitting. Washing and exposure to ethylene during degreening did not affect pitting. Shellac-based water emulsion waxes from three companies and a polyethylene-based wax stimulated pitting but carnauba-based wax did not. Evaluation of internal gases of the fruit showed that all but the carnauba-based wax resulted in low O2 (<5%) and high CO2 (>6%) internal atmospheres. Subjecting nonwaxed fruit to 4% O2 and 9% CO2 storage atmospheres also stimulated pitting. These results suggest that wax application, in conjunction with high-temperature storage, may stimulate pitting by affecting gas exchange and respiration.
A Survey of Planning and Adoption of Zero Runoff Systems in Greenhouse Operations
Authors: Uva Wen-fei L. , Weiler Thomas C.
Published: February 2019

Adopting technology to achieve environmental stewardship is a high priority among greenhouse industry members. Zero runoff crop production systems can protect surface and ground water and use water, fertilizer, and labor resources more efficiently. However, scarce capital and fear of new technology are impediments to change. Our objectives were to characterize decision making and profitability related to zero runoff systems. Managers of 80 greenhouse operations with zero runoff systems in 26 states participated in a survey designed to gather information on the costs–benefits of adoption and production changes and issues related to zero runoff systems for greenhouse operations. The survey results revealed that some adjustments of production practices were essential when adopting zero runoff systems. It also appeared that greenhouse operators believe they are achieving the intended outcomes and efficiencies from their investment. Size of the operation appeared to be closely linked to the growers' willingness to adopt this new technology. Important reasons for making the decision of adopting zero runoff systems were to improve quality of productions, cut production costs, increase production efficiency, and respond to public concern for the environment. Two thirds of the operators surveyed found that special employee training in the operation of zero runoff systems was required. Most employers found in-house training was adequate for their needs. Operators verified that a significant learning curve slows implementation of zero runoff production Adjustments of cultural practices coupled with good production management were keys to growing zero runoff successfully.
An Examination of Resistance to Blighting and Fruit Infection by Monilinia vaccinii-corymbosi in Highhush Blueberry
Authors: Ehlenfeldt Mark K , Stretch Allan W.
Published: February 2019

Previous studies demonstrated a strong positive correlation between early spring shoot growth and susceptibility to the blighting phase of mummy berry. Plants with slow shoot growth derive resistance from avoidance but also may have biochemical resistance. Shoot growth of six highly resistant cultivars was artificially advanced, then plants were exposed to natural infection to assess disease response. Increased susceptibility with increasing shoot length was observed in most cultivars, although degree of response was variable. Within cultivars, there were increases in susceptibility up to shoot lengths of ≈20 mm, beyond which susceptibility decreased. Studies of fruit infection in 48 cultivars found a range of susceptibility and resistance, but little correlation between blighting and fruit infection resistance.
White Pine Blister Rust Susceptibility in Ribes Species
Authors: Hummer Kim E. , Pluta Stan
Published: February 2019

In the late 1800s a European disease called white pine blister rust, Cronartia ribicola Fisher, was introduced into the United States. By 1937 this disease had naturalized and was firmly established in native Ribes across the country. White pine blister rust causes economic damage to white pines and infects leaves of some Ribes late in the summer after harvest. Ribes serve as obligate alternate hosts for this disease. Our objective was to determine which Ribes species were susceptible to white pine blister rust under field conditions in Corvallis, Ore., where inoculum is naturally present. In 1995 and 1996, 57 Ribes taxa from North and South America, Europe, and Asia, were evaluated in mid-August and mid-September for presence of white pine blister rust. Susceptibility was determined by the rust infection of the abaxial leaf surfaces. Rust infection was rated on a scale from 1, no infection observed, to 9, severe infection covering almost the entire surface of at least three or more leaves. Data from 1995 indicated that 22 Ribes taxa were susceptible to white pine blister rust, while 35 others had no infection. The 1996 data will be reported. Species without infection may offer resistance genes to breeders who wish to develop rust-resistant commercial fruit cultivars.
Developing RAPD Markers for Grape Breeding
Authors: Lu J. , Lamikanra O. , Wang Y. , Liu Z. , Ramming D.
Published: February 2019

The grape is an important horticultural crop that is grown worldwide. Breeding a new grape cultivar by conventional means normally will take several generations of backcross, at least 15 years. The efficiency and speed of selection can be accelerated if genetic markers are available for early screening. This project is designed to generate RAPD markers linked to viticulturally important traits, including seedlessness and pistillate genes. A F1 population with 64 progenies of V. vinifera was used for the RAPD analysis. Bulked Segregant Analysis (BSA) method was used for RAPD primer screening. Three-hundred primers were screened between the two pairs of pooled DNA samples, seeded and seedlessness, pistillate and perfect flowers. At least 10 primers produced one polymorphism each between the pools. Further analysis revealed that one of these RAPDs cosegregated tightly with the seedlessness trait, while the others either had loose linkage or no linkage to the traits. To make the RAPD marker useful for breeding selection, an attempt was made to convert it into SCAR marker. The results demonstrated that the RAPD marker may be useful for grape breeding and interpreting inheritance of a particular trait in grapes.
Molecular Mapping of Capsicum and the Comparisons of Synteny with Tomato
Authors: Zhang Yiping , Lackney Vince K. , Prince James P. , Blauth Jim P. , Kyle Molly M.
Published: February 2019

Pepper (Capsicum spp.) has the same basic chromosome number as tomato and other solanaceous plant species (2n = 2x = 24). By using the probes mostly from a tomato map, we have generated three molecular maps of pepper from interspecific F2 crosses of C. frutescens BG 2814-6, C. chinense PI 159234 and C. annuum `NuMex RNaky' with restriction fragment length polymorphisms, isozymes, random amplified polymorphic DNAs, and morphological traits. The best developed map is from C. annuum × C. chinense F2 cross, which currently has 366 markers covered 1081 cM in 18 linkage groups. Three linkage groups were assigned to three chromosomes based on primary trisomics. Several disease resistance genes including monogenic resistance to potyviruses and quantitative trait loci for resistance to tobacco mosaic virus and cucumber mosaic virus have been mapped. The distribution of allele frequency and marker segregation ratios have been analyzed. Chi-square analyses of all clones showed more skewing of segregation ratios in C. annuum × C. chinense population than the other two populations. The skewing occurs throughout the genome and tends towards heterozygote and one of the parents. The order of markers among three pepper maps will be compared and the comparisons of synteny between pepper and tomato maps will be described. A composite of three pepper maps will be presented using JoinMap software.
Altered Morphology of Brassica rapa following Electroporation in the Presence of Foreign DNA
Authors: Williams John O. , Gawel Nick , Ling Jiang-Tian
Published: February 2019

The lengthy generation times associated with woody ornamentals has led to the exploration of alternatives to traditional breeding methods for the development of new cultivars. This report summarizes the results of experiments designed to examine the feasibility of altering plant morphology by DNA assimilation following electroporation of intact seedlings. Brassica rapa (a nonwoody plant) was chosen as a model plant for initial experiments due to its rapid development and short generation time. Seedlings were subjected to either one or five 300-V pulses (99 ms) in the presence or absence of foreign DNA. Foreign DNA used was Ulmus parvarvifolia at a concentration of 200 μg·mL–1. Results indicate a lower survival rate of seedlings electoporated in the presence of DNA. Data were recorded after 21 days for plant height and leaf number. No significant differences were noted for plant height. However, significantly more leaves were produced on plants electroporated (five pulses) in the presence of foreign DNA. These results suggest the possible utilization of this technique for induction of variation in other plants.
A Molecular Marker Linked to a Scab Resistance Gene (Vf) in Apple
Authors: Yang Hong Y. , Korban Schuyler S. , Kruger Jutta , Schmidt Hanna
Published: February 2019

Apple scab, caused by Venturia inaequalis (Cke.) Wint., is the most serious disease of apple trees. Resistance to V. inaequalis, derived from the small-fruited species Malus floribunda 821, is determined by a major dominant gene Vf. Our major objective is to identify RAPD markers linked to the Vf gene. The approach in this paper is based on the introgression of the Vf gene from M. floribunda into commercial cultivars. Almost 200 random sequence decamer-primers have been used to screen a pair of bulked samples and the donor parent M. floribunda clone 821 for markers linked to the Vf gene conferring resistance to apple scab. A single primer has been identified which generated a PCR fragment, OPK16/1300, from the donor parent M. floribunda clone 821 and the scab-resistant selections/cultivars bulk, but not from the scab-susceptible recurrent parent bulk. Co-segregation analysis using a segregating apple progeny and polymorphism analysis of individual scab-resistant Coop selections/cultivars have confirmed that this marker is linked to the scab-resistance gene Vf. OPK16/1300 has since been cloned and sequenced. Sequence-specific primers of 25 oligonucleotides based on the marker have been synthesized and used to screen further M. floribunda clone 821, scab-susceptible apple cultivars, scab-resistant apple cultivars, and scab-resistant Coop selections. The sequence-specific primers have identified polymorphisms of OPK16/1300 based on the presence or absence of a single band.
2-Tridecanone-mediated Mechanisms of Resistance to the South American Tomato Pinworm Scrobipalpuloides absoluta (Meyrick, 1917) (Lepidoptera-Gelechiidae) in Lycopersicon spp.
Authors: Maluf W.R. , Barbosa L.V. , Santa-CecÌlia L. V. Costa
Published: February 2019

Oviposition and feeding of Scrobipalpuloides absoluta was studied on plants of seven different genotypes with varying 2-tridecanone (2-TD) foliage concentrations: Lycopersicon esculentum var. glabratum PI 1344417 (GLA), L. esculentum TSWV-547 (ESC), F1 (ESC × GLA), and four F2 genotypes—two with high 2-TD (HI1, HI2) and two with low foliage 2-TD concentrations (LO1, LO2). GLA, HI1, and HI2 showed 2-TD concentrations above 185 × 10–12 mol·cm2, while ESC, LO1 and LO2 had 2-TD below 40 × 10–12 mol·cm2; F1 had intermediary levels of 2-TD (83.5 × 10–12 mol 2-TD/cm2). Ovipositioning was substantially higher in the low 2-TD than on either the high 2-TD genotypes or in the F1, especially in the upper portion of the plants. Scores for leaf lesion type (LLT), overall plant damage (OPD) and percent leaflets attacked (PLA) were substantially higher for the low 2-TD than for either the high 2-TD genotypes or the F1. The results indicate that 2-TD mediates resistance to Scrobipalpuloides absoluta in the interspecific cross, and strongly suggest that 2-TD acts as both an ovipositioning and feeding deterrent for this insect.
Initial Screening of Sweet Corn Tissues for Allelochemicals that Affect European Corn Borer Larval Development
Authors: Warnock Daniel F. , Davis David W. , Hutchison William D.
Published: February 2019

European corn borer (ECB), Ostrinia nubilalis Hübner, can severely affect sweet corn quality. Selection techniques in field experiments have improved ear feeding resistance associated with morphological features and/or allelochemicals. A laboratory bioassay was used to detect chemical resistance factors in silk and kernel tissues of 10 variously resistant sweet corn genotypes. When added to a nutritively complete diet, kernel tissue from W182E, MN275, and MN272 decreased (P ≤ 0.05) 10-day larval weight (66.3, 61.7, and 54.5 mg, respectively) while kernel tissue from MG15, MN270, and MN3053 increased (P ≤ 0.05) 10-day larval weight (88.3, 81.5, and 80.8 mg, respectively) compared to a cellulose control (71.0 mg). These weight differences, however, were not significant developmentally as 10-day larval maturation (fourth to fifth instar) and pupation time (13.9 to 16.3 days) were similar to the cellulose control (fifth instar and 14.8 days). Silk tissue additions to the diet decreased (P ≤ 0.05) 10-day larval weight compared to the cellulose control (71.0 mg). Larvae exposed to diet containing silk tissue from MN3053, W182E, and `Apache' were lightest (9.1, 8.3, and 7.8 mg, respectively). The heaviest larvae exposed to silk tissue were from diet including `Jubilee' tissue (54.1 mg). Contrary to the instar levels found on the cellulose control, larvae feeding for 10 days on a diet containing silk tissue mainly were at third or early fourth instar excluding larvae exposed to `Jubilee' silk (fourth to fifth instar). For all genotypes, silk additions to diet increased the pupation time compared to kernel additions. Kernel, and especially silk tissue, may contain chemical resistance factors which decrease larval weight and increase developmental time. Identifying sweet corn genotypes with chemical resistance factors may enhance ECB resistance breeding efficiency.
Confirmation of QTL Associated with Common Bacterial Blight Resistance in Phaseolus vulgaris L.
Authors: Jung Geunhwa , Skroch Paul W. , Coyne Dermot P. , Nienhuis James , Arnaud-Santana E.
Published: February 2019

Common bacterial blight (CBB) incited by the bacterial pathogen Xanthomonas campestris pv. phaseoli (Smith) Dye is an important disease of common bean. In a previous study, QTL associated with CBB resistance were described based on RAPD marker analysis of a recombinant inbred population derived from the common bean cross BAC-6 (R) × HT-7719 (S) (resistant × susceptible). The objective of this research is to confirm these previously described candidate marker locus-QTL associations using an inbred backcross PC-50 (S) × BAC-6 (R) and a recombinant inbred Venezuela 44 (S) × BAC-6 (R) population. Two markers previously found to be associated with QTL for CBB resistance in the BAC-6 × HT-7719 population were found to account for 30% of the phenotypic variation for CBB resistance in the PC-50 × BAC-6 inbred backcross population. The three most resistant BC2F3 lines based on marker locus genotypes were ranked 1, 3, and 7 (out of 64) based on phenotypic evaluation. These results provide important confirmation of marker locus-QTL associations and indicate that RAPD markers linked to loci controlling the expression of CBB resistance in common bean may be used to transfer resistance genes into susceptible breeding material.
Determination of Optimum Nitrogen Ratios and Concentrations for Embryo Cultures of Alstroemeria
Authors: Moreck Paula C. , Bridgen Mark
Published: February 2019

The rates of in ovulo germination of embryos of three genotypes of Alstroemeria were observed. Ovules were harvested ten days after pollination and cultured on sixteen different treatments containing Murashige and Skoog (MS) basal medium with no plant growth regulators. The media contained four different concentrations of total nitrogen: 20, 40, 60, 80 mm. Within these concentrations were either 1:0, 1:1, 1:2, or 2:1 ratios of nitrate to ammonium. Standard MS medium, with a concentration of 60 mm total nitrogen and a ratio of 2:1 nitrate to ammonium, was used as the control. The overall rates of germination for all three genotypes were low in all treatments. The percentage of zygotic germination was low while the percentage of somatic embryos produced was high. In some situations, callus or deformed embryos were produced. Effects of the treatments on embryo development and germination will be discussed.
AgNO3 Promotes Callus Production and Regeneration of Immature Buffalograss Inflorescence Culture
Authors: Fei Shuizhang , Read Paul E. , Riordan Terrance P.
Published: February 2019

The use of buffalograss [Buchloe dactyloides (Nutt.) Engelm] in home lawns and golf courses has been increasing because of its drought resistance and low growth habit. In vitro regeneration of buffalograss at a high frequency may provide an effective tool to introduce new variation for breeding use. The positive effects of AgNO3 on friable embryogenic callus production and regeneration efficiency is well documented in maize. In order to determine if AgNO3 has the same effect on buffalograss, two vegetatively propagated cultivars, a female `609' and a male `45-3' were tested at three different concentrations of AgNO3 at 5, 10, and 15 mg·L–1 using immature inflorescences as explants. Murashige and Skoog medium supplemented with 2 mg 2,4-D/L was employed as the control medium. Medium containing AgNO3 significantly promoted the production of friable callus for `45-3' with the highest percentage achieved at 10 mg AgNO3/L. AgNO3 medium led to production of significantly larger calli than found for the control. However, no difference was detected among 5, 10, and 15 mg AgNO3/L with regard to the callus formation ability and the size of callus initiated on these three treatments. Calli were then transferred to MS medium supplemented with BA at 0.1, 0.5 or 1.0 mg·L–1 to induce shoot formation. BA at 0.5 mg·L–1 gave the best differentiation response. Calli formed in the absence of AgNO3 produced more shoots per callus, but more calli were produced in the presence of AgNO3, and the overall regeneration efficiency was much higher with AgNO3 at 10 mg·L–1. In contrast, AgNO3 showed no promotive effect on callus production and regeneration for `609'.
Priming and Accelerated Aging Affect L-isoaspartyl Methyltransferase Activity in Tomato Seed
Authors: Kester S.T. , Geneve R.L. , Houtz R.L.
Published: February 2019

Damage and degradation of cellular proteins is observed during seed deterioration due to aging. L-isoaspartyl methyltransferase (EC 2.1.1.77) is an enzyme hypothesized to play a role in limiting and repairing aging-induced damage of proteins. Tomato seeds (Lycopersicon esculentum `New Yorker') were assayed for changes in L-isoaspartyl methyltransferase activity during accelerated aging and after osmotic priming. Accelerated aging of seeds for 1 to 4 days at 45°C and 100% humidity reduced germination from 94% to 71%, the mean time of germination (MTG) increased from 2.4 to 5.8 days and was accompanied by a correlative decrease in L-isoaspartyl methyltransferase activity R2 = 0.90. Aged and untreated seeds were primed for 7 days at 20°C in darkness using aerated solutions of 3% KNO3 or polyethylene glycol 8000 (PEG) with equivalent osmotic potential (–1.25 MPa). Priming with KNO3 decreased the MTG but not germination percentage for untreated seeds. Priming did not affect L-isoaspartyl methyltransferase activity in untreated seeds but restored activity in aged seeds primed in KNO3 to levels near that of untreated seeds. Priming with PEG did not effectively improve the MTG or increase L-isoaspartyl methyltransferase activity. During germination, enzyme activity remained constant for 48 hours post-imbibition and then declined suggesting the enzyme was developmentally regulated and inactivated or degraded as radicle emergence occurred.
Effects of Hydrating, Boiling, Acid Scarification, and Seed Coat Removal on Emergence of Citrus sp., Poncirus trifoliata, and Citrange Seeds
Authors: Tignor Milton E. , Weber Courtney A.
Published: February 2019

Current efforts in the study of citrus freeze hardiness including gene mapping and elucidating early induction processes require large populations of uniform seedlings. Related genera and intergeneric hybrids are often used in these studies and little is known about factors effecting their seedling emergence. We tested a total of 8 genotypes including Poncirus trifoliata `Rubidoux', Citrus grandis, C. sinensis `Pineapple', C. jambhiri `Schaub', C. paradisi `Duncan', C. aurantium (Brazilian), Carrizo citrange (P. trifoliata × C. sinensis), and Troyer citrange. A total of seven pre-planting treatments were used to evaluate seedling emergence rates. Expanding on the work of previous researchers, treatments were seed coat removal, hydrating in water (96 hours) at either 4, 25, or 35°C, acid scarification, or boiling. Generally, seed coat removal resulted in the most uniform emergence as compared to untreated controls. Presoaking at each temperature enhanced emergence in most varieties tested and 25°C was the best hydrating temperature. Acid scarification greatly delayed emergence in all genotypes tested except Troyer citrange and `Pineapple' orange which had enhanced emergence rates as compared to controls. Preplanting treatment with 100°C water was lethal in all varieties. Pretreatment of citrus seeds can enhance uniformity of germination, although optimum treatments for individual genotypes vary.
Capillary Mats Modify Media Moisture Content during Mist Propagation of Chrysanthemum Cuttings
Authors: Marohnic Jennifer , Geneve Robert , Buxton Jack W.
Published: February 2019

Capillary mats were used to vary the water content in oasis blocks during mist propagation of chrysanthemum cuttings. Mats placed on the surface of the propagation bench extended over the edge of the bench and downward a distance of either 0 or 20 cm. Oasis blocks with chrysanthemum cuttings `Boaloi' and `Salmon Charm' were placed on mats under intermittent mist (10 seconds every 5 minutes) between 5 am and 8 pm. Relative water content, mL of water/gram oasis, and leaf water potential were measured at noon every 5 days. After 26 days number of roots per cutting was evaluated. Water content in the oasis block was reduced by 49% (450 to 219 mL/g dry weight of oasis) by hanging the capillary mat 20 cm over the edge of the bench compared to 0 cm treatment. Cuttings showed an increase in leaf relative water content from 49% and 51% at day 1 to 65% and 71% by day 11 for `Boaloi' and `Salmon Charm', respectively. Following initial root formation, leaf relative water content increased to 85%. Over the course of the experiment `Boaloi' and `Salmon Charm' showed an average reduction in leaf water potential of 0.14 and 0.08 MPA, respectively. `Boaloi' showed overall higher root numbers than `Salmon Charm'; however, no difference in rooting between mat treatments was observed.