bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of PRV Resistance in Transgenic Papaya
Authors: Manshardt R. , Lius S. , Gonsalves D. , Fitch M. , Slightom J. , Sanford J.
Published: February 2019

Transgenic papaya lines carrying the coat protein gene (CP) of papaya ringspot virus (PRV) strain HA 5-1 display PRV reactions ranging from complete susceptibility (39-3 & 39-4), to slight delay in onset of symptoms (39-1) and attenuation of symptoms (60-3), to high-level resistance (55-1, 63-1). Normal Mendelian segregation of transgene expression was lost in R1 of 39-3 and 39-4, and inbred R1 60-3 gave an aberrant 1:1 ratio. R0 55-1 plants were resistant in the field (Hawaii) for 2 years following manual and/or aphid inoculation, and the high-level resistance remained stable in the R1 after repeated manual inoculations in the greenhouse and graft inoculation for up to 1 year (Cornell). However, inoculation with PRV HA-Oahu strain produced symptoms in some plants at Cornell (9% after 6 weeks) and in Hawaii (50% after 1 year). Two 55-1 and one 60-3 plant subsequently underwent remission of symptoms and became ELISA-negative (Hawaii). Transmission of PRV isolates from symptomatic 55-1 plants to other CP+ 55-1 bioassay plants was unsuccessful.
Utilizing Electronic Mail List Discussion Groups on the Internet to Enhance Communication in Specific Commodity Groups
Authors: Cowgill W.P. , VanVranken R.
Published: February 2019

Electronic discussion groups provide a forum in which to enhance the exchange of information between university researchers, extension agents and specialists, students, and their clientele; farmers, wholesalers/brokers, retailers and direct marketers as well as other colleagues in the same field. Three electronic discussion groups; Apple-Crop-Mg, Veg-Prod-Mg, and Direct-Mkt have been implemented and have been extremely effective in providing a unique forum for the sharing of knowledge. Over 400 subscribers are on-line with these groups from more than 30 states, four Canadian Provinces and three other countries. Participant surveys cite the ease of use, the timeliness of replies (often within 24 h), the ability to glean timely information for files and newsletters. These groups have been a valuable communication tool reaching a broad audience rapidly and cost effectively.
Sweet Cherry Breeding in Canada: 1915 to 1995
Authors: Tehrani G. , Lane W.D.
Published: February 2019

Sweet cherry breeding started at Vineland and Summerland in 1915 and 1924 and has resulted in the naming and introduction of 11 and 18 cultivars, respectively. `Victor' and `Van' were the first cultivars named from Vineland and Summerland, respectively, in 1925 and 1944. `Van' has become a popular cultivar in North America and Europe. The main objective in these breeding programs has been to develop cultivars that produce large quantities of firm-fleshed, crack-free, flavorful, large, black cherries with a range of maturity dates to extend the season of harvest. In the 1960's, the development of self-fertile cultivars was added to the objective of the programs. Already several self-fertile cultivars and advanced breeding selections have been named and introduced from Canada. The programs have also contributed to the assignment of cultivars to different pollen-incompatibility groups and verification of pedigree of sweet cherry cultivars. The impact of these long-term breeding programs in Canada and abroad will be discussed in detail.
Monitoring Crop Water Status and Irrigation Needs Using Multispectral Airborne Sensors
Authors: Clarke Thomas R. , Moran M. Susan
Published: February 2019

Water application efficiency can be improved by directly monitoring plant water status rather than depending on soil moisture measurements or modeled ET estimates. Plants receiving sufficient water through their roots have cooler leaves than those that are water-stressed, leading to the development of the Crop Water Stress Index based on hand-held infrared thermometry. Substantial error can occur in partial canopies, however, as exposed hot soil contributes to deceptively warm temperature readings. Mathematically comparing red and near-infrared reflectances provides a measure of vegetative cover, and this information was combined with thermal radiance to give a two-dimensional index capable of detecting water stress even with a low percentage of canopy cover. Thermal, red, and near-infrared images acquired over subsurface drip-irrigated cantaloupe fields demonstrated the method's ability to detect areas with clogged emitters, insufficient irrigation rate, and system water leaks.
The Important Role of Germplasm in Improving Carrot, Onion, and Garlic
Authors: Simon Philipp W.
Published: February 2019

Genetic improvement of carrot, onion, and garlic has depended upon introgression of alleles from foreign cultivars, from wild forms of cultivated species, and from wild species. Introgression of Asian germplasm in European carrots has resulted in more than a doubling of carotene content; wild carrot has provided two of the most widely used male-sterile cytoplasms for production of hybrids; and Daucus capillifolius has been used as a source of resistance to carrot fly. Onion male-sterile cytoplasm used for hybrid production has its origins in a species related to onion, while resistance to several diseases originated in foreign cultivars. Production of true garlic seed has depended on a broad germplasm base for its success. More examples and germplasm utilization strategies will be discussed.
Development and Use of Core Subsets of Cool-season Food Legume Germplasm Collections
Authors: Simon Charles J. , Hannan Richard M.
Published: February 2019

Core subsets have been selected for the USDA chickpea (Cicer arietinum), lentil (Lens culinaris), and pea (Pisum sativum) germplasm collections. These subsets are specifically intended to increase the efficiency of the utilization of the entire collections of these taxa. The cores consist of 13% of the 3873 chickpeas, 12% of the 2390 lentils, and 17.5% of the 2886 pea accessions. They were selected by a proportional logarithmic model, and also contain additional accessions based upon documented concentrations of diversity. Each core has been screened for disease reactions, and results suggest that the cores can effectively direct germplasm users toward portions of the entire collections that contain resistant germplasm. These cores have also been useful for those interested in assessing the adaptation potential of these crops in new environments, because the entire range of adaptation is represented. Although cores may not always enhance access to germplasm with unique or extremely rare characteristics, the legume cores have been very useful for directing users toward desirable germplasm from defined geographic areas, and assisting users at the preliminary stages of germplasm evaluation.
Alternatives to Core Subsets
Authors: Cox T.S.
Published: February 2019

The USDA/ARS National Small Grains Collection currently contains more than 40,000 accessions of common and durum wheats, and about 6000 accessions of other Triticum species. The Wheat Crop Advisory Committee has discussed the use of core subsets in screening this vast collection for traits of interest in breeding. The collection curator is assembling a subset, stratified by geography and morphology, for distribution in response to nonspecific requests and diversity evaluation. However, we have concluded that no subset(s) can be identified, in advance, that would be useful in screening for parental germplasm with traits of interest to breeding programs. Resistances and other traits are often rare in the collection, but the initial subset used for screening can be enriched for the trait of interest by selecting accessions based on knowledge of environmental conditions or occurrence of pests in geographic regions. New database technology will be very useful in this effort.
Use of Hormones and Growth Regulators in Quantifying Bud Dormancy
Authors: Faust Miklos
Published: February 2019

At the beginning and near to the end of the endodormant period, cytokinin-type growth regulators are effective to end dormancy in apple. The same growth regulators are not effective during the middle of this period. Terminal buds require less chilling than lateral buds to emerge from the dormant period. Lateral buds on decapitated shoots also require less chilling, indicating that auxin may be involved in dormancy. Replacing the terminal with IAA keeps water in bound state in the lateral buds, indicating the effect of IAA in dormancy. We have developed the theory that the beginning and the end of the winter-dormant period is governed by apical dominance. It appears that only this period can be manipulated either with dormancy avoidance methods or with dormancy-breaking chemicals. The central portion of the dormant period is not subject to manipulation. Therefore, it is important that the depth of the dormancy is quantified. Certain growth regulators can be used for determining the state of bud dormancy. Thidiazuron gives results within 2 to 4 days.
First Results of Woody Ornamental Trial Network in Québec
Authors: Richer-Leclerc C. , Rioux J.-A.
Published: February 2019

The “Réseau d'essais des plantes ligneuses ornementales du Québec” (REPLOQ) is a research project initiated in 1982 with the mandate to elaborate, develop, and coordinate a cooperative research project to evaluate the winter hardiness of ornamental plants. Systematic evaluation trials provided information on growth potential and hardiness of woody trees and shrubs evaluated over a 5-year period in the principal growing regions of Québec. Zonal range covered was 2 to 5b in the Canadian system. Adequate field testing is critical for new introductions and, since 1984, more than 400 species and cultivars have been introduced and eight evaluated in each climatic zone. Propagation methods, as well as their potential for ornamental purpose, were described. In the 1984 plantation, 30 ornamental species and cultivars were evaluated. Winter damage data observed on each plant during this period were analyzed by Clusters analysis and five groups of plants were determined. Trees, flowering shrubs, and foliage shrubs were discussed separately and winter damages of each group were submitted to “Correspondence analyses” to identify plant response to climatic conditions. Growth and production potentials were defined by SAS analysis. Hardiness zone of each species was detailed, established, or modified.
Enhance Learning Via Interactive Multimedia Presentations
Authors: Needham Douglas C
Published: February 2019

Computer-based authoring tools, e.g. Macromedia Authorware©, allow one to produce interactive applications or computer-based training modules for horticulture teaching and extension. These applications are useful not only as presentation tools, but also as supplementary instruction, whereby a student can interact with an application at his/her own convenience and learning level. “Interactive Lessons for Introductory Horticulture©” is one example of an application used in OSU's HORT 1013: Principles of Horticultural Science course. Students are able to navigate to various topics by selecting chapters and topics within chapters. The information is not just presented, but rather acted upon by the student through movable objects, touch-sensitive areas, text, audio and video clips, etc. Student learning should be enhanced by the variety of stimuli and the ability to review an entire presentation or portion thereof at will.
Cutting Production and Flowering Shoots from Penstemon and Dianthus Stock Plants
Authors: Dushack Dean S. , Hopper Douglas A.
Published: February 2019

Stock plants of two perennial species (Penstemon and Dianthus) were grown in either a warm (16C NT) or cool (10C NT) greenhouse under either natural-day (ND) or long-day (LD) continuous-lighting treatments. Black plastic curtains were placed between the treatments from 1600 to 0800 hr. Starting Apr. 1994 through Jan.1995, the number of cuttings produced and the number of flowering shoots per plant were recorded at ≈3-week intervals. Preliminary analysis shows significantly more cuttings were produced by Dianthus in a warm vs. a cool greenhouse under both ND and LD photoperiods. Penstemon showed only a slight trend toward more cuttings produced in a warm greenhouse. Conversely, Dianthus produced fewer flowering stems in ND as compared with LD conditions in the warm house, due mainly to a greater proportion of stems remaining vegetative in the ND photoperiod. No significant differences in number of flowering stems of Penstemon occurred between any of the treatment combinations.
Developing a Usage Plan for a University Teaching Garden
Authors: Hoel Heidi L.
Published: February 2019

The Allen Centennial Gardens are located at the Univ. of Wisconsin–Madison on the grounds of the National Historical site, the house of the first four deans of the College of Agriculture and Life Sciences. The 2.5-acre garden, developed and managed primarily by the Dept. of Horticulture, replaced the old teaching and display garden space taken over in building additions. Within the past 10 years the grounds have been designed and transformed into a garden, with 26 individual collection gardens, including: turf, fruit and vegetable gardens, classic ornamental gardens (with both herbaceous and woody perennials), and a rock alpine garden. As it receives its finishing touches, an education plan is being developed to complement the education purpose of the garden; the goal of the garden is to become an active site for learning through both observation and interaction with the garden collections. The two main themes of the learning experience are: 1) the biology of the diverse and unique plant collections (including: culture, practices, and production), and 2) the aesthetics of the garden (the organization of space, form, topography, and color). Implementation of education programs will occur on the following four levels: first the university (first the horticulture department, second other departments and university functions); second, area high schools groups; third, community and professional groups; and fourth, elementary school groups. The education programs will include mapping, internships, classes, meetings, volunteerism, and tours. The Allen Centennial Gardens, with its education mission, has already and will continue to be a meeting grounds for the university community, and a meetings ground for both the professional community and Madison-area community.
RAPD Banding Patterns in Sweetpotato Infected with Fusarium lateritium
Authors: Buffone F.A. , LaBonte D.R. , Clark C.A.
Published: February 2019

Chlorotic leaf distortion is a common disease of sweetpotato caused by Fusarium lateritium. This fungus is unique among Fusarium species in that it grows epiphytically on leaves and shoot tips of sweetpotato. Fusarium lateritium mycelia appear as white masses on leaves, and this fungus can cause chlorosis under periods of bright sunlight. When environmental conditions are not favorable for growth, this organism is not readily observed on sweetpotato. The objective of this research was to see if DNA of F. lateritium is amplified using PCR techniques during amplification of sweetpotato DNA. Our results show cTAB extracts of sweetpotato inoculated with F. lateritium have additional bands not present in a control free of F. lateritium. Furthermore, these bands correspond to banding patterns obtained from the F. lateritium isolate DNA when amplified alone. Researchers who use sweetpotato tissue in PCR-based research, e.g., phylogenetic research, should be aware of these amplified products. This situation is further compounded because numerous F. lateritium biotypes are present in the environment.
Propagation of a Threatened Plant Species: American Hart's-Tongue Fern
Authors: Schultz Kathryn Hahne , Garton Stephen
Published: February 2019

Phyllitis scolopendrium var. americana is a rare North American fern species whose range is being threatened by habitat alteration. Research efforts were undertaken to ensure survival of the southern population by applying horticultural techniques to propagate new plants for reintroduction. Several techniques were used to induce spore germination. Aseptic techniques included direct plating of spores onto agar medium in petri dishes and dusting spores into test tubes filled with liquid medium. Spores were spread onto soil samples taken from the fern habitats and onto various other propagation media. Prothalli grown in nutrient solution were transferred onto various nonsterile conventional horticultural media. Results indicated that germination in the nutrient solution and subsequent transfer of prothalli was more efficient and promoted survival of propagules compared to subculture from solidified medium.
The Effect of Heat Shock, ABA, and Salicylic Acid on Induction of Chilling Tolerance in Cucumber Seedling Roots
Authors: Tee Meng-Yee , Jennings Paul H.
Published: February 2019

Chilling injury can be a serious problem during field germination of sensitive crop species. Because heat shock has been shown to induce chilling tolerance of germinating cucumber seeds, an experiment was initiated to determine the effectiveness of other treatments. Cucumber seeds germinated 20 to 24 h were either heat-shocked at 50C for 2 min or treated with ABA or salicylic acid for 4 h. Following treatment, the germinated seeds were chilled at 2C for 96, 120, or 144 h and then incubated at 25C to determine growth effects on the developing root. All treatments induced chilling tolerance compared to the controls, with ABA and heat shock being most effective after chilling. There did not appear to be an additive response when heat shock was used in combination with ABA. The evidence for different treatment mechanisms will be discussed.
Leaf Blower Adapted for Large-scale Inoculation of Plants with Mechanically Transmitted Viruses
Authors: Munger Henry M. , Zhang Yiping , Fenton Susan L. , Kyle Molly
Published: February 2019

Plants to be screened for resistance to mechanically transmitted viruses can be inoculated by using an inexpensive electric-powered leaf blower. This device greatly reduces the amount of time to inoculate large populations when compared with hand-rubbing methods. No significant differences were noted with regard to the frequency of seedlings that escaped infection.
Using Crop Rotation to Control Meloidogyne hapla Chitwood and Improve Marketable Carrot Yield
Authors: Bélair G. , Parent L.E.
Published: February 2019

The influence of various crop rotations on population densities of Meloidogyne hapla, the northern root-knot nematode, and subsequent carrot yields was studied in organic soil under field conditions. Seven 3-year sequences with barley (Hordeum vulgare L.), carrot (Daucus carota L.), onion (Allium cepa L.), or weedy fallow, all with carrot as the third-year crop, were replicated six times in a completely randomized block design. Carrot monoculture, two seasons of weedy fallow, or carrot followed by onion resulted in high M. hapla population densities and severe root damage on carrot the third year. Barley followed by onion or onion followed by barley harbored low M. hapla population densities and provided the highest yields, with 56.8 and 47.2 t marketable carrots/ha, respectively, compared to 2.2 t·ha–1 in the carrot monoculture. A single crop of barley reduced nematode population densities and provided 88% and 73% marketable carrot roots in the subsequent years. High M. hapla population densities and the high proportion of culls recorded in plots in weed fallow emphasize the importance of an effective weed management program for successfully using crop rotation against root-knot nematode in muck-grown carrot.
Using a Rockwool Plug System In Vitro On Amelanchier, Cercis, Kalmia, Cherry, and Apple
Authors: Chu Chin-Chang , Mudge Kenneth W.
Published: February 2019

Rockwool plugs were placed in Magenta G-7 boxes (Sigma) and then autoclaved at 121°C for 20 min. Fifty milliliters of cool autoclaved liquid medium was poured into Magenta G-7 boxes in aseptic conditions before microcuttings of Amelanchier, Cercis canadensis, cherry, and apple were transferred. Murashige and Skoog medium (MS, M-5519, Sigma) containing 30 g·L–1 sucrose, and with/out 1 ppm of NAA, pH 5.5 were used in all experiments. All cultures were incubated at 23 ± 1°C under a 16-hour lighting period with a light intensity of about 4000 lux of white fluorescent light. Microcuttings of Amelanchier, Cercis, Apple, and cherry rooted in rockwool plugs in 3 weeks after transfer and were ready to be out-planted in 6 weeks. Out-planted plantlets were leached with tap water and potted in 4-inch pots with Metrolite mix, then, placed in mist bench under 50% shade for 2 weeks before taking to bench with full sun light. The survival was 100%. Conditions and growth rate of rockwool-plug-rooted plantlets were much better than those plantlets rooted in agar medium. Rockwool plug plantlets had 2–3 flushes of growth before dormancy in greenhouse and were ready to be planted in the field or garden in 8 months after out-planting. Using a rockwool plug system simplifies out-planting procedure, produces better plantlets, increases out-planting survival, and greatly shorten time needed from out-planting to field-plantable size. This system is a very useful system for difficult-to-root woody ornamentals.
Developing a Horticulture Transfer Program at a Two-year Technical College
Authors: Anderson Gary A.
Published: February 2019

The Ohio State Univ.'s Agricultural Technical Institute is a 2-year institution within the College of Food, Agricultural and Environmental Sciences. For over 20 years the school on the Wooster campus has offered technical programs in ornamental horticulture and floriculture leading to the Associate of Applied Science degree. Enrollment in the programs of Floral Design and Marketing, Greenhouse Management, Landscape Contracting, and Construction, Nursery Management, and Turfgrass Management is near 350 students. During the past year, a new program was developed with the primary purpose of serving those students who wish to transfer into a baccalaureate program within the college. Students are granted an Associate of Science degree in Horticulture upon completion of the curriculum requirements at the technical college. Those following this track have a unique opportunity for exposure to two different learning situations. They can progress toward their goal without loss of credit. The curriculum allows students to explore several areas of horticulture before commitment to their specialty. Beginning students have the advantage of a small campus with an active learning assistance program.
Including Stakeholders in the Curriculum Assessment Process
Authors: Stearns Dan T.
Published: February 2019

Decisions regarding curricular direction are often made by departmental committees comprised of faculty who are most closely associated with the curriculum. While knowledgeable about current direction, these faculty may not be positioned to accurately forecast future shifts in industry focus. By including employers, potential employers, alumni, students, and representatives from similar programs in the process, alternative views and opinions critical to the visioning process are generated. Penn State's recent efforts in program assessment will be outlined.
Integrated Cropping Systems—A Multi-discipline Degree
Authors: Dean Bill B.
Published: February 2019

Washington State Univ. Tri-Cities offers a new agricultural degree program titled Integrated Cropping Systems. It is intended to provide a basic education on the fundamentals of crop production and the environmental context in which crops are grown. Courses are offered at the upper division level to interface with the lower division courses offered at local community colleges. The curriculum is composed of courses in environmental science, ecology and conservation as well as crop growth and development, crop nutrition, plant pathology integrated pest management and others. Students need to meet the same requirements as those at other Washington State Univ. campuses in regards to the general education requirements. The purpose of the Integrated Cropping Systems program is to provide an educational opportunity for agricultural professionals and others in the region who are unable to commute or move to the main campus location. The curriculum provides the background needed for such occupations as grower/producer, crop scouting, sales representative and other entry level agricultural professions. It will supply credits toward certification through the American Registry of Certified Professional Agricultural Consultants (ARCPACS). Integrated Cropping Systems is a unique agricultural curriculum designed to help agriculturists integrate their production practices into the local ecosystem in a way that the environment does not incur damage. It emphasizes the use of environmentally conscience decisionmaking processes and sound resource ethics. The program will graduate individuals who have heightened awareness of the impact agricultural practices have on the ecosystem in which they are conducted.
Using Decision Cases in Graduate Education: An Example
Authors: Hoover Emily , Foulk Doug
Published: February 2019

Decision cases have been written for use in horticulture education for some time at the Univ. of Minnesota. How faculty involve graduate students in this process will be discussed using the decision case Sunny Hollow Orchard. This decision case concerns the need to make management decisions in a commercial apple orchard planted largely with Haralson, a russet-susceptible cultivar. The growers involved had to decide whether the application of GA4+7 for russet suppression was appropriate for their operation, given all the factors which required addressing. The case was written for use in fruit production or other intermediate-to-advanced undergraduate course. The case can be used to illustrate the decision-making processes involved in operating a commercial crop production enterprise encompassing such issues as cultural and environmental factors, financial viability and pesticide concerns. The case exposes students to a real-life situation and provides them with the opportunity to face a complex but not uncommon situation for producers in the horticultural industry. We will then focus on how this case fit into the entire PhD research program and how we hope to integrate this kind of experience into graduate education.
Activation of Systemic Acquired Disease Resistance in Cucumber Seed during Germination
Authors: Widders Irvin E.
Published: February 2019

Systemic acquired disease resistance (SAR) involves the activation of the natural physiological defense mechanisms against pathogen infection in a systemic manner within plants. A series of experiments were conducted in which `Beit Alpha' cucumber seed were treated with 2,6-dichloro-isonicotinic acid (INA) during osmotic conditioning or imbibition in water. Following germination and emergence, seedlings were challenge inoculated at the two-leaf stage with Colletotrichum lagenarium and incubated as a bioassay for expression of SAR. INA (289 μm) treatment of imbibed seeds reduced the number of anthracnose lesions per leaf by >90% as compared to untreated controls. Interactions were observed between INA treatment and the solute used for osmotic conditioning. Priming in 0.5 m KH2PO4 or 0.49 m sorbitol in combination with INA resulted in rapid seedling emergence and a 65% to 80% reduction in disease lesion incidence relative to primed controls. Increases in solute concentration, so as to lower the osmotic potential of the priming solution and thus extend the period of exposure to INA, did not result in enhanced SAR expression. Maximum SAR induction occurred when imbibed seeds were exposed to INA at the onset of expansive radicle growth. This study demonstrates that SAR can be abiotically induced in cucumbers during seed germination.
Two-year Grower Survey of Western Flower Thrips and Tospovirus Incidence and Management in Maine Greenhouses
Authors: Stack P.A. , Stack L.B. , Drummond F.A.
Published: February 2019

A mail survey of greenhouse growers was conducted in 1994 and 1995 to determine the presence and importance of western flower thrips (WFT), Frankliniella occidentalis Pergande, in Maine greenhouses in growing years 1993 and 1994. Respondents were licensed growers with at least 1000 ft2 (93 m2) of greenhouse growing area. The survey objectives were to develop a grower demographic profile; determine the incidence of WFT and two WFT-vectored plant viruses, tomato spotted wilt (TSWV) and impatiens necrotic spot (INSV); and identify current WFT management strategies. The survey shows that Maine greenhouse growers are seasonal, experienced and retail oriented. Their growing area averages less than 10,000 ft2 (929 m2) and they produce a diverse crop mix and choose to import production stock as much as propagate it themselves. Both WFT and TSWV/INSV have increased in severity in Maine greenhouses over the past 10 years. Larger, year-round greenhouses are more likely to experience infestations of WFT and higher virus incidence. An integrated pest management (IPM) strategy is employed by the majority of growers surveyed. Insecticide application is the primary tactic used to control WFT. Fewer than 4% of the growers use natural enemies to control thrips. However, 63% responded that future research in pest management should focus on biological control.
Floral Initiation in Pelargonium×domesticum is Affected by Total Cumulative Irradiance
Authors: Loehrlein Marietta , Craig Richard
Published: February 2019

Floral initiation signals the commencement of sexual reproduction in angiosperms. In many plant species this developmental phase is controlled by photoperiod. However, it may be regulated by other factors, such as plant age or specific temperature or irradiance requirements. Floral initiation occurs in Pelargonium ×domesticum (regal Pelargoniums) in response to exposure to cool (7–12°C) temperatures for about 4–6 weeks, or to cumulative irradiance at 18–23°C. Broad genetic variability exists so that floral initiation in some cultivars is almost completely controlled by temperature, while in others it is almost completely controlled by cumulative irradiance. Among the latter group of genotypes, genetic variability exists for the amount of irradiance required. The purpose of this study was to determine the precise irradiance requirements for nine commercially important cultivars. The cultivars varied significantly in their response to irradiance with respect to floral initiation. Low irradiance requiring genotypes developed visible (5 mm) buds with as little as 250 mol of total cumulative irradiance; floral initiation in these cultivars occurred with only 50 mol of irradiance. High irradiance requiring genotypes still had vegetative meristems after 300 mol of total cumulative irradiance. Further studies were conducted on `Majestic', chosen for its high irradiance requirement. The objective of this study was to determine whether cool temperatures (7–12°C) or heat stress (23–28°C) could replace the irradiance effect. The results indicated that neither of these environmental conditions could replace the effects of moderate temperature (18–23°C) and high cumulative irradiance in this cultivar.
Allozyme Variation and Geographic Differentiation in Pawpaw [Asimina triloba (L.) Dunal]
Authors: Huang Hongwen , Layne Desmond R.
Published: February 2019

The pawpaw is the largest tree fruit native to the United States and the only temperate member of the tropical Custard Apple family (Annonaceae). In 1995, Kentucky State Univ. was established as the USDA-ARS-National Clonal Germplasm Repository for Asimina spp. Seedling trees from 400 pawpaw accessions representing 70 distinct geographic regions from 17 states are currently being grown at our research farm. In a preliminary study, 18 pawpaw cultivars were assayed in 30 enzyme systems using an isoelectric focusing polyacrylamide slab gel system of pH 4-9. Twelve enzymes produced high resolution without tissue specificity and were further used for evaluation of allozyme diversity of geographic populations. Degree of genetic diversity within populations and differentiation between populations as evaluated by the expected heterozygosity (He), the proportion of polymorphic loci (P), the average number of alleles per locus (A), chi-squared analysis of allele frequency heterogeneity, Nei's standard genetic distance (D), and identity (I) will be discussed. Dendrograms were generated by cluster analysis using the unweighted pair group method to demonstrate the relationships of geographic populations in the 17 states evaluated. The strategy for germplasm conservation and cultivar development through breeding will also be discussed.
Phenotypic and Marker-assisted Breeding of Capsicum for Cucumber Mosaic Virus Resistance
Authors: Grube R.C. , Zhang Y. , Huang B. , Kyle M.M.
Published: February 2019

Resistance to cucumber mosaic virus (CMV) in Capsicum from two sources is being transferred into three commercial types (bell, jalapeno, and Anaheim) using a backcross breeding scheme. We have optimized our CMV seedling screening protocol, which involves multiple inoculations beginning at the cotyledon stage with a severe CMV serogroup I isolate. Both sources of resistance, C. annuum `French Perennial' and a C. frutescens accession (BG2814-6), exhibit oligogenic recessive inheritance and share some but not all resistance alleles. Selection for type in the BCF1 generation had no effect on the frequency of resistant individuals in the BCF2 generation. We have determined that it is necessary to self-pollinate every other backcross generation to screen for resistance. Occasionally disease symptoms appear in adult plants that were initially resistant to multiple inoculations at the seedling stage, and we are investigating the correlation between seedling resistance and adult plant resistance. We are also exploring the extent to which the different sources of resistance behave differently as a function of genetic background. Additionally, we are mapping quantitative trait loci (QTLs) for CMV resistance in pepper with the goal of converting RFLP and/or RAPD markers into PCR-based markers to facilitate molecular marker-assisted selection for CMV resistance.
Effective Vegetative Growth Control of Apples with BAS 125W
Authors: Greene George M.
Published: February 2019

When applied as a dilute spray (at 125 and 250 ppm), BAS 125W effectively reduced shoot extension growth on `York' Imperial (YI) and `Spartan' (S) apple trees but was less effectively on `Delicious' (D). In 1994, lateral shoot growth of YI/M.26 trees (1 to 2 m tall) from 10 May to 7 July was reduced (35 vs. 7 cm) by sprays applied on May 13. The initial surge of growth by vertical shoots was suppressed by the treatments (16 vs. 35 cm), but there was more regrowth (6.5 vs. 0.5 cm). Some leaf injury was seen on YI. The 1995 experiments were conducted on S/M.111 and D/M.111 in an orchard spaced 3.7 m by 7.3 m. On S, lateral shoot length on five dates from 7 June to 20 Sept. was reduced by the sprays (44 vs. 32 cm on 20 Sept.). The initial surge of growth by vertical shoots was suppressed by the treatments (30 vs. 85 cm), but there was more regrowth (34 vs. 4 cm). There were fewer apples that were <25% red and more that were 25% to 40% and 66% to 85% red. On D, lateral shoot length on five dates from 7 June to 20 Sept. was reduced by the sprays (51 vs. 38 cm on 20 Sept.). The growth of vertical shoots was not influenced by the treatments, possibly due to a light fruit load in the tops of the trees. Growers viewing the 1995 plots estimated enhanced income of $933/ha for D and $780/ha for S.
A Computer-aided Description and Comparison of the Free Development of Unpruned Young Apple Trees, cv. Cox's Orange Pippin and Jonagold
Authors: Planchon Viviane , Crabbe Jacques J.
Published: February 2019

During 5 years from grafting, all annual shoots or growth units appearing on unpruned apple trees were recorded, and their main characteristics (length, node number, location of flower buds) introduced in a database through a code permitting quick and unequivocal identification. From this comprehensive description, the most and highly probable structure of the tree was deduced from year to year. Both cultivars display very similar gross structures, despite minor differences in shape, flowering mode, and productivity. The development occurs in two phases. In the first one, a frame composed of trunk and several storied sets of branches is built. Flowering is rather strictly biennial along each branch system. The second phase is one of reinforcement of the branches by axillary growth but even more by sympodial branching due to increasing and repeated terminal flowering (successive “bourse” shoot formation). `Cox's Orange Pippin' mainly differs from Jonagold by earlier transition to the second phase and regular production of more “bourse” shoots (two to three instead of one).
Regulating Budbreak, Flowering, and Fruit Maturity in Sweet Cherry (Prunus avium L.) cv. `Bing' by Surfactant and Nitrate Applications
Authors: Weis K.G. , Southwick S.M. , Yeager J.T. , Coates W.W. , Rupert Michael E.
Published: February 2019

The years 1995 and 1996 were low chill years in California with respect to stone fruit dormancy. Advancing reproductive budbreak and flowering was accomplished in `Bing' cherry (Prunus avium) by single-spray treatments of a surfactant {a polymeric alkoxylated fatty amine [N,N-bis 2-(omega-hydroxypolyoxyethylene/polyoxypropylene) ethyl alkylamine]} and potassium nitrate in combination when applied at “tightbud,” ≈ 42 days (1 Feb. 1995) before full bloom and with surfactant and potassium nitrate in combination when 10% green calyx was apparent, 33 days before full bloom. Applying 2% surfactant (v/v) + 6% potassium nitrate (w/v) was most effective in advancing bloom, speeding progression through bloom, and advancing fruit maturity when applied at tightbud stage. Surfactant (2% or 4%) applied with 25% or 35% calcium nitrate (w/v) on 2 Feb. 1996 significantly advanced full bloom compared to nontreated controls. Fruit maturity (1995) was somewhat advanced by surfactant–nitrate treatments, but fruit set and final fruit weight were equivalent among treatments. No phytotoxicity was noted in foliage or fruit. In California, marginal and insufficient winter chilling often causes irregular, extended, or delayed bloom periods, resulting in poor bloom-overlap with pollenizers. As a result, flower and fruit development may be so variable as to have small, green and ripe fruit on the same tree, making harvest more time consuming and costly. Data indicate that this surfactant, in combination with a nitrogenous compound, has potential to advance reproductive budbreak and advance maturity in sweet cherry without reducing fruit set or fruit size. Advancing the ripening time of sweet cherry even 2 to 3 days can increase the price received per 8.2-kg box by $10 to $20.
Benefits of Gardening for Elderly Women
Authors: George M.L. , Zajicek J.M.
Published: February 2019

Persons ≥60 years of age comprise a significant and growing segment of the U.S. population. More than one half of the elderly are female, and as age increases, the ratio of women to men increases as well. Gardening has long been known to be beneficial to older adults physically and psychologically. Our quantitative objective was to investigate the relationship between gardening and life satisfaction, self-esteem, and locus of control of elderly women. Our qualitative objective was to investigate the motivations to garden and the personal, self-rated benefits of gardening experienced by older women. About 45 participants were chosen from 1) volunteers in a horticultural therapy program, 2) participants in a community gardening project for older adults, and 3) participants in a community health project. During the first of two interviews, the participants completed survey instruments measuring self-esteem, locus of control, and life satisfaction. They also provided brief information about their gardening history along with demographic variables of age, ethnicity, educational background, and income level. During the second interview, the participants expanded on their experiences as gardeners, relating information such as how they became gardeners, how they learned to garden, and what factors influenced them to continue gardening. They were specifically asked to relate how they have personally benefited from gardening. Results examine the relationship between gardening and the psychological well-being of the older women.
Sweetpotato Genome Fingerprinting and Parental Analysis Using Microsatellites.
Authors: Buteler Mario I. , LaBonte Don R. , Jarret Robert L.
Published: February 2019

Microsatellites or simple sequence repeats (SSRs) were used to characterize 20 sweetpotato genotypes and to assign paternity for offspring from crosses among them. The PCR amplifications were performed with each of the sweetpotato genotypes and primers flanking a SSR loci previously characterized with the varieties Beauregard and Excel and 20 offspring from a cross among them. The PCR reaction products were separated in nondenaturing 12% acrylamide gels run at 25 V·cm–1 for 5 hours, and DNA fragments were visualized with silver staining. Gels were scanned on a flat bed scanner and analyzed using the Pro-RFLP software package. Three primer pairs were sufficient to produce an allelic profile capable of differentiating the 20 genotypes from each other. More than seven alleles/loci were found using each of the three primer pairs assayed. Occasionally primers produced allelic products clearly localized in two or three regions of the gel. These multiple loci segregated independently in a diploid fashion. This evidence suggests that there is not total homology among the three sweetpotato genomes.
Inheritance of Resistance to Halo Blight Flower and Stem Color and Association in Common Beans
Authors: Ariyarathne H.M. , Coyne D.P.
Published: February 2019

Halo blight is one of the most important bacterial diseases of common beans (Phaseolus vulgaris L.). It is serious under moderate temperature and high humidity conditions. The disease is caused by a seed-borne bacterium, Pseudomonas syringae pv. phaseolicola (Burkh.) Dowson (Psp). The inheritance of leaf reactions to Psp, flower, and stem color was studied using greenhouse-grown 109 F9 recombinant inbred lines (RI) from the P. vulgaris cross BelNeb 1 [resistant (R)] (USDA/NE) × A 55 [susceptible (S)] (CIAT). Two Psp strains, HB16 (NE) and 83-Sc2A (NE), were inoculated using the water-soaking method. A segregation ratio of 1 R:1 S RI lines were observed for disease reactions in leaves for both strains indicating major gene control. The presence of recombinants for SR, RS to the strains indicated that different genes were involved. Stem (SC) and flower (FC) color traits were each determined by two major genes. Linkages were found for reactions to the two Psp strains and also between FC and SC. No linkages were observed from FC and also SC with reactions to Psp strains.
Resistance to Race T2 of the Bacterial Spot Pathogen in Tomato
Authors: Scott J.W. , Miller S.A. , Stall R.E. , Jones J.B. , Somodi G.C. , Barbosa V.
Published: February 2019

Thirty-three tomato (Lycopersicon esculentum Mill.) or L. pimpinellifolium (L.) Mill. accessions were inoculated with race T2 of Xanthomonas campestris pv. vesicatoria (Xcv) in a field experiment at Wooster, Ohio, in Summer 1995. These included accessions selected for race T2 resistance in greenhouse tests in Florida, and accessions from Hawaii, Brazil, and Bulgaria. One L. esculentum (PI 114490-1-1) and three L. pimpinellifolium (PI 340905-S1, PI 128216-T2, and LA 442-1-BK) accessions had no Xcv symptoms. This is the first report of resistance to Xcv race T2. Partial resistance was found in PI 271385, PI 79532-S1, PI 155372-S1, PI 195002, and PI 126428. Most of the 33 genotypes were tested for race T1 resistance in Presidente Prudente, Sao Paulo, Brazil in summer 1993. Hawaii 7983, PI 155372-S1, PI 114490, PI 114490-S1, and PI 262173 had greater resistance to T1 than the susceptible control `Solar Set'. Comparisons with earlier experiments in which accessions were inoculated with race T1 or T3 indicated that the most consistent source of resistance to all three races was PI 114490 or selections from it.
Allelic Interaction of a Gene from L. chmielewskii Enhancing Soluble Solids in Tomato
Authors: Yousef Gad G. , Wang Shyh-Shyan , Juvik John J.
Published: February 2019

A segment from chromosome 7 of the wild tomato species, Lycopersicon chmielewskii has been introgressed through backcrossing into the processing cultivar, VF145B-7879. This segment was previously shown to carry a gene or genes that increase the soluble solids content in ripe red tomato fruits. To study the allelic interaction of this gene(s) and ascertain its performance in different genetic backgrounds, this line, homozygous for the L. chmielewskii segment, was crossed to its isogenic parent (VF145B-7879) and three other commercial cultivars (UC204c, E6203, and ChicoIII). The recurrent parent VF145B-7879 was also crossed to the other cultivars to generate two sets of hybrids, one heterozygous for the L. chmielewskii segment and the other homozygous for the L. esculentum segment on chromosome 7. Results from two years of field study revealed that the L. chmielewskii fragment, when either homozygous or heterozygous in the VF145B-7879 background, comparably increased soluble solids concentration in red fruit, suggesting dominant allelic interaction. This increase ranged from 8%–10% higher soluble solids content in these lines compared to the levels found in the recurrent parent (VF145B-7879). The F1 hybrids containing one dosage of this gene(s) showed a significant increase in the soluble solids content compared to the commercial parents. However, due to F1 heterosis observed in all the hybrid combinations, soluble solids content in the hybrids with this gene were not significantly greater than that of the hybrids without this gene. This gene was found to exert no significant influence on fruit pH, weight, and yield.
Resistance of Tomato Fruit (rin and nor Type) to Postharvest Diseases Depends on Stage of Maturity
Authors: Garca-Estrad R. , Siller-Cepeda J. , Bez M. , Muy M. , Araiza E.
Published: February 2019

On Sinaloa State, tomato growers test new varieties every year looking high yield, better quality and long shelf life. However, few studies are done to know the resistance to postharvest diseases. The objective was to identify postharvest pathogens that infect this new tomato varieties with characteristics rin, nor or normals (BR84, S211, S69, and S121). Fruits in two stages of maturity (pink and red) were harvested and stored under simulated marketing conditions (20°C and 80% RH). Pathogens found were aisled on PDA and identified under microscope. Different chemicals were tested to control pathogens [NaOCl; Ca(OCl)2; Supersana; iodine; Citrucidal; Captan; and water]. Six fungus species—Alternaria alternata, Fusarium oxysporium, Rhizopus stolonifer, Colletotrichum sp., Rhyzoctonia sp, and Phomopsis sp—were found on all varieties. BR84 fruit (rin type) harvested on pink stage were more resistant than red ones. S69 fruit (nor type) were more susceptible at the pink than at the red stage. S121 fruits (normal type) were equally susceptible at both stages of maturity. Least resistant variety to fungus infection at both stages of maturity was S211 (rin type). Citrucidal and Ca(OCl)2 gave the best control.