bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison of the Growth, Establishment, and Maturity of Direct-seeded and Transplanted sh2 Sweet Corn
Authors: Welbaum Gregory E. , Frantz Jonathan M. , Gunatilaka Malkanthi K. , Shen Zhengxing
Published: February 2019

Sweet corn (Zea mays L.) cultivars containing the shrunken-2 (sh2) gene have superior kernel quality but often germinate poorly and display poor seedling vigor. The transplanting of sh2 sweet corn was investigated as a method to improve stand establishment and hasten maturity. Three-week-old plants (sh2 cv. Krispy King) were raised in 200-cell polystyrene trays in either plug-trays (PT), float beds (FB), or ebb-and-flood (EF) production systems and compared with direct-seeded (DS) controls for transplant quality, successful establishment, and early harvest. In 1994, when plants were established in early June, PT plants matured 1 week earlier than DS and FB plants, which had similar mean times to harvest. In 1995, when field planting occurred in July, all plants flowered prematurely when only 60 cm tall. In 1996, the experiment was begun in early May, and survival of all transplants was >85% vs. 54% for DS plants. In 1996, transplants matured 10 to 13 days earlier than DS plants, however, >90% of DS plants produced marketable ears vs. 63%, 49%, and 44% of EF, FB, and PT plants, respectively. The DS plants were also taller with better root development than transplants in all years. Transplants produced smaller, lower-quality ears than did DS plants, thus nullifying the benefits of greater plant populations and earlier maturity. The EF system produced high-quality seedlings because of the greater control of water availability during seedling development. In some areas, the increased value of early sh2 sweet corn may be worth the additional cost of transplanting and greater percentage of unmarketable ears.
Paclobutrazol Soaked Marigold, Geranium, and Tomato Seeds Produce Short Seedlings
Authors: Pasian C.C. , Bennett M.A.
Published: February 2019

Bedding plants and many vegetable crop seeds are often sown in plug trays. Some crops, like marigold (Tagetes sp. L.), tend to stretch early after germination, especially if grown in low light environments. By the time growers apply plant growth regulators (PGRs), stretching of the hypocotyl has already occurred and seedling applications are ineffective. Seedling height may be controlled by applying the plant growth regulator directly to the seed. Seeds of `Bonanza Gold' marigold (Tagetes patula L.), `Cherry Orbit' geranium (Pelargonium {XtimesX}hortorum L.H. Bailey), and `Sun 6108' tomato (Lycopersicon esculentum Mill.) were soaked for 6, 16, or 24 hours in paclobutrazol solutions of 0, 500, or 1000 mg·L-1. After the soak treatment, seeds were dried for 24 hours prior to laboratory germination testing or sowing in plug trays. Percentage of emergence and seedling height were measured 16, 26, and 36 days after sowing. Laboratory germination of treated seeds was less than that of the control, which was attributed to the PGR being concentrated around the seed on the blotters. In contrast, seedling survival was unaffected in plugs. The higher concentration of PGR and longer times of soaking increased growth regulation, but also inhibited emergence of geraniums (71% vs. 99%). When seeds were imbibed 6, 16, or 24 hours, growth restriction was 31%, 31%, and 40%, respectively, for tomato, 61%, 37%, and 76%, respectively, for geranium and 30%, 38%, and 41%, respectively, for marigold. These results indicate that PGR application to geranium, marigold, and tomato seeds may be feasible using a 6- or 16-hour soak in 500 mg·L-1 paclobutrazol. Chemical name used: (±)-(R*,R*)-ß-[(4-chlorophenyl)methyl]-{XsalphaX}-(1,1-dimethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Wear Tolerance, Growth, and Quality of Seashore Paspalum in Response to Nitrogen and Potassium
Authors: Trenholm L.E. , Carrow R.N. , Duncan R.R.
Published: February 2019

Damage from traffic can seriously injure athletic field turfgrass, although fertility regimes can influence wear tolerance. While excess nitrogen (N) can reduce wear tolerance, moderate N has improved tolerance and hastened recovery from injury. Potassium (K) may enhance wear tolerance through regulation of turgor potential. This research was undertaken to determine shoot growth and wear tolerance of seashore paspalum (Paspalum vaginatum Swartz) to N and K application. Field studies were conducted in 1998 at the Univ. of Georgia Experiment Station, Griffin. Grasses were established on U.S. Golf Association specification greens in 1996. Fertility treatments were applied at annual N rates of 196 and 392 kg·ha-1 and K rates of 92 and 392 kg·ha-1. The higher N rate increased wear tolerance, shoot growth, shoot density, visual quality, and color of the two ecotypes, AP 10 and AP 14, but reduced their visible range spectral reflectance, indicating greater absorption of photosynthetically active radiation (PAR). Measured responses to K were minimal and no enhancement of wear tolerance in response to K treatment was noted.
Molecular Identification of Malus hupehensis (Tea Crabapple) Accessions Using Simple Sequence Repeats
Authors: Benson Laura L. , Lamboy Warren F. , Zimmerman Richard H.
Published: February 2019

The U.S. National Plant Germplasm System (NPGS) currently holds 36 separate accessions of the `Yichang' clone of Malus hupehensis (Pamp.) Rehd. The `Yichang' clone originally entered the United States in 1908 as seed collected for the Arnold Arboretum by E.H. Wilson near Yichang, Hubei Province, China. The original description of M. hupehensis omits fruit characters, and botanists frequently augment these omissions with descriptions of the `Yichang' clone. Apomixis occurs in Malus, including M. hupehensis, and is strongly associated with elevated ploidy levels. Simple sequence repeats (SSRs) were used to characterize 65 accessions of M. hupehensis. To check for polyploidy, a set of M. hupehensis accessions was evaluated with flow cytometry. The simple sequence repeat phenotypes and ploidy information revealed the `Yichang' clone under various accession names in arboreta. It was neither known nor suspected that the U.S. National Plant Germplasm System held many duplicate accessions of the `Yichang' clone prior to their molecular characterization. Germplasm conservation decisions for Malus species can benefit from an increased knowledge of the genetic variation or lack thereof in naturalized populations and ex situ collections.
Effectiveness of Natural and Engineered Host Plant Resistance in Potato to the Colorado Potato Beetle
Authors: Douches D.S. , Kisha T.J. , Coombs J.J. , Li W. , Pett W.L. , Grafius E.J.
Published: February 2019

The Colorado potato beetle, Leptinotarsa decemlineata (Say), is the most serious insect pest of potatoes throughout the eastern and north central United States. Host plant resistance to the Colorado potato beetle has been identified in wild Solanum species and Bt-transgenic potato lines. Detached-leaf bioassays (72 h) were conducted on insecticide-resistant, first instar Colorado potato beetles to study the effectiveness of individual and combined host plant resistance traits in potato. Potato lines tested include non-transgenic cultivars (`Russet Burbank', `Lemhi Russet', and `Spunta'), a line with glandular trichomes (NYL235-4), a line with high foliar leptines (USDA8380-1), and transgenic lines expressing either codon-modified Bt-cry3A or Bt-cry5 (Bt-cry1Ia1). Bt-cry3A transgenic lines, foliar leptine line, and foliar leptine lines with Bt-cry5 had reduced feeding compared to non-transgenic cultivars. Glandular trichome lines and glandular trichome lines with Bt-cry5 did not reduce feeding in this no-choice feeding study. Some Bt-cry5 transgenic lines, using either the constitutive promoters CaMV35s or (ocs)3mas (Gelvin super promoter), were moderately effective in reducing larval feeding. Feeding on Bt-cry5 transgenic lines with the tuber-specific patatin promoter was not significantly different than or greater than feeding on the susceptible cultivars. Mortality of first instars was highest when fed on the Bt-cry3A lines (68% to 70%) and intermediate (38%) on the Bt-cry5 `Spunta' line SPG3 where the gus reporter gene was not included in the gene construct. Host plant resistance from foliar leptines is a candidate mechanism to pyramid with either Bt-cry3A or Bt-cry5 expression in potato foliage against Colorado potato beetle. Without multiple sources of host plant resistance, long-term sustainability is questionable for a highly adaptable insect like the Colorado potato beetle.
Development of Molecular Techniques for Studying the Metabolism of Carotenoids in Bixa orellana L.
Authors: Narváez José A. , Flores-Pérez Patricia , Herrera-Valencia Virginia , Castillo Fernando , Ku-Cauich Roberto , Canto-Canché Blondy B. , Buzzy Nancy Santana , Rivera-Madrid Renata
Published: February 2019

The tropical plant Bixa orellana L. (annatto) is the sole source of bixin, the most frequently employed natural pigment in the food industry. Little is known about the physiology, biochemistry, and molecular genetics of this crop. Our purpose was to establish a set of analytical tools that could be applied in the genetic improvement of B. orellana, particularly for the screening of characteristics such as bixin content and resistance to diseases or pests. Some preliminary results on the study of carotenoid synthesis are presented. In vitro cultures from several B. orellana tissues were established and DNA, RNA, and proteins were extracted from them and analyzed. Similarly, bixin and total carotenoids were quantified.
Patterns of Ice Formation and Movement in Blackcurrant
Authors: Carter John , Brennan Rex , Wisniewski Michael
Published: February 2019

Ice formation and movement in stems, leaves, and flowers of blackcurrant were observed by infrared video thermography. Stem sections bearing leaves and racemes were cooled slowly to as low as -6.4 °C and allowed to freeze without artificial nucleation. Ice formed in stems first, then moved from stems into leaves and racemes. Patterns of ice movement were complex and depended upon the temperature of the initial nucleation event. Individual flowers froze between -1.6 and -5.5 °C. Survival of flowers after a cooling treatment depended upon whether they froze and the amount of freezing that occurred in the peduncles to which they were attached. Some flowers survived the initial freezing treatments but later died because of peduncle damage. Movement of ice from stems into peduncles sometimes was observed to occur in discrete steps, separated by time and temperature. Several independent freezing events were often observed in a peduncle, rather than one continuous event. Pedicels attached to frozen peduncles often remained supercooled for several minutes to over an hour before freezing. No consistent pattern was evident during freezing of individual flowers in an inflorescence. The range of temperature over which flowers in a single inflorescence froze was in some instances over 4 °C. Both mature and immature flowers supercooled. Barriers to movement of ice appeared to exist at certain anatomical junctions within the plant, notably where the peduncle of an inflorescence attaches to a stem and where a flower pedicel joins a peduncle. The time required for ice to pass through these barriers was inversely related to the degree of supercooling that had occurred prior to freezing.
Allelopathy of Bermudagrass, Tall Fescue, Redroot Pigweed, and Cutleaf Evening Primrose on Pecan
Authors: Smith Michael W. , Wolf Margaret E. , Cheary Becky S. , Carroll Becky L.
Published: February 2019

Two studies were conducted to determine if selected grass and dicot species had an allelopathic interaction with pecan (Carya illinoinensis Wangenh. C. Koch). Leachate from pots with established grasses or dicots was used to irrigate container-grown pecan trees. Leachates from bermudagrass [Cynodon dactylon (L.) Pers.], tall fescue (Festuca arundinacea Shreb. cv. Kentucky 31), redroot pigweed (Amaranthus retroflexus L.), and cutleaf evening primrose (Oenothera laciniata Hill) reduced leaf area and leaf dry weight about 20% compared to the controls. Bermudagrass, tall fescue, and primrose leachate decreased pecan root weight 17%, trunk weight 22%, and total tree dry weight 19% compared to the control. In a second study, trees were 10% shorter than the control when irrigated with bermudagrass or pigweed leachate.
Nutrient Requirements for Lettuce Transplants Using a Floatation Irrigation System II. Potassium
Authors: Soundy Puffy , Cantliffe Daniel J. , Hochmuth George J. , Stoffella Peter J.
Published: February 2019

Although floatation irrigation has numerous advantages for vegetable transplant production, including improved seedling health, lettuce (Lactuca sativa L.) transplants grown with floatation (ebb and flow) irrigation can have poor root systems. Floatation fertigation of `South Bay' transplants with K at 15, 30, 45, or 60 mg·L-1 K applied every 2 to 4 days, increased fresh and dry root weight at 28 days. Higher K (24 mg·kg-1) in the medium did not affect root weight. Fresh and dry shoot weight, leaf area, relative shoot ratio (RSR), relative growth rate (RGR), leaf weight ratio (LMR), and root weight ratio (RMR) were unaffected by applied K, regardless of the initial K concentration in the medium. Available K in a vermiculite-containing medium may have supplied all the K required. When 60 was compared with 100 mg·L-1 N at various levels of K, the applied K again did not influence dry root weight; however, at 100 mg·L-1 N, root weight was reduced as compared with 60 mg·L-1 N, regardless of the level of applied K. In a field experiment, pretransplant K had no effect on growth. Transplants grown with no added K in a peat + vermiculite mix with at least 24 mg·L-1 water-extractable K produced yields equivalent to transplants supplied with 15, 30, 45, or 60 mg·L-1 K via floatation irrigation.
Manganese Deficiency in Pecan
Authors: Smith Michael W. , Cheary Becky S. , Landgraf B. Scott
Published: February 2019

A low leaf Mn concentration was detected in bearing pecan (Carya illinoinensis Wangenh. C. Koch) trees growing in an alluvial soil with an alkaline pH. Trees lacked vigor and leaves were pale in color, but there was no discernible leaf chlorosis or necrosis. Three foliar applications of MnSO4 beginning at budbreak, then twice more at 3-week intervals at rates of 0 to 3.3 kg·ha-1 of Mn increased leaf Mn concentration curvilinearly, and alleviated leaf symptoms. Results indicated that three foliar applications of MnSO4 at 2.15 kg·ha-1 of Mn plus a surfactant were adequate to correct the deficiency.
Fruit of Autumn Olive: A Rich Source of Lycopene
Authors: Fordham Ingrid M. , Clevidence Beverly A. , Wiley Eugene R. , Zimmerman Richard H.
Published: February 2019

Autumn olive (Elaeagnus umbellata Thunb.) has edible fruit with brilliant red or yellow pigmentation. An analysis of the pigment in fruit of five cultivars and six naturalized plants showed that the berries contain lycopene, α-cryptoxanthin, β-cryptoxanthin, β-carotene, lutein, phytoene, and phytofluene. The lycopene content per 100 g ranged from 15 to 54 mg in fresh fruit from the naturalized plants and from 17 to 48 mg in the four cultivars with red-pigmented fruit. A cultivar with yellow fruit had only 0.47 mg/100 g fresh fruit. In contrast, fresh tomato fruit, the major dietary source of lycopene, has a lycopene content per 100 g of ≈3 mg. This newly identified source of lycopene may provide an alternative to tomato as a dietary source of lycopene and related carotenoids.
Inducible Calcium Sinks and Preferential Calcium Allocation in Leaf Primordia of Dracaena sanderiana Hort. Sander ex M.T. Mast. (Dracaenaceae)
Authors: Pennisi Svoboda V. , McConnell Dennis B.
Published: February 2019

The effect of 0, 3, and 7 mm Ca2+ on the allocation and deposition of Ca2+ into intracellular and sub-cuticular periplasmic calcium oxalate (CO) crystals was examined in leaf primordia of rooted cuttings of Dracaena sanderiana Hort. Sander ex M.T. Mast. Crystal development was monitored in two types of cuttings, those rooted in deionized water for 18 months and those rooted in Metro Mix 500 for 6 weeks. Response differed remarkably depending on the type of cutting. Cuttings rooted in deionized water deposited sub-cuticular crystals at the expense of intracellular crystals (raphides). The number of sub-cuticular crystals in leaf primordia of cuttings rooted in deionized water grown in solutions supplemented with either 0, 3, or 7 mm Ca2+ was similar, but crystals were considerably smaller in plants grown in 0 mm Ca2+. Sub-cuticular crystals appeared developmentally earlier in leaf primordia of all cuttings grown in either 3 mm or 7 mm Ca2+ than in cuttings rooted in deionized water grown in 0 mm Ca2+. This finding supports the premise that deposition of sub-cuticular crystals is modulated by Ca2+ levels and could be induced at an earlier ontogenetical stage by raising rhizospheric Ca2+ levels or delayed by lowering rhizospheric Ca2+ levels. The total number of sub-cuticular crystals per epidermal cell did not differ significantly between treatments implying that crystal nucleation sites are predetermined and finite in number. In contrast, the formation of intracellular raphides was highly variable and depended on Ca2+ concentrations. In terms of Ca2+ prioritization, sub-cuticular CO crystals took precedence over intracellular CO raphides.
Mulch Color Affects Radicchio Quality and Yield
Authors: Rangarajan Anusuya , Ingall Betsy
Published: February 2019

Interest in the production of the specialty vegetable radicchio (Cichorium intybus L. var. silvestre Bisch.) has increased among vegetable growers in the northeastern United States due to the popularity and consumption of premixed prepared salads. Growing environments with moderate daytime temperature and high light level have been associated with dense, deep red heads. Production problems include the low percentage of plants producing marketable heads and labor costs associated with hand-weeding. Traditional bareground culture was compared with several colored mulches (white, silver, red, black, and blue) for their effects on head formation, size, yield, and color of two Italian cultivars. Field studies were conducted in Freeville (upstate), N.Y., in 1997 and 1998. The percentage of heads harvested ranged from 32% to 82% over the 2 years of experiments and was lowest in black and red plastic mulch treatments. Yields were significantly higher, heads larger, and harvest earlier for plants grown over silver and white mulch compared to the control and other mulch treatments in 1998. In addition, average head weight was greater in all mulch treatments except blue when compared with the control. Cultivar differences were measured for the number and weight of heads, the percent bolting and marketable heads, and head color in 1998. Air and soil temperatures varied significantly around these mulches; however, these differences in microclimate had no effect on head color quality. Despite relatively moderate temperatures in upstate New York, radicchio responded positively to mulches that lowered average soil temperatures (white and silver) compared with the other treatments.
Nitrogen Nutrition of Greenhouse Pepper. II. Effects of Nitrogen Concentration and NO3: NH4 Ratio on Growth, Transpiration, and Nutrient Uptake
Authors: Bar-Tal A. , Aloni B. , Karni L. , Rosenberg R.
Published: February 2019

The objective of this research was to study the effects of N concentration and N-NO3: N-NH4 ratio in the nutrient solution on growth, transpiration, and nutrient uptake of greenhouse-grown pepper in a Mediterranean climate. The experiment included five total N levels (0.25 to 14 mmol·L-1, with a constant N-NO3: N-NH4 ratio of 4) and five treatments of different N-NO3: N-NH4 ratios (0.25 to 4, with a constant N concentration of 7 mmol·L-1). Plants were grown in an aero-hydroponic system in a climate-controlled greenhouse. The optimum N concentrations for maximum stem and leaf dry matter (DM) production were in the range of 8.0 to 9.2 mmol·L-1. The optimum N-NO3: N-NH4 ratio for maximal stem DM production was 3.5. The optimum value of N concentration for total fruit DM production was 9.4 mmol·L-1. Fruit DM production increased linearly with increasing N-NO3: N-NH4 ratio in the range studied. The N concentration, but not N source, affected leaf chlorophyll content. Shorter plants with more compacted canopies were obtained as the N-NO3: N-NH4 ratio decreased. The effect of N concentration on transpiration was related to its effect on leaf weight and area, whereas the effect of a decreasing N-NO3: N-NH4 ratio in reducing transpiration probably resulted from the compacted canopy. Nitrogen uptake increased as the N concentration in the solution increased. Decreasing the N-NO3: N-NH4 ratio increased the N uptake, but sharply decreased the uptake of cations, especially Ca.
Fungicidal Effectiveness of Electrolyzed Oxidizing Water on Postharvest Brown Rot of Peach
Authors: Al-Haq Muhammad Imran , Seo Y. , Oshita S. , Kawagoe Y.
Published: February 2019

The fungicidal effectiveness of electrolyzed oxidizing (EO) water on peach [Prunus persica (L.) Batsch.] fruit was studied. Fruit were inoculated with a spore suspension of 5 × 105 conidia/mL of Monilinia fructicola [(G. Wint.) Honey] applied as a drop on wounded and nonwounded fruits, or by a uniform spray-mist on nonwounded fruits. Fruit were immersed in tap water at 26 °C for 5 or 10 minutes (control), or treated with EO water varying in oxidation-reduction potential (ORP), pH, and free available chlorine (FAC). Following treatment, fruit were held at 20 °C and 95% relative humidity for 10 days to simulate retail conditions. Disease incidence was determined as the percentage of fruits showing symptoms of the disease, while severity was expressed as lesion diameter. EO water did not control brown rot in wound-inoculated fruits, but reduced disease incidence and severity in nonwound-inoculated peach. Symptoms of brown rot were further delayed in fruit inoculated by a uniform-spray mist compared with the nonwounded-drop-inoculated peaches. Fruit treated with EO water held for 8 days at 2 °C, 50% RH, did not develop brown rot, until they were transferred to 20 °C, 95% RH. The lowest disease incidence and severity occurred in fruit immersed in EO water for up to 5 minutes. EO water having pH 4.0, ORP 1,100 mV, FAC 290 mg·L-1 delayed the onset of brown rot to 7 days, i.e., about the period peach stays in the market from a packing house to consumer. No chlorine-induced phytotoxicity was observed on the treated fruit. This study revealed that EO water is an effective surface sanitizer, but only delayed disease development.
Winter Pruning Affects Yield Components of 'Black Satin' Eastern Thornless Blackberry
Authors: Takeda Fumiomi
Published: February 2019

Nine-year-old 'Black Satin' blackberry (Rubus subgenus Rubus) plants were dormant pruned to three floricanes with three, six, nine, or twelve 12-node lateral branches (≈108, 216, 324, or 432 axillary buds per plant) to determine the effect of lateral branch number on budbreak, fruit cluster number, fruit number per cluster, fruit weight, total soluble solids (TSS), and yield. Percent budbreak of primary and secondary axillary buds was reduced as the lateral branch number increased. Pruning did not affect fruit weight (6.4 g) or TSS (9.5%). Yield per lateral branch was reduced as lateral branch number increased. A plant with three floricanes, each with 12 lateral branches, produced 21 kg of fruit. The results indicate that pruning lateral branches to a manageable length may be advantageous for eastern thornless blackberry trained on a divided canopy trellis.
Sequentially Reducing Sulfate Fertility During Onion Growth and Development Affects Bulb Flavor at Harvest
Authors: Randle William M. , Kopsell David E. , Kopsell Dean A.
Published: February 2019

A major decision in producing onions with mild flavor on low sulfur soils is determining when to stop applying SO4-2 to the crop. Sulfate (SO4-2) is necessary for good early growth, but high levels of available SO4-2 late in the season increase bulb pungency. The objective of this research was to determine how sequentially reducing the availability of SO4-2 during onion growth and development would affect flavor intensity and quality of Granex-type onions. Starting 77 days before harvest, SO4-2 concentrations were lowered from 1 mm to 0.05 mm on different blocks of onions in a greenhouse experiment at bi-weekly intervals. Total leaf and bulb S were measured at harvest to monitor S accumulation as SO4-2 fertility was sequentially reduced. Bulbs were harvested and analyzed for flavor precursors and their biosynthetic intermediates, gross flavor intensity as measured by enzymatically developed pyruvic acid (EPY), and soluble solids content. As SO4-2 fertility reductions were delayed during the experiment, total leaf and bulb S increased linearly. In addition, bulb EPY concentrations increased linearly as SO4-2 reduction was delayed, indicating increases in overall flavor intensity. While the total concentration of flavor precursors did not significantly change in response to lowering SO4-2 fertility during the experiment, the concentrations of MCSO to 1-PRENCSO did. MCSO concentration decreased and then increased in a quadratic manner. MCSO produces fresh onion and cabbage like flavors. 1-PRENCSO, on the other hand, increased linearly as the high SO4-2 fertility level was extended through bulb maturation. Increasing concentrations of 1-PRENCSO causes onions to have significantly more heat and mouth burn when eaten. Reducing available SO4-2 49 days prior to harvest coincided with a reduction in EPY and a change in the flavor biosynthetic pathway that appeared to be associated with the metabolic changes occurring with the onset of bulbing. Chemical names used: enzymatically developed pyruvic acid (EPY); methyl cysteine sulfoxide (MCSO); 1-propenyl cysteine sulfoxide (1-PRENCSO).
Nitrogen Form Affects Growth, Mineral Nutrient Content, and Root Anatomy of Cotoneaster and Rudbeckia
Authors: Kraus Helen T. , Warren Stuart L. , Anderson Charles E.
Published: February 2019

Five ratios of NH4+: NO3-(100:0, 75:25, 50:50, 25:75, and 0:100) were evaluated for impact on growth of Cotoneaster dammeri Schneid. `Skogholm' (cotoneaster), a woody ornamental shrub, and Rudbeckia fulgida Ait. `Goldsturm' (rudbeckia), an herbaceous perennial. Nitrate alone decreased dry weight and leaf area of cotoneaster and rudbeckia compared with mixtures of NH4+ and NO3- and NH4+ alone. Additionally, NO3- alone suppressed accumulation of cationic nutrients and N in cotoneaster, while mixes of NH4+ and NO3- enhanced accumulation of nutrients in roots and shoots of rudbeckia compared with solutions containing either NH4+ or NO3- alone. The steles of roots of cotoneaster and rudbeckia contained more secondary xylem with larger tracheary elements with a mix of 25 NH4+: 75 NO3- than with NO3- alone.
Genotypic Variation in Prolonged Dormancy Symptoms in Apple Progenies
Authors: Labuschagné Iwan , Louw Bill , Schmidt Karin , Sadie Annalene
Published: February 2019

The variability of characteristics associated with prolonged dormancy in apple (Malus ×domestica Borkh.) progenies planted in the Western Cape region of South Africa was recorded over a three-year period. The time of initial vegetative and reproductive budbreak, the number of vegetative and reproductive budbreak, and the flowering duration were used as criteria. Data were collected on bearing trees of apple seedling families where the cultivars Anna and Golden Delicious were used as a common parent. Analysis of variance detected significant variation among seedling families for time of budbreak, number of breaking buds, and flowering duration in `Golden Delicious' families. `Braeburn' × `Golden Delicious' consistently produced seedlings with higher numbers of breaking buds and `Golden Delicious' × `Prima' showed significantly lower numbers than other `Golden Delicious' families. In `Anna' families, significant differences were found for time of budbreak. `Anna' families showed higher variability within families than `Golden Delicious' families. Comparisons of progenies of `Anna' and `Golden Delicious' showed large differences in variation for the time of budbreak and for duration of flowering. Mean budbreak of `Anna' progenies did not differ from `Golden Delicious' progenies. Associations were found between initial time of budbreak and number of breaking buds as well as time and flowering duration. Results reveal high genetic variance in prolonged dormancy symptoms among seedlings within apple families which can be directly ascribed to high levels of heterozygosity in the cultivars used, and should be further explored for the purposes of breeding and selection.
Division Size and Shade Density Influence Growth and Container Production of Hakonechloa macra Makino 'Aureola'
Authors: Harvey Michael P. , Brand Mark H.
Published: February 2019

Hakonechloa macra Makino 'Aureola' is an ornamental, shade tolerant landscape grass that grows slowly and commands high prices. Hakonechloa plants grown from four initial division sizes, of 1-2, 4-6, 8-10, or 12-15 tiller buds, were evaluated following a complete growing season (105 days). Based on visual observation, we rated 100% of plants grown from the two larger division sizes to be salable compared with only 30% of those from divisions containing 4-6 growing points, and none from the smallest division size. However, divisions of 1-2 tiller buds produced twice as many new shoots and tiller buds per initial tiller bud as did larger division sizes. To produce salable plants in one growing season, results suggest the use of 8-10 tiller bud divisions, but for propagation and increase of stock material, where it is important to obtain the greatest number of new growing points per initial growing point, use of the smaller division sizes is indicated. Hakonechloa plants were grown under shading densities of 0%, 30%, 50%, or 70% provided by polypropylene shade cloth. Shading increased overall growth and improved the appearance and leaf color of Hakonechloa, but at 70% shade density, plants appeared languid and open. For this reason, 50% shading is recommended for nursery production of Hakonechloa macra 'Aureola'.
Tolerance to Quinclorac by Seedling Creeping Bentgrass
Authors: Reicher Zachary J. , Hardebeck Glenn A. , Yelverton Fred F. , Christians Nick E. , Bingaman Barbara , Turner Jay
Published: February 2019

Annual grassy weeds often inhibit establishment of spring-seeded creeping bentgrass (Agrostis palustris Huds.) on golf courses. The objective of this experiment was to evaluate the safety of the annual grass herbicide quinclorac in spring-seeded creeping bentgrass in varying climatic regions of the United States. Experiments were initiated in Indiana, Iowa, and North Carolina in Spring 2000. Treatments included siduron at 6.72 kg·ha-1 a.i. applied immediately prior to planting (PRE), and quinclorac at 0.84 kg·ha-1 a.i. applied 7 days before seeding (DBS), PRE, and 14 or 28 days after emergence (DAE). Herbicides were applied to three creeping bentgrass cultivars at each location. Siduron reduced establishment of `Providence', `L93', and `Putter' creeping bentgrass in Indiana. Quinclorac applied PRE, 14 DAE, and 28 DAE caused short-term phytotoxicity, primarily in `Providence' in Indiana. Quinclorac applications did not significantly affect cover of `Providence', `L93', or `Putter' in Indiana or `L93', `Pennlinks', or `Penncross' in Iowa. All applications of quinclorac reduced cover of `L93', `Pennlinks', and `Penncross' in North Carolina. Though quinclorac applications resulted in no long-term damage when applied to creeping bentgrass seedlings in Indiana or Iowa, results from North Carolina indicate that caution should be exercised when using quinclorac on seedlings of creeping bentgrass. Chemical names used: 3,7-dichloro-8-quinolinecarboxylic acid (quinclorac); 1-(2-methylcyclohexyl)-3-phenylurea (siduron).
Turf Performance of Mixtures and Blends of Tall Fescue, Kentucky Bluegrass, and Perennial Ryegrass
Authors: Dunn John H. , Ervin Erik H. , Fresenburg Brad S.
Published: February 2019

Various mixtures of tall fescue, Festuca arundinacea Schreb., Kentucky bluegrass, Poa pratensis L., and perennial ryegrass, Lolium perenne L., may be beneficial for turf culture because of genetic diversity and improved tolerance to environmental stresses compared with a single species. Turf-type tall fescue, dwarf tall fescue, Kentucky bluegrass, and perennial ryegrass were seeded as cultivar blends and in all possible combinations as species mixtures in two locations, irrigated and nonirrigated. Turf was mowed at 19 and 51 mm and subjected to an interval of brief, but intensive, simulated traffic. Perennial ryegrass was the dominant species in all mixtures with tall fescue, Kentucky bluegrass, or both. After 5 years, turf-type tall fescue comprised 62% of mixtures with Kentucky bluegrass when averaged over locations. Dwarf tall fescue comprised 48% of mixtures compared with Kentucky bluegrass at 44%. Kentucky bluegrass was more competitive with tall fescue in the irrigated vs. nonirrigated location. Mowing height effected small changes in populations year to year while simulated traffic had little effect on populations at 1 year following treatment. The advantage of mixing species compared with individual species to reduce disease occurrence was evident on several occasions. Our study supports earlier research reports that tall fescue will remain competitive in mixture with Kentucky bluegrass several years after seeding.
Optical Properties of Paper and Polyethylene Mulches Used for Weed Control in Lettuce
Authors: Brault D. , Stewart K.A. , Jenni S.
Published: February 2019

Optical properties of paper and plastic mulches were determined in experiments on mulched head lettuce (Lactuca sativa L.) grown in organic soil in 1997-98. Mulches used in 1997 were a coextruded white/black polyethylene, a beige paper coated with latex on both sides and a black paper coated with latex on both sides. Three supplementary mulches were added in the 1998 experiment: beige paper coated with a biodegradable polymer either coated on the underside, on the top side or on both sides. Optical properties of the polyethylene mulch remained stable over the course of the experiment. As the paper mulches aged, they changed structurally, spectrally, or both, but remained in place until harvest. The black paper was the only mulch that offered complete weed control, although the weeds under the other mulches did not develop beyond the cotyledonary or two-true-leaf stage.
A Survey of Fruit Firmness in Highbush Blueberry and Species-introgressed Blueberry Cultivars
Authors: Ehlenfeldt Mark K. , Martin Robert B.
Published: February 2019

Eighty-seven highbush blueberry and species-introgressed blueberry cultivars were evaluated for fruit firmness in the 1998-2000 growing seasons with a FirmTech 1 automated firmness tester. Significant differences were observed among cultivars. An average firmness of 136.1 g·mm-1 of deflection (g·mm-1 dfl) was observed across all studied cultivars, and a range of 80.4 g·mm-1 dfl (`Herbert') to 189.0 g·mm-1 dfl (`Pearl River'). Species ancestry was not consistently related to firmness; however, cultivars with higher firmness values often possessed a higher percentage of Vaccinium darrowi Camp and V. ashei Reade ancestry. Conversely, cultivars with softer than average fruit often possessed a higher percentage of lowbush (V. angustifolium Ait.) ancestry. This information may help to identify sources of breeding material for increased firmness in highbush blueberry hybrids.
α-L-Arabinofuranosidase Activity during Development and Ripening of Normal and ACC Synthase Antisense Tomato Fruit
Authors: Sozzi Gabriel O. , Fraschina Adela A. , Navarro Agustín A. , Cascone Osvaldo , Greve L. Carl , Labavitch John M.
Published: February 2019

α-l-Arabinofuranosidases (α-Af) are plant enzymes that have the capacity to release terminal arabinofuranosyl residues from a wide variety of pectic and hemicellulosic polymers, as well as different glycoconjugates. Our interest in α-Af is related to its potential role in ripening-related loss of arabinose from tomato fruit cell walls. Using both control (cv. VF 36) and ACC synthase antisense (A11.1) tomatoes (Lycopersicon esculentum Mill.), we demonstrate that tomato α-Af activity is present during the entire ontogeny of the fruit. Immature 10-day-old fruit displayed 6-fold more α-Af activity on a per gram fresh weight basis, than mature green fruit. In VF 36 fruit, α-Af activity increased 45% from mature green 4 (48 days post anthesis) to light red stages (55 days) when fruit ripened on the vine. In contrast, no similar increase was detected in ACC synthase antisense fruit that do not ripen in the same time frame. However, when A11.1 fruit were detached at 48 days after anthesis and treated continuously with 100 mL·L-1 ethylene the fruit ripened and α-Af increased, as in ripening normal fruit. The α-Af activity pattern is similar to that reported for tomato β-galactosidases. The increasing α-Af activity during ripening and the decreased activity in antisense ACC synthase fruit after reaching the mature green stage suggest a role for ethylene in the ripening-related synthesis or activation of this enzyme.
Mapping of Quantitative Trait Loci Involved in Ornamental Traits in Alstroemeria
Authors: Han Tae-Ho , van Eck Herman J. , De Jeu Marjo J. , Jacobsen Evert
Published: February 2019

An F1 population, derived from an intraspecific cross between two Alstroemeria aurea accessions, was used to map quantitative trait loci (QTL) involved in ornamental and morphological characteristics. One QTL for leaf length was mapped on linkage group three of both parents near marker E+ACCT/M+CGCA-I165 explaining 20% and 14.8% phenotypic variation. Two putative QTL were detected on leaf width on A002-3 and A002-6. One QTL and three putative QTL, involved in the leaf length/width ratio were identified accounting for 46.7% of the phenotypic variance in total. Significant interaction was observed between two QTL, S+AC/M+ACT-I162 and S+AC/M+AGA-I465 in a two-way analysis of variance (ANOVA). For the main color of the flower one QTL and putative QTL accounted for up to 60% of phenotypic variance suggesting simple genetic control of flower color. A two-way ANOVA of these QTL suggested an epistatic interaction. A QTL was detected for color of the inner side of outer lateral tepal with 26.5% of the phenotypic variance explained. This QTL was also associated with main color of the flower just below the 95% threshold value. Two QTL were detected with the Kruskal-Wallis test for the tip color of inner lateral tepal near QTL for other flower color traits. Consequently flower color traits were significantly correlated. A QTL and a putative QTL for the flower size was mapped near marker E+ACCG/M+CGCT-I193 and E+ACCG/M+CGCG-197, respectively. One putative QTL was detected for the stripe width of the inner lateral tepal.
Resistance to Phytophthora Root Rot in Contemporary Rhododendron Cultivars
Authors: Krebs Stephen L. , Wilson Michael D.
Published: February 2019

Fifty-seven rhododendron cultivars (genus Rhododendron L.) were screened for resistance to root rot caused by Phytophthora cinnamomi, using two levels of inoculum. While a majority (77%) of genotypes was susceptible, six cultivars had moderate resistance, and seven cultivars exhibited a high level of resistance to the disease. In these resistant groupings, the severity of root rot did not increase significantly with a 3-fold increase in inoculum. Comparisons of micropropagated and conventionally propagated plants revealed no significant difference in root rot ratings. The species R. keiskei was identified as a possible source of resistance to P. cinnamomi in two of the rhododendron cultivars.
Resistance of Impatiens Germplasm to Western Flower Thrips Feeding Damage
Authors: Herrin Bejie , Warnock Daniel
Published: February 2019

Western flower thrips (WFT) [Frankliniella occidentalis (Pergande)] are an ever-present problem in greenhouse floricultural crops. To determine if host plant resistance varied in impatiens [Impatiens wallerana Hook. f.] nine genotypes were evaluated for resistance to WFT feeding damage. Individual insect-free plants of each genotype were inoculated with ≈30 laboratory-reared WFT. Thrips were allowed to feed on individual plants for a 4-week period during which visual evaluations were conducted every 2 weeks to estimate feeding damage. Feeding damage varied among genotypes and increased with time. At 4 weeks after inoculation, `Cajun Carmine' and `Super Elfin Lavender' had significantly less feeding damage than all other genotypes. The San Vito Wild-type germplasm was determined to be highly susceptible to thrips feeding damage based on visual evaluations. Because WFT feeding damage varied among genotypes, the potential for improving impatiens resistance to WFT exists within commercially available germplasm.
Evaluation of Methods for Flowering Advancement of Herbaceous Peonies
Authors: Halevy Abraham H. , Levi Menashe , Cohen Menashe , Naor Vered
Published: February 2019

Experiments to advance early production of herbaceous peony (Paeonia lactiflora Pall.) flowers were conducted over 8 years in the higher elevation, cooler regions of Israel. Anatomical studies during the summer revealed that flower bud initiation of apical buds in the crowns began at the end of July and continued also in lateral buds from mid-August until the plants became dormant in mid-November. Container-grown plants of various cultivars were moved to cold rooms maintained for 10 to 13 weeks at 2 °C, from mid-August to mid-October, then drenched with 250 mL of various concentrations of GA3 and transferred to a greenhouse. The optimal GA3 concentration for flower production was 100 mg·L-1. Plants treated in this way flowered 2-3 months before the natural flowering period. Field-grown plants in uncovered greenhouse structures were exposed to natural winter cold temperatures (0-10 °C), until they had received various chill units according to a “dynamic model” (for details see Erez et al., 1988). The crowns were then drenched with various amounts and concentrations of GA3, and the greenhouses were covered with plastic sheets. The optimal chill units for most cultivars was 40 and the optimal GA3 drench treatment was 250 mL of 100 mg·L-1. Covered and GA3-treated field-grown plants flowered ≈1 month earlier than untreated plants grown in the open field. The GA3 treatment also greatly increased the number of produced flowers.
Drip Irrigation Management Affects Celery Yield and Quality
Authors: Breschini S.J. , Hartz T.K.
Published: February 2019

Trials in nine commercial celery (Apium graveolens L.) fields were conducted between 1997-99 to evaluate grower drip irrigation management practices and their effects on yield and quality. Surface drip irrigation tapes with flow rates higher and lower than the grower-installed tapes were spliced into the field system; as the cooperating growers irrigated and applied N fertigation according to their routine practices these drip tapes delivered either more or less water and N than the field drip system. Total grower water application during the drip-irrigated portion of the season ranged from 85% to 414% of seasonal reference evapotranspiration (ETo). Water volume per irrigation varied among fields from 1.8 to 3.8 cm, with irrigation frequency varying from an average of every other day to once a week. Grower management of drip irrigation was not consistently successful in maintaining soil water tension (SWT) in a desirable range. SWT was often below -30 kPa, and in some cases below -70 kPa. These transient stresses were more often a result of inappropriate irrigation frequency than applied water volume. In four of the fields plots receiving less water than that delivered by the field system produced equivalent marketable yield and quality, indicating a significant potential for water savings. An economically important incidence of petiole pithiness (collapse of parenchyma tissue) was observed in four fields. Infrequent irrigation under high ETo summer conditions, rather than irrigation volume applied, appeared to be the major factor in pith development. N fertigation amount and crop N status appeared to be unrelated to pithiness severity. We conclude that celery drip irrigation management could be substantially improved by maintaining a closer proportionality between irrigation and crop evapotranspiration (ETc), increasing irrigation frequency, and reducing volume per irrigation.
Compatibility of Acaricide Residues with Phytoseiulus persimilis and Their Effects on Tetranychus urticae
Authors: Cote Kenneth W. , Lewis Edwin E. , Schultz Peter B.
Published: February 2019

The twospotted spider mite, Tetranychus urticae Koch, is a serious pest of many nursery crops. Regular acaricide applications are required to maintain acceptable population levels of this pest. Phytoseiulus persimilis Athias-Henriot is a commercially available predator used to control T. urticae populations. The effects of acaricide residues were tested on P. persimilis and T. urticae using a leaf disk system. Both species were exposed to residues for 24 hours 1, 3, 7, and 14 days after acaricide application. Abamectin, Gowan 1725, hexythiazox, horticultural oil, neem oil, pyridaben, and spionosyn residues caused no mortality to P. persimilis 1, 3, 7, or 14 days after application. Chlorfenapyr was harmful to both species at all times after application. Bifenthrin residue was toxic to P. persimilis at all times after application, but was only harmful to T. urticae up to one week after application. Tetranychus urticae mortality from Gowan 1725, horticultural oil, and neem oil residues was significantly greater than the control 24 hours after application, but not thereafter. Tetranychus urticae mortality from hexythiazox and spinosad residues was not significantly greater than the control. Proper pesticide selection may create favorable conditions for release of P. persimilis and reduce acaricide dependency.
Cooling Method and Fruit Weight: Efficacy of Hot Water Quarantine Treatment for Control of Mexican Fruit Fly in Mango
Authors: Shellie K.C. , Mangan R.L.
Published: February 2019

The objective of this research was to determine whether immediate cooling of mangoes (Mangifera indica L.) in water or air affected survival of Mexican fruit fly (Anastrepha ludens Loew) larvae. Two tests were conducted with mortality of late third instar Mexican fruit fly larvae evaluated after infested mangoes were immersed in 46.1 °C water for 65, 75, or 90 minutes depending on fruit weight and immediately cooled in water or air at 22 to 26.5 °C. Results suggest a need to amend the current hot water quarantine dip treatment schedule to require cooling of fruit for 30 minutes in air. We suggest a 25-g allowance in maximum permitted fruit weight be established for the 65-, 75-, and 90-minute dips and a monitoring system used to ensure compliance. Synchronization between maximum permitted fruit weight for each hot water dip duration and commercial sizing practices would facilitate monitoring of fruit weight. We also recommend confirmation of efficacy for the 75-minute treatment of flat-elongated mangoes that weigh 375-570 g.