bluuebunny/crossref_metadata_2025 huggingface dataset:
High Relative Humidity Increases Yield, Harvest Index, Flowering, and Gynophore Growth of Hydroponically Grown Peanut Plants
Authors: Mortley D.G. , Bonsi C.K. , Loretan P.A. , Hill W.A. , Morris C.E.
Published: February 2019

Growth chamber experiments were conducted to study the physiological and growth response of peanut (Arachis hypogaea L.) to 50% and 85% relative humidity (RH). The objective was to determine the effects of RH on pod and seed yield, harvest index, and flowering of peanut grown by the nutrient film technique (NFT). `Georgia Red' peanut plants (14 days old) were planted into growth channels (0.15 × 0.15 × 1.2 m). Plants were spaced 25 cm apart with 15 cm between channels. A modified half-Hoagland solution with an additional 2 mm Ca was used. Solution pH was maintained between 6.4 and 6.7, and electrical conductivity (EC) ranged between 1100 and 1200 μS·cm–1. Temperature regimes of 28/22 °C were maintained during the light/dark periods (12 hours each) with photosynthetic photon flux (PPF) at canopy level of 500 μmol·m–2·s–1. Foliage and pod fresh and dry weights, total seed yield, harvest index (HI), and seed maturity were greater at high than at low RH. Plants grown at 85% RH had greater total and individual leaflet area and stomatal conductance, flowered 3 days earlier and had a greater number of flowers reaching anthesis. Gynophores grew more rapidly at 85% than at 50% RH.
Growth, Pod, and Seed Yield, and Gas Exchange of Hydroponically Grown Peanut in Response to CO2 Enrichment
Authors: Stanciel K. , Mortley D.G. , Hileman D.R. , Loretan P.A. , Bonsi C.K. , Hill W.A.
Published: February 2019

The effects of elevated CO2 on growth, pod, and seed yield, and gas exchange of `Georgia Red' peanut (Arachis hypogaea L.) were evaluated under controlled environmental conditions. Plants were exposed to concentrations of 400 (ambient), 800, and 1200 μmol·mol–1 CO2 in reach-in growth chambers. Foliage fresh and dry weights increased with increased CO2 up to 800 μmol·mol–1, but declined at 1200 μmol·mol–1. The number and the fresh and dry weights of pods also increased with increasing CO2 concentration. However, the yield of immature pods was not significantly influenced by increased CO2. Total seed yield increased 33% from ambient to 800 μmol·mol–1 CO2, and 4% from 800 to 1200 μmol·mol–1 CO2. Harvest index increased with increasing CO2. Branch length increased while specific leaf area decreased linearly as CO2 increased from ambient to 1200 μmol·mol–1. Net photosynthetic rate was highest among plants grown at 800 μmol·mol–1. Stomatal conductance decreased with increased CO2. Carboxylation efficiency was similar among plants grown at 400 and 800 μmol·mol–1 and decreased at 1200 μmol·mol–1CO2. These results suggest that CO2 enrichment from 400 to 800 μmol·mol–1 had positive effects on peanut growth and yield, but above 800 μmol·mol–1 enrichment seed yield increased only marginally.
Seasonal Patterns of Photosynthesis and Stomatal Conductance in Lowbush Blueberry Plants Managed in a Two-year Production Cycle
Authors: Hicklenton Peter R. , Reekie Julia Y. , Gordon Robert J. , Percival David C.
Published: February 2019

Seasonal patterns of CO2 assimilation (ACO2), leaf water potential (ψ1) and stomatal conductance (g1) were studied in three clones (`Augusta', `Brunswick', and `Chignecto') of lowbush blueberry (Vaccinium angustifolium Ait.) over two growing seasons. Plants were managed in a 2-year cycle of fruiting (year 1) and burn-prune (year 2). In the fruiting year, ACO2 was lowest in mid-June and early September. Rates peaked between 10 and 31 July and declined after fruit removal in late August. Compared with the fruiting year, ACO2 in the prune year was between 50% and 130% higher in the early season, and between 80% and 300% higher in mid-September. In both years, however, mid-season maximum ACO2 for each clone was between 9 and 10 μmol·m–2·s–1CO2. Assimilation of CO2 increased with increasing photosynthetic photon flux (PPF) to between 500 and 600 μmol·s–1·m–2 in `Augusta' and `Brunswick', and to between 700 and 800 μmol·s–1·m–2 in `Chignecto'. Midday ψ1 was generally lower in the prune year than in the fruiting year, reflecting year-to-year differences in soil water content. Stomatal conductance (g1), however, was generally higher in the prune year than in the fruiting year over similar vapor pressure deficit (VPD) ranges, especially in June and September when prune year g1 was often twice that observed in the fruiting year. In the fruiting year, g1 declined through the day in response to increasing VPD in June, but was quite constant in mid-season. It tended to be higher in `Augusta' than in the other two clones. Stomatal closure imposes limitations on ACO2 in lowbush blueberries, but not all seasonal change in C-assimilative capacity can be explained by changes in g1.
Tomato Root Growth Is Influenced by Tillage, Cover Cropping, and Nitrogen Fertilization
Authors: Sainju Upendra M. , Singh Bharat P. , Rahman Syed , Reddy V.R.
Published: February 2019

The influence of tillage [no-till (NT) vs. moldboard plowing (MP)], cover crop [hairy vetch (Vicia villosa Roth) (HV) vs. no hairy vetch (NHV)], and N fertilization (0 and 180 kg·ha–1 N) on root distribution and growth rate of tomato (Lycopersicon esculentum Mill.) transplants was examined in the field from May to August in 1996 and 1997. Experiments were conducted on a Norfolk sandy loam (fine-loamy, siliceous, thermic, Typic Kandiudults) in central Georgia. Root growth was estimated every 1 to 2 weeks with minirhizotron tubes installed in the plot. Roots were well distributed at soil depths between 1 and 58.5 cm and a maximum root count of 3.14 roots/cm2 soil profile area was found at 19.5-cm depth with MP and no N fertilization in 1996. In general, NT with HV or with 0 kg·ha–1 N increased root proliferation at a depth of 6.5 to 19.5 cm, while MP with 180 kg·ha–1 N increased root proliferation at greater depths. Total root count between 1 and 58.5 cm was not influenced by management practices, but increased linearly at rates of 0.35 roots/cm2 per day from 20 June to 11 July 1996, and 0.03 roots/cm2 per day from 16 May to 5 Aug. 1997. Root growth thereafter was minimal. Because of the higher temperature during early development, growth rate and number of roots were greater in 1996 than in 1997. Superior moisture conservation, accompanied by increased N availability, may have increased root proliferation in the surface soil in NT with HV or with 0 kg·ha–1 N compared with NT with NHV or with 180 kg·ha–1 N, and MP with or without HV or with or without N fertilization. Root growth, however, was not related with aboveground tomato yield.
Association of Marginal Leaf Scorch with Sodium Accumulation in Salt-stressed Peach
Authors: Karakas Bedri , Bianco Riccardo Lo , Rieger Mark
Published: February 2019

The effect of specific ion toxicity during salt stress was tested in the present study. The experiment was repeated twice, in 1996 and 1998, with `Nemaguard' peach seedlings and rooted cuttings grown in hydroponics under two NaCl concentrations (50 and 30 mm). Foliage was separated in symptomatic and symptomless leaves and the amount of sodium (Na+) and chloride (C1–) was determined. Significantly higher Na+ content was found in symptomatic than in symptomless leaves in both experiments, whereas in only two of the six cases was Cl– content higher in symptomatic than in symptomless leaves. The Na+ threshold for leaf scorch was somewhere between 4 and 6 mg·g–1 dry weight. Results indicated that Na+ accumulation, rather than Cl– accumulation, was associated with the familiar marginal and interveinal scorch symptoms seen in salt-stressed peach leaves.
Evaluation of Seedlings of Fraser, Momi, and Siberian Fir for Resistance to Phytophthora cinnamomi
Authors: Hinesley L. Eric , Parker K.C. , Benson D.M.
Published: February 2019

Containerized seedlings of Fraser fir [Abies fraseri (Pursh) Poir.], momi fir (A. Firma Sieb. & Zucc.), and Siberian fir (A. siberica Ledeb. var. argentea) were tested for resistance to Phytophthora cinnamomi Rands (two experiments). Fraser fir was very susceptible, with many plants dead after 4 to 5 weeks. Symptoms developed more slowly in Siberian fir, but most plants were dead or dying after 10 weeks. Momi fir appeared somewhat resistant to the pathogen. Though undesirable as a Christmas tree, momi fir might be useful as a rootstock for grafting better quality species in areas affected by root rot.
A Greenhouse Method for Screening Grapevine Seedlings for Resistance to Anthracnose
Authors: Hopkins D.L. , Harris J.W.
Published: February 2019

Screening for resistance to Elsinoe ampelina (de Bary) Shear, causal agent of grape anthracnose, in grapevine seedlings is commonly conducted by natural infection over 3 to 4 years in the vineyard. The objective of this research was to develop a greenhouse screening method for selecting grapevine seedlings with resistance to anthracnose. Spores of E. ampelina were obtained from 3- to 4-week-old cultures on potato dextrose agar. Inoculum concentrations ranging from 1.3 × 103 to 1.3 × 107 E. ampelina conidia per mL were evaluated and 106 conidia/mL was optimum. The time of incubation of seedlings in a moist chamber after inoculation varied from 24 to 120 hours with 24 to 72 hours resulting in good symptom development. Temperatures in the moist chamber from 16 to 32 °C were evaluated and the most consistent results were obtained at 20 to 28 °C. The most effective method for selecting anthracnose-resistant grape seedlings in the two-to-three true-leaf stage was misting the seedlings with a suspension containing 106 conidia/mL in water and placing the inoculated seedlings in a moist chamber at 24 °C for 48 hours, followed by 8 days on a greenhouse bench. Resistant seedlings from the greenhouse screening (those with <10 foliar lesions) were transplanted into the vineyard and found to be resistant to anthracnose infection under rainy, humid conditions. This greenhouse procedure for selecting grapevine cultivars and breeding lines with resistance to anthracnose is accurate, economical, and labor-saving.
Reduction in Snap Bean Emergence by Seed Treatment with Dried Canola Residue
Authors: Smith V.L.
Published: February 2019

Emergence of snap beans (Phaseolus vulgaris L.) in field soil in 1995 to 1997 was reduced by the addition of dried, ground canola [Brassica napus L. ssp. oleifera (Metzg.) Sinsk. f. biennis] leaves and petioles to the furrow at planting. Soil amendment with the tissue increased the number of nodules on bean roots in all years. In plots with reduced stand, leaf area was increased and yield on a per-plant basis was larger than in plots with a better stand. Total yield was increased in plots with fewer plants only in 1995. Frequency of isolation of fungi that cause damping-off was not affected by the addition of canola at planting. When used as a seed treatment and incorporated at planting, canola residues were detrimental to emergence of snap bean.
Scanning Electron Microscopic Study of Modified Chloroplasts in Senescing Broccoli Florets
Authors: Terai Hirofumi , Watada Alley E. , Murphy Charles A. , Wergin William P.
Published: February 2019

Structural changes in chloroplasts of broccoli (Brassica oleracea L., Italica group) florets during senescence were examined using light microscopy, scanning electron microscopy (SEM) with freeze-fracture technique, and transmission electron microscopy (TEM) to better understand the process of chloroplast degradation, particularly at the advanced stage of senescence. Light microscopy revealed that chloroplasts, which initially were intact and green, became obscure in shape, and their color faded during senescence. Small, colored particles appeared in cells as the florets approached the final stage of senescence and became full- to dark-yellow in color. Scanning electron microscopy showed that stroma thylakoids in the chloroplast initially were parallel to each other and grana thylakoids were tightly stacked. As senescence advanced, the grana thylakoids degenerated and formed globules. The globules became larger by aggregation as senescence progressed, and the large globules, called “thylakoid plexus,” formed numerous vesicles. The vesicles ultimately were expelled into the cytosol, and the light microscope revealed many colored particles in the senescent cells. These results indicate that the degradation of chloroplasts in broccoli florets progresses systematically, with the final product being colored particles, which are visible in yellow broccoli sepal cells.
Cane Stabilization Improves Yield of Red Raspberry (Rubus idaeus L.)
Authors: Heuvel Justine E. Vanden , Sullivan J. Alan , Proctor John T.A.
Published: February 2019

Treatments of either staked (stabilized) or not staked (control, freestanding) canes were applied to Rubus idaeus L. `Boyne' and `Regency' during the 1997 and 1998 seasons to determine the effect of stabilizing fruiting canes in a windy environment. Treatments were applied in late April of each year, and canes were removed following harvest for growth analysis. Stabilizing (staking) floricanes increased yield per cane in `Boyne' by 68% and in `Regency' by 189%, primarily through increases in fruit number per cane. Leaf area of the staked canes was 41% larger for `Boyne' and 159% for `Regency' than that of the control canes, suggesting that more leaf area was retained for photosynthesis, resulting in greater yield. Primocane diameter in `Boyne' and primocane height in `Regency' were also increased by staking, but floricane structure was unaffected.
Assessing Chilling Tolerance in Roses using Chlorophyll Fluorescence
Authors: Hakam Nadia , DeEll Jennifer R. , Khanizadeh Shahrokh , Richer Claude
Published: February 2019

Chlorophyll fluorescence (CF) was evaluated as a technique to assess chilling injury of rose (Rosa sp.) leaves exposed to low temperatures. In the more susceptible genotypes, variable fluorescence (Fv) decreased dramatically as the temperature was lowered. In the less susceptible genotypes, Fv was more stable and decreased more slowly as temperature fell. Our results suggest that measurement of CF may provide a rapid method to prescreen genotypes for chilling susceptibility, as required in plant breeding.
Viability of Pollen of Two Fruit Crop Cacti of the Genus Hylocereus Is Affected by Temperature and Duration of Storage
Authors: Metz Christiane , Nerd Avinoam , Mizrahi Yosef
Published: February 2019

Hylocereus undatus (Haw.) and H. polyrhizus (Weber) are new fruit crops of the Cactaceae. In Israel, flowers of the two species, which are self-incompatible, are hand cross-pollinated. In order to ensure a current supply of compatible pollen and guarantee good yields, we have developed a procedure for long-term storage of pollen. Pollen for storage was collected in the evening or in the morning. Its moisture content ranged between 45% to 50% in the evening and between 18% to 22% in the morning. Pollen was first dehydrated in a vacuum desiccator until the moisture content was reduced to 5% to 10% and then stored at various temperatures (+4, -18, -70, -196 °C) for 3 or 9 months, after which it was used for cross-pollination. Percent fruit set and fruit fresh weight (FW) were affected by the temperature but not the duration of pollen storage; storage at +4 °C reduced fruit set, fruit FW, and seed number more than did storage at subfreezing temperatures. The FW of fruits produced by frozen pollen was similar to that produced by fresh pollen in commercial orchards. The rate of seed germination was high (≈90%) regardless of the temperature during pollen storage.
Black Polyethylene Tunnel Covers Affect Plant Production and Quality of Sweetpotato Transplants
Authors: La Bonte D.R. , Villordon A.Q. , Schultheis J.R. , Monks D.W.
Published: February 2019

The influence of a black polyethylene tunnel cover (BTC) was evaluated for its effect on quantity and quality of sweetpotato [Ipomoea batatas (L.) Lam.] transplants in plant beds in Louisiana and North Carolina. Use of BTC increased production of `Beauregard' transplants from 63% to 553% in comparison with the bare ground control. `Jewel' was less responsive; BTC treatments increased transplant production by at least 48% in Louisiana over the bare ground control, but no increase was observed in North Carolina. Individual transplant weight was at least 34% less in BTC treatments than in the control. The first harvest of cuttings in BTC beds was at least 14 days prior to that in control beds. Transplant quality was assessed as yield of storage roots in repeated trials that extended throughout the normal growing season. Yield of storage roots was not affected by BTC in early season plantings, but was frequently lower for BTC treatment transplants in middle and late season plantings. We therefore do not recommend this method as a means of increasing sweetpotato plant production from bedded roots.
Growth, Survival, and Aesthetic Quality of Boxwood Cultivars as Affected by Landscape Exposure
Authors: Le Duc Alice , Parsons Linda R. , Pair John C.
Published: February 2019

Three cultivars of boxwood, `Winter Gem' (Buxus microphylla Sieb. & Zucc.), `Green Velvet', and `Green Mountain' [B. sinica (Rehd. & Wils.) Cheng var. insularis (Nakai) M. Cheng × B. sempervirens L. `Suffruticosa' L.], were planted in 12 different landscape exposures (N, ENE, NNE, E, SSE, ESE, S, WSW, SSW, W, NNW, WNW) at Manhattan and Wichita, Kans., representing U.S. Dept. of Agriculture hardiness zones 5 and 6, respectively. In Kansas, winter stress is often the greatest threat to plant survival, and Winter 1995-96 was one of great extremes. Official lows of -25 °C for Manhattan and -23 °C for Wichita were recorded, along with sharp 24-hour temperature drops of 31-32 °C in January and March. Differences in cultivar performance were noted between sites. Better winter quality was exhibited by `Green Velvet' and `Green Mountain', although significant bronzing occurred on the former in Manhattan. Locations on N, ENE, NNE, NNW, and WNW exposures resulted in better plant quality of all cultivars, whereas plant performance was poorer at S and SE exposures. Differences in canopy temperatures of up to 15.7 °C were recorded, on the same cold winter day, between NNW and ESE. Recovery from winter dieback and growth during Summer 1996 varied with cultivar, site, and exposure. `Winter Gem' grew most in height, and `Green Velvet' grew most overall at Manhattan. Growth rates were dependent on exposure, with greater growth at NNE, E, SSW, and WNW. Performance of `Green Velvet' and `Green Mountain' indicated that they could be used in any exposure with conditions similar to those of the test sites.
Nitrogen and Carbon Mineralization Dynamics of Manures and Composts
Authors: Hartz T.K. , Mitchell J.P. , Giannini C.
Published: February 2019

Nitrogen and carbon mineralization rates of 19 manure and compost samples were determined in 1996, with an additional 12 samples evaluated in 1997. These organic amendments were mixed with a soil: sand blend at 2% by dry weight and the amended blends were incubated at constant moisture for 12 (1996) or 24 weeks (1997) at 25 °C. Net N mineralization was measured at 4- (1996) or 8-week (1997) intervals, C mineralization at 4-week intervals in 1997. Pots of the amended blends were also seeded with fescue (Festuca arundinacea Shreb.) and watered, but not fertilized, for 17 (1996) or 18 weeks (1997); N phytoavailability was estimated from fescue biomass N and mineral N in pot leachate. An average of 16%, 7%, and 1% of organic N was mineralized in 12 weeks of incubation in 1996, and an average of 15%, 6%, and 2% in 24 weeks of incubation in 1997, in manure, manure compost, and plant residue compost, respectively. Overall, N recovery in the fescue assay averaged 11%, 6%, and 2% of total amendment N for manure, manure compost, and plant residue compost, respectively. Mineralization of manure C averaged 35% of initial C content in 24 weeks, while compost C mineralization averaged only 14%. Within 4 (compost) or 16 weeks (manure), the rate of mineralization of amendment C had declined to a level similar to that of the soil organic C.
Tillage, Cover Cropping, and Nitrogen Fertilization Influence Tomato Yield and Nitrogen Uptake
Authors: Sainju Upendra M. , Singh Bharat P. , Rahman Syed , Reddy V.R.
Published: February 2019

Management practices can influence tomato (Lycopersicon esculentum Mill.) yield and N uptake. The effects of tillage (no-till, chisel plowing, and moldboard plowing), cover crop [hairy vetch (Vicia villosa Roth) vs. none], and N fertilization (0, 90, and 180 kg·ha-1 N) on transplanted tomato yield and N uptake were studied in the field from May to August in 1996 and 1997 on a Norfolk sandy loam (fine-loamy, siliceous, thermic, Typic Kandiudults) in central Georgia. Plowing increased fresh and dry fruit yield and N uptake in 1996 and N fertilization increased yield and N uptake in 1996 and 1997. Plowing also increased stem and leaf dry weights and N uptake from 40 to 118 days after transplanting (DAT) in 1996. Fertilization increased stem weight and N uptake with or without hairy vetch from 54 to 68 DAT in 1996 and stem and leaf weights and N uptake at 68 DAT in 1997. Both hairy vetch and N fertilization increased leaf N concentration in 1997. Recovery of N by the plants was lower with hairy vetch than with N fertilization, but was similar to or greater with 90 than with 180 kg·ha-1 N. We conclude that reduced tillage, such as chisel plowing, with 90 kg·ha-1 N can sustain tomato yield and N uptake, with reduced potentials of sediments and/or NO3 contamination in surface and groundwater.
Hormonal and Physiological Responses of Gerbera jamesonii to Flooding Stress
Authors: Olivella C. , Biel C. , Savé R. , Vendrell M.
Published: February 2019

The effects of flooding (3 days) and recovery (3 days) on leaf gas exchange parameters (stomatal conductance, net photosynthetic assimilation rate, and leaf transpiration rate) were studied in five, 1-year-old gerbera (Gerbera jamesonii Bolus) cultivars under greenhouse conditions. Flooding reduced the measured parameters in all cultivars, which had not recovered 3 days after flooding ceased. A more detailed study was conducted with the `Beauty' cultivar, in which leaf water potential (Ψw); root hydraulic resistance (Rh); and hormonal concentrations of ABA, IAA, and CK were measured in leaves and roots. Plants were flooded for 2 days, then allowed to recover for 4 days. After 2 days of flooding, Ψw had decreased and Rh had increased. Leaf ABA content increased and IAA and CK content decreased from the start of flooding and did not change during recovery. In roots a transient increase in root ABA levels occurred during flooding and a sharp decrease was measured during recovery, which was related to root death. Similar patterns were observed in root CK concentrations. The IAA concentration in roots remained constant throughout the experiment. The results suggest that ABA and CK may act as signals of flooding stress. Also, the marked intolerance of gerbera to flooding could be a serious barrier to its culture under anaerobic conditions, and hence careful irrigation management is required. Chemical names used: abscisic acid (ABA); indoleacetic acid (IAA); cytokinin (CK).
Sprayer Type and Pruning Affect the Incidence of Blueberry Fruit Rots
Authors: Hanson Eric , Hancock Jim , Ramsdell Donald C. , Schilder Annemiek , VanEe Gary , Ledebuhr Richard
Published: February 2019

Highbush blueberries (Vaccinium corymbosum L.) in Michigan are treated annually with fungicides to control fruit rots caused by Colletotrichum acutatum J.H. Simmonds, Alternaria sp., and Botrytis cinerea Pers.:Fr. Control with recommended fungicide programs is often inadequate. The goal of this study was to compare the effects of two spray treatments and three levels of pruning severity on fruit rot levels in mature `Jersey' bushes. Two spray treatments were tested for 3 years: 1) recommended fungicide rates applied with a conventional airblast sprayer; 2) 67% of recommended fungicide rates applied with a multifan/nozzle, above-row sprayer. Pruning treatments included light and heavy pruning (compared for 1 year), and light, moderate, and heavy pruning (compared for 3 years). Fruit rot incidence was determined after incubating individual fruit at 100% relative humidity and 21 °C for 7 to 11 days, and after exposing 0.24-L plastic clamshell containers of fruit to simulated commercial handling. The above-row sprayer provided fruit rot control at least equivalent to the airblast sprayer even though less chemical was applied. Anthracnose rot in berries from the top of the bush canopy were reduced by pruning, but those in the bottom of the bush, and levels of other diseases were not consistently affected. Pruning also reduced yields, although the study was too short in duration to determine the long-term impact on production.
Postproduction Leaching Affects the Growing Medium and Respiration of Subirrigated Poinsettias
Authors: van Iersel Marc
Published: February 2019

Poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch) were grown in pots filled with 1.5 L of soilless growing medium and subirrigated daily with a fertilizer solution containing N at 210 mg·L-1 [electrical conductivity (EC) = 1.5 dS·m-1] for 128 days. After production, plants were placed in a whole-plant photosynthesis system and the effects of applying different volumes of water (0, 0.75, 1.5, and 3 L) to the top of the pots were quantified. Leaching with 0.75, 1.5, or 3 L of water reduced the EC in the top and middle layers of the growing medium. Applications of 0.75 or 1.5 L of water significantly increased the EC in the bottom third of the pots, where most of the root growth occurred. However, even in these treatments the EC in the bottom layer was only 2.6 dS·m-1 (saturated medium extraction method), which is well within the recommended range. The 0.75- and 1.5-L treatments also reduced the respiration rate of the plants by 20%, but none of the treatments had a significant effect on the photosynthesis of the plants. Regression analysis indicated a negative correlation between the EC of the bottom layer of the growing medium and dark respiration, while the EC of the top and middle layer had no significant effect on respiration. Although top watering can increase the EC in the bottom layer of the growing medium, this effect is unlikely to be large enough to cause significant plant stress and damage.
Chlorophyll Fluorescence as a Nondestructive Indicator of Broccoli Quality during Storage in Modified-atmosphere Packaging
Authors: DeEll Jennifer R. , Toivonen Peter M.A.
Published: February 2019

The objective of this study was to determine if chlorophyll fluorescence could be used as an indicator of anaerobic respiration in broccoli (Brassica oleracea L., Italica group) during modified-atmosphere packaging (MAP). Two types of packages were used, PD-941 bags, which provided optimum MAP conditions for broccoli (≈3 kPa O2 plus 5 kPa CO2), and PD-961EZ bags, which allowed the CO2 to accumulate (≈11 kPa CO2). After 28 days in MAP at 1 °C, the broccoli from both types of bag had similar appearances and weight losses. However, broccoli held in the PD-961EZ bags had developed slight to moderate alcoholic off-odors and had higher ethanol, acetaldehyde, and ethyl acetate content, as compared with broccoli in PD-941 bags. Chlorophyll fluorescence parameters (Fv/Fm, T1/2, Fmd, and ΦPSII) were lower for broccoli held in the PD-961EZ bags than in PD-941 bags, and these differences increased with storage duration. These results indicate that chlorophyll fluorescence is a reliable, rapid, nondestructive indicator of broccoli quality during MAP, and that it could be used to determine if broccoli has developed off-odors without opening the bag and disrupting the package atmosphere.
Leaf Gas Exchange Characteristics of Red Raspberry Germplasm in a Hot Environment
Authors: Stafne Eric T. , Clark John R. , Rom Curt R.
Published: February 2019

Net CO2 assimilation (A), evapotranspiration (ET), and stomatal conductance (gs) were determined in two experiments for 14 and 18 raspberry (Rubus sp.) genotypes, respectively, grown in 4-L containers and exposed to 35 °C daytime temperatures 2 weeks and 4 weeks after placement in growth chambers. Measurements were taken on two successive leaves on the same primocane between the third and seventh node (≈75% to 85% of full leaf expansion). In Expt. 1, selections from Louisiana exhibited higher A (3.10-5.73 μmol·m-2·s-1) than those from Oregon (0.50-2.65 μmol·m-2·s-1). In Expt. 2, the genotype × time interactions were nonsignificant, and time of measurement did not affect A or ET (P ≤ 0.05). Assimilation ranged from 2.08 to 6.84 μmol·m-2·s-1 and varied greatly among genotypes, indicating that diverse A levels exist at high temperatures in raspberry germplasm. NC 296, a selection of R. coreanus Miq. from China, and `Dormanred', a southern-adapted raspberry cultivar with R. parvifolius Hemsl. as a parent, had the highest A rates. Evapotranspiration and gs did not differ among genotypes. Average gs for all genotypes declined from 234 mmol·m-2·s-1 in week 2 to 157 mmol·m-2·s-1 in week 4. Our findings, coupled with plant performance under hot conditions, can be used to identify potential parental raspberry germplasm for breeding southern-adapted cultivars.
A Test Cross Protocol for Determining the Seedcoat Genotype at the C Locus in Common Bean
Authors: Bassett Mark J.
Published: February 2019

Studying the genetics of seedcoat color in common bean (Phaseolus vulgaris L.) in F2 progenies is very difficult because of complex epistatic interactions, and the analysis is complicated further by multiple allelism, especially at the C locus. An alternative approach is to study seedcoat genetics by analyzing the F1 progeny of test crosses between a variety with unknown seedcoat genotype and genetic tester stocks with known genotypes. Twenty varieties, 18 with known genotype at C, were test crossed with the genetic tester stock cu BC3 5-593, where 5-593 is a recurrent parent with seedcoat genotype P [C r] D J G B V Rk. The resulting F1 progenies were classified into seven phenotypic classes and discussed. The crosses g B v BC3 5-593 × cu BC3 5-593 and cu BC3 5-593 × v BC3 5-593 were made and the F2 progeny classified for flower color and seedcoat color and pattern. No tiny cartridge buff flecks were observed in the segregants with C/cu v/v, whereas C/cu V/- always showed such flecks. The contrasting seedcoat color expression at C in different environmental conditions is discussed.
Size of In Vitro Plantlets Affects Subsequent Tuber Production of Acclimated Calla Lily
Authors: Chen Junne-Jih , Liu Ming-Chung , Ho Yang-Hsiu
Published: February 2019

Tuber production of calla lily (Zantedeschia elliottiana Spreng cv. Super Gold) was investigated using three size ranges (7-10, 4-7, and <4 mm shoot diameter) of in vitro plantlets acclimated in either pots or soil beds in a protected house. The shoots and tubers of large plantlets exhibited higher rates of dry-matter accumulation than did those of small plantlets. The diameter of tubers harvested from pots ranged from 0.67 to 4.1 cm with median values of 2.7, 2.1, and 1.9 cm for the plants derived from large, medium, and small plantlets, respectively. Plants grown in soil beds, regardless of size, produced larger tubers than did those grown in pots. Tubers >3 cm in diameter developed on 25% and 52% of plants grown in pots and soil beds, respectively. Our results suggest that improved calla lily production could be realized by using larger in vitro plantlets as the source material and growing them in soil beds in a protected house.
001 Viruses Associated to Alstroemeria Varieties and Epidemiology of Tomato Spotted Wilt in cv. `Rosario'
Authors: Gutierrez-Estrada Arcenio , Zavaleta-Mejl̀a Emma , Mora-Aguilera Gustavo
Published: February 2019

Viruses associated to eight Alstroemeria varieties and the relationship of thrips density and environmental factors with Tomato Spotted Wilt (TSW) intensity as well as the TSW effect on yield were studied in `Rosario' in Central Mèxico. Using hosts range the viruses detected were Tomato Spotted Wilt Tospovirus (TSWV), Impatiens Necrotic Spot Tospovirus (INSV), Alstroemeria Mosaic Potyvirus (AlMV), Alstroemeria Streak Potyvirus (ASV), Arabis Mosaic Nepovirus (ArMV), and Cucumber Mosaic Cucumovirus (CMV). With serology it was confirmed the presence of TSWV in `Jubilee', `Rosario', and `Regina' varieties; INSV in `Anabel', `Jubilee', and `Red Sunset'; and AlMV in `Rosario', `Red Sunset', `Rosita', `Yellow King', `Jubilee'. and `Rojo Sangria'. TSWV and AlMV were found coinfecting `Rosario' plants. Five percent of plants were serologically positive to TSWV in the first flower harvest (25 Jan.-5 Apr.), 10% in the second (12 Ap.-21 June), and third (5 July-13 Sept.), and 18% in the last harvest (23 Sept.-6 Dec.). The highest peak density of thrips (520 to 630 individuals per sticky trap) were registered when the maximum temperature was higher than 35 °C and the relative humidity was between 40% to 60%. However, such peak density was not correlated with a significant increase of TSW incidence. Number and quality of inflorescences and the stem growth rate were significantly higher (P = 0.05) in plots with asymptomatic plants than that with plants showing putative symptoms of TSW.
007 Evaluation of the Spring Frost Susceptibility of Strawberry Genotypes Using Chlorophyll Fluorescence Measurements
Authors: Khanizadeh S. , DeEll J.R. , Hakam N.
Published: February 2019

Frost tolerance of flower buds is one of the most important characteristics of strawberry cultivars that produce fruit early or very early in the season. The objective of this study was to evaluate chlorophyll fluorescence (CF) as a suitable rapid method to assess spring frost injury of strawberry flowers. More specifically, to determine if there was a relationship between a decrease in CF and the appearance of visual symptoms (visual expression of necrosis (VEN) based on the amount of dark, damaged, and/or water soaked tissue of the pistil) due to frost. Sixty-six strawberry genotypes with varying levels of chilling susceptibility were used. The plants were grown in a greenhouse under a 16-h light period at 20-22 °C during the daytime and 16-18 °C at night. For the CF and VEN measurements, the plants were stored at -3 °C for 24 h followed by 24 h in the greenhouse. The CF measurements were made on dark-adapted tissue, using the Fv/Fm test of an OS-500 modulated fluorometer. For the VEN method, the flowers which had dark, damaged, and/or water soaked pistils were counted. The results showed that variable fluorescence (Fv) decreased as the temperature was lowered. The spring frost resistant cultivars maintained Fv at a stable level and had a smaller regression slope (ß1), whereas the susceptible cultivars showed a very dramatic decrease in Fv. The CF method gave results that correlated with the VEN results. The strong relationship between chilling tolerance determined via visual and florescence techniques supports the use of CF in selecting resistant spring frost selections in a breeding program. The use of CF will allow the breeder not only to select for spring frost-resistant selections independently of environmental changes, but also to select frost resistant seedlings prior to planting in the field.
008 Virulence of Entomopathogenic Fungi (Hyphomycetes) against Anthonomus fulvipes (Coleoptera:Curculionidae) in Organically Grown Barbados Cherry Trees: Laboratory and Field Trials
Authors: Lezama-Gutierrez R. , Molina-Ochoa J. , Rebolledo-Dominguez O. , Ramirez M. Gonzalez , Lopez-Edwards M.
Published: February 2019

Virulence of several isolates of the entomopathogenic fungi Beauveria bassiana (Bals.) Vuill., Metarhizium anisopliae (Metsch.) Sor. and Paecilomyces fumosoroseus (Wize) Brown & Smith were evaluated on adult weevils of Anthonomus fulvipes Boheman at dose of 108 spores/mL under laboratory conditions. The study was complemented by testing one isolate each of M. anisopliae and P. fumosoroseus against adult weevils on organically grown Barbados cherry trees at dose of 2 × 1015 spores/ha. All fungi species showed high virulence against A. fulvipes adults, with mortality ranging from 92% to 100%. LT50 values varied 2.7 to 4.8 d. The M. anisopliae isolate 10, and the P. fumosoroseus isolate 1 were selected for field evaluation because laboratory insect cadavers presented the best sporulation. After applying the fungi to the trees, total weevil captures were 38, 56, and 100 for the P. fumosoroseus, M. anisopliae, and the check (untreated) plots, respectively. Statistical differences in fruit damage were detected among treatments: M. anisopliae and P. fumosoroseus treatments showed an average of 50% of undamaged fruits, whereas in the control plots presented 36% of undamaged fruits. Laboratory and field experiments suggest that entomopathogenic fungi have a potential as microbial control agents against the weevil A. fulvipes in organically grown Barbados cherry trees.
009 Susceptibility of Mexican Fruit Fly Larvae to Entomopathogenic Nematodes (Steinernematidae and Heterorhabditidae)
Authors: Lezama-Gutierrez Roberto , Molina-Ochoa Jaime , Contreras-Ochoa Oscar L. , Gonzalez-Ramirez Martin , Rebolledo-Dominguez Oscar , Lopez-Edwards M.
Published: February 2019

The susceptibility of third-instar larvae of Anastrepha ludens (Loew) to the entomopathogenic nematodes Steinernema carpocapsae (Weiser) (All and Tecomán strains), S. feltiae (Filiipjev), S. glaseri (Steiner) (NC strain), S. riobrave (Cabanillas, Poinar & Raulston), and Heterorhabditis bacteriophora Poinar (NC, Patronato, and Tecomán strains), was evaluated under laboratory conditions. Sterile distilled water (1.0 mL) with 4000 infective juvenile nematodes were applied on 300 g of moistened sterile soil into 1000-mL pots, and 20 third-instar larvae were placed on the soil surface, 1 mL of distilled water without nematodes was applied as control. Each nematode treatment was replicated four times. After nematode application, pots were incubated at 25 °C. Mortality of larvae and pupae was evaluated 6 and 12 d after inoculation. Cadavers of larvae and pupae were dissected and examined for the presence of nematodes. Our results showed that Mexican fruit larvae were susceptible to entomopathogenic nematodes. S. riobrave and S. carpocapsae All strain caused 90% of larval and pupae cumulative mortality, H. bactetiophora NC strain and S. feltiae killed more than 80%, whereas H. bacteriophora Tecomán and S. glaseri caused a 52.5% mortality. These results suggest that the nematodes S. riobrave and S. carpocapsae All strain have a potential as biological control agents against A. ludens.
010 Exotherm Characteristics and Cold Hardiness Mechanisms within the Buds of Some Deciduous Fruit Trees
Authors: Ding Pinghai , Gu Sanliang
Published: February 2019

Exotherm characteristics of dormant apple, pear, peach, plum, grape, persimmon, and black walnut buds were investigated from late autumn to early spring. Differential thermal analysis indicated differences in the high-temperature exotherm (HTE) and low-temperature exotherm (LTE) among the fruit species and sampling dates. According to exotherm characteristics and cold hardiness, the species tested could be divided into two groups, those without LTE (apples and pear) and those with LTE (grape, persimmon, black walnut, peach, and plum). The later group with LTE could be further categorized into two sub-groups those possessing three stages of hardiness development (peach and plum group) and those with five stages of hardiness development (grape, persimmon, and black walnut). In peach and plum group HTE and no LTE could be detected in the first and last stages when bud water content was higher than 55%. The second stage both HTE and LTE could be detected when bud water content was between 40% and 50 %. In the grape, persimmon, and black walnut group the first stage with only HTE was from bud formation to deep supercooling initiation when bud water content was higher than 52%. The second stage with both HTE and LTE was when bud water content was between 40% and 48%. The third stage when only LTE could be detected and bud water content was usually lower than 40%. The fourth stage was from HTE reappearance to LTE disappearance before bud swell. The fifth stage was from LTE disappearance to when only HTE could be detected. No detection of LTE in the buds of apple and pear and no detection of HTE in the buds of grape, persimmon and black walnut were both closely associated with water status in the buds.
011 Emulsions of Edible Plant Oils Reduce Fruit Decay in `Delicious' Apples and `Ya Li' Pears
Authors: Duan Yousheng , Ju Zhiqiang , Ju Liye , Guo Aixin
Published: February 2019

Effects of 10% plant oils (corn, soybean, peanut, canola, sunflower, safflower, rape seed, linseed, and cottonseed), 100 mg·L-1 chlorine, or 100 mg·L-1 chlorine plus 10% oil combinations on pathogen (B. cinerea, P. expansum, or G. cingulata) infection and fruit decay in `Delicious' apples and `Ya Li' pears were studied. None of the oils showed inhibition on spore germination of the three pathogens by in vitro test. In inoculated fruit, oil treatments did not affect incidence but reduced severity of decay after 6 months storage at 0 °C plus 7 days at 20 °C, but no difference was found among the oils at the same concentration. In non-inoculated fruit, oils reduced fruit decay to low levels (4%) even in the most severe season. Oils also maintained fruit quality attributes, reduced water loses, and controlled scald in apples and internal browning in pears. Chlorine reduced incidence but did not reduce severity in decayed fruit. Fruit first drenched with chlorine then dipped in oil emulsions without pathogen inoculation remained decay free, while control fruit developed 10% to 15% or 13% to 23% decay after 6 months at 0 °C plus 7 days at 20 °C in both apples and pears, respectively.
019 Effect of Fungicidal Spray Program on Resveratrol Production of Muscadine Grapes (Vitis rotundifolia Michx.)
Authors: Magee J.B. , Smith B.J. , Rimando Agnes
Published: February 2019

Control of muscadine diseases is necessary to minimize yield loss and is especially important for highest quality if the berries are to be marketed fresh. Throughout the 1998 growing season, vines of five muscadine cultivars (`Noble', `Summit', `Cowart', `Higgins', and `Carlos') were treated under a systematic disease control spray program; four fungicides registered for use on grapes were applied sequentially at 10- to 20-day intervals from early bloom until just before harvest. Control plants received no fungicide. The objectives of the study were to determine the effects of the spray schedule on foliage and berry diseases and to study the relationship between disease incidence and resveratrol content of the berries. Resveratrol is a phytoalexin and has been favorably implicated in cardiovascular disease and certain cancer processes. Foliar diseases were rated visually twice during the season. Berry disease ratings were made at harvest. All fungal foliage and berry diseases were significantly reduced by the fungicide treatments. Resveratrol concentrations were determined separately on berry skins, seed and pulp/juice by GC/MS. Overall, resveratrol levels in berry skins from unsprayed vines were much higher than those of sprayed vines. Concentrations varied by cultivar and within cultivar by treatment. The relationship of skin concentration and total disease score or scores of specific diseases has not been established. Seed resveratrol concentrations differed by cultivar but were not affected by the fungicide treatments. Mean concentration of seed was lower than that of skins. Accumulation of resveratrol in juice/pulp was much lower than in skins and seeds.
022 Manipulation of the Greenhouse Microclimate to Improve the Efficacy of Entomopathogens for Control of Greenhouse Pests
Authors: Shipp J.L. , Zhang Yun
Published: February 2019

Application of entomopathogenic fungi by inundative releases has been attempted for control of a wide range of insect pests, with generally poor results. This is largely because entomopathogens are often treated as direct substitutes for chemical insecticides and applied without an adequate knowledge of their interactions with the local environment. Humidity of greater than 90% RH has long been regarded as the a critical condition for germination and infection by the spores. With both temperature and humidity controlled, greenhouse crops offer an excellent potential for pest control using entomopathogens. The long-term maintenance of >90% RH, however, is not standard practice in greenhouse production. This study explored the possibility of improving the efficacy of the fungi by temporarily changing greenhouse humidity without adversely affecting crop growth. The study included laboratory and greenhouse trials. In laboratory trials, four humidity levels of 75%, 80%, 89%, and 97.5% RH were evaluated over a 48-h period. Three commercial products of Beauveria bassiana were evaluated (Naturalis-O, Botanigard 22 WP, and Botanigard ES). Greenhouse pests of green peach aphid, melon aphid, western flower thrips, whitefly, and two-spotted spider mite were used as target insects. The infection rate of B. bassiana was found to increase when the sprayed adult insects were exposed to higher humidity levels with the maximum infection obtained at 97.5% RH. Percent infection and difference between humidity levels, however, were formulation- and host-dependent. The highest overall control efficacy was obtained by using Botanigard ES. Botanigard ES was highly effective to adult green peach aphid, melon aphid, and greenhouse whitefly at high humidities. Effects of B. bassiana against biological control agents for greenhouse vegetable crops were also evaluated. Greenhouse trials were conducted in two adjacent greenhouse compartment with high and low humidity conditions for 48 h, respectively, for selected pest insects to valid laboratory results.
030 Use of Beauveria bassiana for Silverleaf Whitefly (Bemisia argentifolii Bellows & Perring) Management in Muskmelon
Authors: Farías-Larios J. , Orozco-Santos M. , Ramírez-Vazquez N.R.
Published: February 2019

Bemisia argentifolii is a major pest of melon crop in key production areas of Mexico. Foliar applications of chemical insecticides for their management have been ineffective. The purpose of this research was to evaluate the use of commercial formulations of Beauveria bassiana and different rates for biological control of silverleaf whitefly in cantaloupe melon grown under tropical conditions. Experimental plots were treated with three rates of Mycotrol ES and only an of Naturalis-L or Endosulfan as conventional insecticide. Treatments were arranged in a randomized complete-block design with four replicates. Effects of the treatments on B. argentifolii larval and adult populations and the amount of damage to the foliage and yield melon were recorded. There was not a significant difference between Mycotrol ES rates in nymphs and adults killed. Mycotrol ES, Naturalis and Endosulfan have a similar effect on nymphs and adults control. The nontreated control melon plants had significantly greater number of silverleaf whitefly nymphs and adults than Mycotrol ES, Naturalis-L and Endosulfan treatments. Also, marketable yield was lower for the nontreated control melon plants due to higher whitefly infestations. Results from this study indicate that B. bassiana use resulted in consistently lower whitefly infestations compared to the control. The field results are promising and confirmed the potential of B. bassiana as a microbial control agent against B. argentifolii in melon crop under tropical conditions.