bluuebunny/crossref_metadata_2025 huggingface dataset:
Blueberry Splitting Tendencies as Predicted by Fruit Firmness
Authors: Marshall Donna A. , Spiers James M. , Stringer Stephen J.
Published: February 2019

To improve the quality of berries during handling and shipping, blueberry breeders have strived to develop a fruit that is firm in texture. However, some previous studies have suggested that blueberry cultivars with firmer fruit were more susceptible to splitting. This study was conducted to further investigate the correlation between splitting susceptibility and fruit firmness. Various cultivars and selections of rabbiteye (Vaccinium ashei) and southern highbush (interspecific hybrids primarily consisting of V. corymbosum) blueberry were used to determine whether berries displaying higher fruit firmness also have a higher incidence of splitting. Three distinctly different measurements of berry firmness were obtained using two instruments: QTS25 and FirmTech2. Berries were subsequently submitted to laboratory procedures to induce splitting. In general, firmness measured as either deformation (FirmTech2) or modulus of elasticity (QTS25) correlated with splitting tendencies. There are exceptions, however, that need to be further examined.
The Influence of Three Plant Growth Regulators on Susceptibility to Cold Injury Following Warm Winter Spells in Fraser Fir [Abies fraseri (Pursh) Poir] and Colorado Blue Spruce (Picea pungens)
Authors: Nzokou Pascal , Nikiema Paligwende
Published: February 2019

The effects of three plant growth regulators (PGRs) (prohexadione–calcium, paclobutrazol, and flurprimidol) on the resistance of Fraser fir (Abies fraseri) and Colorado blue spruce (Picea pungens) to cold injuries were investigated. Treated and untreated seedlings were first allowed to harden before exposure to warm temperatures in a greenhouse. The seedlings were then subjected to an artificial freezing test to simulate the return to normal winter conditions. Chlorophyll fluorescence, relative electrolyte leakage, bud survival, and posttreatment plant survival were recorded to evaluate the effectiveness of the treatments. Results showed that treatments with paclobutrazol and flurprimidol maintained the photosynthetic ability of the plants and reduced the extent of needle cold injuries. There was no effect on bud and plant survival, possibly as a result of the timing of the PGR application. Further studies with adjustment of the timing and rates of PGR treatments are needed to validate these results.
Estimation of Normative Supply Function and Price Elasticity of Hazelnut: A Case Study in Turkey
Authors: Kilic Osman , Ceyhan Vedat , Cinemre H. Avni , Bozoglu Mehmet , Sumelius John
Published: February 2019

In this study, a variable price programming model was developed to derive normative hazelnut function and calculate price elasticity of supply for hazelnut in Carsamba Plain of Samsun, Turkey. Economic analysis revealed that the composition of the total assets of hazelnut farms seemed to be unbalanced. In addition, the efficiency of resource use was not adequate in sample hazelnut farms. Research results also showed that hazelnut production would stop on the Carsamba Plain completely when the hazelnut price is less than $ 0.57 per kilogram. Calculated price parities between hazelnut and corn, rice, and sugar beet were 3.87, 1.77, and 15.21, respectively. In conclusion, relying on market forces would increase land and labor use efficiency.
Effects of Night-heating of Fruit on Cell Size and Sucrose Accumulation in the Outer Portion of Watermelon (Citrullus lanatus Matsum. et Nakai)
Authors: Kano Yasutaka , Ikeshita Youichi , Kanamori Yuri , Fukuoka Nobuyuki
Published: February 2019

To investigate the effects of night temperature on sugar accumulation in watermelon fruit, fruits were treated with higher nighttime temperature under a greenhouse. The minimum nighttime ambient temperature of the heating box (18 °C) was ≈6 °C higher than that of the control. The heat-treated fruit weighed at the end of heating treatment, 16 days after anthesis (DAA), was greater than that of control, but fruit weight at harvesting, 42 DAA, was almost the same in both treatments. Cells of all portions of the heat-treated fruit at 16 DAA were much larger than those of the control, and cells in the outermost rectangular parallelepipeds (RPs; 15-mm long samples that were serially collected from a 10-mm thick disk along a 10-mm wide strip removed at the maximum transverse diameter of the fruit) of the heat-treated fruit were 80 μm or more larger than those of the control. At 16 DAA, the number of RPs with sucrose contents of 2 g·L−1 or more were six and nine in control and heat-treated fruit, respectively. At 42 DAA, content in the outer RPs of the heat-treated fruit was greater than that in the outer RPs of the control. The number of RPs with sucrose contents of 40 g·L−1 or more was five in the control and 11 in heat-treated fruit. Mean sucrose, glucose, and fructose in fruit at 16 DAA did not differ in the treated fruit from the control. However, the sucrose content of heat-treated fruit was 32% higher than that of the control at 42 DAA. Glucose and fructose content were lower in heat-treated fruit than in the control.
Morphophysiological Characteristics Associated with Vase Life of Cut Flowers of Anthurium
Authors: Elibox Winston , Umaharan Pathmanathan
Published: February 2019

The vase life of 26 anthurium (Anthurium andraeanum Hort.) cultivars was evaluated in three separate trials. In the first trial, the influence of 12 morphophysiological characteristics of the cut flower on vase life was investigated. Of these, only spathe color and abaxial stomatal density were able to accurately predict vase life. A vase life prediction equation based on abaxial stomatal density, green/not green and white/not white was able to explain the cultivar variation in vase life in two separate trials conducted over two seasons. The equation was further validated using a different set of anthurium cultivars. Although vase life varied over seasons, the relative ranking of cultivars was similar as indicated by joint regression analysis. Changes in vase life over season were mediated through changes in stomatal density. Time to spadix necrosis was the only senescence indicator that occurred in all cultivars and was highly correlated to vase life determined by a complex criterion in all trials. Time to spadix necrosis is therefore suggested as a simplified criterion for vase life assessment. The possible mechanism for vase life deterioration and an approach to improving vase life in anthurium is discussed.
An Efficient and Inexpensive System for Greenhouse Pot Rotation
Authors: Hardy Erik M. , Blumenthal Dana M.
Published: February 2019

Large greenhouse experiments require frequent pot rotation to minimize the effects of variation in greenhouse climatic conditions. A manual rotation process is often cumbersome and labor-intensive. To increase the efficiency of the rotation process, we propose an inexpensive, modular system fabricated from widely available equipment typically used in materials handling applications.
Sweet Corn Growth and Yield Responses to Planting Dates of the North Central United States
Authors: Williams Martin M.
Published: February 2019

Sweet corn is planted over a 3-month period in the north central United States to extend availability for fresh market and processing; however, the extent to which development and growth of sweet corn changes during this period is unreported. Field experiments were conducted in 2006 and 2007 to determine the effect of five planting dates, ranging from mid-April to early July, on sweet corn establishment, growth, and yield components. Day length at the time of silking decreased from 15.1 h in the mid-April planting to 13.7 h in the early July planting. Development took 13 to 25 fewer days from emergence to silking for the hybrid ‘BC0805’, an 82-day augmented sugar enhancer endosperm type, as planting was delayed from mid-April to early July. Maximum height generally increased through planting dates with as much as 23% taller plants in early July versus mid-April planted sweet corn. While leaf mass was unaffected by planting date, maximum leaf number and rate of leaf appearance steadily decreased with later planting dates. Lower reproductive and total biomass at silking as well as marketable ear yield components were lowest in the early July planting date and were associated with presence of maize dwarf mosaic virus in leaf samples. In response to environmental conditions, the crop canopy undergoes distinct morphological changes as planting is delayed, and those changes may have implications for crop production.
Biolistic-mediated Transformation of Lilium longiflorum cv. Nellie White
Authors: Kamo Kathryn , Han Bong Hee
Published: February 2019

Slow-growing compact calluses were initiated from bulb scales of Lilium longiflorum cv. Nellie White that had been cultured for at least 6 months on Murashige and Skoog (MS) medium with 9 μm dicamba. To develop a reliable selection system, the sensitivity of nontransformed calluses and in vitro plants to different selective agents such as phosphinothricin, kanamycin, geneticin, paromomycin, and hygromycin was tested when grown on MS medium. Nontransformed calluses showed high sensitivity to 0.5 mg·L−1 phosphinothricin, 25 mg·L−1 geneticin, and 5 mg·L−1 hygromycin. Nontransformed plants grown in vitro died on either 2 mg·L−1 phosphinothricin or 75 mg·L−1 hygromycin. Plants did not die when grown on either 200 mg·L−1 kanamycin or 100 mg·L−1 geneticin, and 100 mg·L−1 paromomycin stimulated plant growth. Transformation was achieved using biolistics on callus bombarded with either the bar-uidA fusion gene under control of the CaMV 35S promoter or npt II and uidA under control of the CaMV 35S promoter. One week after biolistic bombardment, callus bombarded with the bar-uidA fusion gene was cultured for 1 month on MS medium supplemented with 9 μm dicamba and 0.1 mg·L−1 phosphinothricin and then transferred to 0.2 mg·L−1 phosphinothricin for 1 month followed by 1.0 mg·L−1 for the next 4 months. Regenerating shoots and well-established plants were cultured on MS medium lacking hormones and with either 0.2 mg·L−1 or 2.0 mg·L−1 phosphinothricin, respectively. Callus bombarded with the npt II gene was cultured on MS medium with 50 mg·L−1 geneticin until shoots regenerated. Regenerated shoots were cultured on MS medium lacking hormones. Under optimal conditions, 10 transgenic plants were selected from seven plates of callus bombarded with the bar-uidA fusion gene using phosphinothricin for selection. Both Southern hybridization of genomic DNA and polymerase chain reaction analysis verified the presence of the transgene in transformed ‘Nellie White’ plants. Transgenic plants were phenotypically normal, and they were crossed with nontransformed plants of L. longiflorum cvs. Sakai, Yin tung, Sakai, and Flavo. The presence of the bar gene in 41% of the T1 progeny plants confirmed stable integration of the transgene into the genomic DNA of transgenic lily plants. β-glucuronidase expression resulting from the uidA gene was demonstrated in leaves and roots of some of the transgenic lily plants by histochemical staining, determination of the specific activity of the β-glucuronidase enzyme, and Northern hybridization.
Assessing Viability of Prevariety Germplasm of Native Coreopsis Species
Authors: Norcini Jeffrey G. , Aldrich James H.
Published: February 2019

Dormancy issues and lack of approved protocols have led to increasing use of the pregermination tetrazolium test to assess whether seeds of premium-priced, prevariety germplasm of native wildflower species are living and have the potential to germinate and develop normally under field conditions, that is, whether seeds are viable. A major concern is the limited amount of industrywide training on how to conduct and interpret results of tetrazolium (TZ) tests for the multitude of native species. Precise methods that yield uniform results are especially critical for testing of prevariety germplasm of native species given their high value and economic consequences of inaccurate test results. In preliminary work, we observed that embryos extracted from intact seeds of native Coreopsis species subjected to TZ testing were viable if they were turgid and appeared normal and were stained pink, red, or were pure white with or without the radicle tip stained pink to red. In this study, we conducted an in-depth analysis of TZ testing of intact seeds of prevariety germplasm of four native Coreopsis species to: 1) verify our preliminary conclusions; and 2) to determine if staining could be improved by preconditioning or gibberellic acid (GA3) because relatively low percentages of embryos of intact seeds stained pink or red. In addition, we evaluated two other methods to assess viability: the excised embryo test and emergence tests in soil and a soilless medium under ambient conditions. We confirmed that embryos extracted from intact seeds subjected to TZ testing were viable provided that embryos were turgid and appeared normal and were stained pink, red, or were pure white ± a pink to red radicle tip. Embryo staining was not consistently improved by moist preconditioning or GA3. Results of pregermination TZ tests of intact seeds and/or germination plus postgermination TZ tests of intact, nongerminated seeds were not consistently accurate and/or uniform across all species and seed lots, issues usually encountered in seed lots that were relatively dormant or of poor quality, and in postgermination TZ testing of seed lots with relatively low dormancy. Moreover, these issues are likely to be encountered even with standard TZ testing protocols given the widely accepted challenges of accurately interpreting TZ tests of native species in general. The most precise, uniform method of assessing viability was the excised embryo germination test because all viable seeds germinated, results were easy to interpret so the likelihood of false-positives or -negatives was nil, and results were very uniform across replications. Emergence tests under ambient conditions substantially underestimated viability. In summary, the high cost of prevariety germplasm seeds of native Coreopsis species, inherent genetic and phenotypic variability, and unknown dormancy characteristics warrant the use of the embryo excision test for determining viability and for increased sample sizes, especially for any tests involving TZ.
Differential Responses of Hybrid Bluegrass and Kentucky Bluegrass to Drought and Heat Stress
Authors: Abraham Eleni M. , Meyer William A. , Bonos Stacy A. , Huang Bingru
Published: February 2019

This study was designed to investigate differential responses of hybrids from Texas bluegrass (Poa arachnifera Torr.) × Kentucky bluegrass (Poa pratensis L.) (KBG) and KBG genotypes to drought and heat stress. Plants of two hybrids, ‘845’ and ‘BDF’, and two KBG genotypes (‘Midnight’ and ‘C-74’) were grown under optimal temperature (22/18 °C) and well-watered (control) or unwatered (drought) or superoptimal temperatures (35/30 °C; heat stress) conditions for 35 days in growth chambers. Under optimal conditions, the two hybrids and two KBG genotypes were not significantly different in turf quality, leaf photochemical efficiency expressed as chlorophyll fluorescence ratio (Fv/Fm), leaf net photosynthetic rate (Pn), transpiration rate, water use efficiency (WUE), root dry matter, or root viability. The results suggest that the interspecific hybridization resulted in similar growth and physiological traits in the hybrid bluegrass as in a turf-type species under optimal temperature and irrigation regimes. Under drought stress, all these parameters were comparable to those for KBG ‘Midnight’, but significantly higher than the corresponding parameters for KBG ‘C-74’. Under heat stress, both hybrids had significantly higher turf quality, Fv/Fm, Pn, transpiration rate, WUE, root dry weight in deeper soil depth (40 to 60 cm), and root viability in the upper 40-cm layer compared with both KBG genotypes. These results suggested that hybrid bluegrass exhibited improvement in drought and heat tolerance, particularly in comparison with KBG ‘C-74’, but to a great extent for heat tolerance. The maintenance of higher transpiration and photosynthesis, WUE, and root viability was associated with the improvement in heat tolerance in hybrid bluegrass.
Ridge–furrow–ridge Rainwater Harvesting System with Mulches and Supplemental Irrigation
Authors: Gosar Borut , Baričevič Dea
Published: February 2019

New ridge–furrow–ridge rainwater-harvesting (RFRRH) system with mulches has been promoted in agricultural production to improve economic potential for high-value plant production. In this system, plastic mulch covers two ridges and the furrow between them, which serves as the rainwater-harvesting zone. To test this system more effectively, a field study using purple coneflower (Echinacea purpurea Moench) as an indicator crop was conducted to determine the effect of the RFRRH system with or without a covering of two different types of polyethylene mulches and with or without supplemental irrigation on soil water content, crop yield, and time dedicated to weed control during the growing seasons of 2007 and 2008. In the non-irrigated plots, the results showed significantly higher soil water content during dry periods at the beginning of plant growth in the mulch-covered RFRRH system in comparison with the control (uncovered ridges). In comparison with the control, the mulch-covered RFRRH system significantly increased yield and reduced time dedicated to weed control. In the event of a rainfall deficiency, the mulch-covered RFRRH system enabled simple supplemental irrigation, using an agricultural vacuum tanker, by flooding the polyethylene mulch-covered furrow with hardly any ridge erosion. However, in only 1 year did supplemental irrigation significantly increase yield.
Development of Simple Sequence Repeat Markers for Chionanthus retusus (Oleaceae) and Effective Discrimination of Closely Related Taxa
Authors: Arias Renée S. , Techen Natascha , Rinehart Timothy A. , Olsen Richard T. , Kirkbride Joseph H. , Scheffler Brian E.
Published: February 2019

The genus Chionanthus (Oleaceae Hoffmans. & Link) includes deciduous or evergreen trees and shrubs distributed widely in tropical and sub-tropical areas, including a few temperate species. Although Chionanthus species are planted as ornamental garden plants and commercialized for natural products, genetic information for Chionanthus spp. is lacking. We created microsatellite-enriched libraries of Chionanthus retusus Lindl. & Paxton, assembled 1072 contigs, and detected 1010 repeats. The frequency of the repeats decreased with the increase in repeat length, and the most abundant motifs were: AG, AC, AAG, ACC, AT, and ACTC. We screened 384 markers on 12 accessions of four related taxa that included C. retusus, Chionanthus virginicus L., Chionanthus pygmaeus Small, and Osmanthus americanus (L.) Benth. & Hook. A total of 195 simple sequence repeat (SSR) markers amplified and discriminated six accessions of C. retusus and 57 SSR markers amplified and discriminated across the four Oleaceae species screened. To identify the best markers to use in future experiments, the “Unique Pattern Informative Combination” (UPIC) values were calculated for all the markers and the 100 markers that were most effective are reported here. The percentage of heterozygous loci across the 384 markers was lowest for C. retusus (29.3%) and highest for O. americanus (68.9%). The SSR markers developed here could assist in taxonomy and hybridization investigations for breeding programs and authentication of varieties used as medicinal plants.
Spatial and Temporal Distribution of Bromide as a Nitrate Tracer in Deficit, Drip-irrigated Wine Grape Vineyards
Authors: Davenport Joan R. , Stevens Robert G. , Whitley Kelly M. , Winkler Tanya
Published: February 2019

Understanding water and nutrient movement in arid climate-regulated deficit, drip-irrigated vineyards is imperative for understanding grape vine canopy management. However, little research has been conducted in these environments to aid in the understanding of where the vine accesses nutrients and/or soil water and how that translates into soil and/or plant tissue sampling approaches. We used bromide (Br) as a tracer to study nitrate movement in soils as well as into grape leaves in two ‘Merlot’ vineyards in central Washington State. Bromide movement closely followed water movement. Although Br was detectable in grape petioles, it was not detectable in leaf blades, likely as a result of a dilution factor related to the amount of tissue. Relationships between soil Br and soil moisture as well as petiole and soil Br concentrations suggests that soil sampling for nitrate should be taken from a diagonal position between the vine and the emitter, between 20 and 60 cm from the drip line. This is consistent with the recommendation for soil moisture sampling in a published companion study.
Modeling Carbon Footprints of Organic Orchard Production Systems to Address Carbon Trading: An Approach Based on Life Cycle Assessment
Authors: Page Girija , Kelly Terry , Minor Maria , Cameron Ewen
Published: February 2019

Carbon footprint is widely accepted as an indicator of greenhouse gas emissions and global warming. Modeling carbon footprints based on life cycle assessment is applied as a way to evaluate the net contribution of greenhouse gases to the atmosphere from orchard production systems over one growing year. This net balance approach considers the sources and sinks of carbon and therefore provides a better reflection of an orchard system's net contribution to climate change. Carbon footprinting of organic kiwifruit and apple production systems in New Zealand indicated that the studied systems had a net sequestration from 2.4 to 5 t of CO2e/ha/year and therefore can be potentially considered as carbon sinks under the Kyoto Protocol. This finding implies that the organic kiwifruit and apple orchardist can gain a monetary benefit by earning carbon credits. However, further research to improve and validate this approach is essential before it can be practically used for decision-making at the orchard level and for policymaking at the national level.
Improved Transformation of Anthurium
Authors: Fitch Maureen M.M. , Leong Terryl C.W. , He Xiaoling , McCafferty Heather R.K. , Zhu Yun J. , Moore Paul H. , Gonsalves Dennis , Aldwinckle Herb S. , Atkinson Howard J.
Published: February 2019

Methods to increase transformation efficiency and yields of transgenic Anthurium andraeanum Linden ex. André hybrids were sought while effecting gene transfer for resistance to the two most important pests, bacterial blight (Xanthomonas axonopodis pv. dieffenbachiae) and nematodes (Radopholus similis and Meloidogyne javanica). Differentiated explant tissues, embryogenic calli, and comingled mixtures of the two were transformed with binary DNA plasmid constructs that contained a neomycin phosphotransferase II (nptII) selection gene with a nos promoter and terminator. Explants included ≈1-cm long laminae, petioles, internodes, nodes, and root sections from light- and dark-grown in vitro plants. Bacterial blight resistance genes were NPR1 from Arabidopsis, attacin from Hyalophora cecropia, and T4 lysozyme from the T4 bacteriophage. For nematode resistance, rice cystatin and cowpea trypsin inhibitor genes were used. Cocultivation with Agrobacterium tumefaciens strains EHA105, AGLØ, and LBA4404 ranged from 2 to 14 days. Over 700 independent, putatively transformed lines were selected with 5 and 20 mg·L−1 geneticin (G418) for cultivars Midori and Marian Seefurth, respectively. Putative transgenic lines were selected 1 to 11.5 months, but on average 5.2 to 8.4 months, after cocultivation depending on the tissue type transformed. Significantly more embryogenic calli (one line per 5 mg calli) produced transgenic lines than did explants (one line per 143 mg explants) (P < 0.004) from ≈30 mg of tissue. Calli grew selectively from all explant types, but the type of explant from which each selection was made was not recorded because root, internode, and petiole explants were difficult to discern by the time calli developed. Shoots formed 3 months after calli were transferred to light. Non-transgenic control and transgenic ‘Marian Seefurth’ formed flower buds in the greenhouse ≈28 months after cocultivation. The plants resembled commercially grown plants from a private nursery. No non-transformed escapes were detected among the selections screened for NPTII by enzyme-linked immunosorbent assay and polymerase chain reaction (PCR). The selections were positive for transgenes as assayed by PCR and Southern hybridizations. Southern blots showed single-copy insertions of the NPR1 regulatory gene. The ability to produce large quantities of independent transgenic lines from embryogenic calli in a relatively short time period should enable researchers to evaluate the effectiveness of any transgene by screening numerous anthurium lines for improved performance.
Effect of Foliar Application of Titanium Dioxide on Bacterial Blight of Geranium and Xanthomonas Leaf Spot of Poinsettia
Authors: Norman David J. , Chen Jianjun
Published: February 2019

This study is the first report of using titanium dioxide (TiO2) to control Xanthomonas bacterial blight on geranium and leaf spot on poinsettia. Potted zonal geranium ‘Patriot Bright Violet’ and poinsettia ‘Snowcap’ were grown in a greenhouse and treated with a foliar spray of TiO2 at 25 and 75 mm, respectively, twice. Titanium-treated and control geranium plants were inoculated with Xanthomonas hortorum pv. pelargonii and poinsettias were inoculated with Xanthomonas axonopodis pv. poinsettiicola. The experiment was repeated once. The numbers of lesions on geranium leaves sprayed with TiO2 at 25 and 75 mm were 53% and 67%, respectively, less than in control plants in the first trial, but there were no significant differences among treatments in the second trial. Results on poinsettia, however, showed significant decrease in lesion numbers in both trials. Plants treated with TiO2 at 25 and 75 mm showed 85% and 93% reduction in lesions, respectively, in the first trial and 87% and 92% reduction in lesions in the second trial. No symptoms of phytotoxicity were observed. This study suggests that TiO2 has potential as an alternative to currently labeled products for controlling Xanthomonas bacterial blight in geranium and leaf spot on poinsettia.
Horticultural and Economic Considerations in the Sustainability of Three Cold-climate Strawberry Production Systems
Authors: Stevens Matthew D. , Black Brent L. , Lea-Cox John D. , Feuz Dillon
Published: February 2019

Three cold-climate strawberry (Fragaria ×ananassa) production systems, conventional matted row (CMR), advanced matted row (AMR), and cold-climate plasticulture (CCP), were compared for horticultural and economic aspects of sustainability over a 3-year planting cycle. The systems were tested using a single cultivar, Allstar, to avoid treatment × cultivar interaction. System-specific management operations and materials affected the total production costs of each system. Both CMR and AMR had higher management costs than CCP as a result of labor costs for weed control, but CCP had much higher cost of materials. Overall expenses were lowest for CMR and highest for AMR. Yields in the first fruiting year were highest for CMR at 17.4 Mg·ha−1 followed by AMR and CCP at 13.2 Mg·ha−1 and 11.8 Mg·ha−1, respectively. In the 2004 harvest season, CMR and AMR were the highest yielding at 10.0 Mg·ha−1 and 9.0 Mg·ha−1, respectively, with CCP the lowest yielding at 6.0 Mg·ha−1. Low yield and fruit size in the second year and high material costs for establishment limit the economic viability for CCP when managed as a perennial system.
Continuous Automatic Measurement of Water Uptake and Water Loss of Cut Flower Stems
Authors: Lü Peitao , Huang Xinmin , Li Hongmei , Liu Jiping , He Shenggen , Joyce Daryl C. , Zhang Zhaoqi
Published: February 2019

In studying the postharvest water relations of cut flowers, researchers aim to determine rates of water uptake and water loss along with changes in fresh weight. An automatic apparatus was devised for continuous monitoring of these indices. The novel apparatus consists of two balances automatically recording mass at a relatively high data acquisition rate (min−1), a personal computer, two containers, and plastic tubing. The apparatus is accurate, labor-saving, and real-time. It enabled dynamic synchronous recording of water uptake as well as fresh weight of the cut flower stem, from which precise water uptake loss rates during vase life can be accurately determined. Rates of water uptake and water loss of individual cut rose (Rosa hybrida cv. Movie Star) stems were measured using the apparatus under alternating 12-h light and dark periods. Both water uptake and water loss rates fluctuated with the light to dark shift over 120 h of observation. Stem fresh weight increased rapidly over the first 40 h of vase period and decreased gradually thereafter. Cut lily (Lilium hybrida cv. Yellow Overlord) stems showed similar trends in water uptake and water loss rate to cut rose stems. The accuracy and sensitivity of the new apparatus was validated by comparison with manual weighing using a balance at 2-h intervals under alternating 12-h light and dark periods over 108 h. The apparatus described here constitutes a suitable method for direct measurement of water uptake and fresh weight, including capturing relatively rapid water balance responses to changes in the postharvest environment.
Nitrogen and Light Affect Water Use and Water Use Efficiency of Zoysiagrass Genotypes Differing in Canopy Structure
Authors: Erickson John E. , Kenworthy Kevin E.
Published: February 2019

Irrigation of residential lawns represents one of the major uses of potable water in many regions. An increased understanding of physiological responses underlying effects of turfgrass genotypes and management practices on water use rates and water use efficiencies could contribute to water conservation. Thus, we evaluated the effects of nitrogen (N) fertilization (0.0 and 2.5 g·m−2) and light environment (full sun and 50% shade) on average daily evapotranspiration (ETAVE), daily ET per unit leaf area (ETLA), carbon exchange rate (CER), and water use efficiency (WUE) in upright (experimental TAES 5343-22) and prostrate (‘Empire’) zoysiagrasses (Zoysia japonica Steud.) during two repeated trials. Across all treatments, ETAVE was 4.0 and 5.4 mm·d−1 during Trials 1 and 2, respectively. In the upright-growing genotype, ETAVE was ≈10% greater than the prostrate genotype during Trial 1. Nitrogen fertilization increased water use by ≈20% compared with non-fertilized pots. However, N fertilization reduced ETLA and increased WUE. Thus, ETAVE was positively related with WUE. As a result, there was a tradeoff between ETAVE and WUE, indicating that efforts to achieve reductions in water use through low N fertilization or genotypes can be accomplished, but in some cases at the expense of using water less efficiently to assimilate carbon for plant growth processes. In turfgrass, reductions in growth and WUE might be acceptable to minimize water use, but vigor and quality need to be maintained.
Tall Fescue and Perennial Ryegrass Reseeding Intervals for Amicarbazone
Authors: McCullough Patrick E. , Brosnan James T. , Breeden Gregory K.
Published: February 2019

Turf managers applying amicarbazone for annual bluegrass (Poa annua L.) control in cool-season turfgrasses may wish to reseed into treated areas. Field experiments were conducted in Georgia and Tennessee to investigate perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.) reseeding intervals after amicarbazone applications. Perennial ryegrass and tall fescue cover were reduced similarly (less than 10% from the untreated) by all herbicides applied 2, 4, or 6 weeks before seeding. Bispyribac-sodium at 0.1 kg a.i./ha reduced tall fescue and perennial ryegrass cover more than amicarbazone at 0.1 or 0.2 kg a.i./ha when applied the day of seeding. Applied on the day of seeding in Georgia, amicarbazone at 0.4 kg·ha−1 reduced turf cover of each species similar to bispyribac-sodium; however, this response was not observed in Tennessee. Results suggest tall fescue and perennial ryegrass can be safely seeded the day of amicarbazone applications at 0.1 or 0.2 kg·ha−1, but practitioners may need to wait 2 weeks before seeding these turfgrasses into areas treated with amicarbazone at 0.4 kg·ha−1 or bispyribac-sodium at 0.1 kg a.i./ha.
Use of a Chlorophyll Meter to Diagnose Nitrogen Status of ‘Fuyu’ Persimmon Leaves
Authors: Choi Seong-Tae , Park Doo-Sang , Kang Seong-Mo , Park Soo-Jeong
Published: February 2019

A possible relationship between leaf SPAD readings and nitrogen (N) concentrations was evaluated at different growing stages of ‘Fuyu’ persimmon trees under different N regimes in pots and in the field. When 5-year-old trees grown in pots received 0 to 40 g N over the growing season, leaf SPAD reading, N concentration, and specific leaf weight tended to increase with increasing N rate. The correlation between leaf SPAD reading and N concentration was statistically significant from late April to early November (R2 = 0.72 to 0.97). It was noted that the slope of regression line decreased as the season progressed. Similar significant correlations were found from pot-grown 4- to 7-year-old trees grown under various nutrient regimes (R2 = 0.67 to 0.96). Significant correlations were also confirmed with the leaves collected from 31 commercial orchards at different locations. The highest coefficient of determination was observed from the leaves collected at harvest time in both the pot and field experiments. Although the regression equations differed depending on the growing stage of trees, SPAD readings were found useful in estimating leaf N status at a specific time and in quickly judging the need for N application at that time. Seasonal changes of leaf SPAD readings from five well-managed orchards are presented as a reference guide for practical use.
A Significant Loss in Photosynthetic Activity Associated with the Yellow Vine Syndrome of Cranberry
Authors: Zhang Fan , Wei Zi , Jeranyama Peter , DeMoranville Carolyn , Hou Harvey J.M.
Published: February 2019

Numerous observations of yellow vine syndrome of cranberry have been reported from commercial cranberry growers. The molecular mechanism resulting in yellow vine syndrome is unknown. We have previously reported on the shading effect as an approach to explore the mechanisms of yellow vine formation and proposed photoinhibition as a possible cause. To compare the photosynthetic performance of yellow vine-affected and normal cranberry leaves, we conducted chlorophyll fluorescence analyses over 1 period of 1 day and 3 weeks, respectively. Both experimental data sets indicated that the maximum quantum efficiency of photosystem II, the size of the quinone pool, the numbers of reaction centers (RCs) per chlorophyll absorption, and the photosynthesis performance index of the yellow vine samples are substantially lower than those of normal cranberry leaves. These results are in line with the data of yellow vine leaves, having 26% to 28% less in chlorophyll than the normal leaves as measured by spectrometric and high-performance liquid chromatography analysis. We concluded that yellow vine syndrome is associated with poor photosynthetic activity and is likely becoming a threat for the long-term growth and crop production of cranberries.
Diversity Analysis of Arabidopsis thaliana (L.) Heynh Ecotypes for Glucosinolates in Shoots and Seeds
Authors: Panthee Dilip R. , Kopsell Dean A. , Sams Carl E.
Published: February 2019

Glucosinolates (GS) are important secondary plant metabolites present in several plant species, including Arabidopsis thaliana (L.) Heynh. Although genotypic differences among a limited number of samples from a limited geographical range have been reported, there have been few studies exploring the variation from a wider genetic base. The objective of this study was to explore the genetic variation for GS in A. thaliana collected throughout the world. We screened 58 A. thaliana ecotypes collected from the geographic area of lat. 15° N to lat. 59° N and long. 137° E to long. 123° W. Elevation in these areas ranged from sea level to over 480 m. We believe that this study has covered a large geographical region and captured most of the available genetic variation in A. thaliana for GS. There was no geographical trend in A. thaliana shoot or seed tissue for GS concentration. Total shoot GS ranged from 1.1 to 52.8 μmol·g−1 dry weight (DW), averaging 9.3 μmol·g−1 DW among all ecotypes. Total seed GS ranged from 1.6 to 41.8 μmol·g−1 DW with an average of 16.8 μmol·g−1 DW among all ecotypes. Low and high GS-accumulating A. thaliana ecotypes identified in this study may provide a basis for further genetic analysis for GS metabolism. Information provided may also prove useful for improving concentrations of nutritionally beneficial GS in vegetable Brassicas.
Practical Breeding of Red-fleshed Apple: Cultivar Combination for Efficient Red-fleshed Progeny Production
Authors: Umemura Hitomi , Shiratake Katsuhiro , Matsumoto Shogo , Maejima Tsutomu , Komatsu Hiromitsu
Published: February 2019

We re-investigated the flesh color and S-genotypes of progenies of red-fleshed apple cultivar JPP35, which was produced by ‘Jonathan’ × ‘Pink Pearl’, and clarified that 100% and 96% of progenies from ‘Shinano Sweet’ (S1S7) × ‘JPP35’ (S3S7) and ‘Orin’ (S2S7) × ‘JPP35’ (S3S7) containing S3-RNase allele, respectively, showed the red flesh trait. Using this tight linkage between red flesh trait and self- and cross-compatibility relating allele such as S3-RNase allele, we showed suitable cultivar combinations for efficient production of various red-fleshed apples. We also identified an unknown S-RNase allele in ‘Pink Pearl’ as S11 and determined its partial genomic sequence, including a complete intron with its known S3-RNase allele.
Use of Flying Dragon Trifoliate Orange As Dwarfing Rootstock for Citrus Under Tropical Climatic Conditions
Authors: Mademba-Sy François , Lemerre-Desprez Zacharie , Lebegin Stéphane
Published: February 2019

Citrus fruit trees grown under tropical climatic conditions have a high level of vigor and, consequently, late fruit-bearing and low productivity. The use of Flying Dragon trifoliate orange [Poncirus trifoliata var. monstrosa (T.Itô) Swing.] (FD) rootstock could overcome these negative effects by inducing small trees with early production. Trials including eight commercial cultivars began in Dec. 1992 on an irrigated plot on the main island of New Caledonia (South Pacific). Growth of the trees was observed over a 13-year period through twice-yearly measurements of tree height, canopy between and in the rows, and trunk diameter. Fruit production was recorded beginning 2 years after planting. According to the climatic and pedological conditions of the experimental site, trees grafted on FD could, depending on cultivar, be planted in densities from 519 to 1111 trees/ha. Over the 13 years, yields were 0.5 to 2.8 times greater than those of the same cultivar on the standard rootstock. ‘Tahiti’ lime cumulative planting and maintenance costs were only 1.5 times higher for a density five times as great, and the level of productivity per hectare (gross margin/ha) was 3.3 times that of traditional orchards. Grafting citrus cultivars on FD, which is seldom used in the Mediterranean zone as a result of its excessive dwarfing effect in relation with the climatic conditions, could prove, on the other hand, promising in tropical areas.
Resistance to Lettuce Aphid (Nasonovia ribisnigri) Biotype 0 in Wild Lettuce Accessions PI 491093 and PI 274378
Authors: McCreight James D. , Liu Yong-Biao
Published: February 2019

The lettuce aphid, Nasonovia ribisnigri Mosley (Hemiptera: Aphididae), is a major insect pest of lettuce, Lactuca sativa L, in many commercial lettuce production areas around the world. Resistance to lettuce aphid biotype 0 (Nr:0) was first reported in Lactuca virosa L. accession IVT 280 and characterized as complete, i.e., virtually no aphids survived, and genetically dominant to partial resistance in L. virosa accession IVT 273. Complete and partial resistances to Nr:0 were conditioned by two alleles, Nr (complete resistance) and nr (partial resistance), but the genetic relationship to susceptibility was not reported. We previously reported two new potential sources of unique genes for resistance to Nr:0 in Lactuca serriola L. accession PI 491093 and L. virosa PI 274378. We report on the genetic and phenotypic nature of resistance to Nr:0 in these two wild lettuce accessions. Resistance to Nr:0 in PI 274378 is complete and allelic to complete resistance in IVT 280. Resistance to Nr:0 in PI 491093 was partial, recessive to complete resistance in ‘Barcelona’ that was derived from IVT 280, but dominant to susceptibility in ‘Salinas’. We propose the revised gene symbols for resistance to Nr:0: Nr:0C for complete resistance and Nr:0P for partial resistance, which was originally designated as nr but may now be regarded as the symbol for susceptibility to all strains of lettuce aphid. The dominance relationships among these three alleles are Nr:0C (in IVT 280, ‘Barcelona’) > Nr:0P (in PI 491093) > nr (in susceptible genotypes). Expression of partial resistance in PI 491093 was variable in controlled infestation tests, but in a naturally infested field test provided a potentially useful level of resistance to Nr:0. Partial resistance, where complete resistance has not been widely deployed, may either alone or as a component of integrated pest management delay or prevent emergence of genotypes that overcome complete resistance controlled by Nr:0C.
Velvet Bentgrass and Creeping Bentgrass Growth, Rooting, and Quality with Different Root Zone Media and Fertility Regimes
Authors: Watson John , Hébert François , Lyons Eric M. , Blom Theo , Jordan Katerina S.
Published: February 2019

Two complementary greenhouse studies were conducted to examine the effects of different root zones and fertilization regimes on ‘SR7200' velvet bentgrass (Agrostis canina L.) and L-93 creeping bentgrass (Agrostis stolonifera L.). In the first study, in which only velvet bentgrass was studied, peat content in the root zone mixture contributed significantly to initial establishment of this species and high seeding rates increased cumulative shoot dry weight early in establishment but became less significant as the turfgrass matured. Higher phosphorus rates contributed to increased cumulative shoot dry weight over the first 4 weeks of the experiment. Nitrogen rate was the most significant factor positively affecting both cumulative shoot dry weight and turfgrass quality. In the second experiment with both velvet bentgrass and creeping bentgrass, nitrogen rate significantly increased turfgrass quality when measured at Week 5, halfway through the experiment. Over time, however, turf growth and quality were negatively impacted in both species with increasing nitrogen rates. Root zone composition had a significant effect on initial establishment of both bentgrasses with greater peat content leading to higher quality early on. Cumulative shoot dry weight increased with increasing nitrogen rate but at higher rates, there was a concomitant decrease in root production.
Seasonal Development of Dollar Spot Epidemics in Six Creeping Bentgrass Cultivars in Maryland
Authors: Ryan Christopher P. , Dernoeden Peter H. , Grybauskas Arvydas P.
Published: February 2019

This 3-year field study evaluated the incidence and severity of dollar spot (Sclerotinia homoeocarpa F.T. Bennett) in six creeping bentgrass (Agrostis stolonifera L.) cultivars maintained as a golf course fairway. Comparison of area under the disease progress curve (AUDPC) data clearly indicted two resistance groups among the six cultivars. ‘Crenshaw’ and ‘Backspin’ were classified as highly susceptible (HS) and the other four cultivars (i.e., ‘Penncross’, ‘Providence’, ‘L-93’, and ‘007’) were classified as moderately susceptible (MS) to dollar spot. In all three study years, there were three epidemics that began in May. Data could not be collected in HS cultivars after the first epidemic in each year as a result of severe damage. In MS cultivars, the first epidemic ended and a second began between early July and late August. The second epidemic ended approximately mid-October and a third epidemic appeared in MS cultivars between late October and early December. The second epidemic was longest and most severe, and the third fall epidemic was least severe and of shortest duration. The first epidemic in HS cultivars developed up to two weeks earlier and progressed more rapidly and severely than in MS cultivars. A growing degree-day (GDD) model, using a base air temperature of 15 °C and a start date of 1 Apr., was accurate in predicting the onset of the first epidemic in HS (60 to 70 GDD) and MS (105 to 115 GDD) cultivars during each of the three study years. Growing degree-day models are greatly influenced by the many microclimates found on golf courses and need to be evaluated for accuracy in diverse environments.
Development of Advanced Interspecific-bridge Lines among Cucurbita pepo, C. maxima, and C. moschata
Authors: Zhang Qi , Yu Enda , Medina Andy
Published: February 2019

Interspecific hybridization among the three most economically important cultivated species of Cucurbita spp., Cucurbita pepo, C. moschata, and C. maxima can be made but not readily. By means of various pollination measures, different mating systems, and varying selection methods, nine advanced interspecific-bridge lines were developed, in which the crossing barrier among the species and the male sterility of the F1 and subsequent generations were overcome over a 12-year period from 1999 through 2011. Despite the considerable influence of parental cultigens and environmental factors on the incompatibility of interspecific crosses, the plant and population compatibility significantly increased when a backcross with a recurrent parent in the same species or a multiple-way cross with a parent in the different species was made. As the generations advanced, the percentage of fertile seeds (PFS) significantly increased in all the sib- and self-families. The four advanced interspecific-bridge lines out of nine not only have gained the normal crossability of interspecific hybridization, but also could eliminate the sexual obstacles of the subsequent generations. The results demonstrate that a two- or three-species bridge line with crossing compatibility can be created by two- or three-species recombination and continuous selection. More importantly, the breakthrough of the advanced interspecific-bridge lines could provide a powerful platform for breeders to transfer favorable traits freely among the species and create more valuable and unique types or varieties through a conventional breeding process.