bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Aluminum Tolerance and Nutrient Uptake of 50 Centipedegrass Accessions and Cultivars
Authors: Yan Jun , Chen Jingbo , Zhang Tingting , Liu Jianxiu , Liu Haibo
Published: February 2019

Centipedegrass [Eremochloa ophiuroides (Munro) Hack] is a native grass of China, and information on soil adaptation ranges, including acid soils, among centipedegrass cultivars is limited. Therefore, objectives of this study were 1) to conduct a preliminary evaluation of relative aluminum tolerance of 48 centipedegrass accessions plus a cultivar, TifBlair, and a common centipedegrass under aluminum (Al) stress (0 and 1500 μM Al) by using a solution culture method; and 2) to determine Al effects on nutrient uptake between resistant-group and sensitive-group accessions among the 50 accessions and cultivars. Differences were found among accessions and cultivars, and the CV of relative root weight, relative shoot weight, and relative total weight were 39.9%, 32.9%, and 33.6%, respectively. After growing 28 days in an acid subsoil, the resistant-group accessions showed much better growth than the sensitive-group accessions. The Al concentrations in roots and shoots of the two groups of accessions were increased under Al treatment, but most absorbed Al remained in roots with greater Al absorption among the sensitive group compared with the resistant group. The concentrations of phosphorus (P), magnesium (Mg), calcium (Ca), and potassium (K) in the two groups were reduced under Al stress with reductions of 59.3%, 54.8%, 47.9%, and 41.3% in shoots and reductions of 8.70%, 52.5%, 43.2%, and 34.4% in roots, respectively. Under Al stress, differences in P, Mg, and Ca concentrations were found between the two groups; however, differences were not found for K. The resistant-group accessions maintained higher concentrations of Mg and Ca than the sensitive group.
Characterization of Resistance to Squash Silverleaf Disorder in Summer Squash
Authors: Young Kristen , Kabelka Eileen A.
Published: February 2019

Feeding nymphs of the silverleaf whitefly, Bemisia argentifolii (formerly known as Bemisia tabaci Gennadius, B strain), cause a physiological disorder known as squash silverleaf (SSL) in summer squash (Cucurbita pepo L.). This disorder is characterized by a progressive silvering on the upper leaf surface caused by the development of large air spaces between the palisade mesophyll cells and the adaxial epidermis. Severely symptomatic plants can exhibit stunting and fruit yield reduction. A University of Florida C. pepo breeding line, designated Zuc76, confers resistance to this disorder and its inheritance was characterized. Data from F1, F2, and backcross progeny from crossing a SSL disorder-susceptible zucchini squash (C. pepo) with Zuc76 indicated resistance is conferred by a single recessive gene. Determining the mode of inheritance of SSL disorder resistance found in Zuc76 will contribute to future studies to develop SSL disorder-resistant C. pepo cultivars with superior horticultural potential.
Screening Indoor Plants for Volatile Organic Pollutant Removal Efficiency
Authors: Yang Dong Sik , Pennisi Svoboda V. , Son Ki-Cheol , Kays Stanley J.
Published: February 2019

Twenty-eight ornamental species commonly used for interior plantscapes were screened for their ability to remove five volatile indoor pollutants: aromatic hydrocarbons (benzene and toluene), aliphatic hydrocarbon (octane), halogenated hydrocarbon [trichloroethylene (TCE)], and terpene (α-pinene). Individual plants were placed in 10.5-L gas-tight glass jars and exposed to ≈10 ppm (31.9, 53.7, 37.7, 46.7, and 55.7 mg·m−3) of benzene, TCE, toluene, octane, and α-pinene, respectively. Air samples (1.0 mL) within the glass containers were analyzed by gas chromatography–mass spectroscopy 3 and 6 h after exposure to the test pollutants to determine removal efficiency by monitoring the decline in concentration over 6 h within sealed glass containers. To determine removal by the plant, removal by other means (glass, plant pot, media) was subtracted. The removal efficiency, expressed on a leaf area basis for each volatile organic compound (VOC), varied with plant species. Of the 28 species tested, Hemigraphis alternata, Hedera helix, Hoya carnosa, and Asparagus densiflorus had the highest removal efficiencies for all pollutants; Tradescantia pallida displayed superior removal efficiency for four of the five VOCs (i.e., benzene, toluene, TCE, and α-pinene). The five species ranged in their removal efficiency from 26.08 to 44.04 μg·m−3·m−2·h−1 of the total VOCs. Fittonia argyroneura effectively removed benzene, toluene, and TCE. Ficus benjamina effectively removed octane and α-pinene, whereas Polyscias fruticosa effectively removed octane. The variation in removal efficiency among species indicates that for maximum improvement of indoor air quality, multiple species are needed. The number and type of plants should be tailored to the type of VOCs present and their rates of emanation at each specific indoor location.
Optimizing Initiation and Maintenance of Vitis Embryogenic Cultures
Authors: Dhekney Sadanand A. , Li Zhijian T. , Compton Michael E. , Gray Dennis J.
Published: February 2019

Stamens and pistils from mature grapevines and leaves from in vitro micropropagation cultures were used to optimize parameters influencing somatic embryogenesis in Vitis. Embryogenic competence was dependent on species/variety, explant type and developmental stage, medium composition, and growth regulator concentration. Of varieties evaluated, a greater number produced embryogenic cultures from stamens and pistils (26) compared with leaves (six). Among the different stamen and pistil stages, Stage II and III explants produced the maximum embryogenic response regardless of genotype and medium composition. Of seven culture media tested, the highest embryogenic response was recorded from varieties cultured on MSI (18) and PIV (16) media. Experiments annually repeated over 3 to 10 years demonstrated reproducible results. Highly reliable protocols for somatic embryogenesis were obtained for 29 Vitis species and varieties, including 18 Vitis vinifera varieties, Vitis riparia, Vitis rupestris, Vitis champinii, and eight Vitis hybrids. Embryogenic cultures were maintained on X6 medium for a period of 6 months to 2 years depending on the variety and used in studies involving genetic transformation and transgenic plant regeneration.
Low-temperature Germination of Melons Is Affected by Seedcoat Characteristics and Embryo Genotype
Authors: Edelstein Menahem , Nerson Haim
Published: February 2019

Germination percentage and germination rate were examined in two melon accessions differing in their ability to germinate under low temperature and in their reciprocal F1, F2, and BC1 progeny. The seedcoat structure, pressure force required for seedcoat splitting, and the response to hilum sealing of the reciprocal F1s were examined as well. The purpose of this study was to elucidate the effects of embryonic genotype and seedcoat characteristics on the ability of melon seeds to germinate under low temperature. The results of the study point out that both components are strongly involved in low-temperature germination. The cold tolerant parent, ‘Persia 202’ (P202), germinated greater than 90% at 15 °C, whereas the cold-sensitive parent, ‘Noy Yizre'el’ (NY), did not germinate at all. The P202 × NY F1 and the reciprocal F2 germinated 80% to 90%, whereas the NY × P202 F1 germination percentage was only 71%. Backcrosses of the reciprocal F1 to the parents revealed that if the cross was to the tolerant one, the seeds germinated greater than 90%, but if the F1s were backcrossed to the sensitive parent, the seeds had only 56% to 60% germination. Data collected suggest that several dominant genes are carried by P202 for low-temperature germination. On the other hand, the difference in germination percentages between the reciprocal F1 demonstrates that the different seedcoats also play a role.
Weed Control and Organic Mulches Affect Physiology and Growth of Landscape Shrubs
Authors: Cregg Bert M. , Schutzki Robert
Published: February 2019

Landscape mulches are widely promoted to improve soil moisture retention, suppress weeds, and improve the growth of landscape plants. The objective of this project was to determine the effect of common landscape mulches (pine bark, hardwood fines, cypress mulch, color-enhanced ground pallets) on soil moisture, soil pH, weed control, and physiology and growth of landscape shrubs. Two additional treatments were not mulched: no mulch + no weed control and no mulch + weed control. Growth was measured on eight taxa (Euonymus alatus ‘Compactus’, Spiraea ×bumalda ‘Goldflame’, Weigela florida ‘Java red’, Taxus ×media ‘Runyan’, Thuja occidentalis ‘Golden Globe’, Hydrangea paniculata ‘Tardiva’, Viburnum dentatum ‘Synnestvedt’, Viburnum trilobum ‘Compactum’). Leaf gas exchange [net photosynthesis and stomatal conductance (g
s)] were measured on Hydrangea paniculata, V. dentatum, and V. trilobum only. All mulches increased soil moisture compared with no mulch + weed control. There was no difference in soil pH or foliar nitrogen among treatments. All mulches, except cypress mulch, increased plant growth of most shrub taxa compared with no mulch without weed control. Mulches increased g
S relative to no mulch without weed control. Photosynthetic rates of plants mulched with cypress mulch were less than the other mulches and not different from no mulch. Overall, the result suggests that, except for cypress mulch, the organic mulches tested are equally effective in improving growth of landscape plants. Reduced photosynthetic efficiency and growth of shrubs with cypress mulch suggest potential allelopathic effects.
Blue Fescue Overseeding Improves Performance of Fairway Height Buffalograsses
Authors: Abeyo Bekele G. , Shearman Robert C. , Gaussoin Roch E. , Wit Leonard A. , Serba Desalegn D. , Bilgili Ugur
Published: February 2019

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] use as a fairway turfgrass is limited in northern portions of its adaptation zone by its extended winter dormancy and tan coloration in early spring and late fall. Cool-season grasses mixed with buffalograss could enhance turfgrass appearance and performance in fall and early spring. Research was conducted near Mead, NE, with eight buffalograss genotypes maintained under fairway conditions to determine the effect of blue fescue (Festuca ovina L. var. glauca Lam.) overseeding rate on turfgrass performance. Interactions were nonsignificant in most cases so main effects are emphasized. Differences were observed between seeding rates and genotypes for most traits studied. Overseeding blue fescue enhanced spring green-up, fall color retention, stand density, and turfgrass quality. These effects were most pronounced in late fall and early spring, when buffalograss plants were entering or exiting winter dormancy. The 5 g·m−2 blue fescue overseeding rate improved all performance traits studied when compared with the nonoverseeded buffalograss control and was not different from the 10 g·m−2 seeding rate treatment. Thus, the 5 g·m−2 blue fescue overseeding rate appeared to be near optimum for overall turfgrass performance, offering reduced seed cost and decreased potential for species interference. The ‘Legacy’ buffalograss and ‘SR-3200’ blue fescue mixture had the best performance of the genotypes studied as a result of their visual compatibility in terms of color similarity.
Reproductive Response of Okra and Native Rosella to Long-day Treatment with Red, Blue, and Green Light-emitting Diode Lights
Authors: Hamamoto Hiroshi , Yamazaki Keisuke
Published: February 2019

We investigated the reproductive responses of three cultivars of short-day plants to day-extension and night-break treatment with red, blue, and green light-emitting diodes (LEDs). The plants examined were all Malvaceae species: two cultivars of okra [Abelmoschus esculentus (L.) Moench.] and a cultivar of native rosella [Abelmoschus moschatus ssp. tuberosus (Span.) Borss.]. To create day extension or night break, we provided supplemental light from LED panels with peak photon emissions of 470 (blue), 520 (green), or 650 (red) nm. Day-extension treatment using red or blue LEDs inhibited flower and bud appearances; the response was especially pronounced with red LEDs. Night-break treatment with red LEDs also delayed flower bud appearance, but night break with blue LEDs did not produce a clear effect. Night break with green light delayed flowering more strongly than blue light but a little less than red light. We concluded that the dark period-regulated reproductive processes of these plants are most sensitive to disruption by red light, closely followed by green light, but that they are insensitive to blue light, especially when the exposure period is short.
The Interaction Effect of Carbon Dioxide and Ethylene in the Storage Atmosphere on Potato Fry Color Is Dose-related
Authors: Daniels-Lake Barbara J. , Prange Robert K.
Published: February 2019

Previous studies have shown that the fry color of stored potatoes (Solanum tuberosum L.) can be negatively affected by an interaction between elevated CO2 (2 kPa) and ethylene gas (0.5 μL·L−1) from various sources. Two consecutive trials were conducted during each of two storage seasons (2006 and 2007) to study the effects of varying concentrations of these two gases. In each year, CO2 at 0, 0.5, 1.0, or 2.0 kPa plus 0, 0.25, or 0.5 μL·L−1 ethylene was applied in a factorial design to ‘Russet Burbank’ tubers for 9 weeks. Trials that began in Jan. 2006 and Jan. 2007 comprised the dormant-tuber experiment; trials that began in Apr. 2006 and Apr. 2007 comprised the nondormant-tuber experiment. Fry color of the tubers was evaluated at the start of each trial and thereafter at intervals of 3 weeks. In all trials, when tubers were exposed to different concentrations of CO2 but without ethylene, fry color was the same as in untreated controls. When only ethylene was applied, the fry color was 7 to 22 Agtron percent reflectance units darker than the controls. In the nondormant-tuber experiment, the darkening resulting from ethylene was dose-related, in agreement with previous research. When the tubers were exposed to both CO2 and ethylene, dose-related responses to both gases were observed in the nondormant-tuber experiment, i.e., fry color was darker with an increase in either CO2 or ethylene when both gases were present. Neither the dose–response to ethylene nor the interaction between ethylene and CO2 was statistically significant in the dormant-tuber experiment. In both experiments, the darkest color was observed when both gases were present at the highest concentrations. A dose–response of potato fry color to CO2 in the presence of ethylene has not been reported previously.
Factors Influencing Flowering of Different South African Iridaceae
Authors: Ehrich Luise , Ulrichs Christian , Grüneberg Heiner
Published: February 2019

Because South African Iridaceae have a high potential as new floricultural crops, four spring-flowering geophytic species originating in the Cape Floral Region were investigated. A total of 900 corms for each Freesia laxa, Sparaxis ×tricolor, Tritonia deusta, and Tritonia securigera were exported from South Africa during dormancy in 2 subsequent years. Experiments in Berlin, Germany, focused on storage conditions after export and different temperature and light intensity regimes for forcing, in particular their effect on plant habit, inflorescence induction, and flowering success. The results showed that after export, dormancy could be further maintained in storage at temperatures above 20 °C. Temperature was found to be the main criterion to successfully realize flowering after planting; cultivation at 13 °C at night was essential with temperatures of 17 °C and above possible during the day. During summer months, the failure of inflorescences in the terminal bud to develop completely, or the abortion of flower primordia within the corms, was the result of the high temperatures present. Also, low natural light levels during fall months could be linked to flower abortion of the investigated species. However, the results indicate that if forced as pot plants for the European fall and winter, the low temperature requirements of the investigated species during cultivation could represent substantial energy savings for future growers.
Southern Highbush Blueberry Production in High Tunnels: Temperatures, Development, Yield, and Fruit Quality During the Establishment Years
Authors: Ogden Andrew B. , van Iersel Marc W.
Published: February 2019

Growers interested in producing early, high-quality, southern highbush blueberries (Vaccinium corymbosum L.) in high tunnels face a lack of information regarding appropriate cultural methods. We sought to elucidate the optimal date to close high tunnels to hasten vegetative and reproductive growth of organic southern highbush blueberry cultivars Emerald and Jewel grown in Georgia. The three dates selected to close the high tunnels were 15 Dec., 2 Jan., and 16 Jan. High tunnels raised soil and daytime air temperatures during winter months, but the tunnels did not retain heat at night and did not provide freeze protection without the use of propane heaters. The high tunnel microclimate advanced both vegetative and reproductive growth compared with outdoor plants. Averaged over the 2-year study, the 15 Dec. tunnel closure advanced flower initiation by 38 days for ‘Emerald’ and 39 days for ‘Jewel’ compared with outdoor control plants. Synchronization of flowering of the two cultivars was poor in 2007 when ‘Emerald’ flowered much earlier than ‘Jewel’ and much better in 2008. In 2007, flower and fruit development of ‘Jewel’ were faster than that of ‘Emerald’ with Jewel going from the appearance of individual flowers to ripe fruit in 80 days as compared with 105 days for ‘Emerald’. Total yield was strongly correlated with fruit set (r = 0.94). ‘Emerald’ fruit contained higher concentrations of soluble solids and anthocyanins than ‘Jewel’ fruit, and anthocyanin concentrations increased throughout the harvest period. No fruit matured in 2008 as a result of freeze damage. The biggest obstacle for high tunnel production of southern highbush blueberries appears to be preventing freeze damage and assuring pollination. Cost-effective freeze protection and ways to promote good fruit set will be critical to successful production of early southern highbush blueberries in high tunnels.
Influence of Spray Application Technique on Spray Deposition in Greenhouse Ivy Pot Plants Grown on Hanging Shelves
Authors: Braekman Pascal , Foqué Dieter , Van Labeke Marie-Christine , Pieters Jan G. , Nuyttens David
Published: February 2019

As a result of the decreasing availability of authorized plant protection products, adequate pest control becomes more difficult in many ornamental crops and almost no information is available about the optimization of spray application techniques in ornamental crops. Yet, spray boom systems—instead of the still predominantly used spray guns—might improve crop protection management in greenhouses considerably. Application rate, nozzle type, and configuration will influence the spray deposition and, as such, its efficiency. In this study, spray deposition in ivy pot plants [Hedera algeriensis cv. Montgomery, Hibb.], grown on hanging shelves in greenhouses, was compared with a traditional spray gun with a disc-core nozzle and a manually pulled trolley equipped with two vertical spray booms. The sprayings with the spray gun were performed at an application rate of 8500 L·ha−1. For the vertical spray boom system, two different reduced application rates (2500 and 5000 L·ha−1) with five different combinations of nozzle type, size, and pressure for each application rate were investigated. This research underlined that, besides the application rate, also the spray application equipment used has an important effect on the spray depositions. Nozzle type, size, and pressure on the vertical spray boom system only had a minor effect on the spray deposition. Although the spray gun performed well on the easily accessible crop zone with the runners, its performance in the more dense main crop zone was inferior. With 240% more sprayed liquid (8500 L·ha−1) and chemicals, the realized depositions in this crop zone were not significantly different from the ones obtained with the vertical spray boom system applying only 2500 L·ha−1. Spraying at 5000 L·ha−1, the vertical spray boom system achieved a 82.9% higher overall spray deposition in the main crop canopy zone compared with the spray gun at an application rate of 8500 L·ha−1. For the sprays applied with the vertical spray boom system, doubling the application rate resulted in equally higher spray depositions, except for the inner canopy deposition for which higher application rates were more effective.
In Vitro Shoot Regeneration and Polyploid Induction from Leaves of Hypericum Species
Authors: Meyer Elisabeth M. , Touchell Darren H. , Ranney Thomas G.
Published: February 2019

Hypericum L. H2003-004-016 is a complex hybrid among Hypericum frondosum Michx., Hypericum galioides Lam., and Hypericum kalmianum L. and exhibits valuable ornamental characteristics, including compact habit, bluish green foliage, and showy flowers. Inducing polyploidy may further enhance the ornamental traits of this hybrid and provide new opportunities for hybridizing with other naturally occurring polyploid Hypericum sp. In this study, in vitro shoot regeneration and treatment of regenerative callus with the dinitroaniline herbicide oryzalin (3,5-dinitro-N4,N4-dipropylsufanilamide) were investigated as a means of inducing allopolyploidy. First, in vitro regeneration was optimized for callus and shoot induction by culture of leaf explants on medium supplemented with benzylamino purine (BA) or meta-topolin (mT) at 5, 10, or 15 μM in combination with indoleacetic acid (IAA) at 0, 1.25, 2.5, or 5 μM. Both BA and mT treatments successfully induced regenerative callus and shoots. Multiple regression analysis estimated maximum regenerative callus (94%) and shoot induction (18 shoots per explant) in medium supplemented with 5 μM BA and 3.75 μM IAA. In the second part of the study, exposure of regenerative callus to oryzalin at 0, 7.5, 15, 30, 60, or 90 μM for durations of 3, 6, or 9 d was investigated for polyploid induction. There was no survival for any of the calli in the 60- or 90-μM oryzalin treatments, but calli subjected to the other treatments exhibited some survival and polyploid induction. Duration had no effect on callus survival or ploidy level, but oryzalin concentration was a significant factor in both. The greatest percentage (44%) of polyploids was induced with 30 μM oryzalin. Spontaneous chromosome doubling was observed in 8% of control explants receiving no oryzalin treatment.
A Scale-up System for Lowbush Blueberry Micropropagation Using a Bioreactor
Authors: Debnath Samir C.
Published: February 2019

In an attempt to improve the micropropagation protocol for lowbush blueberry (Vaccinium angustifolium Ait.), a protocol using a bioreactor system combined with a semisolid gelled medium has been developed. Cultures of cultivar Fundy and two wild clones (‘NB1’ and ‘QB1’) were established in vitro on a gelled modified cranberry basal medium (BM) containing 5 μM zeatin or 10 μM N6-[2-isopentenyl]adenine. Multiple shoots were obtained within 8 weeks by transferring zeatin-induced shoots from the gelled BM to a bioreactor containing liquid BM with 1 to 4 μM zeatin. Genotypes differed significantly with respect to multiplication rate in liquid and gelled BM containing 1 μM zeatin with ‘NB1’ producing 8.5 ± 1.1 and 2.9 ± 0.3 shoots per explant in liquid and gelled media, respectively, after one subculture followed by ‘QB1’ (7.1 ± 0.6 and 2.6 ± 0.4 shoots per explant, respectively) and ‘Fundy’ (5.8 ± 0.4 and 2.0 ± 0.2 shoots per explant, respectively). With subculture, there was an increase of shoot multiplication rate for all genotypes. Bioreactor- and gelled medium-proliferated shoots were treated with 39.4 mm indole-3-butyric acid powder, rooted in a 2 peat:1 perlite (v/v) medium, plantlets acclimatized, and eventually established in the greenhouse with 64% to 74% rooting of microshoots and 90% to 99% survival of rooted shoots. Results obtained suggested the possibility of large-scale multiplication of lowbush blueberry shoots in bioreactors.
Stem Versus Foliar Uptake During Propagation of Petunia ×hybrida Vegetative Cuttings
Authors: Santos Kathryn M. , Fisher Paul R. , Argo William R.
Published: February 2019

Nutrient uptake during adventitious root formation is not clearly understood, resulting in variable fertilization strategies in propagation and increased potential for nutrient deficiency or nutrient runoff. The objective was to quantify rooting response to fertility treatments and tissue nutrient concentration changes in response to basal or apical nutrient supply during three rooting phases in propagation of Petunia ×hybrida ‘Supertunia Royal Velvet’ and ‘Supertunia Priscilla’ stem tip cuttings. One of two treatments [a complete fertilizer solution (in mg·L−1) 56 NO3-N, 19 NH4-N, 13 phosphorus, 88 potassium, 39 calcium, 28 magnesium, 20 sulfur, 11 sodium, 1.1 iron, 0.5 manganese, 0.5 zinc, 0.25 copper, 0.29 boron, 0.1 molybdenum, and 0.01 aluminum] or clear tap water was applied to the cuttings. Tissue N–P–K concentrations declined as plant development increased from Stage 0 to 3 regardless of fertilizer treatment or location applied. Foliar application of N–P–K during propagation maintained tissue nutrient concentration at higher levels before Stage 2 (initial root emergence) compared with plants that received clear water only; however, overall, a decline in concentration was measured from Stage 1 to Stage 3. Measurable N–P–K uptake occurred during root development from the foliar and basal portions of the cuttings. Basal fertilizer applications resulted in increased root length and root number compared with plants treated with clear water. These results emphasize that nutrient uptake occurs from both the stem and foliar portion of Petunia cuttings, and nutrient availability at the stem base at root emergence improves root development.
Isolation and Characterization of 17 Polymorphic Microsatellite Loci for Musella lasiocarpa (Musaceae)
Authors: Yang Chun-yan , Huang Yuan , Long Chunlin
Published: February 2019

Seventeen microsatellite markers were isolated from 24 wild individuals collected from three populations of Musella lasiocarpa (Franch.) C. Y. Wu ex H. W. Li, a plant endemic to southwest China. The average allele number of these markers was 3.6 per locus, ranging from two to seven. The expected (He) and observed (Ho) heterozygosities varied from 0.4672 to 0.8183 and from 0.0417 to 1, respectively. Eleven loci were significantly deviated from Hardy-Weinberg equilibrium as a result of the heterozygote deficiency. These microsatellite primers will be used for studying genetic population structure and genetic diversity of M. lasiocarpa.
Ploidy Level and DNA Content of Perennial Ryegrass Germplasm as Determined by Flow Cytometry
Authors: Wang Ying , Bigelow Cale A. , Jiang Yiwei
Published: February 2019

Perennial ryegrass (Lolium perenne L.) is a widely used cool-season turfgrass species. The exact ploidy levels of the worldwide perennial ryegrass accessions in the USDA National Plant Germplasm System (NPGS) are unknown, which could complicate future use and breeding efforts. The objective of this study was to determine the ploidy level and DNA content of the 194 USDA NPGS perennial ryegrass accessions and six commercial cultivars (Brightstar SLT, Catalina II, Divine, Inspire, Manhattan 4, Silver Dollar) using flow cytometry. Among the 200 accessions, 194 diploids and six tetraploids were identified. Three tetraploids originated from Canada with the remaining from Ireland, Japan, and The Netherlands. The average DNA content was 5.60 pg/2C for the diploid and 11.45 pg/2C for the tetraploid. The 2C DNA content was positively correlated (r = 0.23, P < 0.01) with seedling plant height but not seedling leaf width. This ploidy data provide important information for future marker trait analysis and cultivar improvement.
Grafting Eggplant onto Tomato Rootstock to Suppress Verticillium dahliae Infection: The Effect of Root Exudates
Authors: Liu Na , Zhou Baoli , Zhao Xin , Lu Bo , Li Yixiu , Hao Jing
Published: February 2019

Verticillium wilt (caused by Verticillium dahliae), a soilborne disease, often causes significant reductions of yield in eggplant (Solanum melongena L.) production where crop rotation is limited. Rootstock replacement through grafting is considered an effective method to control this disease. This 2-year study investigated the eggplant yield, resistance to verticillium wilt, and allelochemicals in root exudates of eggplant grafted onto a tomato rootstock. Both disease incidence and disease severity on grafted eggplant were markedly lower than those of nongrafted eggplants. Fifteen days after V. dahliae inoculation, grafted eggplants did not exhibit any infection, whereas the disease incidence and disease severity index of the nongrafted eggplants were 68.3% and 37.8% in 2006 and 66.7% and 36.3% in 2007, respectively. Twenty-five days after inoculation, disease incidences on grafted eggplants were only 8.1% and 9.5% in 2006 and 2007, respectively, but those of the nongrafted eggplants increased to 100%. As a result, early yield, total yield, and average fruit weight were significantly increased by grafting when inoculated with V. dahliae in 2006 and 2007. Mycelium growth of V. dahliae was inhibited by the root exudates of grafted eggplants. In contrast, the root exudates of nongrafted eggplants enhanced the mycelium growth. The gas chromatography–mass spectrometry analysis revealed that the composition in the root exudates released by grafted eggplants differed not only from the nongrafted eggplants, but also from the tomato rootstock plants. Ten chemical classes were isolated and identified in root exudates of grafted eggplants. Carbazoles, amines, azulene, and fluorene were only detected in the grafted eggplants. The relative contents of ester compounds were the highest in the root exudates from the grafted eggplant followed by derivatives of benzene, whereas the relative contents of benzene derivatives were much higher than that of the ester compounds in the root exudates from the nongrafted eggplant and tomato rootstock.
Effect of Alum Treatments on Turfgrass Coverage and Runoff Losses during Establishment
Authors: Vietor Donald M. , Schnell Ronnie W. , Provin Tony L. , White Richard H. , Munster Clyde L.
Published: February 2019

Incorporation or top-dressing of composted biosolids (CB) can enhance turfgrass establishment and sod properties at harvest, but soil phosphorus (P) and nitrogen must be managed to protect water quality. Alum treatment of CB could reduce soluble P concentrations in amended soil and limit runoff loss of P. The objective was to evaluate CB and Alum effects on turfgrass coverage of soil and runoff losses during ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers. var. dactylon × C. transvaalensis Burtt-Davey] establishment from sprigs or transplanted sod. Three replications of eight treatments comprised a complete randomized design. Four treatments were composed of ‘Tifway’ sprigged in soil with and without incorporation of CB and Alum. Four remaining treatments were sods harvested from ‘Tifway’ grown with and without top-dressed CB that were transplanted with and without a surface spray of Alum. Surface coverage of ‘Tifway’ sprigged in soil mixed with inorganic fertilizer or CB was comparable to transplanted sod 25 days after planting. In contrast, Alum incorporation acidulated soil, slowed coverage rates of sprigged ‘Tifway’, and increased NH4-N runoff loss during early establishment in treatments without CB. Incorporation of Alum with CB or inorganic fertilizer in soil before sprigging reduced soil water-extractable P (WEP) more than 38% and reduced runoff loss of soluble reactive P (SRP) in three of four establishment treatments. Although SRP runoff loss from CB-amended sod was greatest among treatments, the Alum spray minimized SRP loss after transplanting. Alum effectively reduced runoff loss of SRP from CB, soil, and turfgrass sources during establishment from sprigs or sod. Additional field research is needed, but incorporated or surface sprays of Alum offer a potential new practice for mitigating runoff loss of SRP from establishing turfgrass.
A Long-term Study on Native Variation of Flowering and Fruiting in Spur-type ‘Delicious’ Apple
Authors: Bukovac Martin J. , Sabbatini Paolo , Zucconi Franco , Schwallier Phillip G.
Published: February 2019

Alternate cropping is a common physiological trait in several important apple cultivars, including spur-type ‘Delicious’. Alternate bearing usually develops slowly in apple trees as they mature, but may be dramatically induced by environmental or biotic stresses. We describe the native temporal and within-year variation of bloom and yield of a highly uniform spur-type ‘Delicious’/M.106 population (n = 95) over a period of 9 years. Crop load was adjusted by hand in the first year to establish a defined normal fruit population distribution. Thereafter, all trees received identical practices. Bloom density (BD) was rated (1 to 10) and yield and fruit size distribution were determined annually on an individual tree basis. Temporal profiles for bloom and yield had four periods above and below the general mean (GM). There were two 3-year periods of nonbienniality. Annual variation in BD ranged from 3.1 to 8.0 and in yield from 54 to 168 kg/tree. Variation in cropping was greater when expressed as percentage deviation from the GM. Annual mean fruit weight was inversely related to yield, but percentage of small- (51 to 64 mm) or large-diameter fruit (70 to 82 mm) was not consistently related to yield. The within-year cv ranged from ≈11% to 66% for BD and from 13% to 42% for yield. The degree of synchrony (within-year variation) was lowest in the year after crop adjustment (to normal distribution), became highly synchronized in ≈4 years, and then decreased. The relationship of native variation of individual trees to the population and to flower initiation and fruiting are discussed in relation to the alternate bearing cycle and significance in selecting trees for experimentation.
Crabapple and Lilac Growth and Root-zone Temperatures in Northern Nursery Production Systems
Authors: Neal Catherine A.
Published: February 2019

Crabapple (Malus ‘Donald Wyman’) and common lilac (Syringa vulgaris ‘Monge’) were grown from liners to marketable size in five production systems: field-grown, plastic container, pot-in-pot (PiP), bag-in-pot (BiP), and above-ground system (AGS). The objectives were to compare growth in modified container systems, which could potentially eliminate overwintering requirements in northern production nurseries and to compare the effects on tree root growth during landscape establishment. There were no significant differences in crabapple root or shoot mass after two seasons except PiP dry root weights exceeded field-grown trees. For lilacs, there were significant differences in growth and shoot dry weight with field-grown and PiP plants being largest. PiP root-zone temperatures (RZTs) were similar to field-grown RZTs. Container, BiP, and AGS systems all exceeded lethal high and low RZT thresholds, resulting in root damage. Five trees from each treatment were transplanted into a low-maintenance landscape and dug up 3 years later. There were no significant differences in top growth, but the effects of the production systems were evident in the root architecture. BiP and field-grown trees had fewest root defects and the greatest number of roots extending into the landscape soil.
Potassium Silicate Drenches Increase Leaf Silicon Content and Affect Morphological Traits of Several Floriculture Crops Grown in a Peat-based Substrate
Authors: Mattson Neil S. , Leatherwood W. Roland
Published: February 2019

Silicon (Si) is a beneficial nutrient that improves biotic and abiotic stress tolerance of several crop species. Previous Si research with container-grown floriculture crops has either focused on a limited number of species or has been conducted in hydroponics using purified water, but little research has been conducted with plants grown in soilless substrates. The objective of this experiment was to examine whether weekly potassium silicate drenches would alter leaf Si concentration or affect morphological traits of several floriculture species grown in soilless substrate. Rooted liners of 21 cultivars were transplanted into a peat-based substrate. Control plants received no Si supplementation, whereas treated plants were given weekly drenches of 100 mg·L−1 Si from potassium silicate for 10 weeks. Leaf Si concentration of control plants ranged from 211 mg·L−1 for petunia (Petunia ×hybrida Vilm. ‘Cascadias Cherry Spark’) to 2606 mg·L−1 for argyranthemum [Argyranthemum frutescens (L.) Sch. Bip. ‘Sunlight’]. Si supplementation increased leaf Si concentration of 11 cultivars; leaf Si concentrations for these supplemented plants were 13% to 145% greater than control plants. Among the taxa studied, Si supplementation response was variable; Si either increased or decreased height, diameter, fresh weight, dry weight, flower diameter, and leaf thickness. For three cultivars, these morphological traits were apparently unaffected by Si supplementation despite accumulating Si. Similarly, significant morphological differences were observed in four cultivars that did not accumulate Si. Eight cultivars both accumulated Si and showed significant morphological differences. Our results demonstrate that many common floriculture species grown in a peat-based substrate do take up Si and that SI may have an effect on plant development. Consequently, more work is needed to determine the appropriate rate of Si supplementation and to examine additional species.
Mummy Berry Fruit Rot and Shoot Blight Incidence in Blueberry: Prediction, Ranking, and Stability in a Long-term Study
Authors: Ehlenfeldt Mark K. , Polashock James J. , Stretch Allan W. , Kramer Matthew
Published: February 2019

Mummy berry (Monilinia vaccinii-corymbosi) is an important disease of cultivated blueberry (Vaccinium spp.). The disease has two distinct phases: a blighting phase initiated by ascospores and a fruit infection stage initiated by conidia during bloom. In this study, we investigated, in a nursery setting, blueberry cultivar resistance to both phases of the disease and, using multiple “standards” with a range of susceptibilities, examined, over 9 to 12 years, factors affecting disease incidence in controlled inoculations. The analyses of our data show that a minimum of 8 years of testing is necessary to obtain stable rankings of cultivar susceptibility for the fruit infection phase of the disease. Insufficient years of data were available to estimate this for the blight phase. Eight years are necessary largely as a result of uncertainty arising from the large environment × genotype interaction, estimated to be more than double any other source of observed variation, other than that resulting from sampling/individual plants. For individual cultivars, temperature and the amount and frequency of precipitation in January to March (when neither plant nor pathogen were presumed active and when both were in cold frames somewhat protected from environmental conditions) were predictive of later disease incidence. For most cultivars, the same weather variables at the same time period were found to be predictive for independently modeled cultivars. Additional cultivars, with only a few years' data, were grouped with the standard with which they shared similar environmental (year) responses and possibly similar disease predictive models.
Maximizing Adhesion of Auxin Solutions to Stem Cuttings Using Sodium Cellulose Glycolate
Authors: Blythe Eugene K. , Sibley Jeff L.
Published: February 2019

Auxin solutions prepared with sodium cellulose glycolate (SCG; a thickening agent, also known as sodium carboxymethylcellulose) and applied to stem cuttings using a basal quick-dip extend the duration of exposure of cuttings to the auxin and have previously been shown to increase root number and/or total root length on stem cuttings of certain taxa. In a series of three experiments, 3.75-cm stem sections (representing the bases of stem cuttings) of three ornamental plant taxa were dipped to a depth of 2.5 cm for 1 s in solutions prepared with selected rates of SCG using either deionized water or a 10% dilution of an alcohol-based rooting compound (Dip 'N Grow). Each stem section was weighed before and after being dipped in the solution. Regression equations were determined for each experiment and the rate of SCG providing the maximum ratio of SCG solution weight to stem piece weight was determined by setting the first derivative of the regression equation equal to zero. Maximum adhesion of solution was obtained using SCG at 13.35 to 13.71 g·L−1 with an average rate of 13.5 g·L−1.
Organic Soil Amendment and Tillage Affect Soil Quality and Plant Performance in Simulated Residential Landscapes
Authors: Loper Shawna , Shober Amy L. , Wiese Christine , Denny Geoffrey C. , Stanley Craig D. , Gilman Edward F.
Published: February 2019

The urban soil environment is usually not conducive to healthy root growth and function, leading to problems with plant establishment, growth, and aesthetic quality. The objective of this study was to determine if the addition of compost with or without the application of shallow tillage or aeration will improve soil physical and chemical properties and plant growth compared with an unamended control in simulated new residential landscapes. Twenty-four mixed landscape plots were established in a randomized complete block design to simulate new residential landscapes. Each plot was constructed using 10 cm of subsoil fill material over a compacted field soil and planted with Stenotaphrum secundatum and mixed ornamental plant species. Composted dairy manure solids were applied as an organic soil amendment at a depth of 5 cm (≈256 Mg·ha−1) in combination with two mechanical soil treatments (tillage to 15 cm and plug aeration) for a total of five soil management treatments plus an untreated control. Soil physical and chemical properties, plant growth, and quality and plant tissue nutrient concentrations were assessed periodically to determine the effect of soil treatment on soil and plant quality. Applications of compost to soils significantly reduced soil bulk density and pH and increased soil organic matter, electrical conductivity, and Mehlich-1 phosphorus and potassium concentrations. All ornamental plant species, with the exception of Raphiolepis indica (L.) Lindl. ex Ker Gawl., exhibited more growth when grown in soils amended with composted dairy manure solids. In most instances, plant tissue nitrogen and phosphorus concentrations were higher for plants grown in soils receiving compost. Results of our study suggested that the addition of composted dairy manure solids to soils can improve soil properties and enhance plant growth in residential landscapes when sandy fill soils are used. In contrast, shallow tillage and aeration had little effect on soil properties or plant growth.
Yield and Postharvest Quality of Lettuce in Response to Nitrogen, Phosphorus, and Potassium Fertilizers
Authors: Hoque M. Murshidul , Ajwa Husein , Othman Mona , Smith Richard , Cahn Michael
Published: February 2019

Commercial lettuce production requires adequate levels of nitrogen (N), phosphorus (P), and potassium (K) to provide high-quality postharvest attributes needed for longer shelf life. Factorial experiments were conducted in Salinas, CA, to evaluate yield and postharvest quality of both romaine and iceberg lettuce using fertilizers containing various levels of N, P, and K. Lettuce was evaluated for yield and postharvest quality parameters, including color, wilt, turgidity, glossiness, decay, brittleness, fringe burn, and salt burn. Uptake of N, P, K, calcium, and silicon by plants was also determined. Regardless of fertilizer treatment, shelf life and visual quality were better in the iceberg lettuce than romaine lettuce when cold-stored at 1 °C for 14 d. Yield increased with increased N application rate, but post-harvest quality fell at high levels of N (337 kg·ha−1) and P (225 kg·ha−1). The most economical treatment providing the highest yield and best post-harvest quality was the combination of 225 kg·ha−1 N and 112 kg·ha−1 P.
Use of Selenium-enriched Mustard and Canola Seed Meals as Potential Bioherbicides and Green Fertilizer in Strawberry Production
Authors: Bañuelos Gary S. , Hanson Bradley D.
Published: February 2019

New plant-based products can be produced from seed harvested from Brassica species used for phytomanaging selenium (Se) in the west side of central California. Se-enriched seed meals produced from canola (Brassica napus) and mustard (Sinapis alba) plants were tested as potential bioherbicides and green fertilizers in strawberry production under controlled and field conditions for two seasons. Treatments consisted of adding each meal (containing 2.2 mg Se/kg dry mass) to the soil at rates equivalent to 0, 2, and 6 t/acre, respectively, 7 days before planting. In growth chamber studies, the highest rates of either meal lowered berry yields by a high of 30% compared with no application (control). Among the nutrient accumulation, berry Se, calcium (Ca), manganese (Mn), and zinc consistently increased with most Brassica meal treatments and most significantly with the mustard meal. In the field studies, mustard treatments lowered the emergence of summer-germinating and resident winter annual weeds more than canola and control treatments. Strawberry fruit yields increased with all Brassica treatments, except a 42% fruit yield reduction was observed at a 6 t/acre rate of mustard meal. Increases in fruit Se concentrations and increases in Ca, phosphorus, and Mn were often observed for all Brassica treatments. Amending soils with Brassica seed meals may have more practical viability in organic agriculture as a potential bioherbicide and green fertilizer.