bluuebunny/crossref_metadata_2025 huggingface dataset:
Broadleaf Weed Control and Cabbage Seed Yield following Herbicide Application
Authors: Al-Khatib Kassim , Libbey Carl , Kadir Sorkel
Published: February 2019

Broadleaf weed control with trifluralin, oxyfluorfen, pendimethalin, clopyralid, pyridate, and metolachlor in cabbage (Brassica oleracea L.) grown for seed was evaluated. No single herbicide controlled broadleaf weeds adequately, with the exception of pendimethalin at 1.92 and 3.84 kg a.i./ha. However, combinations of trifluralin + oxyfluorfen, pendimethalin + clopyralid, and oxyfluorfen + pyridate effectively controlled weeds and did not reduce seed yields. Herbicides caused slight to moderate injury symptoms to cabbage plants, with the greatest injury caused by pendimethalin and the least by trifluralin and metolachlor. However, plants recovered from these symptoms and appeared normal at the bud stage. None of the herbicides applied alone or in combinations adversely affected cabbage population, height, or flowering date. Chemical names used: 3,6-dichloro-2-pyridinecarboxylic acid (clopyralid); 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene (oxyfluorfen); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); O-(6-chloro-3-phenyl-4-pyridazin-yl)S-octylcarbonothioate (pyridate); 2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine (trifluralin).
Deficit Irrigation to Control Vegetative Growth in Apple and Monitoring Fruit Growth to Schedule Irrigation
Authors: Ebel Robert C. , Proebsting Edward L. , Evans Robert G.
Published: February 2019

A standard fruit growth curve, used commercially as an aid to hand thinning, was compared to periodic volume measurements of apple fruit (Malus domestica Borkh. `Delicious') subjected to early season regulated deficit irrigation (RDI) to determine when to end RDI, which is used to control vegetative growth and save water. RDI suppressed stem water potential, stomatal conductance, and fruit growth rate compared to the trickle- and furrow-irrigated controls, which wetted about one-half and the entire soil volume, respectively. Full irrigation was restored to RDI trees by trickle and microsprinklers, which wetted about one-half and the entire soil volume, respectively, after terminal buds set. Stem water potential, stomatal conductance, and fruit growth rate of RDI trees increased to that of the controls, except for RDI/trickle trees, which had 80% the stomatal conductance of the other treatments. Fruit weight at harvest was affected by an interaction of irrigation treatment and cropload. RDI trees had similar or less vegetative growth and similar or higher yield efficiency than the controls. We recommend ending RDI before fruit growth declines below the standard curve.
Drastic Changes of Endogenous Phytohormones in Dormant Gladiolus Corms Treated with Methyl Disulfide
Authors: Hosoki Takashi
Published: February 2019

Effects of methyl disulfide (MeS2) on sprouting and phytohormones in dormant corms of spring-flowering gladiolus (Gladiolu×Tubergenii Hort. `Charm') were studied. Corms treated with MeS2 sprouted 30 days earlier than nontreated corms. The concentrations of endogenous promoters in the corm tissue increased and inhibitors decreased within 24 h of treatments. High concentration of inhibitors were present in the nontreated corms.
Response of Central European Pyrus Germplasm to Natural Fire Blight Infection and Artificial Inoculation
Authors: van der Zwet Tom , Bell Richard L.
Published: February 2019

Of 133 Pyrus accessions (predominantly P. communis L.), collected in Central Europe and previously rated in the resistant U.S. Dept. of Agriculture (USDA) blight scores 10–6, only 77 (57.0%) remained in these scores after an additional 5 years of exposure to fire blight [Erwinia amylovora (Burr.) Winsl. et al.]. Of these, 24 originated from three states in former Yugoslavia. Following several years of severe blight epiphytotics, only 5 (10.4%) of 52 accessions released from quarantine since 1986 and planted at Appalachian Fruit Research Station scored 6 or above. All accessions were highly susceptible to artificial blossom inoculation, and only 10 accessions were at least moderately resistant to artificial shoot inoculations.
Screening Pyrus Germplasm for in Vitro Rooting Response
Authors: Reed Barbara M.
Published: February 2019

Micropropagated shoots of 49 Pyrus species and cultivars and one selection of Pyronia veitchii (Trabut) Guillaumin were evaluated to test their responses to several in vitro rooting techniques. Auxin treatment was required for rooting in most cases. Eighteen of 50 accessions rooted ≥50% with a 15-second, 10-mm IBA dip followed by growth on medium with no growth regulators (NGR). Twelve accessions rooted on a medium with 10 μm IBA applied for 1 week followed by NGR medium for 3 weeks; NGR medium alone was effective for only two accessions. Twenty-eight accessions rooted poorly with IBA treatments; an additional treatment of a 15-second dip in 10 mm NAA followed by NGR medium produced ≥50% rooting for eight genotypes. Root production increased for 10 of 19 especially recalcitrant genotypes by 10 μm IAA treatments in darkness or at 30C and NAA dip treatments. Of rooted shoots, 73% survived acclimation in the greenhouse. Selections of Pyrus betulifolia Bunge, P. calleryana Decne., P. hondoensis Kikuchi and Nakai, P. koehnei C. Schneider, P. pashia Buch.-Ham. ex D. Don, P. pyrifolia (Burm.f.) Nakai cv. Shinseiki, P. regelii Rheder, P. ussuriensis Maxim., and the Pyronia veitchii selection failed to root in any of the treatments. Twenty-five of 32 P. communis L. cultivars and three other species rooted on at least one of the treatments. Chemical names used: 1-naphthaleneacetic acid (NAA), 1H-indole-3-butyric acid (IBA), 1H-indole-3-acetic acid (IAA).
Flowering of Eustoma grandiflorum (Raf.) Shinn. Cultivars Influenced by Photoperiod and Temperature
Authors: Harbaugh Brent K.
Published: February 2019

Seedling growth and flowering responses were examined for four Eustoma cultivars exposed to photoperiod × temperature treatments during two seedling ages. Seedlings were grown under short days (SD, 12-hour photoperiod) or long days (LD, 18-hour photoperiod) in soil at 12 or 28C from 14 to 43 days after sowing. Seedlings from each treatment were then subdivided into four lots and subjected to the same photoperiod × temperature treatments from 43 to 79 days after sowing, for a total of 16 treatments. To determine flowering response, seedlings were grown subsequently for 120 days at 22C under the same photoperiod that they received from day 43 to 79. For all cultivars and both seedling ages, seedlings were larger and had more leaves when grown at 28C rather than at 12C, but the tallest plants at flowering were from seedlings exposed to 12C. Seedlings from some treatments bolted but did not initiate visible flower buds, and some seedlings developed visible buds that later aborted, resulting in plants that did not flower by the termination of the experiment (199 days). Cultivar and interactive effects of photoperiod and temperature influenced the percentage of flowering plants. Vegetative growth and flowering responses were similar for `Yodel White', `Heidi Pink', and `Blue Lisa'. They flowered as LD plants when seedlings were grown at 12C from day 14 to 43 or day 43 to 79. Seedlings of these cultivars that were grown under SD at 28C from day 43 to 79 did not flower, regardless of photoperiod or temperature treatments from day 14 to 43. However, SD photoperiod or 28C did not decrease flowering for `GCREC-Blue'.
Ammonium and Nitrate Accumulation in Containerized Southern Highbush Blueberry Plants
Authors: Merhaut Donald J. , Darnell Rebecca L.
Published: February 2019

Ammonium and uptake and partitioning were monitored in `Sharpblue' southern highbush blueberry plants (Vaccinium corymbosum L. interspecific hybrid) using 10% 15N-enriched N. Shoots and roots were harvested at 0, 6, 12, 24, and 48 hours after labeling. The rate of -N uptake was higher than that of -N uptake, averaging 17.1 vs. 8.6 g N/g plant dry weight per hour during the 48-hour period for -N and -N plants, respectively. At the end of the 48 hours, -N accumulation averaged 79 mg N/plant compared to 40 mg accumulated by the -N plants. Similarly, the translocation rate of -N to shoots was higher than translocation of -N to shoots (7.7 vs. 1.9 g N/g shoot dry weight per hour, respectively) during the 48 hours. Shoot accumulation of -N averaged 40 mg N/plant at the end of 48 hours, while accumulation in shoots of -N plants averaged 10 mg N/plant. Short-term uptake and translocation to shoots appears to be limited relative to uptake and translocation in southern highbush blueberry when plants are previously fertilized with NH4NO3.
Seed Maturity and Desiccation Affect Carbohydrate Composition and Leachate Conductivity in shrunken-2 Sweet Corn
Authors: Borowski Alicia M. , Fritz Vincent A. , Waters Luther
Published: February 2019

This study was conducted to determine if changes in the raffinose: sucrose ratio in embryos of shrunken-2 sweet corn (Zea mays L.) hybrids were related to differences in seed leachate conductivity between two hybrids harvested at four maturities and artificially dried to 0.10 g H2O/g fresh weight. The ratio of raffinose: sucrose differed for `Crisp N' Sweet 710' (CNS) and `How Sweet It Is' (HSII). The mass ratio of raffinose: sucrose in CNS was >0.3 in seed harvested between 0.44 to 0.64 g H2O/g fresh weight and increased as seed dried from the initial harvest moisture to 0.10 g H2O/g fresh weight. Raffinose: sucrose ratios of HSII were <0.3 at all harvests between 0.55 to 0.72 g H2O/g fresh weight, but changes during desiccation were not as pronounced. Leachate conductivity of whole seeds of CNS and HSII decreased as seeds were harvested at progressively lower moisture contents. We suggest that a higher raffinose: sucrose ratio may be indicative of increased seed vigor in shrunken-2 hybrids.
Economic Analysis of Irrigation and Fertilization Management of Avocados
Authors: Takele Etaferahu , Meyer Jewell L. , Arpaia Mary L. , Stottlemyer David E. , Witney Guy W.
Published: February 2019

The effect of integrated applications of various irrigation and fertilization rates on productivity (yield and size) and returns of the `Hass' avocado (Persea americana Mill.) have been analyzed from 1987 to 1991 in western Riverside County. Eighteen treatment combinations comprised of three irrigation levels [80%, 100%, and 120% crop water use (ETc)], three N fertilizer levels (0.16, 0.7, and 1.4 kg/tree per year), and Zn (0 and 0.2 kg/tree per year) were included in the analysis. Using a partial budgeting procedure, returns after costs were calculated for each treatment combination. Costs of treatments, harvesting, hauling, and marketing were subtracted from the value of the crop. The value of the crop was calculated as the sum of crop returns in each size category. Three years of data on the relationship between irrigation and N showed 1) irrigating at 80% ETc would be ineffective even at very high water prices; 2) for groves where 100% ETc is sufficient, its application with either low or medium N would be beneficial; and 3) at higher irrigation (120% ETc), N application should be at or beyond the medium level.
Fresh-market Tomato Production in a Low-input Alternative System Using Cover-crop Mulch
Authors: Abdul-Baki Aref A. , Teasdale J.R. , Korcak R. , Chitwood D.J. , Huettel R.N.
Published: February 2019

A low-input sustainable agricultural system for the production of staked, fresh-market field tomatoes (Lycopersicon esculentum Mill.) is described. The system uses winter annual cover crops to fix N, recycle leftover nutrients, produce biomass, and prevent soil erosion throughout the winter and spring. Yields of tomato plants grown in hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), and rye (Secale cereale L.) plus hairy vetch mulches were higher than those grown in the conventional black polyethylene (BP) mulch system in 2 of 3 years. Fruit were heavier with the plant mulches than with BP mulch. Eight weeks after transplanting, N levels in tomato leaves were higher with plant than with BP mulch, although the plant mulch plots received only 50% of the N applied to the BP plots. The cover crops had no effect on populations of five phytoparasitic nematode species.
Budding Method Affects Transmission of Xylella fastidiosa in Plum
Authors: Boyhan G.E. , Abrahams B.R. , Norton J.D. , Huang Hongwen
Published: February 2019

Detection of Xylella fastidiosa Wells et al. by enzyme-linked immunosorbent assay indicated that plums (Prunus hybrids) had higher absorbance values than peaches [Prunus persica (L.) Batsch]. The slip-budded trees had lower readings than those that were chip budded; however, the scion × method interaction was significant. Further comparison of slip vs. chip budding indicated that the lower absorbance value of slip budding occurred in plums only; there was no difference between budding methods in peach.
Gray Mold in and Quality of Strawberry Fruit following Postharvest Heat Treatment
Authors: García José M. , Aguilera Cayetano , Jiménez Antonia M.
Published: February 2019

Strawberries (Fragaria × ananassa Duch. `Tudla') were inoculated with gray mold conidia (Botrytis cinerea Pers.) and were subjected to postharvest heat treatment by dipping in water at various temperatures for 15 min. Heat treatment delayed Botrytis proliferation, but using dips at ≥48C caused fruit to soften and develop an atypical pink pigmentation. Fruit treated at 44 or 46C showed the best retention of firmness and maintained initial quality, developing neither an off-color nor an off-flavor.
Cultivar and Maturity Affect Postharvest Quality of Fruit from Erect Blackberries
Authors: Perkins-Veazie P. , Collins J.K. , Clark J.R.
Published: February 2019

Fruit at three stages of ripeness were harvested from four erect blackberry (Rubus spp.) cultivars, `Navaho', `Choctaw', `Cheyenne', and `Shawnee', for 2 years to evaluate fresh-market shelf life during 7 days of storage at 2C, 95% relative humidity. Ethylene production was highest from dull black fruit and varied widely among cultivars, ranging from 7.3 to 51.1 pmol·kg–1·s–1 for `Navaho' and `Choctaw' fruit, respectively. Weight loss ranged from 0.8% (`Shawnee') to 3.3% (`Navaho') after storage. Mottled (50% black) fruit of all cultivars were higher in fruit firmness and titratable acidity and had lower soluble solids and anthocyanin concentrations than fruit at other stages of maturity. Cultivars did not differ in total anthocyanin concentration, but dull black fruit had a higher anthocyanin concentration than shiny black fruit. Dull black `Choctaw', `Shawnee', and `Cheyenne' fruit were softer and had more leakage and decay than shiny black fruit. Both shiny and dull black `Navaho' fruit had less leakage than fruit of other cultivars. All cultivars at the shiny black stage were considered marketable after 7 days at 2C because fruit were firm with little decay or leakage. However, red discoloration appeared more frequently on shiny black than on dull black fruit. Mottled fruit of erect cultivars should not be harvested, while shiny black fruit of `Cheyenne', `Shawnee', and `Choctaw' might be suited for regional markets. Either shiny black or dull black `Navaho' fruit could be shipped to distant markets.
IN VITRO CONSERVATION OF THE NORTHERN GENOME OF LUPINUS LEPIDUS
Authors: Luk Victor , Ellis Brian
Published: February 2019

Lupinus lepidus is a dwarf perennial lupine native to British Columbia. It possesses high horticultural potential, but the only known population in British Columbia averages 70 plants and is under constant threat of destruction. Lupinus lepidus is variable from seed and very difficult to propagate from cuttings. To protect the northern genome of L. lepidus, and to help introduce this plant to the nursery trade, we have investigated the feasibility of micropropagation for expansion of the supply of plant material. A regeneration procedure has been developed that enables multiple L. lepidus plantlets to be obtained directly from cotyledon explants of 10-day-old seedlings. More than 40 microshoots per explant were induced from cotyledonary node explants after placing them on MS medium containing BAP at 1 mg·liter–1 and NAA at 0.05 mg·liter–1 for 3 weeks. The regenerated shoots grew vigorously on a hormone-free, half-strength MS medium and could be multiplied on the same medium every 2 weeks. This micropropagation cycle has been used continuously for 9 months. Alternatively, 15 to 20 plantlets can be forced to develop from the axillary buds on the stems of 5-month-old seedlings by withholding sucrose from half-strength MS medium. The induced plantlets could be further propagated on the same medium, but they displayed less vigor than those obtained from the cotyledonary node explants.
Hairy Vetch Mulch Favorably Impacts Yield of Processing Tomatoes
Authors: Abdul-Baki Aref A. , Stommel John R. , Watada Alley E. , Teasdale John R. , Morse Ronald D.
Published: February 2019

Ten cultivars of processing tomatoes (Lycopersicon esculentum Mill.) grown in bare soil or on black polyethylene and hairy vetch (Vicia villosa Roth.) mulches were evaluated for yield, fruit processing quality, and leaf necrosis. Yields were higher, fruit was heavier, and leaf necrosis less in hairy vetch than in bare soil or black polyethylene mulch. With the exception of pH, yield and fruit quality component responses to mulch treatments were not cultivar-dependent. Fruit pH, soluble solids concentration, and color equaled values obtained using bare soil production practices. Percent solids was highest with black polyethylene and lowest in hairy vetch. The hairy vetch mulch delayed fruit maturity compared to the bare soil and black polyethylene. The hairy vetch cultural system has the potential to increase yield of processing tomatoes.
Styrene-lined and Copper-coated Containers Affect Production and Landscape Establishment of Red Maple
Authors: Brass Thomas J. , Keever Gary J. , Eakes D. Joseph , Gilliam Charles H.
Published: February 2019

Growth response of two red maple cultivars (Acer rubrum L. `October Glory' and `Northwood') to styrene lining or copper hydroxide coating of 23.3-liter black plastic containers was evaluated. After the first growing season, plants were left in their original container, repotted into 51.2-liter nontreated containers, or transplanted into the landscape. Copper hydroxide effectively reduced circling of roots of both cultivars at the medium–container interface during the first year of production, but was less effective during the second growing season. Repotting from copper-treated containers into 51.2-liter containers or transplanting into the landscape resulted in more fibrous root development and enhanced root regeneration outside the original rootball relative to transplanting from nontreated containers. However, when copper hydroxide was applied to styrene lining, root regeneration after transplanting was reduced. Roots of plants grown in styrene-lined containers covered the medium–container interface more thoroughly than those in nonlined containers, but height, trunk diameter, and root regeneration were similar. `October Glory' had a larger trunk diameter, more branching, and better root regeneration than `Northwood'.
Interaction of Nitrogen Source, Application Timing, and Fungicide on Rhizoctonia Blight in Ryegrass
Authors: Fidanza Michael A. , Dernoeden Peter H.
Published: February 2019

Rhizoctonia blight (RB), incited by Rhizoctonia solani Kühn, is a common disease of cool-season turfgrasses. This 2-year field study was conducted to determine the influence of N source, N application timing, and fungicide treatment on RB severity in `Caravelle' perennial ryegrass (Lolium perenne L.). Ringer Lawn Restore (Ringer), a slow-release N source, was compared to water-soluble urea. Nitrogen was applied according to either a spring (March, May, June, and September) or fall (September, October, November, and May) schedule. Plots received either N only or N plus the fungicide iprodione (3.1 kg a.i./ha applied at 21-day intervals). RB was reduced with fall-applied Ringer compared to spring-applied urea in both years in fungicide-free plots. Nitrogen generally enhanced foliar mycelium growth and RB during the initial infection periods (i.e., late June to late July). By mid- to late August there were extremely high levels of blighting among all fungicide-free treatments. Nitrogen source and N application time had no effect on the level of blighting in iprodione-treated plots. During early disease outbreaks, iprodione did not always prevent foliar mycelium from appearing, but it did protect turf from severe RB. Iprodione reduced blighting, but the level of disease suppression and resulting turfgrass quality provided on the extended spray interval was not acceptable for high-quality golf course fairways. Chemical name used: 3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidine carboxamide (iprodione).
Development of Genic Male-sterile Watermelon Lines with Juvenile Albino Seedling Marker
Authors: Zhang X.P. , Rhodes B.B. , Baird W.V. , Bridges W.C. , Skorupska H.T.
Published: February 2019

This research was conducted to develop genic male-sterile lines of watermelon (Citrullus lanatus Matsum & Nakai) homozygous for the juvenile albino (ja) seedling marker. Male-sterile plants (msms) of the genic male-sterile line G17AB were crossed with a Dixielee plant that was heterozygous for the ja locus. Male-fertile, juvenile albino recombinants of the F2 progeny were self-pollinated, resulting in F3 progeny. The male-sterile normal green recombinants of the F2 progeny were crossed with an F1 hybrid plant with genotype MsmsJaja, and three populations (93JMSB-1, -2, and -3) were obtained from these crosses. Juvenile albino recombinants were confined to 93JMSB-1. Of the juvenile albino plants of 93JMSB-1, male-sterile plants were sib-crossed with male-fertile plants, resulting in 93JMSB-1-1. Progeny of 93JMSB-1-1 was homozygous for ja and segregated for ms in a 127 male-sterile: 128 male-fertile ratio, fitting a 1:1 ratio. The male-sterile juvenile albino plants of F3 were crossed with male-fertile juvenile albino plants of 93JMSB-1, resulting in 93JMSF3-1 and -2. Plants 93JMSF3-1 and -2 were homozygous for ja but segregated for ms at 10 male-sterile: 13 male-fertile and 15 male-sterile: 19 male-fertile for 93JMSF3-1 and 93JMSF3-2, respectively, fitting the 1:1 ratio. These three genic male-sterile lines with the ja seedling marker provide valuable germplasm for introducing ms and ja genes into diverse genetic backgrounds and for studying cross-pollination and gene flow in watermelon populations.
Demand Relations of Fresh Sweetpotato in the St. Louis and Chicago Markets
Authors: Wollo Wesseh J. , Jones Rufus
Published: February 2019

The impacts of unloaded quantity, disposable personal income, retail price index of fresh potatoes (Solanum tuberosum L.), and seasonal monthly variables on sweetpotato [Ipomoea batatas (L.) Lam.] price in the St. Louis and Chicago terminal markets were estimated using a regression analysis technique. These markets can absorb a modest increase in sweetpotato quantity without a decrease in wholesale price, but a significant increase in quantity would decrease wholesale price. Sweetpotato price is higher during October, November, and December than in September; therefore, producers must give attention to marketing sweetpotatoes during these months. Also, increased shipments of sweetpotatoes to these markets should not be considered in anticipation of an increase in disposable income.
Foliar SPAD-502 Meter Values, Nitrogen Levels, and Extractable Chlorophyll for Red Maple Selections
Authors: Sibley Jeff L. , Eakes D. Joseph , Gilliam Charles H. , Keever Gary J. , Dozier William A. , Himelrick David G.
Published: February 2019

Twelve red maple selections in an existing field trial were evaluated for leaf chlorophyll content with a SPAD-502 chlorophyll meter, total foliar N concentration with a LECO CHN analyzer, and total foliar chlorophyll content (CHL) by N,N-dimethylformamide extraction. Selections included Acer rubrum L. `Autumn Flame', `Fairview Flame', `Franksred' (Red Sunset™), `Karpick', `Northwood', `October Glory', `Redskin', `Schlesingeri', and `Tilford', and A. ×freemanii E. Murray `AutumnBlaze' (`Jeffersred'), `Morgan' (`Indian Summer'), and `Scarsen' (Scarlet Sentinel™). `Franksred' and `Northwood' had the highest monthly SPAD-502 values in 1993 and 1994. Lowest SPAD-502 values were on `Redskin' and `Autumn Blaze' each year. Foliar N concentration ranged from 2.62% for `Autumn Flame' to 2.01% for Redskin. CHL levels on a fresh-weight basis ranged from 5.38 mg·g–1 for `Fairview Flame' to 3.94 mg·g–1 for `October Glory'. SPAD-502 and extractable CHL values were correlated (r = 0.45; P ≤ 0.001); however, the correlation (r = 0.15; P ≤ 0.38) between SPAD-502 values and total foliar N concentration was nonsignificant.
Root-zone Stress Effects on Water Relations and Growth of Silver, Red, and Freeman Maples
Authors: Zwack James A. , Aiello Anthony S. , Graves William R. , Townsend Alden M.
Published: February 2019

Freeman maples (Acer ×freemanii E. Murray) are suspected to be more resistant to environmental stress than red maples (A. rubrum L.) because the lineage of Freeman maple includes silver maple (A. saccharinum L.). Little is known, however, about stress resistance of silver maple, and few data from direct comparisons of red and Freeman maples are available. Our objectives were to determine effects of root-zone heat on silver maples from northern and southern provenances, and to compare red and Freeman maple cultivars for resistance to rootzone heat stress and drought. There were no provenance-by-temperature interactions when silver maples from 33.3°N (Mississippi) and 44.4°N (Minnesota) latitude were grown with root zones at 29 and 35°C. Plants from 44.4°N latitude had 36% higher fresh mass, 43% more leaf surface area, and 35% and 59% higher, respectively, root and shoot dry masses than plants from 33.3°N latitude. Midday xylem water potential was 68% more negative for plants at 35°C than for plants at 29°C, and transpiration rate was 129% less for plants with root zones at 35°C than for those with root zones at 29°C. During preliminary work with Autumn Flame and Franksred red maple and Indian Summer and Jeffersred Freeman maples, rooted cuttings were grown in 25 and 37°C root zones under both drought and nondrought conditions. Reductions in growth at 37°C were similar for all cultivars. Results of this work could influence development, marketing, and use of Freeman maples.
Morpho-physiological Responses of Pinus halepensis Mill. Seedlings to Drought Stress
Authors: Lombardini Leonardo , Falusi Mauro , Calamassi Roberto , Flore James A.
Published: February 2019

Aleppo Pine (Pinus halepensis Mill.) is known to be the most drought-resistant Mediterranean Pine. This species is widely distributed throughout the Mediterranean region and displays a high intraspecific variability, with respect to its physiological and morphological response to environmental conditions. In this experiment we evaluated the response of Pinus halepensis seedlings to drought. Sixty germinated seeds (accession A6, Shaharia, Israel) were grown in soil for 8 weeks and then transferred to black plexiglass tanks containing half-strength air-sparged Hoagland solution. After 6 weeks of acclimation to hydroponics, the osmotic potential of the solution was lowered by adding polyethylene-glycol (PEG) 8000. Water potential was lowered in 0.2 MPa increments every 4 days, until a final value of –0.8 was reached. The seedlings were then maintained at –0.8 MPa for a further 8 days. Ultrasonic acoustic emissions, pressure–volume (P–V) curves, shoot and root growth, leaf area, xylem diameter, root apex mitotic index and cell length were measured on control and stressed seedlings. Seedlings were then transferred to normal Hoagland solution for 24 hours to simulate rewatering, and P–V curves and ultrasonic emissions measurements were repeated. Results showed that the final root growth is maintained in the stressed seedlings at the same rate as controls, whereas shoot growth was significantly reduced. The leaf area was reduced by stress to 36%, but the xylem diameter only to 10%, leading to a lower leaf area:xylem section ratio in the stressed plants. Ultrasonic emissions in the stressed plants were 365% of the control, and 182%, after rewatering. Specific details of the growth and physiology data are presented.
Lowest Survival Temperature (LST) Estimations in 33 Varieties of Viburnum by Controlled Freezing
Authors: Wachter John F. , Cappiello Paul E.
Published: February 2019

Stems of 33 varieties of Viburnum were screened for low temperature tolerance on five dates. Terminal stem cuttings were shipped overnight to Orono, Maine, from Oregon, Michigan, and Minnesota. Following a controlled freezing regime, stems were incubated for 7–14 days and evaluated for injury by visual observation. Lowest survival temperatures (LST) were estimated as the lowest temperature at which 100% of stems were uninjured. Varieties of V. dentatum, V. lantana, V. opulus, and V. trilobum were rated as consistently very cold tolerant. Viburnum ×pragense, V. dilatatum, and V. rufidulum were rated as consistently moderately cold tolerant. All V. tomentosum varieties showed inconsistent LST estimates. Varieties from the Oregon source were rated as cold intolerant. Direct comparisons by variety and source will be discussed with emphasis on consistent LST estimates. Rates of deacclimation as they occurred over the five testing dates will also be discussed.
A Comparison of Methods to Assess Oxidative Damage Associated with Chilling Stress
Authors: Fitzpatrick Ann , Jennings Paul H.
Published: February 2019

Preliminary studies on the effects of chilling stress during the early stages of germination and radicle emergence in cucumber have suggested that damage may be due to the accumulation of active oxygen species. Several methods are available which are capable of assessing various types of oxidative damage and were selected for use in determining the involvement of active oxygen species in the chilling response of emerging cucumber roots. Oxygen radicals have been shown to interact with cellular proteins resulting in the formation of carbonyl derivatives. A procedure using 2,4-dinitrophenylhydrazine was tested to determine carbonyl protein content. Cellular lipids are also subject to peroxidation by active oxygen species resulting in the production of malondialdehyde and can be quantified by reaction with thiobarbituric acid. Sulfydryl groups may also be attacked by oxygen free radicals and changes monitored by a procedure using 5,5'-dithio-(2-nitrobenzoic acid). A comparison of these three methods for detecting oxidative damage associated with chilling stress in radicles of germinating cucumber seed will be discussed.
Gibberellin Status of Spectral Filter-grown Chrysanthemum Plants
Authors: Maki Sorua L. , Riley Melissa B. , Rajapakse Nihal C.
Published: February 2019

Endogenous gibberellins of chrysanthemum [Dendranthema ×grandiflorum (Ramat)] cv. Bright Golden Anne were characterized in apices from plants grown under control and CuSO4 spectral filters. Expanding shoots were separated into young expanding leaves and apices. Methanolic extracts of young expanding leaves were purified by solvent partitioning, PVPP column chromatography and reversed-phase high performance liquid chromatography. Two bioactive regions corresponding to the HPLC retention times of GA1 and GA19 standards were detected in fractions using the recently-developed non-dwarf rice bioassay. Di-deuterated internal standards of GA12, GA53, GA19, GA20, and GA1 were added to similar extracts of shoot apices. The presence of endogenous GA53, GA19, GA20, and GA1 in chrysanthemum apices was confirmed by isotope dilution using gas chromatography-mass spectrometry-selected ion monitoring and Kovats retention indices. In a preliminary quantification study, GA20 and GA1 levels were found to be higher in apices from plants grown under control filters while GA19 levels were higher in apices grown under CuSO4 filters. The possibility that light transmitted through CuSO4 filters alters gibberellin levels in shoot apices is discussed.
Probit Analysis for Quantitative Comparisons of Time and Duration of Peach Bloom
Authors: Olien William C.
Published: February 2019

The population of flower buds in a peach orchard do not all bloom at the same time, but instead expand to bloom stage over time as a cumulative normal curve. This relationship is similar to seed germination and other processes restricted between 0% and 100% of response. Frequent sampling of bloom development over all treatments to be compared is frequently not possible. Treatment means may be compared on a given day for differences in % bloom, but the opposite question of whether differences exist in time of 50% bloom cannot be answered. Transforming the % response axis to Probits allows comparisons of bloom time and duration. Probit transformation linearizes the cumulative normal distribution curve by converting the % response axis to units of standard deviation. Best fit of a line to data is optimized by the method of maximum likelihood (least squares regression is not appropriate). In an example study on peach, % of total flower buds at or past bloom (pistil exposed) was counted daily on tagged shoots in control trees. Percent bloom on trees treated with different chemical bloom thinning treatments were counted only when control trees reached 10%, 50%, and 90% bloom. Bloom data were converted to Probits and response lines for each treatment were graphed. On this basis, quantitative comparisons among treatments could be made along the time axis for a) time of 50% bloom and b) duration of bloom.
Effect of Radiant-to-thermal Energy Ratio on Poinsettia Plant Quality
Authors: Liu Bin , Heins Royal D.
Published: February 2019

Plant growth and development are driven by two forms of energy: radiant and thermal. This study was undertaken to determine the effect of the ratio of radiant energy to thermal energy on plant quality of Euphorbia pulcherrima `Freedom'. Plants were grown under 27 combinations of temperature (thermal energy), light (radiant energy), and spacing, i.e., factorial combinations of three levels of constant temperature (19, 23, or 27°C:), three levels of daily light integral (5, 10, or 20 mol·m–2·d–1), and three levels of plant spacing (15 × 15, 22 × 22, or 30 × 30 cm), from pinch to the onset of short-day flower induction. Plants were treated for 450 degree-days (base temperature = 5°C) in Expt. 1 or 5 weeks in Expt. 2. The results showed that increasing radiant energy or decreasing average daily temperature during accumulation of 450 degree-days increased plant dry weight. When radiant and thermal energy were calculated into the ratio, plant dry weight increased linearly as the ratio increased Plants exposed to low light: levels and high temperatures, i.e., those at a low ratio, developed thin, weak stems. Higher radiant-to-thermal energy ratios produced thicker stems.
Growth of Plant Tissue Cultures in Ultra-high Levels of Carbon Dioxide under Autotrophic and Heterotrophic Conditions
Authors: Tisserat Brent , Silman Robert
Published: February 2019

A comparative study was undertaken to determine the influence of lighting, carbohydrate concentrations and ultra-high levels of CO2, i.e., >10,000 ppm, on sterile culture growth. Past CO2-sterile studies have confirmed that elevation of CO2 to as high as 1000 ppm resulted in beneficial growth. Within special constructed chambers, tissue cultures were given a variety of CO2 levels for 12–16 hours/day using artificial lighting and natural sunlight. Several different plants (lettuce, beans, pine) and plant culture types were grown in CO2-enriched environments, ranging from 350 to 50,000 ppm. In almost all cases, plant tissue cultures not only tolerated but exhibited enhanced growth using ultra-high levels of CO2. For example, lettuce cultures were found to grow 2 to 4 times faster under ultra-high CO2. levels than under normal atmospheric CO2 levels, i.e., 350 ppm. Natural sunlight was found to be suitable for sterile culture growth. Modes of administration of CO2 in vitro and gas permeability of various culture vessels are presented.
Electronic Advancements in Teaching Floral Design at Texas A&M University
Authors: Zajicek Jayne M. , Bradley Jennifer C.
Published: February 2019

Floral Design (HORT 203) is an increasingly popular course offered at Texas A&M Univ. HORT 203 is offered as a university core curriculum humanities elective and, thus, enrolls many nonhorticulture majors, averaging 95 students per semester. HORT 203 is taught in a large lecture room that does not always lend itself to teaching a hands-on, visual design course. To increase student understanding of the materials, traditional 35-mm slides and overhead transparencies are being replaced by visual computer technology. Colorful, scanned-in images of floral designs are created in Microsoft PowerPoint and incorporated into computer presentations and color transparencies that supplement each instructional presentation. In addition, the Internet is incorporated in the course by providing students with instructors' and lab assistants' e-mail addresses, individual lab section pages, slides for plant identification, reading assignments, as well as classroom lectures. The technologies used for HORT 203 enhance student understanding and ease of teaching while providing a visual alternative to traditional teaching methods. The technologies used for HORT 203 will be discussed and demonstrated including a tour of home-pages, lectures, and plant id lists.
The Landscape Industry Council of Hawaii—An Experiment in Cooperation
Authors: Hensley David L.
Published: February 2019

The Landscape Industry Council of Hawaii was formed in 1987 to bring the landscape professional and trade associations together. The organization's goals are communication between segments of the industry, education, promotion, and legislative action. Current members of the council include: Aloha Arborists Association; ASLA Hawaii Chapter; Hawaiian Association of Nurserymen; PGMS HI Chapter; Hawaii Landscape and Irrigation Contractors Association; HI Professional Gardeners Association; HI Turfgrass Association; and the HI Island Landscape Association. The Council publishes Hawaii Landscape magazine, presents statewide educational programs and trade shows, and works for the common good of the entire green industry. It has been successful in gleaning grant support for several efforts. The Council is on the verge of broadening membership to individuals as well as associations and making significant strides to meet its goals and needs of the Hawaiian landscape industry. The evolution and successes have not been without problems, setbacks, ruffled feathers, and a lot of hard work from a dedicated group of volunteers.
Genes for Retention of Green Fruit Color through Maturity of Acorn Squash
Authors: Paris Harry S.
Published: February 2019

Most cultivars of acorn squash (Cucurbita pepo), such as `Table Queen', have fruit that are light green when young, become dark green by intermediate age, and remain dark green through maturity, carrying genotype D/D l-l/l-1 L-2/L-2. Many other forms of C. pepo that carry this genotype, the most familiar being the Halloween and pie pumpkins, turn orange at maturity. The genetic basis for green color retention of acorn squash was investigated by crossing `Table Queen' with `Vegetable Spaghetti', `Fordhook Zucchini', and accession 85k-9-107-2 (the parental, filial, backcross, and testcross generation progenies being grown out in the field and observed and scored for fruit color at maturity, between 40 and 44 days past anthesis). The results indicated that the three stocks crossed with `Table Queen' carry two recessive genes, designated mature orange-1 (mo-1) and mature orange-2 (mo-2), which act in concert to result in complete loss of green color before maturity in 1-1/1-1 plants. `Table Queen' is Mo-l/Mo-1 Mo-2∼o-2. Genes D and mo-2 are linked, ≈15 map units apart.
Cultivar and Phenological Variation in Foliar Phenolic Content of Apple
Authors: Garcia Maria Elena , Rom C.R. , Murphy J.B.
Published: February 2019

The level of dihydroxyphenolics as influenced by cultivar and leaf phenology was determined for 10 apple cultivars. Newly unfolding leaves were tagged weekly. Once per month, the leaves were collected and analyzed to determine their phenolic content. Replicated collections were made at three times during the summer. Diphenyl boric acid ethanol was the reagent used in this spectrophotometric technique. The phenolic content changed throughout the season. However, no trend was observed for phenolic content variation with leaf age. Each cultivar varied independently in phenolic content with leaf phenology. There were variations in the phenolic content associated with cultivar. Possible hypotheses as to factors affecting the production of phenolics in apple are discussed.
Rethinking Apple Scald: New Hypothesis on the Causal Reason for Development of Scald in Apples
Authors: Song J. , Beaudry R.M.
Published: February 2019

Superficial scald is still one of the most important postharvest physiological disorders in apples. Commercial control of this disorder has been accomplished by selecting resistant cultivars, treating fruit with DPA and ethoxyquin, using oil-soaked fruit wraps and storing the fruit under low O2. However, the causal reason for scald development is still a mystery. Research has indicated that the scald-promoting factor or inducing compound may be formed or accumulated in apple cuticle then rediffused back into the hypodermis, thereby causing damage. Hydroperoxides, auto-oxidative product from α-farnesene, have been thought to be the toxic compounds, inducing scald; however, it is not explained how the hydroperoxides move from the cuticle to the hypodermis. The identification and dynamic changes of 6-methyl-5-heptene-2-one as a natural volatile in apple fruit during ripening were made, which accumulated in higher quantitaty in cuticular wax than in headspace. The close relationship between the chloroplast breakdown and amount of α-farnesene changes, the induction of scald-like symptom on the surface of apple fruit by 6-methyl-5-heptene-2-one and the sensitivity of fruit to this ketone damage were investigated. Our results suggest that the accumulation of 6-methyl-5-heptene-2-one in the cuticular wax of apple fruit might be the causal reason for scald development in apples.
Peel Discs as a Tool to Study Flavor Chemistry in Apple
Authors: Mir N.A. , Song J. , Beaudry R.
Published: February 2019

Peel discs (0.2 mm in diameter) of refrigerated, air-stored apple that were immersed in a medium isotonic with that of fruit sap were allowed to photosynthesize either in a closed or flow-through system. The photosynthetic net evolution of O2 in the light or consumption in the dark was used to predict the duration of the experiment that would be within the critical limits of aerobiosis. Using GC-MS system, volatile emissions from these tissues were determined, in the head space and liquid medium. The volatile profile generated from head space analysis was essentially similar to that of whole fruit. Light, compared to the dark treatment, stimulated the synthesis of nearly all volatiles, especially α-farnesene. The synthesis of 6-methyl-5-hepten-2-one, an oxidative product of α-farnesene that causes scald like symptoms in whole fruit, was observed only under lighted conditions. While O2 content in the medium seemed to have no effect on the volatile build-up in the head space, a C15 sesquiterpene with a mass spectrum similar to hydroperoxide breakdown products of α-farnesene was synthesized only in presence of O2 in the reaction medium. Inhibition of light reactions of photosynthesis with DCMU, suppressed the synthesis of various volatiles in the head space suggesting the role of chloroplast activity in aroma development. We suggest that peel discs work well as a model system to study flavor chemistry in apple.
Development of a Man–Plant Interface for Greenhouse Environmental Computers Using Generic Databases and Virtual Plants
Authors: Ehler Niels , Rose Mark A. , Hansen Jesper Mazanti
Published: February 2019

Currently, greenhouse environmental computers are programmed to monitor and control the macroclimate instead of directly controlling plant growth and development, which are features of more interest to growers. Our objective was to develop a generic system to represent and control the dynamic plant processes that regulate plant growth in the greenhouse. Before plant growth can be directly controlled, the dynamic interactions between the microclimate around plants and plant physiological processes must be further understood. Future computerized control systems must be able to display an intuitive, interactive software program that helps the user understand and make use of the dynamic relationships between climate controls, climate processes, and plant processes. A conceptual framework was designed for a user interface with a biological orientation. This software consists of five different elements: the information provider, the information monitor, the information browser, the growth system controller, and the system visualizer. A demonstrator application illustrating this concept was developed and connected in real time to a standard greenhouse environmental computer. Crop tissue temperature is calculated and used instead of conventional irradiance limits to control shading screens to optimize the amount of radiation absorbed by the crop. The application is based on a set of generic automatically created paradox databases. A graphical user interface on the screen displays virtual plants that are used for visualizing, understanding, and controlling the different processes governing the crop tissue temperature.
Solving the Pest and Landscape Problems of Maryland Residents through an 800 Phone System
Authors: Traunfeld Jon H. , Malinoski Mary Kay , Clement David L.
Published: February 2019

The Home and Garden Information Center was established in 1989 to provide accurate and up-to-date environmental horticulture information to the general public. Maryland residents can speak to trained horticultural consultants 5 days per week via a toll-free number and have 24 hour per day access to pre-recorded tapes covering 23 subjects. The original automated phone system was replaced in May 1995 with a more sophisticated system. The newly designed and implemented system is the first of its kind in the United States. The AT&T Conversant Phone System includes a MAP (multi-application platform), which handles incoming calls and uses advanced speech recognition technology. Other system components include a monitor, keyboard, printer, UPS, and software. The new phone system menus were designed by the authors; the software was written by engineers at AGT International. The menus design is logical and subject-driven. Callers can move quickly through the system using a combination of touch tone and voice input. Clients can speak with a consultant at any time by pressing “0” and can access information and self-help problem diagnostic tapes by entering the four-digit tape number or by navigating menus. Subject tips are also available and are updated every 2 weeks. As of Dec. 1995, >270,000 calls were handled. More than 150,000 callers were assisted by Center staff.