bluuebunny/crossref_metadata_2025 huggingface dataset:
(472) Yeast Expressed Tomato β-Galactosidases 1, 4, and 5 Have Activity against Synthetic and Plant-derived Cell Wall Substrates
Authors: Ishimaru Megumi , Smith David L. , Gross Kenneth C.
Published: February 2019

Fruit softening occurs by several mechanisms, including modifications of cell wall structure by wall degrading enzymes. The most prominent change in tomato fruit pericarp wall composition is the loss of galactosyl residues throughout development and especially during ripening. In order to understand the role of galactosyl turnover in fruit softening, we successfully produced three recombinant tomato β-galactosidase/exo-galactanase (TBG) fusion proteins in yeast. TBG1, 4 and 5 enzyme properties and substrate specificities were assessed. Optimum pH of TBG1, 4 and 5 was 5.0, 4.0, and 4.5 and optimum temperature was 40∼50, 40, and 40 °C, respectively. The K ms for TBG1, 4 and 5 were 7.99, 0.09, and 2.42 mm, respectively, using p-nitrophenyl-β-D-galactopyranoside as substrate. Using synthetic and plant-derived substrates, TBG1 and 5 released galactosyl residues from 1 → 4 linkages. TBG4 released galactosyl residues from a wide range of plant-derived oligosaccharides and polysaccharides. Using tomato fruit cell wall material, TBG1, TBG4 and TBG5 released galactosyl residues from a variety of fruit stages and cell wall fractions. TBG4 released the most galactosyl residues from the ASP fraction and especially the ASP fraction from fruit at the turning stage. Interestingly, even though walls from Turning fruit stage contain less total galactosyl residues than at the Mature Green stage, TBG4 released 3–4 fold more galactose from the CSP and ASP fractions from Turning fruit. These results suggest that changes in structure of wall pectic polysaccharides leading up to the Turning stage may cause the wall to become more susceptible to hydrolysis by the TBG4 product.
Effect of Reclaimed Water and Drought on Salt-sensitive Perennials
Authors: Schuch Ursula
Published: February 2019

Four species of salt-sensitive perennials (Chilopsis linearis, Tecoma stans, Salviagreggii, and Verbena pulchella gracilior) were grown in containers and were irrigated with potable or reclaimed water. Electrical conductivity (EC) was 0.3 dS·m-1 for potable irrigation water and 1.0 dS·m-1 for reclaimed irrigation water. After 12 weeks of growing plants with reclaimed vs. potable water, C. linearis leaf dry weight was reduced by 15%, T. stans root dry weight was reduced by 41%, V. puchella gracilior stem dry weight was reduced by 35%, and S. greggii total dry weight was reduced by 56%. The increase in canopy size was calculated 4, 8, and 12 weeks after treatments began and was not affected by water source for C. linearis and T. stans, but was reduced for S. greggii and V. pulchella gracilior treated with reclaimed water. Up to 12% dieback and reduced flowering were observed on S. greggii irrigated with reclaimed water. Within 4 weeks of treatments, EC in the root zone was 0.5 dS·m-1 for plants irrigated with potable water and 1.9 dS·m-1 for those irrigated with reclaimed water. When exposed to drought, C. linearis and T. stans grown with reclaimed water maintained a more negative water potential as soil moisture was depleted. Osmotic potential started to increase significantly for both irrigation treatments when more than 25% moisture from fully saturated containers were lost. In general, plants irrigated with potable water sustained more damage than those irrigated with reclaimed water after recovering from a drought cycle.
Model-based Moisture Prediction of Root Medium and Irrigation Control in Potted Plant Production using Nutrient-flow Wick Culture (NFW) System
Authors: Son Jung Eek , Kim Sung Kyu , Oh Sung Bong , Lu Yin Ji
Published: February 2019

The uptake of water and nutrient in potted plants is greatly affected by irrigation conditions, and it influences the plant growth. This study aimed to examine the correlations between basic environmental parameters and plant growth in potted plants (kalanchoe) and to develop the models for adequate irrigation control. Growth chambers were developed for the experiments, and four levels of photosynthetic photon flux (PPF) were treated by using different numbers of shading films and lamps. Kalanchoe blossfeldiana cv. New Alter, grown in the nutrient-flow wick culture (NFW) system, was used. The 7-cm pots were filled with a 7:3 mixture of peat moss and perlite medium (v/v). The initial water content was set at about 26%. A total of 150 pots and plants with different growth stage were prepared for 4 weeks. A wick [12 × 1 cm (L × W)] was used in each pot. Leaf areas of plants and surface areas of the medium were analyzed by a plant image analysis system. For measuring the water losses of plants and pots during the growth stage, the initial water content of the substrates was maintained at about 55%. Water losses were measured at 9, 11, 13, 15, and 17 hours for all experiment periods by using an electron balance. Two models were developed for estimating water losses by evapotranspiration and water intake by water absorption. Finally, a model for estimating water content in the medium was tried. Growth and environment parameters showed high correlations with transpiration and evaporation, respectively. There was an interactive effect of VPD and PPF on the change of evapotranspiration. The amount of absorption was increased by time and decreased with increase of initial water content.
Effect of Crop Load on Diurnal Leaf Photosynthesis, Stomatal Conductance, and Annual Carbon Isotope Composition of `Imperial Gala' Apple Tree
Authors: Sabbatini Paolo , Flore James A.
Published: February 2019

The naturally occurring carbon isotope composition (or 13C: 12C ratio, expressed with the notation d13C) of plant tissue may be used as an indicator of water use efficiency during plant growth. d13C has been shown to be an effective tool to study physiological response of plant to environmental conditions, especially water stress. The objective of this work was to test if d13C could be an indicator of carbon limitations or a low source: sink ratio. Trees of `Imperial Gala'/Bud 9 (n = 12), 6-years-old, field grown at the Clarksville Horticultural Research Station (Clarksville, Miss.), were assessed with different crop load (LCL = Low Crop Load, 0.76 ± 0.44 fruit per trunk sectional area (TCA); NCL = Normal Crop Load, 7.25 ± 1.83 fruit/TCA; HCL = High Crop Load, 15.83 ± 1.76 fruit/TCA) and leaf: fruit ratio (LCL: 52.78 ± 8.55, NCL: 13.33 ± 3.06, HCL; 4.31 ± 0.68) immediately following June drop. Net photosynthetic rate of leaves were monitored during the season and elevated rates were observed in NCL and HCL and correlated with the fruiting process. Photosynthesis was inhibited in LCL more in the afternoon (from 20% to 42% in relation to NCL) than in the morning (from 5% to 20%) and this was positively correlated with crop sink strength. Variations of the stable carbon isotope composition of roots (fine and coarse), fruit, leaves, and current-year stems were examined. The d13C varied by tissue (fruit > shoot and leaf > root) and in relation to the level of crop load (d13C‰ in fruit: LCL –23.513 ± 0.248, NCL –24.891 ± 0.594; and HCL –24.935 ± 0.375). These results may have implications for analysis of isotopic signals in carbohydrate stress and fractionation steps will be discussed.
Regulation of Fruit Growth and Fruit Size in Apple
Authors: Malladi Anish , Goldsbrough Peter , Hirst Peter
Published: February 2019

Fruit development in apple cultivars varying in their ultimate fruit size was analyzed using cytology, flow cytometry (FCM), and semi-quantitative RT-PCR. Fruit size variation across cultivars was largely explained by variation in cell number. The cell division phase lasted for less than 30 days in all varieties, less than previously believed. A distinct overlap between the cell division and cell expansion phases was present. Analysis of the relative cell production rate (rCPR) showed a major peak about 10 days after full bloom (DAFB) after which it declined. Comparison of the rCPR across varieties suggested distinct patterns of cell production with `Gala' having a low but sustained rCPR, `Pixy Crunch' a short but high rCPR, and `Golden Delicious' having a high and sustained rCPR. FCM analysis also showed similar patterns with a peak in the proportion of dividing cells about 10 DAFB followed by a decline. To further understand regulation of cell number, four cell cycle related genes were cloned from `Gala'. Cyclin Dependent Kinase B (CDK B) and Cyclin B were found to be highly cell division phase specific in their expression. Analysis of gene expression by semi-quantitative RT-PCR indicated peak expression of these two genes at 5-10 DAFB, consistent with the peaks in rCPR and proportion of dividing cells. Comparison of gene expression across the varieties showed higher peak expression of the above genes in the larger-fruited `Golden Delicious' than in the smaller-fruited `Gala.' This study provides novel insight into the regulation of fruit development in apple and also suggests a role for the cell cycle genes in fruit size regulation.
Apple Fruit Growth and Cell Division in Relation to Embryo and Endosperm Development in Two Climates, New York State and Washington State
Authors: Goffinet Martin C. , McFerson James R. , Lakso Alan N.
Published: February 2019

In 2002 in New York State, we collected king fruit of `Gala' and `Red Delicious' on fruiting spurs from 0 to 66 days after full bloom (DAB). In 2003 in Washington State, we collected king fruit of these cultivars from 14 to 62 DAB. At each collection we determined radial cell number across the fruit cortex and developmental stage of the embryo and endosperm in seeds. Fruit diameter was slightly greater in Washington fruit than in New York fruit until about 40 DAB; thereafter, New York `Delicious' outgrew Washington `Delicious', while `Gala' in the two climates (and two different years) grew identically. The New York fruits had a much earlier rise in fruit growth rate and maintained a slightly higher rate throughout the period. The cortex thickness of Washington fruit was greater than that of New York fruit for both cultivars. Most rapid cell division in the cortex occurred between 10 and 28 DAB and, by 40 DAB, most cell proliferation had ceased. The Washington fruit formed more cells across the radius than did New York fruit. Cortex thickness increased with respect to increase in cortex cell number about 30% to 40% faster in Washington fruit than in New York fruit. Developmental stages of embryos and endosperm followed a sigmoid time pattern for both cultivars in both states. By 60 DAB, embryos and endosperm reached their maximum stage of development. In both cultivars and states, cell divisions were nearly completed by the time the embryo and endosperm approached stage 3: for embryos this is the heart-shaped stage, for endosperm it is near completion of cell wall formation. The completion of wall formation in the endosperm, the near completion of cortex cell division, and the generation of the cotyledons and apical meristems in the embryo are highly correlated processes. We saw no evidence that endosperm development precedes embryo development.
Transfer and Mapping Allium roylei Derived Botrytis Leaf Blight Resistance in Onion
Authors: Goldschmied Pablo A. , Mutschler Martha A. , Lorbeer James W. , Loparco Dave P. , Ellerbrock Leroy A. , Cobb Edward
Published: February 2019

All current onion cultivars are susceptible to Botrytis squamosa (BLB), in varying degrees. The wild onion relative Allium roylei possesses strong BLB resistance. To control this disease, BLB resistant onion populations are being created through backcross breeding using A. roylei. Interspecific sexual barriers reduce fertility and seed set, impeding gene transfer. It is relatively easy to make the interspecific F1 between A. roylei and Alliumcepa; however, sexual barriers severely limit seed production in subsequent generations. Nevertheless, we were able to select BC1F2 plants capable of generating high levels of BC2F1 seed. The BC2F1 plants had horticultural characteristics much closer to onion, and segregated for both BLB resistance and fecundity. One particular BC2F1 population gave the highest proportion of resistant plants in a field screen, and nearly all plants of this population produced true bulbs. 120 selected BC2F1 bulbs were retested for BLB resistance in a chamber assay and the most resistant plants were used to advance the transfer of BLB resistance. In 2004, BC2F2 and BC3F1 populations derived from the BC2F1 selections were screened for BLB resistance and used for seed production. 132 plants were selected in the field screen. The level of resistance in BC2F2 and BC3F1 is similar to BC1F2 and BC2F1, with no evidence of reduction in level of resistance with generations. Molecular screens for markers associated with resistance are routinely used in vegetable crops to transfer resistance genes. The creation of a molecular assay for BLB resistance would accelerate its transfer and release of resistant varieties. We are using AFLP and SSRs in a search for DNA markers associated with BLB resistance in our materials.
Dissection of Linkage Drag in Breeding for Acylsugar-mediated Multiple Pests in Tomato
Authors: Mutschler Martha A. , Xiong Jian Hua , Wally Ahmed , Lobato-Ortiz Ricardo
Published: February 2019

The wild tomato Lycopersicon pennellii is resistant to numerous important pests of cultivated tomato, L. esculentum, including armyworm, fruitworm, aphids, leafminers, and whitefly. The pest resistance of L. pennellii is mediated by the presence of acylsugars, which constitute 90% of L. pennelliitype IV trichome exudate. Transfer of the ability to accumulate acylsugars could result in pest-resistant tomato cultivars, and thus, a reduction in the dependence on synthetic chemicals for insect control for this crop. Initial tomato lines bred for acylsugar production possessed the desired insect resistance, but were of poor horticultural quality due to linkage drag. These tomato lines possessed seven or eight L. pennellii introgressions, some of which were quite large. As a result, about 25% to 30% of the genomes of these acylsugar lines were comprised of L. pennellii DNA. A set of 20 molecular markers was created, providing markers throughout each introgression. The acylsugar breeding program then combined use of a biochemical assay for acylsugars and genomic analyses using these molecular markers to determine which of the introgressions were involved in the linkage drag, and to select plants that either eliminated or shortened those introgressions. Introgressions on chromosomes 2, 3, 5, and 10 were found to be associated with negative characteristics, such as delayed germination, reduced fruit set or size, delayed maturity, or reduced seed set. New acylsugar lines that eliminate or reduce some of these introgressions were created. The new lines show marked improvement in some of the affected traits, while also producing acylsugars. Hybrids created using these lines show marked improvement in horticultural type.
Photosynthetic Daily Light Integral During the Seedling Stage Influences Subsequent Growth and Flowering of Celosia, Impatiens, Salvia, Tagetes, and Viola
Authors: Pramuk Lee Ann , Runkle Erik S.
Published: February 2019

The photosynthetic daily light integral (DLI) dramatically increases during the spring, but effects of DLI on seedling growth and development have not been characterized for many species. We quantified the effects of DLI on growth and development of Celosia, Impatiens, Salvia, Tagetes, and Viola during the seedling stage and determined whether there were any residual effects of DLI on subsequent growth and development after transplant. Seedlings were grown in growth chambers for 18–26 days at 21 °C with a DLI ranging from 4.1–14.2 mol·mol·m-2·d-1. Average seedling shoot dry weight per internode (a measure of quality) increased linearly 64%, 47%, 64%, and 68% within this DLI range in Celosia, Impatiens, Tagetes, and Viola, respectively. Seedlings were then transplanted to 10-cm containers and grown in a common environment (average daily temperature of 22 °C and DLI of 8.5 mol·m-2·d-1) to determine subsequent effects on plant growth and development. Flowering of Celosia, Impatiens, Salvia, Tagetes, and Viola occurred 10, 12, 11, 4, and 12 days earlier, respectively, when seedlings were previously grown under the highest DLI compared with the lowest. Except for Viola, earlier flowering corresponded with the development of fewer nodes below the first flower. Flower bud number and plant shoot dry weight at first flowering decreased as the seedling DLI increased in all species except for flower number of Tagetes. Therefore, seedlings grown under a greater DLI flowered earlier, but plant quality at first flowering was generally reduced compared with that of seedlings grown under a lower DLI.
Predictive Model for Scheduling Fowering of Limonium sinuatum (L.) Mill ×Limoniumperezii(Stapf) Hubb.
Authors: Funnell Keith , Chen Jianyu , Morgan Ed
Published: February 2019

Weekly records of plant development, daily average temperatures (DAT), and light integrals (DLI) were used to develop a predictive model for time to flower, from seven successive plantings of the new Limonium sinuatum x Limonium perezii hybrid `LSLP4' under two light regimes, full sun or 50% shade. Plantings occurred over the period covering fall through to late spring in a temperature-controlled glasshouse under long days. DLI was highly correlated with the time to visible flower, explaining in excess of 80% of the variation. When combined with the plant growth parameter describing the rate of increase in either leaf number (LNAR) or groundcover index (GCIR), a second model was developed that was able to predict the date of visible flowers of LSLP4 and account for more variation than DLI alone. As a result of the uniformity of temperatures between successive plantings, DAT did not significantly contribute to explaining time to visible flower, but was significant for the period from visible flower through to flower harvest maturity. It is recommended that growers of `LSLP4' for cut flowers can use historical records of DLI to determine planting dates to schedule flowering. Once planting has occurred, by measuring actual DLI, DAT, and leaf number per plant, growers can use the second model to modify the predicted date for visible flowers and flower harvest.
Echinacea purpurea `Magnus': Is It an Intermediate-day or a Short-day/Long-day Plant?
Authors: Kim Ki Sun , Cameron Art , Runkle Erik S.
Published: February 2019

Echinacea purpurea Moench., or purple coneflower, has been classified both as an intermediate-day plant and a short-day/long-day plant by different research groups. We performed experiments to determine at what developmental stage Echinacea`Magnus' became sensitive to inductive photoperiods, and identified photoperiods that induced the most rapid flowering. Seedlings were raised under continuous light in 128-cell plug trays, then were transplanted into 11.4-cm plastic pots. Plants were transferred to 10-hour short days (sd) once seedlings developed 3, 4, 5, 6, 7, or 8 true leaves. After 4 or 6 weeks of sd treatment (primary induction), plants were moved to 16- or 24-hour photoperiods until flowering (secondary induction). Plants were also grown under continuous 10-, 14-, and 24-hour photoperiods to serve as controls. At least 4 leaves were required for flower induction; flowering was delayed and the percentage was low when plants had 3 leaves at the beginning of primary induction. Plants under continuous 14-hour photoperiods had the highest flower percentage (100%) and flowered earliest (87 days). Plants under continuous 10- and 24-hour photoperiods did not flower. Four weeks of sd followed by 16-hour photoperiods induced complete flowering and in an average of 95 days. However, 6 weeks sd was required for 100% flowering when the final photoperiod was 24 hours.
Polyploidy in Stokes Aster (Stokesia laevis)
Authors: Gaus Jessica , Werner Dennis , Tallury Shyamalrau
Published: February 2019

Segregation analysis of two different F2 families of stokes aster created by hybridizing two blue-flowered cultivars [`Peaches Pick' (PE) and `Omega Skyrocket' (OSR)] with the yellow-flowered cultivar `Mary Gregory' (MG) gave disparate results. The F2 progeny of PE × MG segregated in the expected 3:1 (blue:yellow) ratio. In contrast, all 782 progeny from the MG × OSR F2 family were blue-flowered. Flow cytometric analysis of the parents and F1 hybrids was conducted to determine if ploidy differences existed among the parents, as such differences could account for aberrant segregation behavior in the MG × OSR F2 family. Peak ratios suggested that MG and PE were diploid, OSR was tetraploid, and F1 hybrids of MG × OSR were triploid. Chromosome counts from root tip squashes confirmed that MG and PE were diploid (2n= 2x= 14), OSR was tetraploid (2n= 4x= 28), and F1 hybrid progeny of MG × OSR were triploid (2n= 3x= 21). Karyotype analysis also confirmed these results. We propose that the lack of recovery of yellow-flowered progeny in the MG × OSR F2 family is due to differences in parental chromosome number. These results document the first report of polyploidy in stokes aster, and suggest the absence of a triploid block in this species.
Evaluation of Herbicides and Herbicide Application Timings for Carrot
Authors: Greenland Richard G.
Published: February 2019

Few herbicides are available for weed control in carrot. Many of those that are available are old and are in danger of being discontinued. From 2000–04, field experiments were conducted on sandy loam soils at the Oakes Irrigation Research Site in North Dakota to evaluate some of the newer herbicides for possible use in carrot production. Herbicides were tested with preplant incorporated (PPI), preemergence (PRE), and/or several postemergence (POST) application timings. The major weed in this study was hairy nightshade. Cloransulam applied PRE severely injured carrot. Dimethenamid reduced carrot stand and isoxaflutole injured carrots when they were applied PRE. Neither controlled hairy nightshade when applied either PRE or POST, resulting in carrot yield reductions. Acetochlor reduced carrot stand when applied PRE and did not control hairy nightshade when applied either PPI or PRE, resulting in reduced carrot yield. Mesotrione killed carrots when it was applied PRE, but only slightly injured carrots when applied POST. Carrot yield was reduced in some years due to lack of hairy nightshade control when mesotrione was applied POST. Sulfentrazone reduced carrot stand and yield when applied PRE. It was less injurious to carrots when applied POST, but carrot yields were reduced in some years due to lack of hairy nightshade control. Flumioxazin severely reduced carrot stand when applied PRE. When it was applied after carrots were 8 cm tall, it slightly injured carrots, but did not reduce yield except in one year when it did not control hairy nightshade. None of the herbicides tested did consistently as well as the old standards of linuron, DCPA, and trifluralin, but flumoixazin, sulfentrazone, and mesotrione may hold some promise if applied POST.
Oryzalin Movement in One-gallon Containers from Spray and Oryzalin-treated Mulch Applications
Authors: Case Luke T. , Mathers Hannah M.
Published: February 2019

Herbicide-treated mulches can increase duration of efficacy; however, it is not known if the herbicide-treated mulches can reduce the amount of herbicide getting into the root zone or leachate water. The objective of this study is to examine herbicide movement and leaching potential using a bioassay between pine nuggets sprayed with oryzalin vs. a direct spray of oryzalin. Oryzalin-treated mulch and direct sprays were applied to 1-gallon pots at 2.0 lbs/acre a.i. (2.2 kg·ha-1 a.i.). The study was repeated in time, with trial 1 starting in Jan. 2004, and trial 2 starting in Nov. 2004. Both were conducted in a glass greenhouse in Columbus, Ohio. There were six dates of evaluation in each study: 0, 4, 8, 16, 32, and 64 DAT. An oat (Avenasativa) bioassay was conducted on three pot levels (0–2, 2–8, and 8–15 cm) and leachate to determine herbicide presence on each evaluation date. In trial 1, pots with direct sprays showed more herbicide presence in the top 2 cm than the oryzalin-treated mulch pots on each of the evaluation dates. In trial 2, results were much the same except for 32 DAT, where the oryzalin-treated mulch showed slightly more presence than the spray treatment at the 0-2 cm level. In both trials, there was a significant increase in herbicide presence in the oryzalin-treated pine nugget pots at the 0–2 cm level from 0 to 4 DAT, suggesting that the mulch does retain the herbicide. Also, results indicated more herbicide leaching into the 2–8 cm zone with the direct sprays compared to the pots containing oryzalin-treated pine nuggets. In trial 2, there was indication of the herbicide getting into the 8–15 cm zone from the direct spray treatment up to 8 DAT. There were no signs of herbicide presence in the leachates from any of the treatments.
Controlling Broad Mites [Polyphagotarsonemus latus (Banks)] Using Neoseiulus californicus McGregor and Sulfur After Transplanting Infested Bell Pepper (Capsicum annuum L.) Seedlings in the Greenhouse
Authors: Jovicich Elio , Cantliffe Daniel J. , Osborne Lance S. , Stoffella Peter J.
Published: February 2019

Pepper seedlings can be infested with broad mites prior to transplanting. Transplanted seedlings may not present visible mite damage symptoms and few microscopic mites will be undetected by growers. A rapid increase of the mite population can subsequently result in yield losses in greenhouse-grown crops. Control of broad mites based on biological (N. californicus) and conventional (sulfur) methods were evaluated after infested transplants were introduced into a production greenhouse. Seedlings were artificially infested with two broad mites, 3 days before they were transplanted in mid-September in a passively ventilated greenhouse in Florida. Plants had either two predatory mites released once [4 days after transplanting (DAT)], or twice (4 and 22 DAT), or were sprayed with sulfur (four weekly applications starting 13 DAT when first damage symptoms were noticed). Damage on plants was assessed by an injury scale transformed into percentage values, with 100% being total damage on untreated infested plants. Broad mites were absent in all plants 38 DAT but the damage caused to the plants at this time was negatively correlated (r= –0.95) with marketable yield at 90 DAT. Plants produced no marketable yield where broad mites were not controlled. One or two releases of predators led to respective damages of 56% and 45%, and fruit yields of 2.0 and 3.0 kg·m-2. Plants sprayed with sulfur had a damage of 7% after reaching a maximum of 74% at 18 DAT; however, yields were 4.3 kg·m-2, which was similar to the yield obtained in the uninfested control treatment (4.6 kg·m-2). Releases of predators prior to transplanting and/or higher predator release densities may be needed under similar conditions and will be evaluated in a subsequent experiment.
Effect of Soil Solarization and Methyl Bromide on Melon Wilt Caused by Fusarium on Cantaloupe in Western Mexico
Authors: Orozco-Santos Mario , Farías-Larios Javier , López-Aguirre José Gerardo , Molina-Ochoa Jaime
Published: February 2019

In the Pacific Central region of Mexico, 17,000 ha are cultivated with cucurbitaceous crops. Most are affected with wilt caused by Fusarium oxysporum f. sp. melonis. The use of fungicides, such as methyl bromide, for soil disinfecting is a common practice; however, this practice has adverse effects on beneficial microorganisms, and soil is rapidly infected again. Soil solarization is a sustainable alternative, and it is feasible to be integrated in production systems. It has been used to delay the establishment of symptoms and to reduce the incidence of fusarium wilt in watermelon fields. The objective of this study was to evaluate the effect of soil solarization and methyl bromide on control of fusarium wilt on cantaloupes in western Mexico. The experiment was conducted in the Ranch Fatima located in the municipality of Colima. Severe wilt incidence and damage were previously observed in the cantaloupe cultivar Impac. Dripping irrigation system was used. Treatments established were: 1) solarization; 2) solarization + vermicompost; 3) solarization + chemical products [methyl bromide + chloropicrine (98/2%)]; 4) methyl bromide; and 5) control (without solarization or chemicals). Soil solarization was done during the 6 months before planting using clear plastic mulching (110 thick). A completely randomized design with five treatments and four replications was used. Six beds, 10 m long and 1.5 m wide, were used as experimental unit. Variables registered were: leaf area, leaf number, dry and fresh weight, propagule number, soil temperature, number of diseased plants showing wilt symptoms, and yield. Treatments 1 and 3 exhibited the highest agronomic variable values, and best control of fusarium wilt and fruit yields.
Development of Organic Control Measures for Walnut Husk Fly in English Walnuts, Cultivar Susceptibility, and Impacts on Nut Quality from Infestation
Authors: Coates William W. , Van Steenwyk Robert A.
Published: February 2019

Walnut husk fly (Rhagoletis completa) is a major pest of English walnuts in California. Research was initiated in 1995 to evaluate reduced-risk pesticides. The first effective control measures were found in 2001—spinosad plus bait and kaolin (Surround). Spinosad was registered for organic use in 2003 as GF-120 NF (a formulation of spinosad and bait) and Entrust (a spinosad formulation to be mixed with existing baits). GF-120 is recommended for low to moderate populations while Entrust + bait is recommended for higher populations. Entrust + bait is price competitive with the standard malathion + bait. Kaolin is also effective for walnut husk fly control; however, control is dependent upon adequate coverage. In 2004, varietal susceptibility was assessed. The cultivars `Payne', `Serr', `Pedro', and `Hartley' were found to be highly susceptible while `Chandler' and `Howard' were somewhat resistant. Infestation in `Chandler' began later in the season than in other cultivars. Quality parameters were also measured. Samples of 100 infested and uninfested `Tulare' walnuts were compared at harvest. There were significant differences in adhering hull, percentage of edible yield, and relative value between infested and uninfested nuts. The relative value of infested nuts was 28% less than uninfested nuts. There were minimal differences in percentage of mold and kernel color. Walnuts sprayed with kaolin had larger nuts, fewer external defects, and an earlier harvest timing.
Impact of Anthracnose on Avocado Production in Kenya
Authors: Wasilwa Lusike A. , Njuguna Joseph K. , Kirigua Violet , Waturu Charles N. , Stafne Richelle A. , Morelock Teddy E.
Published: February 2019

Avocado is the leading horticultural export in Kenya. In 2003, Kenya exported about 19,000 t, compared to 23 t in 1970. Most of the fruit is exported to the European markets. There are several constraints limiting production of avocado in Kenya, including limited superior varieties or planting material, poor infrastructure, poor market information, and poor tree crop management. Although several diseases infect avocado, the most important are fruit rot pathogens, such as anthracnose, cercospora, and scab. However, diseases and pests have not been important to avocado production in Kenya. Recently (2004), the constraint limiting avocado production in Kenya is anthracnose, caused by Colletotrichum gloeospoirioides. Little is known in Kenya on the impact of this disease on production and income realized by small-(<1 acre) or large-scale growers. The objectives of this research were to quantify losses attributed to anthracnose in Kenya, determine the current disease control measures, and recommend good agricultural practice in conformance with EUREP-GAP. A survey was conducted in the avocado growing areas to identify and document constraints limiting avocado production in 2004. The highest losses were reported from central Kenya, where exporters reported up to 100% losses. Because all avocado varieties growing in Kenya are susceptible to anthracnose, it is recommended that good management, i.e., control of pests and diseases and good postharvest handling of fruit to minimize injury used as an entry point by anthracnose, should be enforced.
In Vitro Propagation and Somatic Embryogenesis in Phalsa
Authors: Biswas Bipul , Joshee Nirmal , Yadav Ashish , Yadav Anand K.
Published: February 2019

Phalsa[Grewia asiatica (L.) Tiliaceae] is an exotic fruit with good nutraceutical values. It cannot be grown in temperate climates with severe winters. Therefore, genetic improvement of phalsa for cold tolerance is essential. In order to apply biotechnology through genetic transformation to enhance cold hardiness, a reliable and rapid micropropagation system is needed. Thus, developing the most dependable micropropagation protocols for phalsa was the primary goal of this research. Phalsa explants prepared from different tissues, including leaf, nodes, internode, and zygotic embryos, were collected from mature trees growing in the specialty plants house, cultured on MS medium supplemented with various cytokinins alone or along with auxins and incubated under a 10-hour photoperiod at ambient temperature. In vitro propagation of phalsa tissues through both organogenesis and somatic embryogenesis was achieved. Of these, single shoots were developed from nodal explants as a result of budbreak on MS medium supplemented with BAP, kinetin, and zeatin separately. Somatic embryos were developed from the zygotic embryos when cultured on MS medium with 0.023 μm BA + 0.022 μm zeatin, for 2 weeks following a pulse treatment on NN medium supplemented with 5% sucrose, 0.11 μm BAP, 0.22 μm 2,4-D, and 29.20 μm L-glutamine. Somatic embryogenesis was also observed on modified basal medium supplemented with 13% sucrose, 58.40 μm L-glutamine, and 1.75 μm IAA. Enormous callusing was a major problem for in vitro studies with this species, irrespective of media composition. Further studies for multiple shoot development and higher frequency of SE induction are under way.
Embryo-rescue Culture in `Galia' Male Parental Line Melon [Cucumis melo (L.) var. reticulatus Ser.]
Authors: Nunez-Palenius Hector G. , Cantliffe Daniel J. , Klee Harry J. , Huber Don J.
Published: February 2019

Embryo abortion and empty seeds after self-pollination occur in some transgenic (ACO antisense) `Galia' male parental lines. An embryo-rescue system in this melon was developed to save potential viable embryos. To obtain the best and reliable embryo-rescue technique, several parameters were used including an improved (five new supplements) nutrient medium (named E-21) from the E-20A basic medium (Sauton and Dumax de Vaulx, 1987), an inoculation system (removing the embryo from the seed or intact seed), and the use of different fruit harvesting dates of the wild type and a transgenic `Galia' male parental line. Fruits of wild type (WT) and transgenic (ACO gene in antisense orientation) `Galia' male parental line were harvested at 4, 10, 17, 24, and 30 days after pollination (DAP). Fruits were surface sterilized by dipping in a 20% commercial bleach solution for 30 minutes. Subsequently, seeds were removed from fruit under sterile conditions. These seeds were either used to dissect the embryos or placed directly with the hilum facing E-20A or E-21 medium. Seedlings from all treatments were transferred to E-21 elongation medium, incubated 4 weeks, and transferred to soil to evaluate growth. The efficiency of this technique was greater when the time after pollination (4, 10, 17, 24, and 30 DAP) to rescue the embryos was increased. Thus, 30 DAP was the best time to rescue the embryos. The number of rescued embryos using E-21 medium was greater than with E-20A. We did not find any significant differences in survival efficiency rate between WT and transgenic embryos. We have obtained a competent embryo-rescue technique for WT and transgenic `Galia' male parental line, which can be applied to rescue valuable GMO hybrid-melon embryos.
Recent Progress using Somatic Hybridization and Cybridization in Efforts to Develop High Quality Seedless Mandarin Hybrids
Authors: Grosser Jude , Calovic Milicia , Serrano Patricia , Gmitter Fred , Chandler J. L.
Published: February 2019

The international fresh citrus market now demands high-quality, seedless fruit that must also be easy to peel for consumer convenience, especially when considering new mandarin varieties. High quality varieties that historically perform well in Florida are generally seedy. Florida is therefore losing market-share to `Clementine' and other seedless varieties produced in Mediterranean climates, including Spain, Morocco, and California. In our ongoing program, somatic hybridization and cybridization via protoplast fusion are now playing a key role in strategies to develop competitive seedless mandarin hybrids adapted to Florida. Somatic hybridization is being used to combine elite diploid parents to produce high quality allotetraploid breeding parents that can be used in interploid crosses to generate seedless triploids. Several thousand triploid mandarin hybrids have been produced under the direction of F.G. Gmitter, Jr. Some of our allotetraploid somatic hybrids are producing fruit with direct cultivar potential, i.e., 'Valencia' sweet orange + `Murcott' tangor. New somatic hybrids produced in our program will be discussed, including `Page' tangor + `Dancy' mandarin, `Page' tangor + `Kinnow' mandarin, and `Hamlin' sweet orange + LB8-9 tangelo. Somatic cybridization is being used to transfer CMS (cytoplasmic male sterility) from the seedless `Satsuma' mandarin to other seedy varieties via mtDNA transfer, in efforts to make them seedless. New somatic cybrids produced in our program that contain the `Satsuma' CMS include `Murcott' tangor and `Kinnow' mandarin. Details of these results and other progress will be discussed.
Genetic Diversities within Camellia Species Confirmed by Random Amplified Polymorphic DNA (RAPD) Markers
Authors: Chen Lianghong , Wang Shizhou , Nelson Mack
Published: February 2019

In this study research was conducted to evaluate the feasibility of characterizing genetic variation within camellia species using random amplified polymorphic DNAs (RAPD) markers. Eight varieties of species Camellia japonica and four varieties of species Camellia reticulata, provided by the America Camellia Society, Fort Valley, Ga., were investigated. RAPD profiles generated by five selected 10-based random primers (out of 20 primers) exhibited distinct patterns of amplified bands for all 12 tested varieties. A total of 344 bands were produced among the eight varieties of species C. japonica, with an average of 8.6 bands, ranging from 220 to 2072 bp in size, scored per primer. Among the 344 amplified bands, 74.4% of the bands presented polymorphic. The four varieties of species C. reticulata produced a total of 180 markers, with an average percentage of 57.8% polymorphisms. The amplified bands were in the range of 236–1760 bp. An average of nine amplified bands was generated per primer. The large percentages of polymorphisms displayed among 12 varieties within the two different species indicate that the expected genetic diversity among varieties within camellia species existed. It was concluded that the RAPD molecular markers are capable of revealing appreciable levels of genetic variation within camellia species.
Changes in Proteolytic Activity and Cysteine Proteinase Gene Expression during the Senescence of etr1-1 Transgenic Petunias
Authors: Jones Michelle , Chaffin Gunching , Clark David
Published: February 2019

Corolla senescence in petunias was accompanied by a decrease in total proteins and a corresponding increase in proteolytic activity. Transgenic petunias that contain the mutated ethylene receptor (35S:etr1-1) have reduced sensitivity to ethylene and delayed flower senescence. Declines in total protein levels and increases in proteolytic activity were also delayed in etr1-1 flowers and corresponded with corolla wilting. Experiments using class-specific proteinase inhibitors indicated that proteolytic activity in petunia corollas was largely due to cysteine proteinases. Total nitrogen levels within the corollas of both wild type and etr1-1 flowers also decreased during senescence. Nine cDNAs encoding putative cysteine proteinases (CPs) were identified from a petunia EST database developed at the University of Florida. Six of these cysteine proteinases showed increased transcript abundance during corolla senescence (senescence-associated CPs) while three decreased in abundance. Of the six senescence-associated cysteine proteinases, only five showed delayed up regulation in etr1-1 flowers that corresponded with corolla wilting. The role of ethylene in the regulation of protein degradation during flower senescence will be discussed.
Molecular Characterization of Photoperiodic Flowering in Cultivated Strawberry
Authors: Stewart Philip , Sargent Daniel , Davis Thomas , Folta Kevin
Published: February 2019

The molecular mechanisms governing photoperiodic flowering has been well defined in the model systems of Arabidopsis thaliana(a facultative long-day plant) and rice (a short-day plant). Photoperiodic flowering control is of great interest to strawberry (Fragaria×ananassa) breeders and growers, and the genetics of photoperiodic flowering have been well studied, indicating that response to day-length is regulated by a small number of genetic loci. Cultivated strawberry is octoploid, so identification of these loci through forward genetic analyses is not practical. Since the componentry of the flowering response is generally conserved between monocots and dicots, we may assume that similar, if not identical, systems are functioning in strawberry as well. The goal of this work is to understand how cultivars likely containing identical photoperiod-sensing components are differentially sensitive to daylength. The expression patterns of genes relevant to the floraltransition were assessed under specific photoperiod conditions to assess similarities and/or differences to the model systems.
Cultivars of Invasive Japanese Barberry (Berberis thunbergii) Demonstrate Different Reproductive Potential and Seedling Traits
Authors: Lehrer Jonathan M. , Brand Mark H.
Published: February 2019

While Japanese barberry (Berberis thunbergii) is an acknowledged invasive plant, the danger posed by its garden cultivars is unknown. This work analyzed the reproductive potential and seedling traits of wild type Japanese barberry and four important cultivars: `Atropurpurea', `Aurea', `Crimson Pygmy', and `Rose Glow'. The germination capacity of cleaned and stratified seeds was determined for all accessions in a greenhouse and seedling foliage color was noted. A subpopulation of seedlings from each accession was grown further in containers outdoors for a full season to ascertain seedling vigor. The average number of seeds produced per landscape specimen ranged from 75 and 90 for `Aurea' and `Crimson Pygmy' to 2967 for `Atropurpurea', 726 for `Rose Glow', and 1135 for wild type B. thunbergii. The vigor of 1-year seedlings—as measured by dry weight of top growth—for progeny derived from `Aurea' (2.29 g) and `Crimson Pygmy' (2.74 g) was less than `Atropurpurea' (3.45 g), `Rose Glow' (3.88 g) and wild type (3.73 g). Seedlings derived from purple-leaf cultivars displayed variable ratios of green and purple leaf phenotype correlated to the proximity and identity of likely Japanese barberry pollinators. `Rose Glow' specimens located among other purple-leaf B. thunbergii produced up to 90% purple seedlings, while other samples growing in isolation or near green-leaf plants produced less than 10% purple progeny. This suggests that some invasive green-leaf Japanese barberry could be derived from cultivars. The results also show that these cultivars express disparate reproductive potential.
Potassium Fertigation Improves Tomato Yield and Fruit Color
Authors: Hartz T. K. , Johnstone P. R. , Miyao E. M.
Published: February 2019

The effect of K fertigation through buried drip irrigation on processing tomato (Lycopersicon esculentum Mill.) was evaluated in two California field trials in 2004, and soil K dynamics was investigated in greenhouse trials. Fertigation trials were conducted in fields with exchangeable soil K of 190 (site 1) and 270 mg·kg-1 (site 2), above the yield response threshold by traditional preplant or sidedress K application established by prior research. Two fertigation strategies were compared to an unfertilized control: continuous fertigation at 100 mg·L-1 K from early fruit set through early fruit color development, and weekly application of 40 kg·ha-1 K over the same period. In both treatments, a total of 200 kg·ha-1 K (from KCl) was applied. K fertigation significantly increased fruit yield at site 2, and improved fruit color at both sites. In the greenhouse experiments, fescue (Festuca arundinacea) was grown for 2 weeks atop columns of eight soils ranging from 120–380 mg·kg-1 exchangeable K; the columns were wetted from the bottom, by capillarity. The fescue roots were separated from the soil by a nylon fabric that prevented root penetration while allowing the penetration of root hairs, creating a two-dimensional root/soil interface. In all soils, fescue K uptake reduced soil exchangeable K only in the top 2 mm of the columns, suggesting that effective K diffusion was very limited. In columns of 200-mm height, applying 100 mg·kg-1 K in the water used to wet the soil had minimal impact on fescue K uptake. In columns of 15-mm height, this method of K application more than doubled fescue K uptake in all soils, suggesting that the effective limit of K movement was between 15-200 mm.
Effects of High Nutrient Solution EC and Its Application Timing on Lycopene, Soluble Sugars, and Chlorophyll Concentrations of Tomato (Lycopersicon esculentum Mill.) Fruit
Authors: Wu Min , Kubota Chieri
Published: February 2019

Manipulation of the electrical conductivity (EC) of the hydroponic nutrient solution has been studied as an effective method to enhance flavor and nutritional value of tomato fruit. The objective of this research was to quantitatively understand the accumulation of lycopene, soluble sugars, and the degradation of chlorophyll in fruits as affected by EC and EC application timing relative to fruit ripeness stages. `Durinta' tomato was grown hydroponically inside the greenhouse under two EC (2.3 and 4.5 dS·m-1). The high EC treatment began immediately after anthesis (HEC treatment) or 4 weeks later (DHEC treatment), when fruits had reached maximum size, but still were green. Fruits were harvested weekly beginning 2 weeks after anthesis, until they reached red ripe stage. The chlorophyll concentration in tomato fruits showed no difference between treatments when compared at the same ripeness stages. The lycopene concentration of red ripe tomato fruits in HEC and DHEC treatments was 29% greater than that in low EC control (LEC treatment). However, there was no significant difference in lycopene concentration between HEC and DHEC. Both DHEC and HEC increased total soluble solid concentration (TSS) of red ripe tomato fruits compared with those grown in LEC; while the DHEC showed an increase of fruit TSS of 12%, the HEC had a greater enhancement of TSS of 19%. In addition, the fruit ripeness was accelerated under high EC, regardless of the timing of treatment. High EC treatment at early and mature green fruit developmental stages enhanced both fruit TSS and lycopene concentration; however, the nutrient solution EC effect on lycopene concentration was not dependent on the time of application during fruit development.