bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Ethylene and CO2 Production, Ethylene Binding Sites, and 1-Aminocyclopropane-1-carboxylic Acid in Different Types of Peppers
Authors: Villavicencio Lucia E. , Blankenship Sylvia M.
Published: February 2019

Peppers are very popular as a vegetable, ornamental, and spice. They have been classified as non-climacteric fruits, but some types of hot peppers have been reported as climacteric. Comparisons of ethylene and CO2 production, binding sites and 1-aminocyclopropane-1-carboxylic acid (ACC) content between pepper types were made. Experiments in both field and greenhouse conditions were conducted. Fruits were harvested at different stages of maturity. They were placed in jars at 27 °C and ethylene and respiration rate were determined by gas chromatography. All the variables studied showed differences among pepper types. These variations were more evident in wild types than in cultivated types. Variability in the results was also higher in wild types. When the same type of pepper grown in the greenhouse and in the field were compared, significant differences were evident. Differences in maturity patterns were observed among types. These results suggest that ripening patterns, ethylene production, respiration rates and ethylene binding sites are highly dependent on the type of pepper. Differences are also dependent upon the stage of maturity and should be taken in account when harvesting and storing pepper fruits.
Water State and Release from Dormancy in Blueberry Flower Buds
Authors: Parmentier Cécile M. , Rowland Lisa J. , Line Michael J.
Published: February 2019

Three blueberry (Vacciunium section Cyanococcus) genotypes, that have different chilling requirements and levels of cold hardiness, were studied. Dormancy was evaluated and water status determined, using Nuclear Magnetic Resonance, throughout the accumulation of chilling that leads to release from dormancy. Among the two highbush cultivars studied, `Bluecrop' (Vaccinium corymbosum) was the most dormant and `Gulfcoast' (Vaccinium corymbosum × Vaccinium darrowi) was the least dormant. The rabbiteye cultivar Tifblue (Vaccinium ashei) had an intermediate dormancy. From estimates of chilling requirements (CRs), it appeared that the cultivar with the deepest dormancy had the highest CR. The NMR results showed that `Bluecrop' buds had the lowest relaxation times (T2), indicating that water was relatively more bound in `Bluecrop' buds than in the buds of the two other cultivars. Whatever the cultivar, no significant variation of T2s and water content of the buds was noted throughout the accumulation of chilling, even after CRs were satisfied. On the other hand, a transition from bound to freer water occured if the plants were placed under forcing conditions (24 °C, long day) after they had received enough chilling to satisfy their CRs. The results suggested that the level of bound water was more associated with the level of cold hardiness rather than with the level of dormancy.
Genetic Relatedness of Pecan Cultivars Determined by Using Random Amplified Polymorphic DNA (RAPD)
Authors: Xiao Yongling , Shin Dong Young , Wetzstein Hazel Y.
Published: February 2019

Although pecan (Carya illinoinensis) is an economically important nut and timber crop, little is known about the nature of genetic variation among pecan cultivars. In addition, the pedigree of many cultivars remains unknown or is questionable. In this study, the genomic DNA of 20 pecan cultivars were analyzed by RAPD, using 20 randomly selected oligoes as primers. Based on their genetic similarities derived from the RAPD data, the 20 pecan cultivars were classified into different groups. Pecan cultivars within the same group displayed very little genetic variation, whereas cultivars in different groups showed significant diversity. The putative origins for some pecan cultivars previously believed to have unknown pedigrees were also identified based on the RAPD data obtained. Results of this study provide information useful for pecan cultivar classification and parent selection in pecan breeding programs.
Thinning Peaches with Dormant Applications of Soybean Oil
Authors: Moran R.E. , Deyton D.E. , Sams C.E. , Cummins J.C. , Lancaster A.L.
Published: February 2019

Dormant applications of 0% to 20% soybean oil were tested as a prebloom thinner of `Georgia Belle' and `Redhaven' peach flower buds. Five separate experiments were conducted with soybean oil applied in late Jan. or early Feb. 1992, 1993, 1995, and 1997. The number of living and dead flower buds was counted on five or 10 shoots per tree before and 1 month after application in Expts. 1, 2, 3, and 4. In Expt. 5, buds were counted on two to three shoots per tree before and after a freeze of –4 °C during petal fall. Soybean oil thinned flower buds in all five experiments. The amount of flower bud death was concentration dependent with maximum bud kill of 53% occurring with application of 12% oil. Thinning was fairly consistent from year to year, ranging from 34% to 51% when 10% oil was applied, but was less uniform when 5% oil was applied and ranged from 6% to 40%. Overthinning occurred in Expt. 3 by all oil concentrations tested. Bud death in untreated trees was 40% in this experiment indicating that no thinning was needed. Mild to moderate spring freezes occurred in Expts. 2, 4, and 5, but did not result in greater yield loss in thinned than untreated trees. Soybean oil at 10% and 12% resulted in greater flower bud survival of a freeze in Expt. 5. Dormant applications of soybean oil thinned flower buds, reduced the amount of hand thinning and hastened fruit maturity.
Surveys Show Extension Workshops Improve Floridians' Adoption of Environmental Landscape Management Practices
Authors: Knox Gary W. , Israel Glenn D.
Published: February 2019

Environmental Landscape Management (ELM), an extension education program, approaches every landscape as a “system” in which cultural practices interact with each other and the environment. ELM guidelines integrate site conditions, landscape design, plant selection, cultural factors, and recycling in a comprehensive, environment-friendly strategy for managing a landscape. Use of ELM practices by Floridians will conserve resources and protect the environment. The ELM program was evaluated from 1992 to 1994 in 10 counties to measure the program's impact on participants' landscape practices and to provide information on ways to improve program delivery and effectiveness. The evaluation was accomplished by comparing pre-program information on the use of ELM practices with that of a follow-up conducted 6 months after the program. Responses of this Program Group (n = 473) were compared to those of a Comparison Group of randomly selected Floridians (n = 186). ELM training increased the Program Group's adoption of most practices pertaining to pest management, irrigation, and mowing and pruning. ELM training increased adoption of some fertilization practices and a few recycling and wildlife practices. Energy conserving practices were not widely used by respondents. Respondents maintaining their own yards or those without a permanent irrigation system were more likely to adopt a wide range of ELM practices. The Program Group generally had higher initial levels of adoption of ELM practices than the Comparison Group.
Studying Children's Perceptions of Garden Benefits Using the Internet
Authors: Waliczek T.M. , Lineberger R.D. , Zajicek J.M.
Published: February 2019

A survey was designed to investigate children's perceptions of the benefits of gardening and is posted on the KinderGARDEN Web page within the Aggie Horticulture network. The KinderGARDEN Web page was developed as a resource for parents and teachers to help them incorporate the garden into the home and school lives of children. The Web site additionally attracts young visitors with a “Fun Page.” The “Fun Page” has descriptions of garden activities that children can experiment with at home or school, garden literature for children and garden Web links. The survey is included on this page. Children respond to the survey via e-mail. The survey requests information about the type of gardening situations in which each respondent participates, the number of children with whom they generally garden, what they feel they learn from gardening and what benefits they feel they gain from gardening. Children responded positively on the value of the garden to their recreation, while also mentioning educational, environmental, aesthetic, social and economic benefits in the survey. Results showed that 81% of children felt they were learning about the environment by working in the garden. Fifty-four percent of children mentioned that the garden taught them about plants and plant-related concepts. Other benefits children mentioned as important to them included recreation and/or “having fun” (31%) and socialization with friends and family (15%).
In Vitro Screening of Azalea for Resistance to Azalea Lace Bug
Authors: Robacker Carol D. , Braman S.K.
Published: February 2019

Azalea lace bug (Stephanitis pyrioides) is the most serious pest on azalea. Results of laboratory bioassays and field evaluations of 17 deciduous azalea taxa have identified three resistant taxa: R. canescens, R. periclymenoides, and R. prunifolium. Highly susceptible taxa are `Buttercup', `My Mary', R. oblongifolium, and the evergreen cultivar `Delaware Valley White'. To determine whether in vitro techniques would have potential value in screening or selecting for resistance, or for the identification of morphological or chemical factors related to resistance, an in-vitro screening assay was developed. In-vitro shoot proliferation was obtained using the medium and procedures of Economou and Read (1984). Shoots used in the bioassays were grown in culture tubes. Two assays were developed: one for nymphs and one for adult lace bugs. To assay for resistance to nymphs, `Delaware Valley White' leaves containing lace bug eggs were disinfested with 70% alcohol and 20% commercial bleach, and incubated in sterile petri plates with moistened filter paper until the nymphs hatched. Five nymphs were placed in each culture tube, and cultures were incubated for about 2 weeks, or until adults were observed. To assay for resistance to adults, five female lace bugs were placed in each culture tube and allowed to feed for 5 days. Data collected on survival and leaf damage was generally supportive of laboratory bioassays and field results. Adult lace bugs had a low rate of survival on resistant taxa. Survival of nymphs was somewhat reduced on resistant taxa.
Analysis of Demographics and Factors Influencing Student Choice of Major at Five Universities
Authors: Kohlleppel Tammy , Bradley Jennifer C. , Zajicek Jayne
Published: February 2019

In recent years horticulture programs at universities across the United States have experienced a decline in student numbers. Researchers at the Univ. of Florida and Texas A&M Univ. have developed a survey to gain insight into the influences on undergraduate students who major in horticulture. Five universities participated in the survey of undergraduate horticulture programs, these include the Univ. of Florida, Texas A&M Univ., Oklahoma State Univ., Univ. of Tennessee, and Kansas State Univ. Approximately 600 surveys were sent to the schools during the 1997 fall semester. The questionnaires were completed by horticulture majors and nonmajors taking classes in the horticulture departments. The survey consisted of two main sections. The first section examined student demographic information, high school history, university history and horticulture background and was completed by all students. Only horticulture majors completed the second section, which examined factors influencing choice of horticulture as a major. Results examine fundamental predictors in promoting student interest in horticulture, demographic variables that may influence student choice of major, and student satisfaction and attitude toward current collegiate horticulture programs. Findings from this study will provide insight into the status of post-secondary horticulture education and assist in identifying methods to increase student enrollment in horticulture programs across the country.
The Characterization of Jalapeno (Capsicum annuum) Germplasm Based on RAPD Markers and Morphology
Authors: Villand Julie M. , Nienhuis James
Published: February 2019

Characterization of germplasm collections is often criticized due to the lack of relevance given to “unadapted” germplasm by commercial breeders. Within Capsicum, only specific pod types are commercially important. Jalapeno peppers are becoming increasingly important due to the increase in sale of Capsicum-based food products. Unfortunately, few Jalapeno cultivars are available to growers. A Capsicum is classified as a Jalapeno based largely on pod shape, rendering a liberal definition of a Jalapeno. Curators and breeders with knowledge of pepper collections submitted accessions characterized as a Jalapeno. These accessions were grown at two locations to cull accessions not included in the Jalapeno market class. Accessions were characterized for traits important to commercial breeders at both locations. In addition, accessions were characterized using a set of RAPD markers dispersed throughout the genome in a separate mapping population. A subset, created from RAPD marker-based estimates of genetic distance, was created to represent the range of genetic diversity available among all Jalapeno accessions analyzed. These accessions will add genetic diversity to a breeding program without changing pod type expectations. The comparison between Jalapeno accessions and currently grown Jalapeno cultivars was examined based on differences in RAPD marker frequency. In addition, differences in marker frequencies were used to compare Jalapenos and other C. annuum market types also characterized with RAPD markers. The characterization of Jalapenos will assist breeders in their future efforts to diversify their Capsicum breeding base.
Evaluation of Square Funnel Containers for Container Nursery Production
Authors: Brooks Claire M. , Yeager Thomas H. , Beeson Richard C. , Haman Dorota Z.
Published: February 2019

A series of experiments was conducted to evaluate the influence of square funnel and round containers on overhead irrigation water collection. Square funnel containers, constructed by attaching a 30.5-cm square plastic extruded funnel surface to the 15.9-cm opening of a conventional round 3-L container, were placed edge-to-edge on a white gravel surface. Conventional round containers were spaced on 30-cm centers. Both container types contained a 2 pine bark: 1 Canadian peat: 1 sand substrate (by volume) in which temperatures were monitored daily at 1600 HR in the center of substrate. Temperatures during August for funnel and conventional containers averaged 34 and 41 °C, respectively. In another experiment, both container types received overhead irrigation either without plants or with small or large (3853 cm2 or 5187 cm2 leaf area, respectively) Viburnum odoratissimum Ker-Gawl. Square funnel containers without plants collected 4.3 times more water than conventional containers; whereas, with plants 1.3 times more water was collected by square funnel containers. Volume of water collected in square funnel and conventional containers with plants was not different due to plant size. Additional information on NO3-N leaching as influenced by water collection and substrate temperature will be presented.
Evaluation of Tomato Varieties for Resistance to Alternaria Fruit Rot
Authors: Kuti Joseph O.
Published: February 2019

Alternaria alternata (Fr.:Fr.) Keissl. (syn. A. tenuis Ness.) causes severe rot of tomato fruits and reduction in yield under field conditions in south Texas. Several fungicidal control measures have been tried against the disease and incorporation of genetic resistance has been found to be economically feasible. The objective of this study was to evaluate resistance and susceptibility of fruits of different tomato cultivars to Alternaria rot. Twenty-five tomato varieties were grown in the field in a randomized complete-block design. Subsequently, the plants were inoculated two times at mature-green stage with A. alternata conidia suspension (104 per ml) to promote moderate to severe fruit rot epidemics. Uninoculated fruits served as controls. Fruit rot incidence was measured by recording numbers of rotted fruit/plant per block and disease severity were rated on a scale of 0 to 3 at red-ripe stage. Three tomato varieties `Celebrity', `Golden Boy', and `Colonial' had little or no fruit rot symptoms, with disease severity indices of less than 1.0. These varieties were regarded as resistant. The tomato varieties `Duke', `GH 761', `Quick-Pick', and `Heat-wave' had disease severity ratings greater 1.5 and were regarded as relatively resistant. The remaining tomato varieties with disease severity ratings greater than 1.5 were regarded as susceptible.
Hydrogen Cyanamide Increases Leafing and Reduces Fruit Development Period of Southern Highbush Blueberry
Authors: Williamson J.G. , Maust B.E. , Darnell R.L.
Published: February 2019

Mature, field-grown `Misty' southern highbush blueberry plants were sprayed to drip with 0, 20.4, and 10.2 g·L–1 concentrations of hydrogen cyanamide in north-central Florida on 20 Dec. and 7 Jan. 1996–97. Plants were dormant and leafless, with slightly swollen flower buds, at the time of spray applications. All hydrogen cyanamide sprays increased the extent and earliness of vegetative budbreak and canopy establishment. The number of vegetative budbreaks per centimeter of shoot length increased linearly with increasing spray concentration of hydrogen cyanamide. Hydrogen cyanamide-treated fruit had greater average fresh weights and shorter average fruit development periods than non-treated fruit. On 15 Apr., 40% ti 60% of hydrogen cyanamide-treated fruit were ripe compared to about 10% of control fruit. Some flower bud damage and subsequent fruit thinning was observed from the 20.4 g·L–1 spray, especially at the later spray date. Hydrogen cyanamide shows potential for increasing early fruit maturity and fruit size of some southern highbush blueberry cultivars in Florida.
Lowbush Blueberry Response to Different Phosphorus/Nitrogen Ratios
Authors: Smagula J.M. , Litten W. , Dunham S.
Published: February 2019

Lowbush blueberries (Vaccinium angustifolium Ait.) in three commercial fields were treated with 67.2 kg P/ha from triple super phosphate (TSP), monoammonium phosphate (MAP), or diammonium phosphate (DAP) and compared to a control in a randomized complete-block design with 12 blocks. Correction of P deficiency by fertilizers with different ratios of P to N was assessed by leaf nutrient concentrations. Samples of stems collected in July from three 0.03-m2 quadrats per treatment plot indicated MAP and DAP had no effect on dry weight of stem tissue, but increased average dry weight of leaf tissue. P and N Leaf concentrations were raised to higher levels by MAP and DAP than by TSP. TSP had no effect on leaf N concentrations but raised leaf P concentrations compared to controls. Stem length, flower buds per stem and flower bud density were increased by both MAP and DAP, but not TSP. MAP and DAP increased fruit yield by about 340 kg/ha compared to the control.
Colorado Commercial Greenhouse Needs Assessment Survey—1997
Authors: Panter Karen L. , Newman Steven E.
Published: February 2019

Greenhouse crop producers in Colorado were surveyed in the fall of 1997 to determine their educational, extension, and research needs and expectations. Four mailings were made to a mailing list of 180: pre-letter, cover letter and survey, follow-up post card, and post-letter with another survey sent only to those who had not responded after the third mailing. One hundred and six usable surveys were returned for a rate of 59%. The survey itself consisted of five sections: Educational Programming Topics, Educational Programming Delivery Methods, Research Needs, Extension Needs, and Personal/Business Data. Results were tabulated via simple frequencies. In the area of Educational Programming Topics, 66% of respondents wanted to learn more about non-chemical pest control and 63% were interested in production of perennials. In Educational Programming Delivery Methods, 76% preferred workshops with the most favorable months for attendance being January, September, and October. In the area of Research Needs, 64% wanted explorations into new crops in general and 73% were interested in new insect management strategies. In the Extension Needs section, 76% expected a field visit from extension personnel on an as-needed basis and 51% were familiar with services offered by extension greenhouse specialists. Finally, in the Personal/Business Data section, 43% reported that they held a bachelor's degree, 50% had 16 or more years experience in the industry, and 50% worked in greenhouses less than 50,000 square feet in size.
Effects of UV-B Irradiance on Blueberry Storageability, Quality, and Shelf Life
Authors: Basiouny Fouad M.
Published: February 2019

Blueberry fruits (Vaccinium ashi Reade cv. `Tifblue'), divided into two groups, were subjected to UV-B irradiance (between 280 and 310 nm) to evaluate fruit sto-reability and shelf-life under cold conditions. Two Westinghouse FS40 sunlamps were mounted above the fruits of each group as the source of UV-B rediation. The emission from the FS40 lamps was filtered through 0.005 mm cellulose acetate (+UV-B) and through 0.005 mm mylar (–UV-B) and served as a control. UV-B lamps were turned on for 6 h daily and filters were changed every week to avoid solariztion. Storeability, quality, and shelf-life of blueberry fruits stored under UV-B radiation were better than similar fruits stored under the same conditions without UV-B radiation. Fruit quality parameters varied between the two treatments.
Photoperiod Affects Growth, Dry Weight and Fructan Partitioning in Dahlia `Sunny Rose' Seedlings
Authors: Legnani Garry , Miller William B.
Published: February 2019

Photoperiod can be an important environmental variable for dahlia seedling (plug) production. During a 7 week plug production scheme, long days provided by a 4-h night interruption with ≈10 fc of incandescent light inhibited tuberous root development while increasing shoot fresh and dry weight, fibrous root dry weight, leaf area, and height. Night interruption reduced plug production time by 1 to 2 weeks and plugs grown under long days showed superior growth following transplanting to 10-cm pots. No significant difference in total plant fresh and dry weight was observed between long-day and short-day plugs, indicating that growth differences were a result of photoperiod alterations in carbohydrate partitioning. Tuberous roots of short-day-grown plugs showed a 156% increase in fructan concentration (mg/g dry wt. basis) over long-day plugs. The carbohydrate status of long-day (night interruption) tuberous root tissue was characterized by high glucose concentration. The accumulation of glucose (a product of fructan synthesis), in plugs grown with night interruption is believed to be the result of slower rates of cell wall formation in long-day plugs compared to short-day plugs. HPAEC-PAD separation of fructans showed a maximum degree of polymerization of ≈30 in short-day tuberous roots and 27 for long-day tuberous roots. Effects of photoperiod on fructan metabolism in dahlia tuberous roots and the practical use of photoperiod in dahlia plug production are discussed.
The Influence of Drought on Growth and Gas Exchange in Fraxinus species
Authors: Schutzki R.E. , Fernandez R.T.
Published: February 2019

Fraxinus americana, F. pennsylvanica, and F. nigra were subjected to short-term drought of 4, 8, and 16 days. Seedlings were obtained from a commerical nursery and grown in 4:1 pine bark:sand media for 3 months prior to the onset of the stress. Seventy-two trees with six replicates per stress treatment were arranged in a completely randomized design. Following each stress period, the appropriate trees were well watering and monitored through recovery. Leaf photosynthesis, shoot growth, leaf emergence, terminal bud set, trunk caliper and soil moisture content were measured through the stress and recovery periods. Drought suppressed shoot growth and leaf emergence in all species; however, Green Ash maintain active growth at higher rates than either White or Black. Leaf photosynthesis was reduced in both White and Black following 4 days of drought whereas Green ash was not adversely effected until day 10. Trees were harvested following recovery and dry weight fractions of leaves, stems, and roots recorded.
Foliar and Spatial Requirements for Watermelon
Authors: Roberts Warren , Duthie Jim , Edelson Jonathan , Shrefler Jim
Published: February 2019

Unrestricted watermelon plants will cover large areas of soil surface, and watermelons are normally planted in rows 2 to 3 m apart to allow vine extension. Even so, machinery used for cultivating, spraying, and harvesting may crush vines, thereby reducing plant size and restricting the ground surface area available to the plant. Insect or disease defoliation may limit the leaf surface area that is available for fruit production. Some farmers intentionally limit vine length or surface area in the belief that this will promote fruit set. Experiments with Citrullus lanatus (cv. Sangria, Crimson Trio, and Scarlet Trio) have been conducted in southeastern Oklahoma to determine the effect of branch number, branch length, melon number, and root volume on fruit yield. Branch length was limited to 1.2, 2.4, 3.7, or 4.9 m, and branch number was limited to either one or two branches per plant. An unpruned control treatment was included for comparison. Limitation of branch length limited fruit yield. Likewise, limitation of branch number limited fruit yield. Watermelons were also grown in a series of 10 containers that ranged in volume from 0.1 to 1.0 m3. Root volume was directly correlated with watermelon yield, but the effect was minimal. Marketable melons were produced in containers as small as 0.1 m3 volume.
Comparative Mapping of Three Bacterial, Three Fungal, and One Virus Disease-resistance Genes in Common Bean
Authors: Jung Geunhwa , Nienhuis James , Coyne Dermot P. , Ariyarathne H.M.
Published: February 2019

Common bacterial blight (CBB), bacterial brown spot (BBS), and halo blight (HB), incited by the bacterial pathogens Xanthomonas campestris pv. phaseoli (Smith) Dye, Pseodomonas syringae pv. syringa, and Pseudomonas syringae pv. phaseolicola, respectively are important diseases of common bean. In addition three fungal pathogens, web blight (WB) Thanatephorus cucumeris, rust Uromyces appendiculatus, and white mold (WM) Sclerotinia sclerotiorum, are also destructive diseases attacking common bean. Bean common mosaic virus is also one of most major virus disease. Resistance genes (QTLs and major genes) to three bacterial (CBB, BBS, and HB), three fungal (WB, rust, and WM), and one viral pathogen (BCMV) were previously mapped in two common bean populations (BAC 6 × HT 7719 and Belneb RR-1 × A55). The objective of this research was to use an integrated RAPD map of the two populations to compare the positions and effect of resistance QTL in common bean. Results indicate that two chromosomal regions associated with QTL for CBB resistance mapped in both populations. The same chromosomal regions associated with QTL for disease resistance to different pathogens or same pathogens were detected in the integrated population.
Fertigations and Foliar Sprays with Potassium Increase Fruit Size of Grapefruit
Authors: Swietlik Dariusz
Published: February 2019

A study was conducted in a mature `Ray Ruby' grapefruit (Citrus paradisi, Macf.) orchard to elucidate the effect of fertigations and foliar sprays with KNO3 on fruit size, leaf and fruit K level, and tree growth. The treatments include: 1) Control–no K applied; fertigations applied in 2) December–April (F1); 3) February–May (F2); 4) May–August (F3); 3 times foliar sprays applied at monthly intervals in 5) January–March (S1); 6) April–June (S2); or 7) June–August (S3). Potassium was injected into microsprayer irrigation lines at the annual rate of 440 g K/tree and foliar sprays were applied at 5% concentration. Compared to the control, the S2 and F2 treatments increased the yield of large fruit, i.e., in commercial sizes 48 and larger, by 59% and 41%, respectively. Fruits this large are marketed fresh and thus provide much higher returns to growers than those realizable from sales of smaller fruit destined for processing. Potassium applications in April and May were most effective in increasing fruit growth. The observed increases in yield of large fruit were caused by a shift in the number of fruit from small to large fruit size categories. This conclusion was supported by the observation that a total fruit number and yield per tree were not affected by the treatments. There was a positive relationship between fruit but not leaf K concentrations measured in May and fruit size. No preference was established between expressing leaf and fruit K concentrations on a dry-vs. fresh-weight basis.
Brushing and Temperature Control Transplant Growth of Float-irrigated Bell and Jalapeno Pepper
Authors: Galloway Bethany , Schultheis Jonathan R. , Monks David W.
Published: February 2019

Experiments were conducted at the North Carolina State Univ. Phytotron facility in late Summer and Fall 1996. Bell and jalapeno pepper were grown in polystyrene flats using continuous float irrigation. Using DIF (the difference between day and night temperatures), three temperature treatments consisting of positive (+DIF), zero (0DIF), and negative (–DIF) DIF were assigned to three growth chambers. DIF treatments were imposed in each chamber for only the first 2 hr after lights were turned on. Half of the plants in each chamber were brushed twice a day. Height was affected by cultivar, brush treatment, DIF treatment, and all combinations of the three treatments at all sampling dates. Jalapeno pepper experienced greater height reductions due to DIF or brushing treatment than bell pepper. Shoot fresh weight was reduced by brushing at all sampling dates, but DIF was less effective. Length of first internode was influenced by brush and DIF treatments, while leaf area was only affected by brush treatment which caused reductions of 13% and 25 % in bell and jalapeno pepper, respectively, at 6 weeks after planting. Brushing increased pepper stem diameter. DIF had little effect on stem diameter but in combination with brushing effectively increased stem diameter over both cultivars.
Use of CD-ROMs for Teaching Systemic Botany and Horticultural Production Courses
Authors: Stewart Katrine
Published: February 2019

Systemic botany often requires the students to visually examine plant materials at different stages of growth and development to determine family characteristics. Fresh plant materials used in these demonstrations are often unavailable to allow the student to review for laboratory examinations. The timing of production courses means that students do not have the chance to see field operations for various crops. CD-ROMs have been developed as a adjunct to lectures to allow students to review and examine material at their own pace in order to better prepare them for examinations.
Laboratory Techniques for Determining Ploidy Levels
Authors: Cramer Christopher S.
Published: February 2019

The determination of ploidy levels is essential for breeding asexually propagated and polyploid crops that may have ploidy chimeras in their tissues or have several polyploid series. This presentation will discuss a laboratory for teaching students how to determine ploidy levels in different plant tissues using different techniques. The different methods for ploidy determination include root tip squashes, pollen mother cell squashes, pollen grain size and germinal pore counts, stomata size and density determination, and gross morphology. After completing these laboratory experiments, students will be able 1) to initiate a study of ploidy determination, 2) to determine the correct course of action in determining ploidy level, and 3) to recognize the various steps required to determine ploidy level in plants.
Does the Preconditioning of Vegetable Crops with Aluminum, Sodium, or Ammonium Reduce the Susceptibility to CMV Infection?
Authors: Taylor Jeff , Simonne Eric , Murphy John
Published: February 2019

Because cucumber mosaic virus (CMV) affects southernpea (Vigna unguiculata) grown in the southeast, plants were preconditioned with different nutrient solutions from germination to the flowering stage, 24 DAT (days after transplanting) and rub inoculated with CMV. Symptoms were observed at a rate of 1/5, 1/5, 4/5, and 4/5 (observed infected plants/plants infected) in the Al, NH4, NO3, and Na treatments, respectively. At 67 DAT, ELISA detected CMV at a rate of 5/5, 5/5, 4/5, and 4/5 (detected infection/plants infected) of the Al, NH4, NO3, and Na treatments, respectively. The interaction of inoculation and preconditioning was nonsignificant for fresh or dry weight (P > 0.10); however, nutritional preconditioning significantly (P < 0.01) affected the fresh and dry weight. These preliminary data suggest that nutritional preconditioning affects southernpea plants' reaction to CMV.
Early Field Performance of Micropropagated Japanese Persimmon Trees
Authors: Tetsumura Takuya , Yukinaga Hisajiro , Tao Ryutaro
Published: February 2019

Growth of micropropagated Japanese persimmon trees (Diospyros kaki L. cv. Nishimurawase) during the initial 3 years after field establishment was compared with that of grafted trees on seedling stocks. Judging from the mean length of annual shoots per tree and the yearly increases in height, trunk diameter, and top and root dry mass, the grafted trees on seedling stocks grew poorly during the first and second growing seasons, while micropropagated trees, raised in an outdoor nursery, developed poorly only during the first growing season. In contrast, micropropagated trees raised in pots fared well soon after field establishment. These trees had more fine than middle and large roots; in contrast, grafted trees on seedling stocks had one large taproot, which died back to some extent after field establishment, with few fine roots.
A Comparison of Three Mathematical Models of Response to Applied Nitrogen: A Case Study Using Lettuce
Authors: Willcutts John F. , Overman Allen R. , Hochmuth George J. , Cantliffe Daniel J. , Soundy Puffy
Published: February 2019

Modern fertilization recommendations must optimize crop yield and quality and minimize chances of negative environmental effects due to overfertilization. Data from fertilizer studies can be fitted to several mathematical models to help determine optimum fertilizer rates, but resulting recommendations can vary depending on the model chosen. In this research, lettuce (Lactuca sativa L.) was used as a case study vegetable crop to compare models for estimating fertilizer N requirements. Greenhouse studies were conducted with `South Bay' and `Sierra' cultivars of crisphead lettuce to measure yield response to applied N. Individual plants were grown in pots and received six rates of N (0.0, 0.2,0.4,0.6,0.8, and 1.0 g/plant) as ammonium nitrate in split applications. Data for plant fresh mass and N uptake were recorded. The logistic model described the data for both cultivars quite well, with correlation coefficients of 0.98 and above. The logistic model was also applied to field data for average head mass of `South Bay' lettuce following application of N at 0,56,112,168,224, and 280 kg·ha-1. Logistic, linear-plateau, and quadratic models were compared for the field data. Coefficients for the linear-plateau model were derived from the logistic model. All three models for lettuce production were compared graphically and analytically. The model coefficients were then used to make improved estimates of fertilizer recommendations for field production of lettuce.
A Selection Procedure for Iron-deficiency Stress Tolerance among Warm-season Turfgrasses Using Ferrihydrite-amended Growth Media
Authors: Green R.L. , Hartwig R.C. , Richie W.E. , Loeppert R.H. , Beard J.B.
Published: February 2019

Iron-deficiency (Fe-deficiency) stress, characterized by chlorosis of leaf tissue, is a major limiting factor in turfgrass production on calcareous soils. The objectives of this study were to: 1) evaluate ferrihydrite-amended growth media and the threshold amount of Fe initially added for use in a whole-plant screening procedure for selecting cultivars that are tolerant to Fe-deficiency stress conditions; 2) measure and evaluate whole-plant growth characteristics that could be an index of Fe deficiency stress; and 3) assess the potential of using a synthetically produced Fe oxide, ferrihydrite, as a slow-release Fe fertilizer source. Iron-stress sensitive `Raleigh' St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] and Fe-stress tolerant `Tifway' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Davy] cultivars were grown under glasshouse conditions in a medium consisting of quartz sand, 5% (m/m) CaCO,, and a ferrihydrite amendment providing Fe in concentrations of 0, 15, 30, 46, or 120 mg·kg-1 media, (equivalent to 2, 3, 4, 5, or 10 mg DTPA-extractable Fe/kg media). There also was a nonlimiting iron control. St. Augustinegrass was first rated for iron chlorosis 83 days after planting (DAP) while bermudagrass was first rated at 294 DAP. Initial Fe levels equivalent to 5 mg DTPA-extractable Fe/kg media showed potential for screening genotypes. Visual estimates of iron chlorosis and chlorophyll contents of leaves were the best indicators of low soil Fe availability. A single ferrihydrite soil amendment at 10 mg DTPA-extractable Fe/kg media was adequate in preventing chlorosis for the duration of the study (174 and 509 days for St. Augustinegrass and bermudagrass, respectively). Chemical name used: Diethylenetriaminepentaacetic acid (DTPA).
Gibberellic Acid and Presowing Chilling Increase Seed Germination of Indiangrass [Sorghastrum nutans (L.) Nash.]
Authors: Watkinson Jonathon I. , Pill Wallace G.
Published: February 2019

Following dry storage for 5 or 11 months (new and old seeds, respectively) at 5 °C, less than 10% of the seeds of Indiangrass germinated as determined by a standard germination test. We attempted to increase germination by subjecting seeds to dormancy-breaking treatments, including sodium hypochlorite soak (5.25% v/v NaOCl; 20 or 60 min), prechilling (5 °C for 2 weeks), gibberellic acid during germination (GA3, 1000 mg·L-1), and combinations thereof. Treatment with NaOCl increased the germination of non-prechilled seeds only when they were germinated in GA3; a 60-min soak in NaOCl increased germination to 53% and 65% in new and old seeds, respectively. Prechilling increased germination to 65% and 47% in new and old seeds, respectively. Germination of new, prechilled seeds was increased further to 86% by either a 20-min soak in NaOCl or germination in GA3. Germination of old, prechilled seeds was not promoted further by treatment with NaOCl, but was increased to 67% by germination in GA3. Since NaOCl treatment alone failed to promote germination, we examined the effects on seedling emergence and growth of providing GA3 at 1000 mg·L-1 during the 2-week prechilling period. While prechilling alone increased emergence to an average 34% for new and old seeds, prechilling with GA3 increased emergence to 75% and 50% for new and old seeds, respectively. These treatments did not influence seedling shoot dry mass. Seed exposure to GA3 during rather than after prechilling was more effective in promoting Indiangrass establishment.
Injury to Strawberry Crowns Caused by European Corn Borer Larvae
Authors: Maas John L. , Enns John M. , Hokanson Stan C. , Hellmich Richard L.
Published: February 2019

Larvae of several insects injure and kill strawberry (Fragaria ×ananassa Duchesne) plants by burrowing into and hollowing out plant crowns. Occasionally, these infestations are serious enough to cause heavy economic losses to fruit producers and nursery plant growers. In 1997 in Beltsville, Md., we observed wilting and dying mature plants and unrooted runner plants in two experimental strawberry plantings. Injury by larvae was extensive; large cavities occurred in crowns, and the central pith tissues were removed from stolons and leaf petioles. Often, insect frass was seen at entrance holes. Larvae removed from hollowed-out parts of injured plants were identified as the European corn borer (Ostrinia nubilalis Hübner) in their fifth instar stage. Their presence in this instance also was associated with a cover crop of millet [Setaria italica (L.) P. Beauv., `German Strain R'] planted between the strawberry rows for weed suppression. This is the first published report of the European corn borer attacking strawberry. Although this insect may occur only sporadically in strawberry plantings, it may become important in the future. Growers and other professionals should become aware of this new strawberry pest and recognize that its management in strawberry will be different from management of other crown-boring insects.
Heat Treatment Affects Postharvest Quality of Kale and Collard, but not of Brussels Sprouts
Authors: Wang Chien Y.
Published: February 2019

Mature leaves of kale (Brassica oleracea L., Alboglabra group) and collard (Brassica oleracea L., Acephala group), and Brussels sprouts (Brassica oleracea L., Gemmifera group) were heated by moist air at 40, 45, 50, or 55 °C for durations of 0, 30, 60, or 90 minutes. Heating of kale at 45 °C for 30 minutes was effective in maintaining better postharvest quality, delaying yellowing, and reducing losses of sugars and organic acids during subsequent storage at 15 °C. Exposure of collard at 40 °C for 60 minutes also delayed yellowing and maintained turgidity of the leaves. Other treatments were either less beneficial, not effective, or caused injury. Heat injury occurred when temperature and duration exceeded the tolerance levels. In some cases, heat-injured tissues remained green but developed fungal infection. Heat treatments had no measurable effects on the rate of senescence or storage quality of Brussels sprouts.
Comparison of Seed Number and Mass of Southern Highbush Blueberries vs. Those of Their F1 Hybrids with V. simulatum after Open Pollination
Authors: Ritzinger Rogério , Lyrene Paul M.
Published: February 2019

Open-pollinated southern highbush (V. corymbosum L. hybrids) and F1 (southern highbush × V. simulatum Small) hybrid blueberry seedlings were compared for fertility in a high-density nursery in Gainesville, Fla. Most of the pollen sources in the field were tetraploid southern highbush seedlings. Berries were collected from 100 southern highbush seedlings and from 100 seedlings from southern highbush × V. simulatum crosses. The seeds were extracted and dried on a laboratory bench for several days before weighing. No significant differences were found in seed mass/berry between the two types of seedlings. Although the F1 interspecific hybrids averaged slightly lower in seed mass per berry, this was due to the smaller size of their well-developed seeds, not to poor seed development. The estimated number of well-developed seeds per berry was 35.4 and 39.1 for southern highbush blueberries and their F1 hybrids with V. simulatum, respectively. These results indicate that reduced fertility should not be a problem in using V. simulatum to breed southern highbush blueberries.
Growth and In Vitro Propagation of Peach Plants Transformed with the Shooty Mutant Strain of Agrobacterium tumefaciens
Authors: Hammerschlag F.A. , Smigocki A.C.
Published: February 2019

Peach [Prunus persica (L.) Batsch] plants #94-1, #99-1, and #40-1, carrying a cytokinin biosynthesis (ipt) gene following transformation with the shooty mutant strain of Agrobacterium tumefaciens, were evaluated for altered growth habit and axillary shoot formation, both in vitro and in the greenhouse. After 9 weeks of in vitro propagation on four different levels of 6-benzyladenine (BA), only transformant #99-1 exhibited significantly greater axillary shoot formation (on 10 μm BA), and significantly greater fresh mass (on 3,10, and 30 μm BA) than the control #RG-3. Tolerance to a supra-optimal (30 μm) concentration of BA was indicated by fresh mass increases for #99-1 shoot cultures. Delayed senescence on 0 μm BA was exhibited by 87% of the transformants, but by only 12% of the control plants. Greenhouse-grown #99-1 and #40-1 were significantly shorter than #RG-3 plants at 6 weeks and at 1 year, but only #40-1 exhibited significantly greater branching than the controls. Chemical names used: 6-benzyladenine (BA); isopentenyl transferase (ipt).
Trinexapac-ethyl Restricts Shoot Growth and Improves Quality of `Diamond' Zoysiagrass Under Shade
Authors: Qian Y.L. , Engelke M.C. , Foster M.J.V. , Reynolds S.
Published: February 2019

Turfgrass is grown under extremely variable light intensities. This presents difficult management problems, and methods are needed to improve turf performance under variable shade conditions. Two experiments were conducted to determine the influence of trinexapac-ethyl (TE) on turf performance and physiological responses of `Diamond' zoysiagrass [Zoysia matrella (L.) Merr.] under several light intensities. In a polyethylene-roofed greenhouse, `Diamond' was sodded in 12 wooden boxes (1.2 × 1.2 × 0.16 m) (Expt. 1) and 18 fiber containers (55 × 38 × 12 cm) (Expt. 2). Treatments applied to boxes or containers included three levels of shade (40%, 75%, and 88%) with and without multiple TE applications at 48 g·ha-1 of active ingredient. Without TE treatment, vertical shoot growth increased linearly with increasing shade levels. Excessive shoot growth under 75% and 88% shade exacerbated energy depletion, as evidenced by the 45% and 67% lower rhizome mass and the 37% and 65% lower total nonstructural carbohydrate content (TNC), respectively, compared with turf under 40% shade. Trinexapac-ethyl reduced excessive vertical shoot growth and increased rhizome mass and TNC. Mean turf quality was increased by 0.7 and 1.4 units for turf receiving multiple TE applications under 75% and 88% shade, respectively. Trinexapac-ethyl did not increase turf quality or TNC under 40% shade. Canopy photosynthetic rate (Pn) was not affected 4 weeks after the initial TE treatment under any shade level. However, 34 weeks after the initial TE treatment a 50% higher Pn was observed for turf treated with TE under 88% shade, possibly because of higher tiller density. Repeated TE application increased turf quality and provided more favorable physiological responses (such as TNC and Pn) under 75% and 88% shade, where conditions favored vertical shoot growth. However, little or no improvement in turf quality was observed under 40% shade, where conditions favored slow vertical shoot growth. Chemical name used: 4-(cyclopropyl-α-hydroxy-methylene)-3,5-dioxo-cyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl).
Humic Acid Application Affects Photosynthesis, Root Development, and Nutrient Content of Creeping Bentgrass
Authors: Liu Chunhua , Cooper R.J. , Bowman D.C.
Published: February 2019

Humic acids (HA) reportedly enhance the growth of numerous crops; however, little information is available as to their effects on turfgrasses. Experiments were conducted to evaluate the effect of a commercial preparation of HA on the photosynthesis, chlorophyll concentration, rooting, and nutrient content of `Crenshaw' creeping bentgrass (Agrostis stolonifera L.). Bentgrass plugs were grown hydroponically in one-quarter-strength Hoagland's nutrient solution containing HA at 0, 100, 200, or 400 mg·L-1 with measurements made weekly for 1 month. The photosynthetic rates of plants growing in 100 or 200 mg·L-1 rarely differed from that of the control, but 400 mg·L-1 significantly enhanced net photosynthesis on all four observation dates. Chlorophyll content was unaffected by HA rate on all observation dates. Root dehydrogenase (DH) activity and root mass regrowth were significantly increased by HA at 400 mg·L-1 on all dates. The 100 and 200 mg·L-1 rates increased root DH activity on two of four observation dates, but root regrowth was unaffected. At one or more of the rates used, HA increased tissue concentrations of Mg, Mn, and S and decreased those of Ca, Cu, and N, but had no influence on the concentrations of P, K, Fe, Mo, and Zn.