bluuebunny/crossref_metadata_2025 huggingface dataset:
Reducing Irradiation Damage to `Arkin' Carambola by Plastic Packaging or Storage Temperature
Authors: Miller W.R. , McDonald R.E.
Published: February 2019

Carambolas (Averrhoa carambola L.) require quarantine treatment for control of the Caribbean fruit fly (Anastrepha suspensa Loew) (CFF) prior to shipment to certain domestic and export markets. Low-dose irradiation, ≤1.0 kGy, is effective for sterilizing CFF and other fruit flies; however, carambolas are susceptible to irradiation-induced peel injury. Low-dose gamma irradiation treatment generally reduced fruit quality, but the effects were mitigated by packaging carambola fruit in “clamshell” polystyrene containers, rather than conventional fiberboard boxes, prior to treatment. Use of clamshell containers reduced peel pitting, stem-end breakdown, shriveling, and loss of mass after storage for 14 days at 5 or 7 °C. In addition, fruit held in clamshell containers were firmer, with slightly less green peel, and had lower total soluble solids, but the flavor was not quite as good as that of fruit stored in fiberboard boxes. There was no difference in the mastication texture or acidity of fruit by package type at final storage. Packing carambolas in clamshell containers increased their tolerance to irradiation-induced peel disorders and improved the potential for usage of low-dose irradiation for quarantine treatment.
A System for Measuring the In Situ CO2 Exchange Rates of In Vitro Plantlets
Authors: Niu Genhua , Kozai Toyoki , Kubota Chieri
Published: February 2019

A system was designed for measuring the CO2 exchange rates [net photosynthetic rate (Pn) and dark respiration rate] of in vitro plantlets in situ (in the vessel with natural ventilation). The system, excluding gas cylinders, was placed in a growth chamber so that the desired photosynthetic photon flux (PPF) and temperature could be maintained during the measurement. The CO2 concentration inside the culture vessel (Ci) was indirectly controlled by controlling the CO2 concentration outside the vessel (Co). The Pn of the plantlets was estimated based on the measured Ci and Co at steady state using a gas chromatograph according to the method described by Fujiwara et al. (1987). The performance of the system was demonstrated by measuring the in situ Pn of sweetpotato [Ipomoea batatas (L.) Lam., cv. Beniazuma] and tomato (Lycopersicon esculentum Mill., cv. Hana Queen) plantlets in vitro under a range of CO2 concentrations and PPF. The photosynthetic parameters of the Pn model (Niu and Kozai, 1997) for the plantlets were then estimated based on the measured Pn. The preliminary measurements demonstrated the potential application of the system.
Pollinator Contribution to the Production of Cowpea in the Amazon
Authors: Vaz Carlos G. , de Oliveira Domingos , Ohashi Orlando S.
Published: February 2019

Cowpea, Vigna unguiculata (L.) Walp., is a very important legume in the diet of the population of the Amazon. Although it is autogamous, this species has a cross-pollination rate of ≈10%. Over several years, the mean productivity of cowpea has declined. We suggest that this is linked to a decrease in or an absence of pollinating insects in the fields. The objective of this study is to ascertain the pollinator contribution to cowpea production, as well as to determine the pollination type of the `BR3-Tracuateua' cultivar. In an experimental design, four treatments were compared: no pollination, with flowers in cages to prevent insect visits; open-pollination, with flowers exposed to all visiting insects; self-pollination, with flowers pollinated with their own pollen; and cross-pollination, with emasculated flowers being pollinated manually with pollen from another plant. We observed higher fruit set in the presence of pollinators (83%) than in their absence (77%, caged flowers). However, cross-pollination reduced both the number of seeds per pod and fruit set relative to self-pollination. This result suggests that pollinators have a complementary role in the yield of cowpea, by creating a mixed pollination system where self-pollination dominates.
Growth Retardant Effects on Visual Quality and Nonstructural Carbohydrates of Creeping Bentgrass
Authors: Han S.W. , Juvik J.A , Spomer L.A. , Fermanian T.W.
Published: February 2019

Plant growth regulators are becoming important tools for managing high-quality turf. However, long-term suppression of growth might affect the potential of the turf to recuperate from summer stresses. This study was initiated to determine the impact of popular commercial turfgrass growth regulators (TGR) on the accumulation of total nonstructural carbohydrates (TNC), and their effect on turf quality. Three experiments, one each year from 1994 through 1996, were conducted on creeping bentgrass (Agrostis stolonifera Huds. `Penncross') in a greenhouse. Growth retardants evaluated included trinexapac-ethyl at 0.28 kg·ha-1, flurprimidol at 0.56 kg·ha-1, and paclobutrazol at 0.28 kg·ha-1. Each retardant was applied at three different intervals: a single initial application or multiple applications every 2 or 4 weeks, for the first 8 weeks of each experiment. The verdure and roots were harvested and analyzed for TNC. Trinexapac-ethyl, flurprimidol, and paclobutrazol significantly increased the TNC of creeping bentgrass 2 weeks after their initial application, but TNC levels began to decrease at week 4. The TNC content was strongly influenced by TGR application rate but not application intervals. A single trinexapac-ethyl application at 0.28 kg·ha-1 reduced TNC content more than did split applications, each at lower rates. Accordingly, TNC levels recovered more rapidly with lower, more frequent application rates; however, the retardation effect on vegetative growth diminished as the concentration was lowered. On the other hand, repeated low application rates of trinexapac-ethyl may have minimal effect on TNC accumulation. Chemical names used: [4(cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester] (trinexapac-ethyl); {α-[1-methylethyl]-α-[4-(trifluoro-methoxy)phenyl]-5-pyrimidine-m ethanol}(flurprimidol);[(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-1,2,4,-t riazole-1-yl)penta-n-3--ol] (paclobutrazol).
Variation of the Nuclear DNA Content of Species of Subtribe Citrinae (Rutaceae)
Authors: Kayum Mukadder , Koç N. Kemal , Rokka Veli-Matti
Published: February 2019

Laser flow cytometry was used to analyze nuclear DNA contents (2C values) of five genera (Severinia Ten., Atalantia Corrèa, Fortunella Swing., Poncirus Raf., and Citrus L.) taxonomically grouped in subtribe Citrinae (citrus fruit trees) of the Rutaceae. The genotypes analyzed had 2C values ranging from 0.67 pg for diploid Severinia buxifolia (Poir.) Ten. to 1.27 pg for tetraploid Hongkong Fortunella hindsii Swing. There was no significant difference in the 2C values within the sexually compatible diploid species of 11 “true citrus fruit trees” [Citrus aurantium L., C. grandis (L.) Osbeck, C. limon (L.) Burm. f., C. limonia Osbeck, C. paradisi Macf., C. reshni Hort. ex Tanaka, C. sinensis (L.) Osbeck, C. volkameriana Ten. & Pasq., Poncirus trifoliata (L.) Raf., and the intergeneric hybrid C. sinensis × P. trifoliata]. The species Atalantia ceylanica (Arn.) Oliv. (a “near-citrus fruit tree”), sexually incompatible with Citrus spp., had a 2C value significantly different from those of the true citrus fruit tree species. The 2C value of Severinia buxifolia (a “primitive citrus fruit tree”), another species sexually incompatible with the Citrus spp., also differed from those of some of the true citrus fruit tree species. The data largely corresponds with taxonomical differences between a) the genera Citrus and Poncirus and b) the genera Severinia and Atalantia, all assigned to subtribe Citrinae.
Uniconazole Retards Growth and Increases Flowering of Young Macadamia Trees
Authors: Nagao Mike A. , Ho-a Elodie B. , Yoshimoto Judy M.
Published: February 2019

Uniconazole (0.2 g a.i. per cm trunk diameter) was applied as a soil drench to 2-year-old potted macadamia (Macadamia integrifolia Maiden & Betche) trees, and reapplied yearly for 4 additional years. Uniconazole significantly reduced tree height and trunk diameter 1 year after initial treatment, and suppressed shoot extension for the duration of the study. It significantly increased flowering the second year after initial treatment, the first year that both the control and treated trees flowered. Subsequently, no differences in flowering were observed until the fifth year, when flowering was significantly less in treated trees, probably due to reduced shoot and trunk growth and tip dieback. Chemical name used: E-1-(p-chlorophenyl)-4,-4-dimethyl-2-(1,2,4-triazole-1-penten-3-ol) (uniconazole).
Management of San Jose Scale on Apple with Soybean-oil Dormant Sprays
Authors: Hix Raymond L. , Pless Charles D. , Deyton Dennis E. , Sams Carl E.
Published: February 2019

The objective of this study was to examine efficacy of soybean oil dormant sprays to manage San Jose scale (Quadraspidiotus perniciosus Comstock) on apple (Malus ×domestica Borkh.). On 14 Feb. 1994 and again on 20 Feb. 1995, `Bounty' apple trees were: 1) left unsprayed (control) or sprayed to runoff with: 2) 3% (v/v) or 3) 6% degummed soybean oil with 0.6% (v/v) Latron B-1956 sticker spreader, or 4) 3% 6E Volck Supreme Spray petroleum oil. Crawler emergence occurred 17 May-28 June, 7 July-30 Aug., and 7 Sept.-24 Oct. 1994. First-generation crawler emergence had started by 8 May in 1995. Both 3% petroleum oil and 6% soybean oil sprays reduced the numbers of first- and second-generation crawlers by 93% in 1994 and first-generation crawlers by 98% in 1995. The 3% soybean oil treatment reduced first- and second-generation crawlers by 60% in 1994 and first-generation crawlers by 83% in 1995. In 1995, apple fruit infestations by first-generation scales on the 3% soybean-, 6% soybean-, and 3% petroleum oil-treated trees did not differ significantly, but all fruit were significantly less infested than the controls.
Spatial Variability of Soluble Solids or Dry-matter Content within Individual Fruits, Bulbs, or Tubers: Implications for the Development and Use of NIR Spectrometric Techniques
Authors: Peiris K.H.S. , Dull G.G. , Leffler R.G. , Kays S.J.
Published: February 2019

Spatial variation in soluble solids content (SSC) of fruits of apple (Malus ×domestica Borkh. cv. Red Delicious), cantaloupe (Cucumis melo L. Cantaloupensis group), grapefruit (Citrus paradisi Macf. cv. Indian River Ruby Red), honeydew melon (Cucumis melo L. Inodorus group), mango (Mangifera indica L. cv. Hayden), orange (Citrus sinensis L. Osbeck. cv. Valencia), peach (Prunus persica L. Batsch. cv. Windblow), pineapple (Ananas comosus L. Merr. cv. Kew) and tomato (Lycopersicon esculentum Mill.), and of bulbs of onion (Allium cepa L. Cepa group) and in dry-matter content (DMC) of potato (Solanum tuberosum L. cv. Russet Burbank) tubers was measured along three directional orientations (i.e., proximal to distal, circumferentially midway along the proximal to distal axis, and radially from the center of the interior to the outer surface). The pattern and magnitude of constituent variation depended on the type of product and the direction of measurement. Radial and proximal to distal variation was greater than circumferential variation in all the products tested. Honeydew had the highest radial variation with a SSC difference of 6.0 % and a cv of 22.8%, while tomato displayed lower radial variation with a cv of 1.0%. Pineapple had a proximal to distal SSC difference of 4.6% with a cv of 13.8%, while the difference in tomato was 0.6% with a cv of 5.1%. Circumferential variation of SSC in all products tested was <2% with cv ranging from 1.1% to 3.8%. The results confirm that considerable constituent variability exists within individual fruit and vegetable organs. This variability may affect the accuracy of calibration equations and their prediction capability. Therefore, within-unit constituent variability should be meticulously assessed when an NIR spectrometric method is being developed for the nondestructive quality evaluation and sorting of a product.
Accelerated Propagation of Chionanthus virginicus via Embryo Culture
Authors: Chan Charlotte R. , Marquard Robert D.
Published: February 2019

Traditional seed propagation (warm/cold stratification) was compared to embryo culture of Chionanthus virginicus L. to determine if germination could be promoted and time necessary to produce a sizable plant could be reduced. Embryos of C. virginicus were extracted from immature fruit collected 9, 16, and 23 Aug. 1995 and grown in vitro on Anderson's rhododendron medium. They germinated in 4 weeks and were transferred ex vitro to flats. Mature fruit from the same source were grown simultaneously using warm/cold stratification. The two groups were evaluated periodically over a 2-year period for percent germination, plant size, and seedling success. The embryo-cultured plants had a lower survival rate (16% vs. 44%) and were more labor intensive. After 2 years, embryo-cultured plants were 13.4-fold the mass and 4.7-fold taller than traditionally grown plants. Ten-month-old cultured plants were comparable in size to 2-year-old plants grown traditionally.
Comparison of Two Citrus Bud-forcing Methods for Rapid Propagation of Scions on New Hybrid Citrumelo Rootstocks
Authors: Bowman Kim D.
Published: February 2019

Bending was compared to cutting off for effectiveness in forcing growth of sweet orange and mandarin scions budded on `Carrizo' citrange, `Swingle' citrumelo, and 17 new hybrid citrumelo rootstocks. For both scion types, more than twice as many plants from the bending treatment than the cut treatment had growing scion buds at 12 weeks. This advantage of the bending treatment was similar for most scion/rootstock combinations except with sweet orange scion on `Carrizo', which produced outstanding bud growth from both forcing methods. Length of growing shoots at 12 weeks was >14 times longer from the bending than the cut treatment for both scions and with all rootstocks. Tree survival and yield of usable trees at 35 weeks old were also significantly better for the bending treatment than for the cut treatment. There was an overwhelming advantage to using the bending treatment instead of cutting off in forcing scion bud growth for propagating citrus trees on citrumelo rootstocks.
Analysis of Michigan Full-service Retail Florist Businesses by Annual Gross Sales
Authors: Collins Carolyn A. , Fails Barbara , Schabenberger Oliver
Published: February 2019

Comprehensive industry statistics are valuable tools for small business owners and managers. The traditional full-service retail florist competes with supermarkets, limited-service flower shops, corner vendors, and telemarketing, catalog, and Internet firms. Although some retail florist business information does exist on a national basis, none specifically addresses Michigan florists. In Mar. 1996, a comprehensive mail survey of Michigan full-service retail florists was conducted with the cooperation of the Michigan Floral Association. The survey focused on 1995 general business operations, delivery services, advertising and marketing practices, staffing and wages, and financial status. Statistical analyses showed total wage expenses and occupancy costs to be major factors controlling net profits. The cost of delivery service and wire service membership also affected profitability. Full-service retail florists must examine and modify the cost structure of their businesses to generate the highest possible net profits.
Photoperiod and Cold Treatment Regulate Flowering of Rudbeckia fulgida `Goldsturm'
Authors: Runkle Erik S. , Heins Royal D. , Cameron Arthur C. , Carlson William H.
Published: February 2019

To determine the flowering requirements of Rudbeckia fulgida Ait. `Goldsturm', plants were grown under 9-hour photoperiods until maturity, then forced at 20 °C under one of seven photoperiods following 0 or 15 weeks of 5 °C. Photoperiods consisted of a 9-hour day that was extended with incandescent lamps to 10, 12, 13, 14, 16, or 24 hours; an additional treatment was a 9-hour day with a 4-hour night interruption (NI). Noncooled `Goldsturm' remained vegetative under photoperiods ≤13 hours, and essentially all plants flowered under photoperiods ≥14 hours or with a 4-hour NI. Flowering percentages for cooled plants were 6, 56, or ≥84 under 10-, 12-, or ≥13-hour daylengths and NI, respectively. Critical photoperiods were ≈14 or 13 hours for noncooled or cooled plants, respectively, and base photoperiods shifted from 13 to 14 hours before cold treatment to 10 to 12 hours following cold treatment. Within cold treatments, plants under photoperiods ≥14 hours or NI reached visible inflorescence and flowered at the same time and developed the same number of inflorescences. Fifteen weeks of cold hastened flowering by 25 to 30 days and reduced nodes developed before the first inflorescence by 28% to 37%. Cold treatment provided little or no improvement in other measured characteristics, such as flowering percentage and uniformity, flower number, plant height, and vigor.
Vernalization and Growing Degree-day Requirements for Flowering of Thalictrum delavayi `Hewitt's Double'
Authors: Huang Ning , Funnell Keith A. , MacKay Bruce R.
Published: February 2019

Vernalization and growing degree-day (GDD) requirements of Thalictrum delavayi Franch. `Hewitt's Double' were investigated by exposing crowns to cold storage for 0, 3, 6, 9, 12, or 15 weeks at 8 °C, and subsequently planting in a heated greenhouse under long-day conditions. Cumulative vernalization of crowns was complete after 6 weeks of cold storage at 8 °C. The time to flower, including time at 8 °C, was 3338 GDD (base temperature of 0 °C) without vernalization and 2802 GDD after complete vernalization. Commercial recommendations for rapid and predictable flowering of T. delavayi `Hewitt's Double' should include cold storage of crowns for a minimum of 6 weeks at 8 °C as part of the 2802 GDD during vernalization and forcing.
The Response of Muskmelon Growth and Development to Microclimate Modification by Shelterbelts
Authors: Zhang Dongsheng , Brandle James R. , Hubbard Kenneth G. , Hodges Laurie , Daningsih Entin
Published: February 2019

The relationships between shelterbelt (tree windbreak)-induced microclimate and muskmelon (Cucumis melo L.) growth and development were investigated at the Univ. of Nebraska-Lincoln Agricultural Research and Development Center near Mead, Nebr., during the 1992 and 1993 growing seasons. Wind speed, wind direction, air and soil temperatures, relative humidity, and soil moisture were monitored in both sheltered and nonsheltered areas. Plant growth parameters (plant height, vine length, plant dry weight, and leaf area) were measured at various stages of development. Shelterbelts provided improved growing conditions for muskmelon transplants. Direct wind damage and duration of higher wind speeds were reduced 47% to 56% in sheltered areas. Air temperatures in sheltered areas were slightly higher during daytime and slightly lower at night, and significantly so early in the growing season. Relative humidity was increased significantly in sheltered areas in 1992 and, while higher in 1993, the difference was nonsignificant. Soil moisture content was not affected significantly by wind protection. Sheltered plants exhibited earlier development and faster growth. The first female flower appeared 2 days earlier in sheltered areas in both years. The first fruit set, as indicated by fruit swelling and retention on the vine, occurred 6 days earlier and matured 5 and 6 days earlier in sheltered areas in 1992 and 1993, respectively. Leaf areas and dry-matter accumulation of sheltered plants were greater than those of exposed plants. The shoot relative growth rate of sheltered plants increased earlier in the growing season, but decreased slightly later in the growing season. The earlier development and faster growth of sheltered plants were related mainly to the reduction of wind speed, higher total accumulated air temperatures during the daylight hours (sum of daily average daytime air temperatures based on hourly averages), and higher soil temperature in sheltered areas. Total yields were not affected significantly in either year; however, early yields were significantly greater in sheltered areas in 1993. If earlier maturity and increased yield are possible in large sheltered fields, this practice would provide an economic benefit to producers.
Inflorescence Removal Affects Root Yield of American Ginseng
Authors: Proctor John T.A. , Percival David C. , Louttit Dean
Published: February 2019

Manual removal of inflorescences from mature (3- and 4-year-old) American ginseng plants (Panax quinquefolium L.) at commercial timing (early July, ≈25% flowers open) increased root yield at harvest. Consecutive inflorescence removal for 2 years (third and fourth) increased yield 55.6%. Inflorescence removal in 4-year-old plants increased yield by 34.7% compared with 26.1% in 3-year-old plants. Analysis showed that the largest portion of roots (≈40%) was in the medium category (10-20 g), and inflorescence removal did not influence root size distribution. Root yield for 3-year-old plants increased quadratically with plant density, with plants lacking inflorescences having an estimated yield increase of 25%. Maximum yields of 2.4 kg·m-2 for deflowered plants were achieved at a plant density of 170 plants/m2. To maximize ginseng root yield, all plants except those needed to provide seed for future plantings should have inflorescences removed.
Coconut Husk and Processing Effects on Chemical and Physical Properties of Coconut Coir Dust
Authors: Konduru Sreenivas , Evans Michael R. , Stamps Robert H.
Published: February 2019

Chemical properties of unprocessed coconut (Cocos nucifera L.) husks varied significantly among 11 sources tested. The pH and electrical conductivities were significantly different among husk sources and ranged from 5.9 to 6.9 and 1.2 to 2.8 mS·cm−1, respectively. The , , Ca, and Mg levels did not differ significantly among husk sources and ranged from 0.2 to 1.8, 0.2 to 0.9, 2.9 to 7.3, and nondetectable to 4.6 mg·kg−1, respectively. Levels of P, B, Cu, Fe, Ni, S, Zn, Mn, and Mo were all significantly different among husk sources and ranged from nondetectable levels to 33 ppm. The levels of Na, K, and Cl were significantly different among husk sources and ranged from 23 to 88, 126 to 236, and 304 to 704 ppm, respectively. Coir dust (CD) produced by screening of waste-grade coir through 3-, 6-, or 13-mm mesh screens had significantly different fiber content, bulk densities, total solids, total pore space, air-filled pore space, water-filled pore space, and water-holding capacities as compared with nonscreened waste-grade coir. However, screen size did not significantly affect the physical properties of CD. Neither compression pressure nor moisture level during compression of CD blocks significantly affected rehydration of compressed CD or physical properties of rehydrated CD.
Efficacy of a Hydrophilic Polymer Declines with Time in Greenhouse Experiments
Authors: Al-Harbi A.R. , Al-Omran A.M. , Shalaby A.A. , Choudhary M.I.
Published: February 2019

The effect of a hydrophilic polymer (Broadleaf P4®; HP) on growth of cucumber seedlings (Cucumis sativus L.) was investigated. Furthermore, the efficiency of HP to absorb water over a period of time was studied. Predetermined amounts of HP (0.0%, 0.1%, 0.2%, 0.3%, and 0.4% dry-weight basis) were mixed with moderately calcareous sandy loam soil in pots. At the end of the first experiment (42 days), the growth of the seedlings was recorded, as well as the maximum soil water-holding capacity (WHC). The same pots were left for a drying period ranging from 2 to 5 months and then used for another four successive experiments. Soil WHC increased significantly with increasing level of HP, but decreased after each experiment. After five experiments, the WHC had decreased 17.3% and 27.8% where HP was added at the rate of 0.1% and 0.4%, respectively. The bulk density of soils decreased significantly with addition of HP and had increased after five growing experiments at each HP rate. Cucumber seedling growth was stimulated by addition of the polymer. The greatest vegetative growth, expressed as leaf area and shoot fresh and dry weights, was observed at 0.3% HP in the first and second experiment, but at 0.4% in the third and fourth.
Mother Stalk Culture Does Not Improve Plant Survival or Yield of Spring and Summer-forced Asparagus in South Carolina
Authors: Dufault Robert J.
Published: February 2019

Short productive lifespan is a major problem with asparagus (Asparagus officinalis L.), whether harvested in the spring or forced in late summer in coastal South Carolina. A modification of the Taiwanese system of mother stalk (MS) culture might enhance asparagus longevity and yield. The objective of this research was to determine if modified MS culture improved plant survival and yields in spring or summer-forced harvests compared with conventional spring clear-cut (CC) harvesting or with nonconventional summer-forced CC harvesting. `Jersey Giant' asparagus was harvested for 3 years (1994-96) using the following harvest systems: 1) spring CC (normal emergence in February in this location); 2) spring MS followed by summer MS (mow fern down on 1 Aug. and establish new mothers); 3) spring MS only; 4) summer CC only (mow fern on 1 Aug. and harvest); and 5) summer MS only. All systems were harvested for ≈7 weeks. All MS plots produced 40 mother stalks per 12-m row length each year before harvesting began. All mother stalks were trellised and tied to prevent lodging. Three-year total yields (kg·ha-1) and stand reduction (%) for nonharvested controls, spring CC harvesting, spring MS culture, spring MS combined with summer MS, summer CC, and summer MS were: 0 and 54%, 1621 and 96%, 779 and 99%, 1949 and 86%, 4001 and 58%, 3945 and 58%, respectively. All spring harvesting systems failed because by midsummer, aged fern, harvest pressures, and, apparently, higher rates of crown respiration reduced crown carbohydrate reserves. Yearly repetition of these stresses ultimately killed the spring-harvested plants. The MS culture did not ameliorate stand loss by significantly increasing carbohydrate reserves. Yields of summer-forced asparagus were consistently acceptable because aged ferns were removed at about the time they apparently became inefficient photosynthetically. After termination of the summer harvest season and with recovery in the following spring, ample carbohydrates were produced well before summer forcing began again in August the following year. Therefore, plant longevity was better sustained by summer forcing than by traditional spring harvesting.
Conditioning Treatments Affect Insect and Mite Populations on Bedding Plants in the Greenhouse
Authors: Latimer Joyce G. , Oetting Ronald D.
Published: February 2019

During greenhouse production in Spring 1995, conditioning treatments were applied to columbine (Aquilegia×hybrida Sims `McKana Giants'), New Guinea impatiens (Impatiens hawkeri Bull. `Antares'), marigold (Tagetes erecta L. `Little Devil Mix') and ageratum (Ageratum houstonianum Mill. `Blue Puffs') plants. Treatments included: mechanical conditioning (brushing 40 strokes twice daily); moisture stress conditioning (MSC) (wilting for ≈2 hours per day); undisturbed ebb-and-flow irrigation; overhead irrigation; high (500 mg·L-1 N) or low (50 mg·L-1 N) 3×/week N fertilizer regimes; daminozide (5000 mg·L-1); or paclobutrazol (30, 45, or 180 mg·L-1). One week after initiation of treatments, individual plants in separate greenhouses were inoculated with two adult green peach aphids (Myzus persicae Sulzer) or five two-spotted spider mites (Tetranychus urticae Koch). A natural infestation of western flower thrips (Frankliniella occidentalis Pergande) in the mite-inoculated greenhouse provided an additional insect treatment. Brushing was the only treatment that consistently reduced thrips and mite populations. Aphid populations were lower on low-N than on high-N plants, but thrips and mite populations were not consistently affected by plant fertilization. Moisture stress conditioning tended to increase aphid populations on New Guinea impatiens and marigold, but had little effect on spider mite or thrips populations. Ebb-and-flow irrigation reduced the mite population on ageratum relative to that on overhead irrigated (control) plants. Plant growth regulators did not consistently affect pest populations. Chemical names used: butane-dioic acid mono(2,2-dimethylhydrazide) (daminozide); β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-1-ethanol (paclobutrazol).
Cooling Accelerates Flowering of Lysimachia clethroides Duby
Authors: Lewis Pamela M. , Armitage Allan M. , Garner James M.
Published: February 2019

The effect of cooling method and duration on off-season cut flower production of Lysimachia clethroides Duby was examined. Rhizomes harvested in October were cooled for 0, 4, 6, 8, 10, or 12 weeks at 4 ± 1 °C in crates with unmilled sphagnum peat moss or in 3.75-L pots filled with a commercial soilless medium prior to forcing in a warm greenhouse. After 6 or more weeks of cooling, shoots emerged from crates in higher percentages than from pots. However, only the duration of cooling, not the method, affected the rate of shoot emergence, visible bud formation, and anthesis of the first bud in the raceme. As cooling increased from 0 to 12 weeks, the greenhouse days required for shoot emergence, visible bud formation, and anthesis decreased linearly. The number of flowering flushes and flowering stems produced per plant varied quadratically with cooling duration, and the highest yields occurred when rhizomes received between 4 and 10 weeks of cooling. High numbers of flowers were produced rapidly after 10 weeks of cooling. As the number of successive flowering flushes increased, the stem length increased linearly while the stem diameter decreased linearly.
Native Wildflower Establishment with Imidazolinone Herbicides
Authors: Beran Daniel D. , Gaussoin Roch E. , Masters Robert A.
Published: February 2019

Native wildflowers are important components of grassland communities and low-maintenance wildflower seed mixtures. Weed interference limits successful establishment of native wildflowers from seed. Experiments were conducted to determine the influence of the imidazolinone herbicides imazethapyr, imazapic, and imazaquin on the establishment of blackeyed susan (Rudbeckia hirta L.), upright prairieconeflower [Ratibida columnifera (Nutt) Woot. and Standl.], spiked liatris [Liatris spicata (L.) Willd.], blanket flower (Gaillardia aristata Pursh.), purple coneflower [Echinacea purpurea (L.) Moench.], and spotted beebalm (Monarda punctata L.). Wildflower response to the herbicide treatments was variable and appeared to be influenced by the level of weed interference. Establishment of the native wildflowers after application of imazethapyr or imazapic at 70 g·ha-1 a.i. was generally improved at sites with greater weed interference. Emergence and density of wildflowers was often reduced by imazapic in sites with low weed interference. Flower density during the second growing season was usually either improved or not reduced by either imazethapyr or imazapic. Based on these findings, imazethapyr and imazapic can reduce weed interference and improve the establishment of some native wildflowers in areas with high weed infestations. Chemical names used: (±) -2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid (imazapic); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid (imazaquin); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid (imazethapyr).
Macro- and Microelement Fertilizers Influence the Severity of Fusarium Crown and Root Rot of Tomato in a Soilless Production System
Authors: Duffy B.K. , Défago G.
Published: February 2019

Host nutritional variables were evaluated for their effects on the severity of crown and root rot of tomato caused by Fusarium oxysporum f.sp. radicis-lycopersici. Tomato (Lycopersicon esculentum Mill.) seedlings (cv. Bonnie Best) were grown in a pathogen-infested, soilless rockwool system in the greenhouse and were fertilized with a nutrient solution that was amended with macro- and microelements at various rates. Disease was evaluated after 2 weeks using an index of 0 to 4, and plant fresh weight was measured. Regression analysis indicated that disease severity was significantly increased by ammonium-nitrogen [NH4Cl, (NH4)6Mo7O24, and (NH4)2SO4], NaH2PO4·H2O, Fe-EDDHA, MnSO4, MoO3, and ZnSO4·7H2O. Disease severity was reduced by nitrate-nitrogen [Ca(NO3)2·4H2O] and CuSO4·H2O. Low rates of NH4NO3 (39 to 79 mg·L-1 N) reduced disease, but rates above 100 mg·L-1 N increased it. Disease was not affected by MgSO4·7H2O. In all cases, plant growth was inversely related to disease severity. Mineral fertilizers had no effect on nutrient solution pH. This information sheds new light on environmental factors that influence plant-pathogen interactions, and may be applied to develop a management strategy for Fusarium crown and root rot based on host nutrition.
Harvest Date and Crop Load Effects on a Carbon Dioxide–related Storage Injury of `Braeburn' Apple
Authors: Elgar H. John , Lallu Nagin , Watkins Christopher B.
Published: February 2019

The incidence and severity of “`Braeburn' browning disorder” (BBD), a CO2-induced disorder of `Braeburn' apple (Malus ×domestica Borkh.), vary markedly with production district and orchard block. We investigated the effects of harvest date, blush, and crop load on fruit maturity, minerals, skin permeance, and BBD incidence. Incidence of BBD was higher in late-than in early-harvested fruit and in fruit on light than on heavily cropping trees, but blush intensity did not influence susceptibility to the disorder. Fruit maturity factors were affected by region, harvest date, blush type, and crop load, but no consistent relationships between these factors and BBD occurrence were found. Concentrations of Ca, Mg, and/or K were influenced by harvest date, blush type, and crop load, and skin permeance to gas exchange was affected by growing region and blush type, but not by harvest date or crop load. However, no physiological or mineral factor measured in this study was strongly correlated with susceptibility of fruit to BBD. Fruit from orchards that have a history of susceptibility to BBD, or subjected to adverse harvest date, regional, crop load, microclimate, and seasonal influences, should be segregated at harvest, and should not be held in controlled-atmosphere (CA) storage. Crop load should be managed to reduce the occurrence of biennial bearing.
Storage Temperature and Fruit Calcium Alter the Sequence of Ripening Events of `d'Anjou' Pears
Authors: Gerasopoulos D. , Richardson D.G.
Published: February 2019

Pear trees (Pyrus communis L.), cv. d'Anjou, received foliar applications of X-77 surfactant and 32.3 mm CaCl2 at 55, 85, 125, and 137 days after full bloom (DAFB) and fruit were harvested at 147 DAFB. Samples of fruit were stored in air either at 20 °C continuously or at 5 or 10 °C for several periods, then transferred to 20 °C, to determine the effects of storage temperature and CaCl2 treatments on the development of the ethylene climacteric and flesh firmness loss. Control fruits held continuously at 20 °C required 70 days for the onset of climacteric ethylene production, which commenced when firmness had decreased to ≈20 N. Calcium-sprayed fruit required 80 days at 20 °C before the rise in ethylene and resisted softening for ≈50 days. Regardless of calcium treatment, pears stored at 5 or 10 °C required only 40 days to produce climacteric ethylene; fruit softening and internal ethylene concentration after storage at 10 °C were intermediate between those of fruits stored at 5 and 20 °C. Calcium application did not alter the sequence of ripening events.
Crown Gall Resistance in Accessions of 20 Prunus Species
Authors: Bliss F.A. , Schuerman P.L. , Almehdi A.A. , Dandekar A.M. , Bellaloui N.
Published: February 2019

Crown gall is an important disease of many fruit and nut crops, but little is known about sources of resistance. We screened germplasm from Prunus armeniaca L., P. angustifolia Marsh., P. argentia L., P. avium L., P. besseyi Bailey, P. bokhariensis Schneid., P. brigantica L., P. cerasifera Ehrh., P. cerasus L., P. dulcis (Mill.) D.A. Webb, P. fruiticosa Pall., P. hortulana Bailey, P. insititia L., P. japonica Thunb., P. mahaleb L., P. persica (L.) Batsch, P. serotina Ehrh., P. simonii Carr., P. sogdiana L., and P. webbii (Spach) Vieh. When either main stems or lateral branches of seedlings were inoculated with strains K12 and C58 of Agrobacterium tumefaciens (Smith and Townsend) Conn., the incidence of resistance was less than 10% except in some accessions of P. mahaleb L. where up to 30% of the plants were resistant. Some resistant plants were identified in other species, with P. insititia L. being the most promising. Symptoms based on presence and size of galls should be allowed to develop for up to 90 days after inoculation to reduce the likelihood of misclassifying plants as resistant when they are slightly susceptible.
A Novel Gene Conferring Citrus Tristeza Virus Resistance in Citrus maxima (Burm.) Merrill
Authors: Fang D.Q. , Roose M.L.
Published: February 2019

`Chandler' pummelo [Citrus maxima (Burm.) Merrill] was found to be citrus tristeza virus (CTV)–resistant. The inheritance of this resistance in 84 progeny of two crosses derived from `Chandler' pummelo and trifoliate orange [Poncirus trifoliata (L.) Raf.] was controlled by a single dominant gene designated Ctv2. Progeny analysis of four molecular markers closely linked to the Ctv gene, which confers resistance to CTV in trifoliate orange, demonstrated that Ctv2 was an independently assorting gene from Ctv.
Rose Germplasm Analysis with RAPD Markers
Authors: Jan C.H. , Byrne D.H. , Manhart J. , Wilson H.
Published: February 2019

The genus Rosa consists of more than 100 species classified into four subgenera, Eurosa, Platyrhodon, Hesperhodos, and Hulthemia, and distributed widely throughout the northern hemisphere. The subgenus Eurosa includes 11 sections. The other subgenera are monotypic. One hundred and nineteen accessions and 213 markers of 36 rose species that include eight sections of the subgenus Eurosa and one species each from the subgenera Hesperhodos and Platyrhodon were used to calculate a similarity matrix, which was clustered with the unweighted pair group method using arithmetic means (UPGMA). The RAPD markers distinguished between all the rose accessions, and species grouped into their respective sections. Therefore, classification of Rosa using RAPD data generally supports traditional classification. The Asian rose sections (Laevigatae, Banksianae, Bracteatae, Pimpinellifoliae, Chinenses, and Synstylae) were consistently separated from the primarily North American sections (Cassiorhodon and Carolinae). The Cassiorhodon and Carolinae sections were grouped together with the subgenera Hesperhodos and Platyrhodon. Both subgenera separated out at the same level as sections within the subgenus Eurosa, suggesting that they are more appropriately classified as sections within the subgenus Eurosa. Sections Cassiorhodon and Carolinae overlapped, and are probably best grouped as one section as previously suggested.
An Efficient Method for Callus Culture and Shoot Regeneration of Garlic (Allium sativum L.)
Authors: Barandiaran Xabier , Martín Nieves , Rodríguez-Conde María Fernanda , Di Pietro Antonio , Martín Jesus
Published: February 2019

The influence of different callus induction media on the regeneration process in garlic was tested. The auxin 2,4 dichlorophenoxyacetic acid frequently used in garlic tissue culture was found to be detrimental when used at the levels described in the literature. However, combinations of growth regulators commonly used for dicot tissue culture produced high levels of callus induction and regeneration that could be used efficiently in a transformation program.
In Vitro Storage Conditions for Mint Germplasm
Authors: Reed Barbara M.
Published: February 2019

Four tissue-cultured mints, Mentha arvensis L., M. spicata L., M. suaveolens Ehrh. hybrid, and M. suaveolens cv. Variegata, were evaluated for survival during storage in media containing three concentrations of N and in four light and temperature regimes. Shoots were placed in plastic, five-chamber, tissue-culture bags on Murashige and Skoog medium (1962) containing 25%, 50%, and 100% of the normal N concentration (MS-N) and stored at 4 °C and –1 °C in darkness, at 4 °C with a 12-hour photoperiod, and at 25 °C with a 16-hour photoperiod. Shoots of all four genotypes stored at 25 °C were in excellent condition after 6 months but required subculture after 18 months. Condition ratings of stored shoots varied with genotype and N concentration. Cultures survived longest at 4 °C with a 12-hour photoperiod on 50% MS-N. Under this regime, all four genotypes were rated in good condition at 30 months but declined to poor condition by 36 months. Based on these data, I recommend that mint cultures be stored on MS medium with 50% MS-N at 4 °C with a 12-hour photoperiod. This regime should provide a minimum of 24 to 36 months of storage before subculture is required. Cold-sensitive genotypes could be stored for 18 months at 25 °C on 50% MS-N medium.
001 Establishment of Methods in Evaluating the Susceptibility of Chinese Cabbage (Brassica campestris spp.) to Soft Rot Disease by Erwinia
Authors: Jun Won , Lee Soo-Seong , Kim Jongkee
Published: February 2019

Three inoculation methods, including cutting of a leaf, drenching, and point inoculation, were compared in an effort to screen the susceptibility of Chinese cabbage to soft rot disease caused by Erwinia carotovora subsp. carotovora. Three- to 4-week-old seedlings from 10 lines of cabbage with 16-h-old bacterial culture were routinely used. Inoculated seedlings were kept at 25.0 ± 10.0 °C for 48 h with saturated water vapor using a plastic tunnel in a greenhouse. Sixty-day-old mature plants were produced and inoculated in a greenhouse. Severity of symptoms, which were observed from percentage of plant infected was scored as from 1 to 9, representing resistant to susceptible, respectively. The correlation between seedlings and mature plants from ten lines was evaluated among the three different inoculation methods. Point inoculation gave the most significant correlation (r = 0.843, P < 0.05) between seedlings and mature plants. A good correlation was also observed between point inoculation of seedlings and drenching of mature plants (r = 0.609, P < 0.05). Cutting of a leaf of seedlings was also correlated with point inoculation of mature plants (r = 0.609, P < 0.05). This method provides the advantage of being able to keep the experimental plant alive, as only one leaf is detached. The point inoculation method is simple and relatively sensitive, so it could be used for large-scale screening for this bacterial soft rot disease. From three different evaluation assays, it was concluded that the breeding lines, C3-28, C3-29 from Cornell Univ. (Geneva, N.Y.) and the cultivar Kweonsim319 were relatively resistant to bacterial soft rot, while the Cornell breeding line CC-25 and the `Rang-no' cultivar were relatively susceptible.
003 Epidemiology and Control of Pepper Stip
Authors: Smith Richard , Mullen Robert , Hartz Tim
Published: February 2019

Pepper stip is a physiological disorder manifested as gray-brown to greenish spots occurring on the fruit of bell, pimento, Anaheim, and other types of peppers, most noticeably on red fruit that mature under fall conditions. Most hybrid bell cultivars are resistant to the malady; the problem is most severe for pepper growers reliant on less-expensive, open-pollinated cultivars. In 1995, we initiated studies to evaluate the possible link between mineral nutrition and this disorder. Two susceptible open-pollinated cultivars and two resistant hybrid cultivars were grown in randomized plots at seven sites. Significant correlations were seen between the levels of potassium (r = 0.59) and calcium (r = -0.37) in whole leaves and the incidence of stip (P = 0.05). The stip-resistant cultivars also maintained less total nitrogen in the whole leaves than susceptible cultivars (P = 0.05). In 1996 and 1997, we undertook field studies to evaluate the effects of varying calcium and nitrogen application rates. Inconsistent results were observed with calcium applications. Moderate reductions in stip incidence was observed at some sites and no reduction at others following foliar calcium applications. Nitrogen nutrition had no effect on stip severity. In 1998, evaluation of a large number of open-pollinated cultivars was undertaken; `Gusto' showed excellent tolerance to pepper stip, followed by `Taurus' and `Cal Wonder 300'. We conclude that growers that are reliant on open-pollinated cultivars can utilize these cultivars to minimize the incidence of pepper stip.
008 Evaluation of Weed Control in a No-tillage Vegetable Production System
Authors: Crosby Christine , Valenzuela Hector , Kratky Bernard , Evensen Carl
Published: February 2019

In the tropics, weed control is a year-round concern. The use of cover crops in a conservation tillage system allows for the production of a crop biomass that can be killed and mowed, and later used as mulching material to help reduce weed growth. This study compared yields of three vegetable species grown in two conventional tillage systems, one weeded and one unweeded control, and in two no-tillage treatments using two different cover crop species, oats (Avena sativa L. `Cauyse') and rye grain (Secale cereale L.). The cover crops were seeded (112 kg/ha) in Spring 1998 in 4 × 23-m plots in a RCB design with six replications per treatment, and mowed down at the flowering stage before transplanting the seedlings. Data collection throughout the experimental period included quadrant weed counts, biomass levels, and crop marketable yields. Weed suppression was compared with the yields of the vegetable crops. The greatest vegetable yields were in the conventionally hand-weeded control and the worst in the un-weeded controls. Weed species composition varied depending on the cover crop species treatment. The rye better suppressed weed growth than the oats, with greater control of grass species. Rye, however, suppressed romaine and bell pepper yields more than the oat treatments. Similarly greater eggplant yields and more fruit per plant were found in the oat treatment than in the rye. Both cover crops suppressed weed growth for the first month; however, by the second month most plots had extensive weed growth. This study showed that at the given cover crop seeding rate, the mulch produced was not enough to reduce weed growth and provide acceptable yields of various vegetable crops.