bluuebunny/crossref_metadata_2025 huggingface dataset:
Stand Establishment of Grafted Vegetable Transplants in the Mediterranean Basin: An Overview
Authors: Koren* Amnon , Edelstein Menahem
Published: February 2019

Achieving a uniform stand of grafted vegetable transplants in the field is critical to the grower because of the high cost of the grafted transplants. Low and erratic stands can lead to monetary losses even in an otherwise successful crop. Establishing a uniform stand of grafted vegetable transplants in the field depends on several additive parameters prevailing in the nursery and in the field. These include seed quality, grafted-transplant quality, and agrotechniques suitable for the special needs of grafted transplants. Seed quality and seed health should be given special emphasis as compared with non-grafted-transplant production. Grafted transplants spend more time in the nursery, are treated manually more, and are more susceptible to seed-borne pathogens. Field preparation, plastic mulch, irrigation and fertilization are important, especially in warm, mediterranean climates.
Grafted Melons: The Phytopathological Aspect
Authors: Cohen* Roni , Burger Yosef , Edelstein Menahem
Published: February 2019

The use of grafted vegetables as one of the alternatives to soil disinfestation with methyl bromide is increasing in Israel. Watermelon (Citrullus lanatus) and melon (Cucumis melo) plants are grafted mainly onto Cucurbita rootstocks for lessening losses due to soil-borne pathogens. The contribution of the rootstock to the grafted plant's resistance depends on the nature of the disease. In general, damage caused by non-specific root-rot pathogens such as Rhizoctonia solani, Macrophomina phaseolina, Monosporascus cannonballus, and Pythium spp. are effectively reduced by using Cucurbita rootstocks. However, these rootstocks provide only partial protection from vascular diseases such as fusarium wilt, in which case better protection can be achieved by grafting susceptible melons onto monogenic fusarium-resistant melon rootstocks. The performance of the grafted plants depends not only on the rootstock but also on the scion response to pathogens and on the effect of the environment on disease development. The response of grafted and non-grafted melons of different cultivars to sudden wilt disease caused by the fungus Monosporascus cannonballus was evaluated in field trials conducted in the fall and spring growing seasons. Significant differences in disease incidence were found among cultivars, between grafted and non-grafted plants, and between seasons. Grafting reduced plant mortality in the spring and fall experiments but prevention of yield losses was more effective in the spring. More emphasis should be given to finding suitable rootstocks and adjusting agrotechniques for successful commercial cultivation of grafted melons in the fall.
Do Plant Guarantees Matter?
Authors: Dennis Jennifer H. , Behe* Bridget K. , Fernandez R. Thomas , Schutzki Robert
Published: February 2019

Consumers face risks each time they purchase and consume products. Guarantees provide a means of potentially decreasing risk for products that cannot be evaluated until consumption has begun, as with ornamental plants. Despite the potential risk reduction, the effect of guarantees on consumer purchases has been a source of debate for many retailers. Research conducted at Michigan State Univ. examined the effects of guarantees on consumer satisfaction and regret of three horticultural products: hanging baskets, potted roses, and perennials. Over half (56%) of respondents stated the retail outlet provided a guarantee. Twenty-six percent stated the guarantee was a deciding factor in choosing that particular plant while 27% stated it was the deciding factor in shopping at that particular retail location. Results show that guarantees reduce risk for consumers, reducing the incidence of regret but have no effect on customer satisfaction.
Connecting Fast Plants to Biotechnology
Authors: Nienhuis* James , Barnard Betsy , Sass Michell
Published: February 2019

We have developed a series of instructional materials integrating a proven teaching tool, Wisconsin Fast Plants, with hands-on molecular techniques. Many biotechnology techniques, including genomics, have developed to a point where appropriate modifications can result in classroom accessible instructional materials that will engage students and teachers. Three “kits” have been developed or are in the process of development. Kit 1-PCR and Fast Plants. This kit is designed to provide an introduction to PCR and a link to Wisconsin Fast Plants. This kit uses a specific robust primer, which can amplify a specific sequence in Brassica rapa (Fast Plants). This kit serves as a hands-on tool to familiarize students with DNA extraction, PCR, gel electrophoresis, and analysis of PCR products. Kit 2-Genetic Diversity—`Veggie interesting'. This kit is based on the development of a specific primer, which is polymorphic between B. rapa (Fast Plants) and B. oleracea (common vegetables). In this kit, we explore the use of molecular markers and PCR to determine the species classification of various Brassica subspecies. This kit can be used to teach students about plant diversity and the use of molecular biology techniques (such as PCR) to determine how plants are related to each other. Kit 3-Genomics. The primary biological component is a simplified DNA chip (microarray) specifically designed for visualization of differential gene expression. This chip contains Arabidopsis thaliana genes that have already been characterized in our laboratory that display differential expression in seedlings grown in light vs. dark. To simplify analysis, the chip contain approximately ten genes rather than the thousands that are typically spotted on research chip.
Developing New Approaches and Tools for Improved Management and Delivery of Online Digital Photos
Authors: Rhodus* Tim , Witney Bud
Published: February 2019

More and more of the Department's academic and outreach communications on the Internet involve the use of digital photos. While enhancing visual appeal and conveying information that cannot be communicated via text is an obvious benefit, it is critical that digital collections be efficiently and effectively managed at the client level (personal workstation) and also the server level. To assist faculty and staff who routinely publish on the web and those who contribute to the Ohio State Univ.'s WebGarden online image database, a new client application was developed to assist in viewing and organizing digital photos on their workstation. Based on FileMaker Pro database software, a standalone program name DPM (Digital Photo Manager) was developed that runs without the user having to have FileMaker software installed on their system. DPM allows the user to scan a folder of digital photos, create thumbnails, add appropriate captions and cataloging information, and even display a full-screen slideshow. When the user is ready to publish on the web, they upload their file into a portion of the department website managed by Gallery software, a free PHP-based application that integrates with various web server programs and handles any number of user-specific digital albums. Following this, a website was developed that allows the user to select a photo from their online album, add 1-3 lines of captioning, and enter their name for a photo credit. The website automatically applies a standard background, creates four different sizes of the image, renames the files into a standard naming convention used for all images on the server, saves each file into a specific folder, and provides the user with the URL address for the digital files.
Cleome hassleriana Germination in Minnesota Prairies, Roadsides and Gardens
Authors: Gomez* Nadilia , Anderson Neil O.
Published: February 2019

Cleome hassleriana is an ornamental garden plant introduced from South America and naturalized in eastern United States with tendencies to reseed primarily in gardens. The objectives of this research were to determine (1) if C. hassleriana cultivars can germinate in Minnesota prairies and roadsides, (2) if germination in cultivated environments reflect germination in non-cultivated environments, and (3) if there are differences among cultivars across environments, with some cultivars germinating well in cultivated habitats and poorly in non-cultivated habitats. In June 2003, 135 seeds from each of four cultivars (Queen Rose, Queen White, Sparkler Rose and Sparkler White) were planted in each of 4 gardens and 8 non-cultivated habitats (4 prairies and 4 roadsides). Germination and survival was recorded once weekly for four weeks. Cleome seeds germinated in Minnesota gardens, prairies and roadsides. By day 14, the proportion of germinated seedlings was significantly greater in gardens (30.5%) than in prairies (1.4%) and roadsides (0.9%). Sparklers had significantly greater germination than Queens in the prairies. The best performing cultivar in the garden (Queen White, 29%) was different than the best performing cultivar in the prairies and roadsides (Sparkler Rose, 1.4% and 1.2% respectively), suggesting that germination in non-cultivated habitats may not reflect germination in the field. Cultivars varied in their ability to germinate in cultivated and non-cultivated environments.
Determination of the Alkalinity Toxicity Limits of Selected Greenhouse Ornamental Plants
Authors: Valdez-Aguilar* Luis A. , Reed David Wm.
Published: February 2019

Tolerance to alkalinity was evaluated in Rose `Pink Cupido', Vinca `Apricot Delight', Chrysanthemum `Miramar', and Hibiscus `Bimini Breeze' and `Mango Breeze'. Plants were potted in a sphagnum peat moss-based growing medium and irrigated with water containing 0, 2.5, 5, 7.5 and 10 mm of Na bicarbonate. In rose, shoot mass was significantly decreased and chlorosis increased at the 5 mm treatment, indicating that the alkalinity toxicity is between 2.5 and 5 mm. In chrysanthemum, the concentration of Na bicarbonate did not significantly affect shoot mass, but caused a significant increase in leaf chlorosis at 5 mm or higher Na bicarbonate. This indicates an alkalinity toxicity level between 2.5 and 5 mm. In Vinca, shoot dry mass was not affected significantly, but leaf chlorosis was significantly increased with 5 mm of Na bicarbonate. This indicates an alkalinity toxicity level between 2.5 and 5 mm. In hibiscus `Mango Breeze', shoot mass was significantly increased at 2.5 and 5 mm, but was significantly decreased at 7.5 mm and above. Leaf chlorosis was significantly increased with a concentration of 5 mm and above, indicating that in hibiscus `Mango Breeze' the alkalinity toxicity level is between 5 to 7.5 mm. In hibiscus `Bimini Breeze', shoot mass was not significantly reduced, but leaf chlorosis exhibited a significant decrease at 7.5 mm. this indicates that in hibiscus `Bimini Breeze' the alkalinity toxicity level is between 7.5 and 10 mm. Growing medium pH increased with increasing levels of Na bicarbonate. The species showed varying capacity for acidification of the growing medium. All species, except rose and vinca, neutralized the alkalinity effect of 2.5 mm, but none of the species neutralized the effect of 5 mm and higher Na bicarbonate.
Relationship Between Plant Morphological Traits and Resistance to Sclerotinia minor in Lettuce
Authors: Grube* R. , Aburomia R.
Published: February 2019

A low to moderate incidence of lettuce drop caused by Sclerotinia minor is commonly observed in commercial lettuce fields of all types of lettuce (e.g. crisphead, romaine, leaf, butter) and although partial resistance has been reported, no sources of immunity have been described. We sought to determine whether there was variability between different types of lettuce and among cultivars within types. Replicated experiments were conducted in an infested field using established inoculation procedures. Significant variation in susceptibility to S. minor was detected among cultivars within as well as between major lettuce types. Correlations between lettuce drop susceptibility and plant canopy size, seedling vigor, and additional morphological traits were determined. Variability between different field experiments was also evaluated for several traits and a subset of cultivars. Our results suggest that cultivated germplasm may provide genes that are as useful or more useful than those found in genotypes with more primitive growth habits in developing cultivars with tolerance to lettuce drop.
Changes of Endogenous Hormones and Polyamines in Cytoplasmic Male Sterile Non-heading Chinese Cabbage During Anther Development
Authors: Shi* Gong-Jun , Hou Xi-Lin , Hu Wei , Jiang Zhong-Chun
Published: February 2019

It studies the changes of endogenous hormones and polyamines in cytoplasmic male sterile non-heading Chinese cabbage (Brassica campestris L. ssp. chinensis Makino var. communis Tsen et Lee). Results showed that the microspore was prone to being sterile when there were lack of IAA, GA and polyamines, especially Put and abundant with ZRs and ABA in the anther. The imbalance of IAA/ZRs also easily caused the anther sterile.
Photosynthesis, Growth, and Water-use Efficiency of Carolina Buckthorn: Comparisons to the Invasive Common Buckthorn
Authors: Stewart* J. Ryan , Graves William R.
Published: February 2019

Some buckthorn species from other continents have proven invasive in North American landscapes. Carolina buckthorn (Rhamnus caroliniana Walt.) is an attractive, native species that would merit increased use in horticultural landscapes if concerns about its potential invasiveness are allayed. Invasiveness often is associated with efficient use of water and other resources. We tested for differences between Carolina buckthorn and common buckthorn (Rhamnus cathartica L.) in photosynthesis, aboveground dry matter accumulation, and water-use efficiency. Seedlings were grown in columns of field soil within insulated pots outdoors for 98 days. Net photosynthesis of Carolina buckthorn was 17% to 39% greater than that of common buckthorn through day 22. This difference between species was reversed through the end of the treatment period with a concomitant increase in leaf temperature of Carolina buckthorn. Final dry weight of aboveground tissues was similar for the two species, but a greater proportion of dry matter was partitioned to stems for common buckthorn compared to Carolina buckthorn. Although common buckthorn initially had higher water-use efficiency (110 mg·g-1 per day) than did Carolina buckthorn (60 mg·g-1 per day), the water-use efficiency of both species decreased to similar values for the remainder of the treatment period. We conclude that young plants of common buckthorn do not use water more efficiently than do young Carolina buckthorn under field conditions in central Iowa. Considering the possible species differences in the relationship between temperature and photosynthesis, comparative water-use efficiency should be tested further in other environments where Carolina buckthorn might be used for landscaping.
Improving Species and Cultivar Specific Estimates of Transpiration by Using Physiologically Based Approaches
Authors: Bauerle* William L. , Rajaraman Nilakantan S.
Published: February 2019

A process-based whole-tree simulation model was used to simulate crown transpiration in several species and cultivars of nursery crops. To validate estimates, we measured transpiration in cultivars of red maple (Acer rubrum L.) to determine if there were differences in intraspecific variation that could affect estimates of whole tree water use. We used a combination of field and published data to parameterize additional species and cultivar differences in response to environment and/or management. The different water use estimates of the species and cultivars were related to their genetic variability in leaf biochemical limitations, where the relationship between stomatal conductance and photosynthetic rate may be so closely matched that stomatal conductance appears to adjust itself to the photosynthetic capacity of the species or cultivar. Model predictions indicated that species and cultivars that had higher biochemical limitation regulated transpiration by down regulation of the rate of carboxylation (Vcmax) and coupled photosynthetic electron transport (Jmax), whereas the reverse occurred as Vcmax and Jmax increased. Our model simulations show significant variation in transpiration due to both inter and intraspecific variation in biochemical limitations. These results suggest that models that do not account for inter and intraspecific variation, to reflect genetic variation in physiology, may over or under estimate transpiration. Therefore, physiology-based species and cultivar variation should be part of process-based simulations that assess nursery water use. Results also suggest that effects of leaf dark respiration adaptation interactions can concurrently reduce variation in water use estimates.
Effects of Transplant Season and Container Size on Landscape Establishment of Kalmia latifolia L.
Authors: Hanson Anne-Marie , Harris* J. Roger , Wright Robert
Published: February 2019

Mountain laurel (Kalmia latifolia L.) is a common native shrub in the Eastern United States; however, this species can be difficult to establish in landscapes. Two experiments were conducted to test the effects of transplant season and container size on landscape establishment of Kalmia latifolia L. `Olympic Wedding'. In experiment one, 7.6-L (2-gal.) and 19-L (5-gal.) container-grown plants were planted into a simulated landscape (Blacksburg, Va., USDA plant hardiness zone 6A) in early Fall 2000 and in late Spring 2001. 19-L (5-gal.) plants had the lowest leaf xylem potential (more stressed) near the end of the first post-transplant growing season, and leaf dry weight and area were higher for spring transplants than for fall transplants. For spring transplants, 7.6-L (2-gal.) plants had the highest visual ratings, but 19-L (5-gal.) plants had the highest visual ratings for fall transplants three growing seasons after transplanting. 7.6-L (2-gal.) plants had the highest % canopy volume increase after three post-transplant growing seasons. In experiment two, 19-L (5-gal.) plants were transplanted into above-ground root observation chambers (rhizotrons) in early Fall 2000 and late Spring 2001. Roots of fall transplants grew further into the backfill than spring transplants at the end of one post-transplant growing season. Overall, our data suggest that smaller plants will be less stressed the first season after transplanting and will likely stand a better chance for successful establishment in a hot and dry environment. Fall is the preferred time to transplant since capacity for maximum root extension into the backfill will be greater than for spring transplants.
Mulch Thickness and Planting Depths Can Interact to Reduce Growth and Survival of Green Ash and Goldenraintree
Authors: Arnold Michael A. , McDonald Garry V. , Bryan* Donita L.
Published: February 2019

Most available information on the effects of planting depths for trees necdotal and/or testing of interactions with other important cultural practices implemented during landscape establishment is lacking. Green ash (Fraxinus pensylvanica H. Marshall, hypoxia tolerant species) and bougainvillea goldenraintree (Koelreuteria bipinnata Franchet, hypoxia intolerant species) were grown from seed in 2.3-L containers which were transplanted to 9.3-L black plastic and grown to a marketable size. Root-collars of the plants were maintained level with the surface of the substrate. Green ash (1 May 2001) and bougainvillea goldenraintree (27 Apr. 2001) were transplanted to clay soil field plots with the root-collars at a 7.6 cm above soil grade, at grade, or 7.6 cm below grade. Planting depths for each species were in factorial combinations with 0, 8, 15, or 23 cm of pine bark mulch covering 2.4 m2 of soil beneath each tree. After 2 years, survival of bougainvillea goldenraintrees planted below grade was one third that of those planted at or above grade. Planting below grade reduced survival of green ash by 25% after 3 years. Even the thinnest layer of mulch reduced bougainvillea goldenraintree height and trunk diameters. Height and trunk diameter responses interacted with planting depth for green ash. Mean soil moisture levels were slightly less negative with 8 cm of mulch (-5.8 kPa) compared to bare soil (-9.1 kPa), but increasing mulch thickness to 23 cm (-16.2 kPa) inhibited penetration of irrigation water/rainfall. This data suggests that planting with the root-collar at or above grade greatly enhances survival and growth potential of green ash and bougainvillea goldenraintree and that mulch application should be only at thin layers to inhibit weeds.
Effects of Paclobutrazol on Production and Landscape Performance of Texas Maroon Bluebonnet
Authors: Bading* Kyle R. , McDonald Garry V. , Arnold Michael A. , Mackay Wayne A. , Parsons Jerry M.
Published: February 2019

Texas maroon bluebonnets (Lupinus texensis Hook. `Texas Maroon') grown for fall planting may be germinated as early as September. Plant growth regulators are commonly applied to control excessive stem elongation during production, but may potentially result in adverse responses in the landscape due to residual effects. In October 2003, an experiment was initiated to observe potential landscape residual effects of paclobutrazol (formulated as Bonzi) applied during the production phase to retard internode elongation. Seedlings were received in six-pack cell units. On 30 Oct. 2003, while still in six-packs, bluebon-nets were sprayed with paclobutrazol. Paclobutrazol was applied at concentrations of 0, 5, 10, and 15 mg·L-1 a.i. at a coverage rate of 10 mL per 0.93 m2. After treatment, half of the plants were transplanted from six-packs to 0.73 L pots and the other half remained in six-packs. Plants were grown in a nursery until they reached a marketable stage (13 Nov. 2003 for six-packs, 20 Nov. 2003 for 0.73-L pots). At the end of nursery production, one half of the plants (both container sizes) were then planted to landscape plots (0.3 m centers) at either College Station, Texas or Dallas, Texas. During the production phase, bluebonnets grown in 0.73-L pots had slightly larger growth indices than those produced in six-packs. As application rates of paclobutrazol increased, growth indices decreased. Possible residual effects on growth and flowering will also be discussed.
Genetic Linkage Mapping and QTL Analysis of Economic Traits in Papaya (Carica papaya L.)
Authors: Srinivasan* Rajeswari , Manshardt Richard
Published: February 2019

QTL mapping gives an insight into the number, position and effect of loci controlling quantitative traits. Although a few linkage maps already exist for papaya, not many economically important traits have been studied. An investigation was undertaken to map two qualitative traits: 1) fruit flesh color and 2) an isozyme locus, phosphoglucomutase (PGM); as well as two quantitative traits: 1) number of nodes to first flowering and 2) stamen carpellody. An F2 population consisting of 281 plants derived from the parents Kapoho X Saipan Red was used for this study. Field observations suggested that there may be a linkage between PGM locus and one of the major QTLs controlling number of nodes to first flowering. Also, phenotypic data suggested that there may be a linkage between flesh color and carpellody. Marker genotyping was performed on a subset of 84 plants chosen from the phenotypic extremes of the population for node number and carpellody. Using AFLP (Amplified fragment length polymorphism) method, 510 markers were generated with 161 primer pairs. Although papaya has a haploid chromosome number of 9, at LOD score 5.0 and a maximum recombination frequency of 0.25, 25 linkage groups with number of markers ranging from 2 to 109 were generated using the software Mapmaker\EXP. Linkage and QTL maps are being constructed to reveal the molecular markers linked with the traits of interest and the nature of QTLs controlling the quantitative traits.
Inactivation of DFR (Dihydroflavonol 4-reductase) Gene Transcription Results in Blockage of Anthocyanin Production in Yellow Onions (Allium cepa)
Authors: Kim* Sunggil , Binzel Marla , Park Sunghun , Yoo Kil-Sun , Pike Leonard
Published: February 2019

Anthocyanin, one of the flavonoids, is a primary determinant of red color in onions. Inheritance studies indicate that a single gene determines the color difference between yellow and red onions. In order to establish which gene might be responsible for this color difference, full-length cDNAs of five structural genes: chalcone synthase (CHS), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), and flavonol synthase (FLS) were cloned using degenerate PCR and RACE (Rapid Amplification of cDNA Ends). RT-PCR was carried out for these five genes to examine differential expression between yellow and red colored bulbs. Accumulation of the DFR gene transcript only occurred in red onions. In F3 populations which originated from the cross between yellow and red parents, DFR transcript was detected only in red F3 lines, not in yellow F3 lines. To design molecular markers for selection of yellow and red DFR alleles, the DFR gene was sequenced from genomic DNA isolated from both types of onions. The genomic DNA sequence revealed the DFR gene consists of six exons and five introns. A PCR-RFLP marker was designed based on 2% polymorphic nucleotide sequence of the DFR gene between yellow and red onions. The co-segregation of markers and red color were observed in F2 segregating populations, supporting the conclusion that color difference in red and yellow onions is likely to be due to the lack of an active DFR gene.
Propagation of Two Native Shrubs, Rhamnus alnifolia and Rhamnus lanceolata
Authors: Sharma* Jyotsna , Graves William R.
Published: February 2019

Rhamnus alnifolia and Rhamnus lanceolata are shrubs of modest size with lustrous foliage. We evaluated seed germination of both species and propagated R. alnifolia by using softwood cuttings collected in early June. For R. alnifolia, cold stratification for up to 90 d resulted in 48% germination and a germination value of 1.9, whereas only 7% germination occurred among seeds stratified for 120 d. Seeds of R. alnifolia did not germinate if they were untreated or if scarified and stratified. Rhamnus lanceolata required 120 d of stratification to germinate, but percentages were low (≤ 5). Survival of germinants of both species was 90 to 100% regardless of prior seed treatment. Seedlings grew uniformly and had a mean leaf count of 11 and a mean height of 20 cm after 102 d. Application of 3000 and 8000 mg/L indole-3-butyric acid (IBA) in talc led to 85% rooting of R. alnifolia, whereas rooting was ≤ 15% after use of solutions with those IBA concentrations. While 75% of untreated cuttings rooted, fewer roots formed without IBA. More roots developed in 100% vermiculite than in 1 vermiculite: 1 perlite (by volume), which also diminished the number and apparent health of leaves on cuttings during the rooting period. We conclude that talc-based IBA and vermiculite should be used to root softwood cuttings of R. alnifolia, and that both species can be propagated from stratified seeds. Rhamnus lanceolata is more recalcitrant than is R. alnifolia and merits further study to optimize germination success.
Comparative In Vitro Growth and Development of Easy- and Difficult-to-Acclimatize Sea Oats (Uniola paniculata L.) Genotypes
Authors: Aracama* Carmen Valero , Kane Michael E. , Philman Nancy L. , Wilson Sandra B.
Published: February 2019

A sea oats (Uniola paniculata L.) micropropagation protocol was previously developed for 28 genotypes that favored multiplication and rooting of shoots in vitro. However, microcutting size, morphology, and acclimatization ex vitro varied considerably among genotypes. In the present study we evaluated the effect of Stage III duration on in vitro morphology, biomass production, and ex vitro survivability of easy-(EK 16-3) and difficult-to-acclimatize (EK 11-1) sea oats genotypes. After 3, 6, and 9 weeks at Stage III, survivability of microcuttings was 85%, 96% and 98% for EK 16-3, and 2%, 27% and 40% for EK 11-1, respectively. After 9 weeks Stage III, EK 16-3 microcuttings had higher shoot dry weights but lower root dry weights than in EK 11-1. Moreover, roots in EK 11-1 were fewer but longer than in EK 16-3. Leaf production was similar in both genotypes. However, leaf elongation was significantly inhibited in EK 11-1, in which 95% of the leaves were ≤ 15 mm long in contrast with EK 16-3, with 50% leaves ≥ 16 mm long after 9 weeks Stage III. Light microscopy examinations showed anatomical similarities between EK 16-3 in vitro leaves and mature ex vitro leaves. Conversely, short in vitro leaves of EK 11-1 exhibited mesophyll disruption and reduced cuticle development. Conceivably, the short leaves had limited photosynthetic competency, thereby reducing ex vitro survival of rooted EK 11-1 microcuttings.
Long- and Short-term Effects of Nitrogen on Formation and Function of Root Nodules on Alnus maritima
Authors: Laws* Michele Tiffany , Graves William R.
Published: February 2019

Symbiotic associations between Alnus maritima (Marsh.) Muhl. ex Nutt. (seaside alder) and the actinomycete Frankia result in root nodules in which atmospheric nitrogen (N) is fixed. This has led to interest in producing seaside alders with minimal N fertilizer and in using the species on low-N soils. Our objectives were to determine how applied N influences nodulation and to characterize how short-term changes in root-zone N affect the function of established nodules. Seaside alders native to the Delmarva Peninsula (Alnus maritima subsp. maritima) were grown in perlite inoculated with soil from roots of indigenous plants. Plants were treated with N-free Hoagland solution supplemented with ammonium nitrate at 0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 2, 4, and 8 mm for 10 weeks. Nodulation decreased as applied N increased. While plants treated with ammonium nitrate at 4 and 8 mm formed nearly no nodules, 0.5 mM resulted in vigorous, healthy plants that formed, on average, 70 nodules. In a second experiment, a nodulated population of seaside alders was established by treating seedlings with 0.5-mm ammonium nitrate in otherwise N-free Hoagland solution for 6 weeks. Plants then were provided ammonium nitrate at 0.5, 2, or 4 mm for two weeks. Acetylene-reduction assays showed that ammonium nitrate at 4 mm suppressed nodule activity. Daily irrigation with N-free solution subsequently led to a rapid depletion of root-zone N and a concomitant resurgence of nodule activity among plants previously provided 2- and 4-mm ammonium nitrate. These results provide useful information on how to manage fertility to optimize nodulation and show suppression of nodule activity caused by N fertilization can be temporary if excess N is leached from the root zone.
Photosynthesis, Respiration, and Water Relations of Vinca and Salvia Subjected to Moisture Stress
Authors: Nemali* Krishna , van Iersel Marc
Published: February 2019

Subjecting bedding plants to non-lethal moisture stress is an established irrigation practice for bedding plants; however information on physiological responses of bedding plants to moisture stress is limited. We examined the CO2 exchange rates (CER) and water relations of salvia (Salvia splendens) and vinca (Catharanthus roseus) during moisture stress. Seedlings of both species were grown from seed in 7-L trays containing a soilless growing medium. After plants completely covered the trays, they were irrigated and shifted into whole-plant gas exchange chambers (27 °C and daily light integral of 7.5 mol/m2) arranged inside a growth chamber. Inside the gas exchange chambers, the growing medium was allowed to dry and plants were re-watered after wilting. Results from this study indicate that the growth rate (moles of CO2 gained by plants in a day) of salvia was higher than vinca before experiencing moisture stress; however the volumetric moisture content of the growing medium at which plant growth decreased was higher for salvia than for vinca. During moisture stress, the decrease in growth rate of salvia was gradual and that of vinca was rapid. After re-watering the plants, leaf water potential (ΨL) and growth rate of vinca revived completely, and ΨL of salvia remained low (more negative), whereas its growth rate revived completely. This study shows that bedding plant species respond differently to moisture stress, particularly with respect to the critical substrate moisture level for initiating moisture stress and the rate of development of moisture stress.
Assessment of Leitneria floridana in Disjunct Native Habitats: Implications for Horticulture and Conservation
Authors: Sharma* Jyotsna , Graves William R.
Published: February 2019

Tolerance of shade, flooding, drought, and nutrient-poor substrate is desirable among ornamental plants installed in managed landscapes. Many attractive native taxa have not been evaluated for their resistance to environmental stressors. We assessed Florida corkwood (Leitneria floridana Chapman) in its natural habitat in four disjunct populations in the United States and tested the physical and chemical properties of the soil at the study sites. Measures at all sites were made within two weeks in late June, 2003. Leaf area, plant height, length of new shoots, and the rate of photosynthesis were higher among plants receiving more than 600 μmol·m-2·s-1 of photosynthetically active radiation (PAR) compared to plants that occurred where maximum PAR was lower. Soil texture ranged from clay loam to fine sand, and soil pH across sites was 4.5 to 6.6. Concentration of nitrate-nitrogen, phosphorus, and potassium ranged from 3 to 75 mg·L-1, 7 to 11 mg·L-1, and 3 to 64 mg·L-1, respectively. Bases of plants in Florida were submersed in water, while soil moisture percentages in Missouri and Texas were 6 to 30. The apparent tolerance of L. floridana to shade, low and high soil moisture, and nutrient-poor soil in native habitats indicates that it could be used in a wide range of managed landscapes. Its capacity to adapt to shade may permit the use of L. floridana as an understory species in managed landscapes, but stewards of natural areas may need to maintain open sites within its native habitat to allow expansion of populations. Because this assessment of L. floridana included native populations across the natural range of the species, our results are uniquely suited for both horticultural and ecological interpretation and application.
Phytophthora Root Rot Mortality in Fraser Fir Seedlings
Authors: Frampton John , Benson D.M.
Published: February 2019

Seventeen-month-old seedlings from three fraser fir (Abies fraseri [Pursh] Poir.) seed sources (Mount Mitchell, Richland Balsam and Roan Mountain) were inoculated in an outdoor lath house with five genotypes of Phytophthora cinnamomi Rands. After 122 days, overall mortality was 90.5% with significant (p ≤ 0.07) differences among seed sources. The Mount Mitchell source had lower mortality (83.2%) than the Roan Mountain source (95.8%), while the Richland Balsam source (92.5%) was intermediate. Mortality curves were developed using nonlinear regression (Richards' function). Due to a significant seed source × inoculum genotype interaction (p ≤ 0.0001), equations were developed for each combination of seed source and inoculum genotype. Results suggest that while the overall frequency of resistance in fraser fir is low, seed sources differ in their frequency of resistance and that more than one resistance gene may be present. Survivors from this or similar inoculations could be cloned via grafting or rooted cuttings for further resistance testing and/or grafted into a Phytophthora-resistant fraser fir seed orchard.
A Fiberoptic-based System for Integrating Photosynthetically Active Radiation in Plant Canopies
Authors: Bauerle William L. , Bowden Joseph D.
Published: February 2019

This report describes a system for integrating photosynthetically active radiation (PAR) using fiberoptics. Many photoelectric sensors or 1-m-long line sensors that integrate individual interception points for spatial averaging were replaced with fiberoptics, which integrate interception points. Depending on the positioning of optical fibers and the amount of fibers terminated at a PAR sensor, whole-plant, canopy layer, and individual leaf light interception can be determined. The use of fiberoptics has the added advantage of being very small in comparison to the bulk of a typical quantum sensor. The fiberoptic-based system potentially is a more accurate, less expensive method to integrate PAR throughout plant canopies than PAR sensors.
A New Disease in Limonium hybrids. I. Molecular Identification
Authors: Gera A. , Maslenin L. , Rosner A. , Zeidan M. , Pivonia S. , Weintraub P.G.
Published: February 2019

Yellows diseases in ornamental crops have become more common in Israel, and phytoplasmas have been detected in several crops. Recently, symptoms typical of a phytoplasma infection were observed on a large number of Limonium hybrids grown in commercial fields in Israel. Examination of samples from diseased plants by electron microscopy revealed the presence of pleiomorphic membrane-bound bodies in the phloem cells. Diseased plants were additionally analyzed by PCR using universal and nested primers and revealed upon sequencing products of 1143, 788 and 722 bp (Li-IL, Li-b2-IL, Li-v3-IL, respectively). Analysis of the PCR products, associated with infected Limonium, clustered within two major groups of phytoplasmas (16SrV and 16SrIX), elm yellows and almond witches broom. This is the first published record of these phytoplasmas in Israel.
Firmness, Respiration, and Weight Loss of `Bing', `Lapins' and `Sweetheart' Cherries in Relation to Fruit Maturity and Susceptibility to Surface Pitting
Authors: Toivonen Peter M.A. , Kappel Frank , Stan Sabina , McKenzie Darrell-Lee , Hocking Rod
Published: February 2019

A convenient and reliable method that used a specially designed tool to apply a uniform bruising force in situ was developed to assess the relative susceptibility to fruit surface pitting in sweet cherry. Assessment of pitting with a visual scale after 2 weeks of 1 °C storage was found to be in close agreement with measurements of pit diameter. Using this method `Bing' showed the greatest susceptibility to pitting in both years of the study and `Bing', `Lapins', and `Sweetheart' cherries showed a decline in susceptibility as fruit matured. The predictive value of fruit firmness at harvest, fruit respiration at harvest, and weight loss in storage was assessed in relation to the severity of pitting. The model to best describe pitting was found to include all three physiological variables (firmness, respiration, and weight loss). While an acceptable model was obtained when combining all three cultivars, the best models were achieved when each cultivar was considered separately. It was concluded that there are likely unmeasured variables involved in determining susceptibility to pitting. Hence the best approach to predicting pitting susceptibility is the application of the pit-induction method described in this work.
Blossom-end Rot Incidence of Tomato as Affected by Irrigation Quantity, Calcium Source, and Reduced Potassium
Authors: Taylor M.D. , Locascio S.J. , Alligood M.R.
Published: February 2019

`Equinox' tomatoes (Lycopersicon esculentum Mill.) were grown during the springs of 2001 and 2002 with black polyethylene-mulch and drip irrigation on an Arredondo fine sand in Gainesville, Fla., to study the influence of water quantity, Ca source, and reduced K on incidence of blossom-end rot (BER), marketable fruit yield, and fruit and leaf Ca concentration. Tensiometers were used to schedule irrigation in main plots when the soil matric potential reached 10 or 25 kPa. Subplot nutritional treatments were no added Ca, Ca(NO3)2, Ca thiosulfate, CaCl2, CaSO4, and K rate reduced by 50%. Interactions between year and treatment were significant. During 2001, total marketable yields were higher with Ca(NO3)2 or CaCl2 compared to plants that received Ca thiosulfate and were higher from plants irrigated at 10 kPa than irrigated at 25 kPa. Number and weight of BER fruit were lower with Ca(NO3)2 and reduced K than with no added Ca and CaSO4. Leaf and fruit Ca concentrations were generally higher with Ca(NO3)2 compared to all other nutritional treatments. Leaf and fruit Ca concentrations were generally higher from plants irrigated at 10 kPa than at 25 kPa. The reduction of NH4+-N, by the supply of N as NO3-, and the addition of supplemental Ca reduced the incidence of BER, and increased the leaf and fruit Ca concentrations. During 2002, marketable yields were higher with CaSO4 than with CaCl2 and reduced K. Weight and number of BER fruit were lower with irrigation at 10 kPa than at 25 kPa. Leaf and fruit Ca concentrations were higher or similar from plants that received Ca(NO3)2 than with all other nutritional treatments. During the 2002 season, rainfall was less and temperatures and daily evapotranspiration (ET) were higher than in the 2001 season. In the 2002 season, 3.28 × 106 L·ha-1 of irrigation was applied as compared to 1.58 × 106 L·ha-1 in 2001. With an average Ca concentration of 76 mg·L-1 in the irrigation water, much more Ca was applied during the higher ET 2002 season. With the higher transpiration and temperature, water uptake and hence, Ca uptake were increased. During both seasons, the lowest Ca concentration was observed at the blossom end of the fruit and the highest Ca at the stem end of the fruit. Fruit Ca concentrations were lower and BER was 5 times higher in the lower ET, higher rainfall (lower irrigation) 2001 season compared to the higher ET, lower rainfall (higher irrigation) 2002 season. These data support that BER was a symptom of Ca deficiency and this deficiency was aggravated by high rainfall, low ET, and the resulting reduced irrigation applied and reduced Ca uptake.
Response to Copper Toxicity for Three Ornamental Crops in Solution Culture
Authors: Zheng Youbin , Wang Linping , Dixon Mike A.
Published: February 2019

Electrolytically generated copper is increasingly used to control diseases and algae in the greenhouse industry. However, there is a shortage of information regarding appropriate management strategies for copper in ornamental crop production. The objectives of this study were to characterize the response of three ornamental crops (Dendranthema ×grandiflorum L. `Fina', Rosa ×hybrida L. `Lavlinger', Pelargonium ×hortorum L. `Evening Glow') to different solution levels of Cu2+ (ranging from 0.4 to 40 μm) and to determine the critical levels above which toxic responses became apparent. The following measurements were used to assess the treatments: leaf chlorophyll fluorescence (Fv/Fm), leaf chlorophyll content, and visible injury of leaf and root. Excessive copper reduced plant root length, root dry weight, total dry weight, root to shoot ratio, leaf area, and specific leaf area in all three species. The critical solution level of Cu2+ that resulted in significantly reduced plant dry weight for chrysanthemum was 5 μm; for miniature rose, 2.4; and for geranium, 8 μm. Plant visible root injury was a more sensitive and reliable copper toxicity indicator than visible leaf injury, leaf chlorophyll content, Fv/Fm, or leaf and stem copper content. Generally, all the species exhibited some sensitivity to Cu2+ in solution culture, with chrysanthemum and miniature rose being most sensitive and geranium being least sensitive. Caution should be taken when applying copper in solution culture production systems.
Creeping Bentgrass Seedling Tolerance to Herbicides and Paclobutrazol
Authors: Kaminski John E. , Dernoeden Peter H. , Bigelow Cale A.
Published: February 2019

The tolerance of creeping bentgrass (Agrostis stolonifera L.) seedlings to many herbicides has not been evaluated. Three field studies were conducted between fall and spring from 1998 to 2002 to assess creeping bentgrass seedling tolerance to five herbicides and paclobutrazol. The primary objectives of this investigation were to assess bentgrass tolerance to these chemicals when applied at various timings following seedling emergence, and establishment of new seedlings as influenced by potential soil residues in the spring following a fall application of the chemicals. Treatments were applied 2, 4, or 7 weeks after either `Crenshaw' or `L-93' creeping bentgrass seedlings had emerged. Siduron (6.7 and 9.0 kg·ha-1) and bensulide (8.4 kg·ha-1) were noninjurious when applied two weeks after seedling emergence (2 WASE). Bensulide (14 kg·ha-1), ethofumesate (0.84 kg·ha-1), prodiamine (0.36 kg·ha-1) and paclobutrazol (0.14 kg·ha-1) were too injurious to apply 2 WASE, but they were generally safe to apply at 4 WASE. Chlorsulfuron (0.14 kg·ha-1) was extremely phytotoxic to seedlings when applied 2 WASE. Plots were treated with glyphosate and overseeded the following spring. The overwintering soil residuals of prodiamine and bensulide (14.0 kg·ha-1) unacceptably reduced spring establishment. All other herbicides and paclobutrazol had little or no adverse residual effects on spring establishment. Chemical names used: N-(phosphonomethyl)gycline (glyphosate); (±)-(R*,R*)-beta-[(4-chlorophenyl)methyl]-alpha-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol); 2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate (ethofumesate); S-(0,0-diisopropyl phosphorodithioate) ester of N-(2-mercaptoethyl) benzenesulfonamide (bensulide); [1-(2-methylcyclohexyl)-3-phenylurea] (siduron); N3,N3-di-n-propyl-2,4-dinitro-6-(trifluoromethyl)-m-phenylenediamine (prodiamine); 2-chloro-N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonyl] benzenesulfonamide (chlorsulfuron).
Cultural and Chemical Control of Ground Ivy (Glechoma hederacea)
Authors: Kohler Eric A. , Throssell Clark S. , Reicher Zachary J.
Published: February 2019

Ground ivy is a common broadleaf weed that disrupts turf uniformity and is difficult to control. The objective of this field research was to evaluate cultural and chemical control of ground ivy. Increasing annual nitrogen fertilizer applications from 0 to 196 and 293 kg·ha-1 reduced ground ivy cover by 24% and 32%, respectively. At 26 weeks after treatment, 1.1 kg·ha-1 isoxaben applied in May limited ground ivy spread by 34% compared to the control. Triclopyr, 2,4-D, or fluroxypyr applied at the highest-labeled rate in October provided superior ground ivy control by the following May. Combining an annual fertility program of 196 kg·ha-1 nitrogen and an application of 1.1 kg·ha-1 isoxaben with or after an application of 2,4-D, fluroxypyr, or triclopyr in the fall can maximize ground ivy control. Chemical names used: N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide (isoxaben); [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr); (2,4-dichlorophenoxy)acetic acid (2,4-D); [(4-amino-3,5-dichloro-6-fluoro-pyridyl)oxy]acetic acid (fluroxypyr).