bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity of Broccoli Inflorescence Development to High Temperature
Authors: Bjorkman Thomas , Pearson Karen
Published: February 2019

Production of broccoli in areas where summer temperatures exceed 30C is difficult because the head may not form properly. The high temperature causes an unevenness in the head due to widely differing sizes of buds. The sensitive stage of development was determined for the early maturing variety `Galaxy' by exposing it to 1-week at 36C at varying developmental stages, and subsequently analyzing the head structure. The injury is a cessation of bud enlargement during the high-temperature exposure. There is no corresponding cessation of bud initiation at the apex. The patter of injury is consistent with susceptibility over a relatively small range of bud development: even with a 1-week exposure, only about 1/3 of the buds will be affected. The plant's most developmental stage at this sensitive period still appears vegetative, but the youngest leaves are just beginning to reorient as a consequence of the reduced stem elongation rate. The meristem is less than 1 mm wide, and scanning electron micrographs show floral primordia just forming, still subtended by leaf primordia. The injury is fully expressed when the head is first exposed (≈10 mm wide), though it becomes more apparent as the head matures. The buds that were delayed in development by the high temperature developed into fertile flowers, albeit about a week late.
Genetic Variations in Chlorophyll Fluorescence, Photosynthesis, and Carbon Partitioning into Sorbitol, Sucrose, and Starch in Apple Leaves
Authors: Wang Zhongchun , Quebedeaux Bruno
Published: February 2019

Chlorophyll fluorescence measurements are providing insights into Photosystem II (PSII) quantum efficiency and hence are able to provide a good estimation of carbon assimilation under field conditions. A F2 generation of sibcross seedlings from a cross of `Goldspur' × `Redspur' were selected to identify genetic variations and the relationships among fluorescence parameters, carbon assimilation, and carbon partitioning in apple leaves. Mature leaves from extension shoots were analyzed for chlorophyll fluorescence with a CF-1000 chlorophyll fluorescence measurement system, photosynthetic rate with a LI-6200 portable photosynthesis system, and carbohydrates with a Shimadzu HPLC. Significant variations in leaf chlorophyll fluorescence parameters and photosynthetic rates were found. The ratio of Fv: Fm, an estimation of photochemical efficiency of PSII, decreased from ≈0.90 in June to ≈0.75 in September while the photosynthetic rates decreased from ≈8.5 in June to ≈4.5 μmol·m–2·s–l in September. The relationships between fluorescence parameters, photosynthesis, and carbohydrate partitioning were analyzed and the ratio of sorbitol to sucrose in relation to the efficiency of PSII and NADPH production will be discussed.
Factors Affecting Anthocyanin Accumulation in Solanum tuberosum
Authors: Hung Chen-Yi , Tong Cindy B.S. , Murray John R.
Published: February 2019

The color of red potatoes is due to an accumulation of anthocyanins in periderm tissues. The objective of this study was to examine the effect of several factors on tuber redness. Using the red tuber-producing S. tuberosum ssp. tuberosum cultivar Norland, we observed that chroma (intensity of redness) and anthocyanin content of greenhouse-grown tubers decreased as tuber weight increased. There was a slight or no increase in hue (tint). We used HPLC to determine that pelargonidin and peonidin are the major anthocyanidins (aglycones of anthocyanins) in tuber periderm. The ratio of pelargonidin to peonidin increased as tuber weight increased up to 25 g fresh weight. The decrease in chroma was not due to an increase in cell sap pH; we observed a decrease in cellular pH as tuber weight increased. Controlled-atmosphere storage had no effect on tuber chroma or anthocyanin content compared to air storage. Methyl jasmonate, sucrose, or light treatment did not increase anthocyanin accumulation. Tubers exposed to light had less anthocyanin than those kept in the dark. We are examining the developmental expression of anthocyanin biosynthetic genes, as well as the effect of maize transcription factors on anthocyanin synthesis, in tuber periderm.
The Effect of Various Pollen Grains on Growth and Development of P. vera Nuts
Authors: Riazi Ghodratollah , Khanizadeh Shahrokh , Rahemi Majid
Published: February 2019

The xenial and metaxenial effects of five different male sources on cross pollination of three pistachio cultivars, were studied in 1990 and 1991 in Rafsanjan/Iran. The pollen grains used were P. atlantica Desf., P. mutica F.& M., P. vera L. (Momtaz), P. vera L. (Soltani), and an open pollination. The female cultivars chosen were `Owhadi', `Kalleh-ghuchi', and `Momtaz', which occupy the largest cultivation area. Experiment was done in two successive years in a completely randomized design. Results of this study agreed with previous studies regarding the retardance of pistachio nut development by wild pollen species rather than P. vera L. The greatest change in various characteristics of nuts, e.g., kernel weight and shell splitting, occurred when P. mutica F.& M. pollen grains used followed by P. atlantica Desf. pollen grains. Thus, some manifestations of xenia and metaxenia could be inferred. In general, larger kernels and increased shell dehiscence resulted from the use of P. vera L. pollen grains. Greater kernel weight of `Kalleh-ghuchi', higher shell splitting of `Momtaz', and higher blank of `Owhadi' produced by pollination with P. vera L. in some extent could also be cultivar characteristics.
Chemical or Air Pruning Influences Containerized Roots of Carambola, Longan, and Mango Seedlings
Authors: Marler Thomas , Willis Dwayne
Published: February 2019

Carambola, longan, and mango seedlings were planted in containers coated with paint containing up to 200 ppm CuCO3, and carambola and mango seedlings were planted in containers designed to provide air pruning of roots. Some plants were bare-rooted following a period of growth, and the roots were dried to a constant weight. The remainder of the plants were removed from the containers and planted in silica sand with container medium intact. The new root growth was determined after 3 to 6 months by carefully washing away the sand then removing the exposed roots. Chemical treatment of containers increased total root growth during container production and new root growth after removal from the container for longans. In contrast, chemical treatment did not influence roots of mango or carambola. Air pruning, however, increased the percentage of roots in the upper half of the container and the new root growth following removal from the container for both of these species. No circling roots were visible growing along the sides or bottom of chemically treated containers for longan and air pruning containers for mango and carambola.
Induction of Roots on Jujube Softwood Cuttings Using Agrobacterium rhizogenes
Authors: Hatta Muhammad , Beyl Caula A. , Garton Stephen
Published: February 2019

Trees of jujube (Ziziphus jujuba), particularly older ones, root with great difficulty. A greenhouse experiment was conducted to assess the effects of two strains of Agrobacterium rhizogenes (A4 and TR105) on softwood cuttings from two trees—a tree 10 years old not currently bearing flowers, which we called “juvenile” because it still exhibited many juvenile characteristics; and a tree ≈70 years old containing many flower buds, which we called “mature”. The cuttings were collected on 11 May 1994 and trimmed to 7.5 cm. Both strain and source of cutting influenced inoculation success—TR105 was more responsive to A. rhizogenes than was A4 and the “juvenile” cuttings more responsive than “mature” cuttings. Strain TR105 was very effective in increasing rooting percentages and root number. “Juvenile” cuttings had better rooting percentages, greater root number, and greater root length than did “mature” cuttings. Agrobacterium rhizogenes exhibits great potential for rooting other difficult woody ornamental or fruit tree species as well.
Electron and Light Microscopy Structure and Polysaccharide and Pectic Composition of Highbush and Rabbiteye Blueberries
Authors: Marroquin E. , Silva J.L. , Magee J. , Braswell J. , Spiers J.
Published: February 2019

Rabbiteye (Vaccinium ashei) blueberries were harvested in Mississippi and highbush (V. corymbosum) blueberries were harvested in Michigan. The berries were rapidly cooled to 5C after harvest and kept at this temperature for 48 h before being analyzed as fresh fruit or freezing for later analyses. Microstructural (light and scanning/transmission electron microscopy) and chemical (pectins, cellulose, hemicellulose, lignin, and fiber) evaluations were performed to evaluate differences between the two types of blueberries. Scanning electron micrographs showed that rabbiteye spp. have thicker epidermal and subepidermal cells than highbush spp. Transmission electron micrographs also showed that rabbiteye spp. have a thicker, more uniform cuticle layer than highbush spp. Rabbiteye spp. contained higher fiber and complex polysaccharides than highbush spp. Although, there were no differences in total pectins, rabbiteye berries had lower water soluble pectins and oxalate soluble pectins than highbush blueberries. Differences in polysaccharides and pectins between highbush and rabbiteye berries indicate that their cell wall components differ. These differences, along with the variation in subepidermal, epidermal and cuticle layers of the skin, provide valuable information to explain the textural differences between rabbiteye and highbush blueberries.
Horticultural Crops Grown at Home Gardens in Rural Areas of South Sumatra, Indonesia
Authors: Lakitan Benyamin
Published: February 2019

A survey has been conducted to evaluate kinds of horticultural crops grown at home gardens at 40 villages in South Sumatra Province. The villages were purposely selected to represent all geomorphological regions of the province, from highland (>1400 m above sea level) to tidal swamp along the coastal. Ten home gardens were randomly selected at each village. Most common horticultural crops found at home gardens were fruits crops such as banana, pineapple, and soursop. Surprisingly, vegetable crops were rarely (<22.0%) found at home gardens. Based on Sorenson's similarity index, it can be concluded that kinds of fruit crops grown were similar at most villages surveys, except for those at altitudes higher than 1000 m above sea level. Average density of perennial fruit tress was 4.6 trees/100 m2, with a range from 1.7 to 10.9 trees/100 m2.
An Evaluation of Focus Groups as a Technique to Determine the Market Potential for Wildflower Sod
Authors: Barton S.S. , Mercer J.
Published: February 2019

Two focus group sessions were conducted to determine the market potential for a new horticultural product, wildflower sod. One session included homeowners with suburban lots and an interest in wildflowers. Another session included landscape professionals, property managers, and garden center operators. Participants viewed a slide presentation about the uses of wildflowers and wildflower sod; a videotape illustrating wildflower sod installation; and a demonstration plot with wildflower sod planted at different spacings (solid, 50%, 25%, or plugs at 1”, 18”, or 24” centers) and at different times of year (fall, spring). The discussion was conducted by an unbiased facilitator. Participants cited the instant effect of wildflower sod as a major advantage. The price was viewed as acceptable for small areas, especially if sod was broken apart and spaced as plugs. Comments from participants were also used to develop an ideal product description and a marketing plan.
Gender Resource Utilization in Integrated Postharvest System for Citrus Fruits
Authors: Smith-Kayode Oluwatimilehin (Timi)
Published: February 2019

Integrated postharvest system comprising the fresh-market and juice processing from citrus fruits was the model system selected to evaluate gender participation in fruit agribusiness in Nigeria. This was in realization of the role of women in family support and food security. Results showed 60% of the labor force engaged in citrus processing and fresh fruit marketing are women. Fruit retailing involves partial processing through peeling and short-term modified-atmosphere packaging, while key unit operations of processing cover juice production, handling, and quality control. Retail activities attract higher income relative to factory work. Implications of seasonality in fruit supply in terms of income generation, employment, rural development, and strategies to empower the gender for greater productivity are discussed in the presentation.
Scoring and Girdling Pretreatment of Sweetgum, Chinkapin Oak, and Hackberry Trees for Shitake Mushroon Production
Authors: Sabota Catherine M. , Creel Kenneth W. , Beyl Caula A.
Published: February 2019

To determine if production of shiitake mushrooms [Lentinus edodes (Berk.) Pegler] could. be increased, sweetgums (Liquidamber straciflua) chinkapin oaks (Quercus muehlenbergii) and hackberries (Celtis occidentalis) were scored or girdled in May 1993. Scoring was done by removing a 3-cm-wide strip of bark in a spiral from around the tree so that the end was ≈5 cm below the starting point. Girdling was done similarly, forming a continuous ring. For each tree species, there were three replications of the three treatments. In May 1994, the trees were felled, cut into 100-cm sections, and the logs were inoculated with shiitake mushroom spawn. In Oct. 1994, when production began, 30% of the logs from scored oak trees produced a total of 1720 g of shiitake mushrooms; from the girdled oak trees 36% of the logs produced a total of 963 g; and 28% of logs from control trees produced 704 g. Although a higher percentage of scored and girdled sweetgum logs came into production, the yield of mushrooms from controls was equal to that of girdled and higher than that of the scored.
Legume Ground Covers for Low-input Pecan Management
Authors: Shiferaw A. , Smith M.W. , Eikenbary R.D. , Arnold Don C.
Published: February 2019

Perennial legume ground covers were evaluated to supply N and increase beneficial arthropod densities in pecan orchards. Treatments were pure stands and a mixture of `Kenland' red clover (Trifolium pratense L.) and `Louisiana S-l' white clover (Trifolium repense L.). The control plot was a grass sod. Nitrogen was applied at 0 to 200 kg·ha–1 in 50-kg intervals to the trees in the grass plots, but no N was applied to the legume plots. Aphids and beneficial arthropods were monitored in legumes and pecan canopies. Beneficial arthropods monitored were Coccinellidae, Chrysopidae, Nabis, Syrphid, and spiders. The most abundant beneficial arthropods were spiders, Coccinellidae, Chrysopidae, and Nabis respectively. In pecan canopies, spiders, Coccinellidae, Chrysopidae were the most abundant. The legumes supplied ≤156 kg N/ha to the pecan trees.
Agroecological Study and Determination of Yield Potential of Garambullo (Myrtillocactus geometrizans) in Queretaro, Mexico
Authors: Perez-Gonzalez S.
Published: February 2019

The garambullo is a native cactus that grows wild in the semiarid region of central and northeastern Mexico. It is highly appreciated by local people for the quality of its fruits and as a pigment source for the food industry. However, there is no information available about its real production potential. The main objective of this work is to collect field data about tree density, phenology, and yield components of natural stands. Six plots (2000 m2 each) were randomly selected where garambullo grows wild in southwestern Querétaro and the following data was collected: number and distance among trees, age distribution, blossom and harvest season, fruit weight and number/tree, fruit/areole, areoles/fruiting arm, arms/branch and branches per tree. Tree density and yield varied greatly among plots and trees, from less than 20 to 237 trees/ha, and from less than 100 to 10,000 fruits/tree. Average fruit weight was 0.97 g and mean yield/tree was 2.79 kg. Possibilities for increasing yield efficiency will be discussed.
Effects of De-inking Sludge on soil Properties and Corn Growth
Authors: Erhioui Mohamed Badrane , Karam A. , Yelle S.
Published: February 2019

The large amount of organic carbon content present in de-inking residues makes them attractive for use in agricultural soils as an organic soil amendment. Greenhouse bioessays were undertaken to evaluate the agronomic value of de-inking sludge (DS). It was incorporated in a sandy soil to study the effects of different rates of de-inking residue amendments and N fertilizer combinations on soil properties and growth of corn. Particular attention was given to trace element concentrations. In a split factorial design, three variables were investigated: harvest time (after 20, 40, and 60 days), application rates of DS (0, 35, 70, and 105 t·ha–1), and four N rates (0, 140, 280, and 420 kg·ha–1). Chemical analyses of the fresh residues did not indicate the presence of heavy metals at levels potentially toxic to the environment. Soil chemical properties were clearly improved following the incorporation of DS. For example, adding different amounts of DS had a significant impact on the pH, the cation exchange capacity, and soil moisture. In addition, salinity was not affected with DS application. Seed germination was high in all the treatments and was not significantly influenced by DS application. Moreover, results on vegetative growth indicated a good relationship between the C:N ratio and biomass production. The DS combined with supplemental fertilizer seems to have a positive effect on plant growth. Overall, these results suggest that the limiting factor in de-inking paper sludge valorization is the amount of N available to the plant. Also, no other toxic products were found that could be harmful to the environment.
Shelters Improve Tree Establishment under Herbaceous Competition
Authors: Kjelgren R. , Rupp L.A.
Published: February 2019

We investigated how shelters and competing herbaceous vegetation affected tree growth and water relations during establishment. A bunch-type forage grass was concurrently seeded around 1-year-old bigtooth maple (Acer grandidentatum) and gambel oak (Quercus gambelii) planted in a silt loam field soil. During the second year following planting, irrigation was withheld, and midday water potential was measured twice to determine differences in water stress. At the end of the season, we measured total survival, elongative growth, and leaf area, as well as root growth of trees without competition. In the presence of competing vegetation, trees in shelters were less water stressed by –1.0 MPa than those without shelters. All maples without shelters and with competition died, and oak survival was 28%. Survival of both species in shelters was 86%. All trees without competing vegetation survived, but shelters affected maples differently than oaks. Maples without shelters had multiple stems that resulted in less shoot elongation and coarse roots but higher leaf area than those in shelters, and there were no differences in midday water potential. By contrast leaf area, elongation, and root growth of oaks in shelters were not different from those without shelters, but water potential was less negative. Tree shelters mitigated the effects of competition during establishment, but overall growth in shelters varied with species as oaks did not grow as well as maples.
Recycling Irrigation Water in Nursery Production
Authors: Tardif P. , Caron J. , Duchesne I. , Gallichand J.
Published: February 2019

Overhead sprinkler systems in nurseries use large amount of water and fertilizers and generate runoff losses that may alter the quality of surface or subsurface water. Moreover, the cost associated with these losses is important. Water recycling may reduce that cost and the losses to the environment. Our objective was to evaluate the performance of two recycling systems (recycling and storing water in a tank and recycling solution through subirrigation on capillary mats) relative to a conventional overhead sprinkler system with no recycling. Two species (Prunus × Cistena and Spirea japonica `Little Princess') and seven substrates were used on plots subject to these irrigation practices. Treatments were compared for the water balance and the plant growth. After the first season, preliminary results showed that water and nutrient consumption were 65% less for sprinkler irrigation with recycling and with subirrigation on capillary mats. Plant yield and soil water content were statistically the same for the three treatments.
Evaluation of Four Irrigation Systems for Containerized Ornamentals
Authors: Hicklenton Peter R. , Cairns Kenneth G.
Published: February 2019

Containerized Cotoneaster dammeri `Coral Beauty' and Forsythia `Northern Gold' were grown in a 2 bark: 1 peat: 1 sand (by volume) medium containing 5 kg·m–3 Nutricote 16N–4.4P–8.1K, Type 140, under four irrigation regimes: drip (DR; 20 min/day; two periods), overhead (OV; 90 min/day; two periods), overhead pulse (OP; 28 min/day; four periods), and subirrigation (SU). Volumes of 0.33, 0.35, and 0.14 liters·day–1 were delivered to each container in the DR, OV, and OP systems, respectively. SU was supplied from a geotextile-covered sand bed. End-of-season dry weights of Cotoneaster and Forsythia were 41% and 55% greater, respectively, in SU-grown plants compared to their OV-irrigated counterparts. Differences in growth between the other three regimes were minor for both species. Pre-dawn and dusk water potentials did not differ between plants in the four regimes, but midday potentials were slightly lower in SU- and DI-irrigated plants. End-of-season foliar N and P content differed only slightly between irrigation treatments, but K levels were significantly higher in SU plants. The reasons for better growth under SU remain obscure but may be related to improved medium nutrient retention and improved fertilizer use efficiency under an irrigation regime in which water moves upwards from the pot base to top.
Influences of Shade Leaves on Ground Cover and Sward Height of Turfgrass
Authors: Kuhn Maristela P.S. , Kamp Atelene Normann
Published: February 2019

Five experiments were performed from Jan. to Nov. 1993 with ornamental and sportive purpose turfgrass species [Axonopus araujoi Valls (nomen nudum); A. compressus var. compressus (Swartz) Beauv.; A. barretoi Valls (nomen nudum); Stenotaphrum secundatum (Walt) O. Kuntze; and Zoysia matrella(L.) Merr.] to evaluate percent ground cover and sward heights under four levels of shade. The design was in randomized blocks, with four treatments (0%, 50%, 75%, and 87% of shade) and four replications; the results were submitted to variance and regression analysis. All the species seemed to be sensitive to shade, increasing the sward heights and decreasing the percent ground cover at the highest shade levels; S. secundatum and Z. matrella were the most affected grasses, showing the greatest differences in characteristics evaluated among treatments.
Evaluation of the Efficiency of Winter Protections against Winter Damage on Poa annua Golf Greens
Authors: Dionne J. , Laganière M. , Desjardins Y.
Published: February 2019

Extensive winterkill of golf greens is a major problem in northern climates. In this study, the efficiency of several protective covering materials used to shelter Poa annua golf greens from winter damages was evaluated over 2 years. The bioclimatological environment under these protective covers was studied at crown level and at 5, 10, and 20 cm under the ground Treatments (permeable and impermeable covers, curled wood Excelsior mat, straw mulch protected by an impermeable cover, geotextile material with an impermeable cover, and air space under an impermeable cover) were compared to a control treatment without protection. Results indicate that temperature profile was strongly influenced by both winter protection covers and snow depth Temperatures at crown level were stable and just below 0C under plots covered with a significant amount of snow. However, temperatures varied considerably, when snow cover was <15 cm. Snow thermal conductivity was increased by periods of rain during the winter. Impermeable covers minimized the negative effect of this change in the insulation properties of the snow cover by limiting temperature fluctuations at the crown level. Temperature profiles under permeable covers were similar to profiles observed on control plots. Temperature profiles were comparable for 5 and 10 cm air space treatments and were not significantly different when compared to impermeable covers spread directly on the turf. Straw with an impermeable cover and Excelsior mats maintained crown level temperatures at >0C and the incidence of disease was higher under these highly insulative materials.
Wound-induced Free-radical Formation in Corn Seedlings
Authors: Girma Mitiku , Smirnov Alex I.
Published: February 2019

Recent studies performed at the Univ. of Sheffield (Sheffield, England) have established a correlation between the onset of senescence and the loss of viability in plants with a development of stable free-radicals that can be observed by Electron Paramagnetic Resonance (EPR) spectroscopy. We explored the possibility of free-radical formation following root injury of corn seedlings (Zea mays L.). Free radical signals were detected by EPR spectroscopy at 9.5 GHz. In all cases, we observed a single-line free-radical signal (g value ≈2.004) superimposed with six-line EPR spectrum from Mn2 + ions naturally present in the plant tissues. We determined a consistent increase in the intensity of single-line EPR signal after inducing root injury. This signal presumably is attributed to a quinone-derived radical and, as speculated, is associated with stressed respiratory transport chains. Based on our results, we suggest that free-radical reactions can be induced by root injury. Furthermore, an appearance of free-radical signal in the root may serve as an indication of a stress, natural and induced. If the precursors of observed free-radical signal can be determined, this will provide better insight on free-radical processes in plants followed by an injury. This work used the resources of the Illinois EPR Research Center (NIH P4 1 -RR0 1811).
Photoinhibition and Iron Deficiency in Mango
Authors: Nir Gil , Ratner Kira , Gussakovsky Eugene E. , Shahak Yosepha
Published: February 2019

Photoinhibition (PI; light stress) was studied in leaves of 3-year-old, potted, mango plants, following changes in chlorophyll fluorescence characteristics. Iron deficiency was induced by calcareous soil mix. It was found that during summer days, the photochemical quantum yield (measured as Fv: Fm) was reduced by 15% to 30% in sun-exposed leaves by noon (under 2000 μmol·m–2·s–1). This apparent PI was mostly recovered by the next day. In Fe-deficient plants, the reversible PI was enhanced further. In addition, Fe-deficiency increased the “I” phase (i.e., the QB-nonreducing centers) and the non-photochemical quenching (qN) and reduced the photochemical quenching (qP). Photosynthesis rates in the deficient plants were half the control rates. Overnight chilling at 7C, which by itself did not affect the Fv: Fm ratio much, dramatically increased the susceptibility of the plants to photodamage on the following day (indicated by fluorescence and gas exchange assays). This postchilling PI was mostly irreversible but could slowly (within about 1 week) be recovered in a thermostated greenhouse. These results agree with our observations of field-grown Fe-deficient mango trees that develop severe necrosis and leaf-drop each autumn in the Jordan Valley when the days are still sunny and warm and the nights turn cold.
Cold Hardiness of Floral Buds in Three Southern Highbush Blueberry (Vaccinium coymbosum × V. Darrowi) Cultivars
Authors: Silva Gena R. , Matta Frank B. , Spiers James M.
Published: February 2019

Late spring frosts are a major concern to blueberry growers in the southeastern United States. Cold hardiness of flower buds (stages 4 to 6) was evaluated in three southern highbush blueberry cultivars (`Cooper', `O'Neal', and `Gulfcoast'). Differential thermal analysis (DTA) and tissue browning tests revealed that the critical temperature and ovary damage occurred at –11C in `Cooper', –12C in `O'Neal', and –13C in `Gulfcoast'.
CITPATH: Diagnostic and Hypertext Software for Fungal Diseases of Citrus Foliage and Fruit
Authors: Ferguson James J. , Zazueta Fedro S. , Valiente Juan I.
Published: February 2019

Fungal diseases have their greatest impact on citrus in Florida by reducing tree vigor, fruit yield, and quality. Given the complex etiology of these diseases, this software was developed to facilitate diagnosis of symptoms and to explain the dynamics of Alternaria brown spot of mandarins, greasy spot, melanose, Phytophthora brown rot, post-bloom fruit drop, and sour orange scab. CITPATH includes a diagnostic key to identify symptoms of the major fungal diseases of citrus foliage and fruit in Florida and a hypertext program containing a description and graphic display of symptoms, maps of geographic occurrence, diagrams of disease development, and management strategies. Users can also consult a list of citrus cultivars susceptible to specific diseases and a reciprocal list of diseases affecting specific cultivars. Chemical control methods are discussed briefly with reference to the current Florida Citrus Spray Guide, a hardcopy of which is included with the software purchase. Developed for commercial growers, county extension programs, citrus horticulture classes, and master gardeners, this software is available on CD-ROM disks containing other citrus databases and as a separate disk for MS-DOS-based computers.
CD-ROM Image Analysis Used in Determining Disease Severity in Dogwoods under Physiological Stress
Authors: Pacumbaba Rodulfo O. , Beyl Caula A.
Published: February 2019

CD-ROM technology, scanners, and image capture software have enabled an alternate approach to determining disease severity. When estimating disease damage, information on disease severity may be as important as information on disease incidence. Disease incidence is the proportion of leaves infected on each tree; disease severity is the number of lesions or amount of tissue damage per tree. The Mielke and Langdon scale was used to determine the incidence of dogwood anthracnose on dogwoods under physiological stress; the CD-ROM system was used to determine the severity of the disease. Dogwood seedlings were exposed to four shade and three water levels for 12 weeks. Leaf images were stored on a photo-CD for image analysis. Water availability at 100% water-holding capacity significantly increased disease severity on dogwood leaves inoculated in vitro. The system allowed detection of a significant effect of water availability on susceptibility of the leaf to dogwood anthracnose that was not detected when incidence of infection was evaluated on a whole-plant basis
Using Internet in Distance Education
Authors: Martsolf J. David
Published: February 2019

In Spring 1994, a 2-h course in Agricultural Meteorology was handled primarily by e-mail. Six off-campus students asked to take the course by e-mail, and two on-campus students voted to join them. Seven students communicated with each other and the instructor via VAX-mail on the UF IFAS Computer Network [ICON]. The remaining student used a NASA supplied link to Internet. A few students used V-mail on ICON's VAX, in preference to the basic MAIL facility. A good textbook was found indispensable because the rest of the course content flowed through the network. The conversational characteristic of e-mail messages accommodated questions about the text and a term paper topic well. There is a tradeoff of commuting costs vs. computer and modem costs. Each participant worked at an individual—an advantage for students who have production responsibilities. Those students ranked the course as highly desirable [compared with the average for other courses in the department 1.33 vs. 1.39 (where 1 is top score and 5 lowest)]. Procrastination is a hazard, and the keyboard is a limiting factor. Both the preparation for and conduction of the course is more time consuming than conventional methods. This time requirement is expected to decrease with familiarity, the use of graphics, and commercial links to Internet.
Testing of Interactive Multimedia Instruction in Postsecondary Plant Materials Courses
Authors: Zampardo Mark , Kling Gary , Lindsey Christopher
Published: February 2019

An integrated teaching system was developed and tested on students enrolled in a woody landscape plants identification course. A Microsoft Windows-based system incorporates high-quality digital images and text in an interactive computer environment. The goal of the software program was to enhance retention of course material through the use of many images along with accompanying text and a variety of special features. In alternating 4-week periods, one-half of the students in class were randomly selected and given password access to the software. The other half served as a control group. All students continued to receive traditional lecture and laboratory presentations of the material, including weekly slide coverage of each plant. The exams incorporated material from lectures and labs and included slide images from which students were to identify the plant taxa. The study took into account time on the computer and test scores. Results showed that increased time on the computer was positively correlated with increased test scores. Student performance on the slide portions of the exams were consistently higher for computer users than control groups.
Teaching Horticultural Marketing to Undergraduate Students
Authors: Johnson Clarence
Published: February 2019

Most horticultural students at Fort Valley State College (1890 land grant college) have little or no background in aspects of horticultural marketing. We offer a course in Marketing Technology to address this lack of background in horticultural marketing. In this course, students learn how to obtain a business license and a tax number. The significance of financial planning is stressed through practice. Students learn the strategies involved in merchandising and pricing, the proper display techniques, and the importance of advertising. Field-trips to local horticultural businesses allow for students to interact with professionals in horticulture. Students are required to do reports on each field-trip taken in the course.
Job Satisfaction in Public Horticulture
Authors: Larkin Patrick S.
Published: February 2019

Much has been written about how job satisfaction may or may not affect production, morale, and quality of work. However, most job satisfaction studies have been conducted in the area of manufacturing and management, but none have been conducted in the field of public horticulture. Job satisfaction was examined in 245 employees from 30 public horticulture institutions in the mid-Atlantic region of the American Association of Botanic Gardens and Arboreta (AABGA) using the Job Descriptive Index (JDI) and Job in General (JIG). Our purpose was to determine if differences in job satisfaction existed based on an individual' s job (management, horticulture, or other), sex, or other demographic information. In general, public horticulture employees reported satisfaction with work on their current job, supervision of co-workers, and their jobs in general, but showed dissatisfaction with their opportunities for promotion. They were ambivalent about their current pay. However, significant differences (P < 0.05) were seen between the sexes on satisfaction with current pay and among management, horticulture, and other staff on work on current job, current pay, opportunities for promotion, and co-workers.
Student Teaching and Research Initiative through Volunteer Employment
Authors: Haque Mary Taylor , Albano Joseph P. , Miller William B. , Whitwell Ted , Thomason Kristy
Published: February 2019

Student Teaching and Research Initiative through Volunteer Employment (STRIVE) is an innovative new program developed collaboratively by faculty and students to offer students work experience opportunities in the Dept. of Horticulture while assisting with horticultural needs. The program promotes volunteerism and education while strengthening participating faculty, staff, and students in areas of research, teaching, or public service. STRIVE requires a voluntary commitment of 3 h/week in an area agreed on by participants and their supervisors. Participants are formally acknowledged by the department for their contributions after completing the semester-long program. Students participating thus far have assisted in teaching laboratories, program development, and greenhouse management.
Water-quality Education Program Affects Consumer Behavior and Attitudes
Authors: Day Susan D. , Relf Paula Diane , Aveni Marc T.
Published: February 2019

A multi-faceted extension education program to reduce consumer contributions to nonpoint source pollution by encouraging proper landscape management was initiated in Prince William County, Va., and funded through the USDA-extension service. The program now is being replicated in several counties in Virginia, primarily in the Chesapeake Bay watershed. The program recruits participants through educational field days, advertisement and other means. Educational techniques include one-on-one assistance from Master Gardener volunteers and the use of Extension publications developed for this program. Publications developed include The Virginia Gardener Easy Reference to Sustainable Landscape Management and Water Quality Protection—a concise reference of Virginia Cooperative Extension landscaping recommendations that includes a calendar for recording fertilizer and pesticide applications, IPM, and other maintenance activities. The Virginia Gardener Guide to Water-wise Landscaping, was recently added to supplement the program in the area of water conservation. In Prince William County, over 700 people have participated. Most of those who complete the program report being more satisfied with their lawn appearance and spending less money. Participation also resulted in consumers being more likely to seek soil test information before applying fertilizer. Other effects include greater participation in leaf composting and grass clipping recycling and greater awareness of nonpoint source pollution.
Master Gardener's Public Demonstration Garden Offers Success beyond Educating the Public
Authors: Stack Lois Berg , Gray Gleason
Published: February 2019

The Penobscot County (Maine) Master Gardeners (MGs) initiated a demonstration garden in 1994, on a 0.75-acre plot at the Univ. of Maine's sustainable agriculture farm. In addition to producing public education through on-site events, newspaper articles and weekly television broadcasts, the garden is the venue for these program successes. 1) New MGs see the garden as an on-going volunteer project and 2) grow as gardeners by working in the garden. 3) The Garden helps develop the camaraderie that begins among MGs during their training. 4) Advanced training is easily accomplished in the garden. 5) The garden provides an infrastructure for new project, 6) accomplishes positive public relations for Cooperative Extension and the MG program, and is an excellent MG recruitment tool.
Farmer's Bookshelf Information System for Predicting Phosphorus Requirements of Some Hawii Soils
Authors: Kobayashi Kent D. , Bittenbender H.C. , Hue N.V.
Published: February 2019

Most soils of Hawaii contain high amounts of iron- and aluminum oxides or amorphous alumino silicate clays, which react strongly with P making it virtually unavailable for plant uptake. Acceptable crop production is not possible unless adequate P fertilizers are applied. Growers need to know if a soil needs P and if so how much. The Farmer's Bookshelf hypermedia information system, which runs under the software HyperCard, can quickly provide these answers. A screen is displayed in which the soil series and the crop to be grown are specified through pull-down menus. The user then enters the Truogextractable P value of the soil and clicks on a “Calculate” button. The soil solution P value is calculated and compared to the minimum soil solution P needed to adequately grow the crop (80% to 95% of maximum yield). If the value is greater than the minimum value, then P fertilizer is not recommended. Otherwise, the program recommends the amount of fertilizer to add as P, P2O5, and treble superphosphate in pound per 1000 square feet and pound per acre. The recommendations, presented in a table, can then be printed for clientele use.
Phenotypic and Genetic Stability of Petunias Expressing Sense and Antisense RNAs of Endogenous Genes
Authors: Woodson William R.
Published: February 2019

The target of many genetic engineering experiments is to inhibit the expression of an endogenous gene. For example, research in my laboratory attempts to suppress the expression of ethylene biosynthetic pathway genes to inhibit the production of ethylene and delay flower senescence. The silencing of endogenous genes is generally accomplished by engineering plants to express either antisense or sense RNAs homologous to the target sequence. The mechanism by which gene silencing occurs is not clearly understood. Genetic and molecular analyses of transgene-induced silencing has revealed both meiotically reversible and fully stable phenotypes resulting from the expression of the transgene. In several cases, the mechanisms potentially involved in the silencing of the transgene and concomitant reversion of phenotype have been studied. These include transgene copy number, configuration of the integrated DNA, level of transgene RNA, and environmental factors. In many cases the silencing of transgenes was correlated with DNA methylation. These phenomena and the implications for engineering horticultural crops to express transgenes will be discussed in this workshop.
Horticulture on the Web—A Tool to Communicate the Depth and Breadth of the Discipline has Finally Arrived
Authors: Lineberger R. Daniel
Published: February 2019

A tool with enough power and versatility to communicate the depth and breadth of the art and science of horticulture has emerged with the development of the World Wide Web. First created to meet the rapid communication needs of high-energy particle physicists, the Web has proven to be a powerful information-providing tool enabling communication with all the diverse audiences of horticulture. Web-browsing software is multimedia in nature, and graphically based. Information can be colorful, interactive, commercial, amateur, or arcane, depending on the skill and objectives of the information provider. The target audience can be school children, horticultural producers, home gardeners, or academic researchers. Access to the Web is inexpensive and becoming widely available. These features enable audiences that previously had difficulty accessing the vast stores of horticultural information that reside within the confines of academic and governmental libraries to get that information from their schools or homes. The ever-growing demand for information, the need to integrate Web technology into teaching at all levels, and the adoption of the Web as a resource for distribution of peer-reviewed scholarly work has led to the development of various creative solutions among academic, professional, and avocational horticulturists. Some of these will be examined in detail during the workshop.
Root Growth and Biological, Chemical, and Physical Gradients in CIPS
Authors: Green James L. , Linderman R.G. , Blackburn B. , Smith K.A.
Published: February 2019

Verticle gradients of moisture, salinity, specific fertilizer ions, and pH in the root zone in the closed, insulated pallet system (CIPS) are relatively stable compared with those in the open container system (OCS). Establishment of the VA mycorrhizal fungus Glomus intraradices and maintenance of the biocontrol fungus Trichoderma harzianum and the entomopathogenic nematode Steinernema carpocapsae were greater in CIPS than in control OCS. In CIPS, percent corn root length colonized by G. intraradices was greatest in roots in the top stratum of the root medium. Colonization was significantly greater in copper-coated root-containment pouches. Population maintenance in CIPS of T. harzianum, initially uniformly inoculated throughout the root medium, was highest in the top stratum of the root medium where K+ and concentrations were highest. Efficacy of S. carpocapsae in parasitizing Galleria mellonella larvae, while greater in CIPS, was significantly related to host plant in CIPS but not in OCS. Inoculation with bacterial antagonists Bacillus cereus, Enterobacter aerogenes, and Serratia plymuthica significantly increased plant growth in CIPS, but not in OCS. Phytophthora cinnomomi root rot infection readily occurred in inoculated plants, but did not spread to noninoculated plants in CIPS when roots were contained within plant pouches. Because of the stability of the root zone parameters and the lack of leaching-dilution of exudates, volatiles, and other materials from the root zone, CIPS is an excellent system for evaluating effects of microorganism and other factors on root growth and development.
Statistical Analysis of Root Count Data
Authors: Glenn D. Michael
Published: February 2019

The minirhizotron approach for studying the dynamics of root systems is gaining acceptance; however, problems have arisen in the analysis of data. The purposes of this study were to determine if analysis of variance (ANOVA) was appropriate for root count data, and to evaluate transformation procedures to utilize ANOVA. In peach, apple, and strawberry root count data, the variance of treatment means was positively correlated with the mean, violating assumptions of ANOVA. A transformation based on Taylor's power law as a first approximation, followed by a trial and error approach, developed transformations that reduced the correlation of variance and mean.
Quantification of Bud Dormancy—Physiological Approaches
Authors: Fuchigami L.H. , Wisniewski M.
Published: February 2019

The purpose of this presentation is to discuss the value of identifying growth stages of bud dormancy numerically. The Degree Growth Stage Model (°GS Model) will be used to quantify the annual growth stages and the various developmental stages of endo-, eco-, and paradormancy. The model is divided into 360°GS's, illustrated either as a sine curve or a circle, that serve as a timeline for the cyclical passage of temperate woody plants, through five distinct point events (growth stages). The sine curve illustrates the relative degree of development of the segment events between the point events. This paper will focus on the °GS model as a relative method of quantifying the various segment events and improving our communication of the annual physiological processes of temperate woody plants. In addition, recent evidence on altering dormancy, and its impact on dormancy models, will be presented.
A Comparison of Huckleberry (Vaccinium pahalae) and Bilberry (Vaccinium myrtillus) Shoot Culture Performance on Different Support Systems
Authors: Walker Linda J. , Rogers R.B. , Smith M.A.L.
Published: February 2019

In vitro cell cultures of huckleberry and bilberry are sources of phytochemicals for use as food colorants and bioactive chemopreventives. Shoot cultures provide a convenient, presterile source of explants for production of callus rich in extractable pigments or other chemicals. Efficient callus formation only occurs with good-quality shoots. In this study, liquid and gelled support systems were compared in terms of their effect on shoot growth. Gellan gum-based support resulted in excellent shoot proliferation and suitable shoot length for huckleberry cultures, whereas bilberry performed slightly better on agar and agar/gellan gum support. Bilberry had a more-rapid growth rate than huckleberry. Hyperhydricity was found with the use of rafts for both species. These shoot cultures have been used as vegetative explants for callus, and have produced vivid anthocyanins in solution cultures.