bluuebunny/crossref_metadata_2025 huggingface dataset:
Transgenic Tomato Plants Expressing Satellite RNA Are Tolerant to Some Strains of Cucumber Mosaic Virus
Authors: McGarvey P.B. , Montasser M.S. , Kaper J.M.
Published: January 2019

Transgenic tomato plants (Lycopersicon esculentum Mill.) expressing cucumber mosaic virus (CMV) satellite RNA fused to a gene for β-glucuronidase were produced using Agrobacterium-mediated transformation. The R1 progeny of self-crossed R0 plants were challenge-inoculated with virion or RNA preparations of CMV or tomato aspermy virus (TAV). The transgenic plants challenged with CMV-1 showed mild disease symptoms in the first 2 weeks postchallenge followed by a decrease in symptoms, resulting in little difference between the transgenic and uninfected control group by the fourth week. Enzyme-linked immunosorbent assay results showed about a 10-fold decrease in virus accumulation in the transgenic plants compared to controls. Tolerance was evident only in plants that contained the recombinant insert and produced mature unit-length satellite RNA after CMV infection. Plants challenged with TAV showed no significant tolerance to virus-induced symptoms.
Estimating Water Use and Irrigation Requirements of Coffee in Hawaii
Authors: Gutiérrez Marco V. , Meinzer Frederick C.
Published: January 2019

Crop evapotranspiration (ETc) was measured as evaporative heat flux from drip-irrigated coffee (Coffea arabica L. cv. Yellow Catuai) fields at different stages of canopy development using the Bowen ratio-energy balance technique. Irrigation requirements were determined by comparing the ETc values obtained against reference values (ET0) derived from a modified Penman equation, and expressed as the ETc/ET0 ratio, or crop coefficient (Kc). In 1991, the average Kc was 0.75 to 0.79 for fields containing 2- to 4-year-old plantings. This ratio was 0.58 for a field containing a 1-year-old planting. Crop coefficient was 30% lower in 1992 due to higher ET0 values and lower stomatal conductance. Measurements made between July and August and again between September and November 1991 suggested that Kc may vary seasonally. Crop transpiration (T), determined with the stem heat balance technique, comprised from 40% to 95% of ETc as the leaf area index increased from 1.4 to 6.7. Behavior of Kc and T during a 25-day soil drying-reirrigation cycle indicated that the crop was able to maintain relatively high levels of gas-exchange activity during periods of severe water deficit.
Transplant Production Systems Influence Growth and Yield of Fresh-market Tomatoes
Authors: Leskovar Daniel I. , Cantliffe Daniel J. , Stoffella Peter J.
Published: January 2019

`Sunny' tomato (Lycopersicon esculentum Mill.) containerized transplants were grown with the standard or conventional systems (SS) and with recently developed flotation systems (FS). Standard system and FS transplants, and direct-seeding using coated seeds were evaluated in the field for root and shoot growth and yield at Parrish, Bradenton, and Naples during fall, winter, and spring plantings. Plant growth characteristics were measured weekly before, during, and after transplanting or sowing. In the Parrish and Bradenton Fall 1987 and Bradenton Spring 1988 experiments, SS transplants had greater leaf area, root volume, shoot dry weights, and shoot: root ratios than FS transplants. During early development, the FS transplants had more lateral root growth than SS transplants, but had similar total root growth and horizontal and vertical root distribution after transplanting in the field. Transplants and direct-seeded plants allocated 72% of the total root mass in the upper 0 to 10 cm of the soil. In Fall 1987, SS transplants had between 29% and 41% more fruit yield than FS transplants at Bradenton and Parrish, respectively. In the Naples Winter 1988 and Parrish and Bradenton Fall 1989 experiments, both transplant types had similar fruit yields, but more than direct-seeded plants. Transplants grown with the flotation system are recommended for use provided that seedlings are grown and maintained with minimum hardening before establishment in the field.
Spatial and Temporal Variation of Light inside Peach Trees
Authors: Génard Michel , Baret Frédéric
Published: January 2019

Gap fractions measured with hemispherical photographs were used to describe spatial and temporal variations of diffuse and direct light fractions transmitted to shoots within peach trees. For both cultivars studied, spatial variability of daily diffuse and direct light transmitted to shoots was very high within the tree. Diffuse and daily direct light fractions transmitted to shoots increased with shoot height within the tree and for more erect shoots. Temporal variations of hourly direct light were also large among shoots. Hourly direct light fractions transmitted to shoots were analyzed using recent developments in multivariate exploratory analysis. A gradient was observed between shoots sunlit almost all day and other shoots almost never sunlit. Well sunlit shoots were mostly located at the top of the tree and were more erect. Shoots located in the outer parts of the tree crown were slightly but significantly more sunlit than others for one cultivar. Principal component analysis additionally discriminated shoots according to the time of the day they were sunlit. This classification was related to shoot compass position for one cultivar. Spatial location of the shoot in the tree explained only a small part of light climate variability. Consequences of modeling light climate within the tree are discussed.
Analysis of Zinnia Capitulum Composition
Authors: Miyajima Daiichiro , Nakayama Masaaki
Published: January 2019

Composition of capitula and their making by florets of zinnia (Zinnia violacea Cav.) were analyzed to improve seed production. For each cultivar, mature capitula were classified into three types based on shape. A capitulum was made of the accumulation of <20 newly opened florets per day for >15 days. The total number of florets per capitulum was 210 to 330, 220 to 290, and 160 to 240 for the two pumila double cultivars Kumamotonokagayaki and Snowball and for the pompon cultivar Purple Zem, respectively. The numbers of tubular florets were negatively correlated with the numbers of ray florets. Ornamentally superior capitula, which were the basic capitulum types for pumila doubles and pompons, had more ray florets and fewer tubular florets than the ornamentally inferior capitulum (the single-flowered type). Results indicate that maintaining a high percentage of plants with double-flowered capitula may decrease seed yield.
Promoting Stenospermic Grape Seed Trace Development and Germination with Plant Growth Regulators
Authors: Bordelon Bruce P. , Moore J.N.
Published: January 2019

Plant growth regulators (PGRs) [antigibberellins (mepiquat chloride, uniconazole, ancymidol, daminozide, chlormequat, ethephon, methazole), cytokinins (BAP, kinetin, BTP, 2iP), and ABA] were evaluated at various concentrations and timings for promotion of seed trace development and germination of four stenospermic grape cultivars (Vitis spp.): `Venus', `Mars', `Reliance', and `Saturn'. Data include seed trace number per berry, percent of seed traces with endosperm (sinkers), sinker fresh weight, and percent seed trace germination. Several PGRs effectively increased seed number and percent sinkers over control treatments. PGRs had little effect on seed fresh weight and percent germination. PGRs promoted greater increases in percent sinkers than seed number on all cultivars. The number of viable seeds per sample (seed number × percent sinkers) was increased over controls by up to 802% on `Reliance', 239% on `Saturn', 154% on `Mars', and 153% on `Venus'. A moderate percentage of viable seeds from treatments and controls of `Mars', `Venus', and `Saturn' germinated and established normal seedlings. The very small seed traces of `Reliance' did not germinate from either controls or treatments. The results indicate that PGRs can stimulate seed trace formation in some stenospermic cultivars and therefore may be useful tools in grape breeding programs. Chemical names used: abscisic acid (+/-)cis-trans isomer (ABA); a-cyclopropyl-a-(4-methoxy-phenyl)-5-pyrimidinemethanol (ancymidol); 6-benzylaminopurine (BAP); 6-benzylamino-9-(2 tetra-hydropropanyl)-9H-purine (BTP); (2-chloroethyl) trimethyl-ammonium chloride (chlormequat); succinic acid 2,2 dimethyl-hydrazide (daminozide); (2-chloroethyl) phosphonic acid (ethephon); 6-(dimethyl-allylamino) purine (2iP); 6-furfurylaminopurine (kinetin); N,N-dimethyl-piperidinium chloride (mepiquat chloride); [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione] (methazole); E-1-(4-chlorophenyl)-4,4-di-methyl-2-(1,2,4-triazol-1-yl)-1-pentan-3-ol (uniconazole).
Changes in the Antioxidant System Associated with Budbreak in `Anna' Apple (Malus domestica Borkh.) Buds
Authors: Wang Shiow Y. , Faust Miklos
Published: January 2019

The ability of low and high temperatures and S-containing compounds to overcome endo- and paradormancy along with the possible mechanisms involved in these treatments for breaking `Anna' apple bud dormancy were studied. All three treatments induced budbreak in paradormant (July) and endodormant (October) buds. Cold, heat, and allyl disulfide increased ascorbic acid, the reduced form of glutathione (GSH), total glutathione, total nonprotein thiol (NPSH), and nonglutathione thiol (RSH), whereas dehydroascorbic acid and oxidized glutathione (GSSG) decreased. The treatments also increased the ratios of ascorbic acid: dehydroascorbate and GSH: GSSG and the activities of ascorbate free-radical reductase (AFR, EC 1.6.5.4), ascorbate peroxidase (EC 1.11.1.11), dehydroascorbate reductase (DHAR, EC 1.8.5.1), ascorbate oxidase (AAO, EC 1.10.3.3), and glutathione reductase (GR, EC 1.6.4.2) in the buds. These results indicate that budbreak induced by cold, heat, and allyl disulfide is associated with the removal of free radicals through activated peroxide-scavenging systems.
Changes in Metabolic Properties of Grape Buds during Development
Authors: Gardea A.A. , Moreno Y.M. , Azarenko A.N. , Lombard P.B. , Daley L.S. , Criddle R.S.
Published: January 2019

The pattern of respiratory changes during dormancy and development of `Pinot noir' primary grape (Vitis vinifera L.) buds through the broken-bud stage was determined using differential scanning calorimetry. Metabolic heat rates [μJ·s-1·mg-1 dry weight (dw)] decreased during endodormancy and increased during ecodormancy and bud development. Respiration of ecodormant buds was at its minimum (≈1 μJ·s-1·mg-1 dw) in January. Respiration steadily increased, beginning in February and continuing as buds passed through the four developmental stages: ecodormant, initial swelling, fully swollen, and broken bud. Heat of metabolism increased from 5 to 18, 28, and 29 μJ·s-1·mg-1 dw as the buds developed from ecodormant to broken-bud stage. Carbon dioxide evolution from respiring buds increased from 15.9 to 22.2, 57.9, and 68.3 × 10-6 μmol·s-1·mg-1 dw as bud development advanced. Metabolic inefficiency, as quantified by heat (kJ) released per CO2 (mol) produced, was lowest in ecodormant buds, then increased at initial bud swelling and declined again in fully swollen and broken buds. The temperature coefficient of metabolism (μ) [apparent activation energy (Ea)/gas constant (R)] was lower at low temperatures (5 to 15C) in ecodormant buds than at the three more advanced stages. At higher temperatures (20 to 35C), buds at the ecodormant and initial swelling stages had a higher μ than the fully swollen and broken buds. These results suggest there may be a major change in metabolic pathways between the ecodormant bud stage and bud swelling.
Urea Penetration of Isolated Tomato Fruit Cuticles
Authors: Knoche Moritz , Petracek Peter D. , Bukovac Martin J. , Shafer Warren E.
Published: January 2019

14C-urea penetration of isolated tomato (Lycopersicon esculentum Mill. cv. `Pik Red') fruit cuticular membranes (CM) was studied as a function of concentration and temperature. There was no significant effect of cuticular wax on urea penetration at 25C, permeances for the CM being 8.4 × 10-10 and dewaxed CM (DCM) 11.1 × 10-10·m·s-1. Time lags were near zero for both CM and DCM. Steady-state diffusion analysis suggests that the relatively low cuticular permeance of urea is due to low partitioning that offsets high diffusivity. Urea flux through the CM and DCM showed ≈1.5- and 1.9-fold increases, respectively, for each 10C increase between 5 and 45C. Urea flux across CM and DCM increased linearly with concentration (10 μm to 1 m) and, thus, was a first-order process.
Characterizing a Cucumber Pollen Sterile Mutant: Inheritance, Allelism, and Response to Chemical and Environmental Factors
Authors: Zhang Qi , Gabert August C. , Baggett James R.
Published: January 2019

A new sterile mutant designated pollen sterile (PS) found in pickling cucumber (Cucumis sativus L.) is characterized by normal corolla in staminate and pistillate flowers, normal fertility in the female, and absence of pollen in otherwise normal-appearing staminate flowers. All F1 plants from PS × male fertile (MF) sib-matings were MF, and F2 progeny segregated 3 MF: 1 PS. Sib-matings of PS segregates with sister MF segregates produced either 1 MF: 1 PS ratios or all normal plants. Thus, PS is controlled by a single recessive gene. The PS gene is not allelic to apetalous (ap), but was shown to be allelic to male sterile-2 (ms-2) and is designated ms-2PS. It was not possible to determine possible allelic relationships between ms-2PS and ms-1 because of strong male and female sterility of the available ms-1 material. F1 generations from gynoecious-PS and monoecious-PS crossed with monoecious, gynoecious (silver-ion treated), and hermaphroditic parents produced no PS plants and sex types did not influence PS levels in F2 progenies, indicating it is not possible to maintain the PS mutants through crosses with different cucumber sex types. It was not possible to change the expression of PS by applying cytokinin, IAA, or GA3, and there were no changes in response to temperature and fertilizer treatment. Unlike gynoecy, which is responsive to some external factors, PS is unresponsive. The results suggest that the use of PS in cucumber F1 hybrid seed production is not practical. Chemical names used: indole acetic acid (IAA), gibberellin (GA3).
Comparing the Resynthesis of Brassica napus L. by Interspecific Somatic and Sexual Hybridization. I. Producing and Identifying Hybrids
Authors: Ozminkowski Richard H. , Jourdan Pablo
Published: January 2019

Brassica napus (genome aacc), a natural allotetraploid derived from hybridization between B. oleracea L. (genome cc) and B. rapa L. (genome aa), was synthesized by sexual and somatic interspecific hybridizations from the same parent plants to compare the two methods of combining genomes and assess the genetic consequences of bypassing the gametophytic phase before hybrid formation. Highly heterozygous species parents were first produced by intraspecific hybridization between two subspecies each of B. oleracea and B. rapa. Leaf tissue from young plants of both parental species served as a source of protoplasts for fusion; the same plants were later used for crosses. Seventy-two somatic hybrids were produced using a polyethylene glycol-mediated fusion protocol and 27 sexual hybrids were obtained by embryo rescue. Somatic hybrids were produced between one B. oleracea and two sibling B. rapa plants. Sexual hybrids were successfully produced with only one of the two B. rapa siblings. Hybrids were identified by morphology, isozyme patterns, and total DNA content. Although fertile allotetraploid somatic hybrids were obtained within 7 months after seeding parent lines, >1 year was required to produce fertile sexual hybrids.
Genetics and Incorporation of Glandular Trichomes and Polyphenol Oxidase Activity into an Advanced Solanum phureja-S. stenotomum Diploid Potato Population
Authors: Vallejo Roger L. , Collins Wanda W. , Schiavone Rocco D.
Published: January 2019

Preliminary data on the genetics of glandular trichomes and the feasibility of incorporating A and B glandular trichomes and polyphenol oxidase (PPO) activity from Solanum berthaultii Hawkes (Ber) into an advanced S. phureja Juz. et Buk.-S. stenotomum Juz. (Phu-Stn) diploid potato population are presented. A random sample of four Phu-Stn clones was intercrossed with a sample of three Ber progenies (pollen bulk per progeny) segregating for high density of A and B glandular trichomes. Nine F1 families [(Phu-Stn) × Ber] were evaluated over two experiments in the greenhouse for A and B trichome density (5 mm2 of abaxial surface) and PPO activity 45 days after planting. A completely randomized design in an experimental hierarchical classification arrangement was used to quantify the genetic variability and to estimate broad-sense heritabilities (defined on an individual basis) for the attributes under study. To characterize the inheritance of these attributes further and to estimate narrow-sense heritabilities, fifteen backcross (BC) families were evaluated in a randomized complete-block design with three replications and analyzed by half-sib family analysis. Phenotypic and genotypic correlations between these attributes were also estimated. In the F1 families, broad-sense heritabilities were 0.59 and 0.41 for density of A and B trichomes, respectively. In the BC population, narrow-sense heritabilities were 0.15 and 0.08 for A trichome density and PPO activity, respectively; expression of B trichomes was almost absent in this generation. Genotype × environment interaction was significant for density of A trichomes and highly significant for density of B trichomes in F1 families. There was some level of positive association between density of A and B trichomes and PPO activity. Additive genetic variance of these attributes was very low in this study; therefore, selection schemes based on family selection and progeny testing would be an appropriate breeding strategy for improving these traits.
Leaf Senescence of Postproduction Poinsettias in Low-light Stress
Authors: Embry J. Lorene , Nothnagel Eugene A.
Published: January 2019

Photosynthetic light harvesting was investigated under low-light stress conditions relevant to the problem of interior longevity of potted ornamental plants. Comparisons of leaf pigment levels and chlorophyll fluorescence excitation spectra were made for `Gutbier V-10 Amy' poinsettia (Euphorbia pulcherrima Willd.), which has poor interior longevity, and `Eckespoint Lilo' poinsettia, which has superior interior longevity. The results show that `Eckespoint Lilo' had higher total chlorophyll content per leaf area and lower chlorophyll a: chlorophyll b ratio than `Gutbier V-10 Amy'. In low-light stress, `Eckespoint Lilo' retained its chlorophyll or even accumulated higher levels than in high light, while `Gutbier V-10 Amy' did not exhibit higher chlorophyll retention in low light. Both cultivars acclimatized to low-light stress by decreasing the chlorophyll a: chlorophyll b ratio, and this acclimatization was evident sooner in younger, outer-canopy leaves above the pinch than in older leaves below the pinch. Both cultivars also increased the chlorophyll: carotenoid ratio in low light. These changes in pigment composition, which were essentially structural changes, were reflected in functional changes in light harvesting, as assessed by measurements of chlorophyll fluorescence excitation spectra.
Role of Ethylene in Opening and Senescence of Gladiolus sp. Flowers
Authors: Serek Margrethe , Jones Rodney B. , Reid Michael S.
Published: January 2019

The opening and senescence of gladiolus (Gladiolus sp.) florets was accompanied by climacteric or nonclimacteric patterns of respiration and ethylene production, depending on variety, and whether data were expressed on a fresh-weight or floret basis. A climacteric pattern of ethylene production by the youngest buds on the spike (which never opened) was stimulated by cool storage, and was not affected by holding the spikes in a preservative solution containing sucrose. Ethylene treatment had no effect on senescence of the florets of any of the cultivars tested. Pulse treatment of the spikes with silver thiosulfate (STS) improved floret opening but not the life of individual florets. Sucrose and STS had similar but not synergistic effects on floret opening, suggesting that STS improves flower opening in gladiolus by overcoming the effects of carbohydrate depletion.
Variation within and among Blueberry Taxa in Flower Size and Shape
Authors: Lyrene Paul M.
Published: January 2019

Variation was studied within and among five Vaccinium taxa for the flower parameters corolla length, corolla aperture diameter, stigma location relative to the apex of the corolla tube, position of the anthers relative to the stigma and to the apex of the corolla, and style length. The objective was to determine whether there was enough genetic variation to breed cultivars with flower shapes that might favor pollination by a wider range of bee species. The taxa studied were cultivated rabbiteye (V. ashei Reade), cultivated southern highbush (mainly V. corymbosum L. with up to 30% introgression from V. darrowi Camp), F1 V. ashei × V. constablaei A. Gray hybrids, V. darrowi, and V. elliottii Chapm. Vaccinium elliottii flowers differed from all others in having short styles that were not exserted from the corolla tube. Vaccinium elliottii was also unusual in that the end of the anther tube extended nearly to the stigmatic surface. Vaccinium ashei corollas were longer and had smaller apertures than those of southern highbush, possibly making them less suitable for honeybee (Apis) pollination. For corolla length and aperture diameter, F1 V. ashei × V. constablaei hybrids were similar to southern highbush, indicating that V. constablaei introgression could be used to breed hexaploid cultivars with shorter, more open flowers. Large clone-to-clone variation within taxa for each flower characteristic indicates much potential for changing the shape of the blueberry flower by breeding, if the shape that maximizes fruit set can be determined.
Shoot Density Affects `Riesling' Grapevines II. Wine Composition and Sensory Response
Authors: Reynolds A.G. , Edwards C.G. , Wardle D.A. , Webster D. , Dever M.
Published: January 2019

`Riesling' grapevines (Vitis vinifera L.) were subjected for 4 seasons (1987-90) to three shoot densities (16, 26, and 36 shoots/m of row) combined with three crop-thinning levels (1, 1.5, and 2 clusters per shoot) in a factorial design. Wines were made from all treatment combinations in 1989. Aroma compounds such as trans-3-hexen-1-ol, linalool, and linalool oxides 1 and 2 in many cases decreased in nonaged and aged wines by increasing shoot density and clusters per shoot, while cis-3-hexen-1-ol increased. Aging wines increased concentrations of cis-3-hexen-1-ol, citronellol, α-terpineol, and the linalool oxides, while linalool decreased. Tasters identified aged wines from the lowest shoot densities and clusters per shoot as having the most ripe-fruit flavor and the least green-fruit flavor and perceived acidity. Flavor descriptors were correlated with linalool, cis-3-hexen-1-ol, and linalool oxide 1. Shoot densities of 20 to 25 shoots/m of row are recommended for low to moderately vigorous `Riesling' vines to achieve economically acceptable yields and high wine quality simultaneously.
Physiological and Mechanical Properties of Kiwifruit Tissue Associated with Texture Change during Cool Storage
Authors: Harker F.R. , Hallett I.C.
Published: January 2019

Kiwifruit [Actinidia deliciosa (A. Chev) C.F. Liang et A.R. Ferguson] flesh firmness can decline by as much as 94% during fruit ripening. This phenomenon was investigated at the cellular level, with the aim of characterizing changes in the physiological condition and mechanical properties of cells. The tensile strength of kiwifruit outer pericarp tissue was measured, and low-temperature scanning electron microscopy was used to examine the mode of cell failure at fracture surfaces. The propensity with which cells ruptured was determined by incubating tissue discs in hypertonic and hypotonic solutions, and water potentials, osmotic potentials, turgor pressures, and tissue density were measured. An initial rapid reduction in flesh firmness—from 80 to 27 N during 6 weeks of storage at 0C—was related to a reduction in the adhesion between neighboring cells. Following tensile tests, an examination of fracture surfaces indicated that cells from freshly harvested fruit had ruptured, exposing the cell interior. After 6 weeks of storage, neighboring cells separated from each other without breaking open. With 23 additional weeks of storage at 0C, flesh firmness decreased from 27 to 5 N. The final softening stage was associated with an increase in the proportion of cells that separated at the middle lamella and an increase in the plasticity of the cell wall.
Harvesting Semidwarf Freestanding Apple Trees with an Over-the-row Mechanical Harvester
Authors: Peterson D.L. , Miller S.S. , Whitney J.D.
Published: January 2019

Three years of mechanical harvesting (shake and catch) trials with two freestanding apple (Malus domestica Borkh.) cultivars on a semidwarf rootstock (M.7a) and two training systems (central leader and open center) yielded 64% to 77% overall harvesting efficiency. Mechanically harvested `Bisbee Delicious' apples averaged 70% Extra Fancy and 10% Fancy grade, while two `Golden Delicious' strains (`Smoothee' and `Frazier Goldspur') averaged 40% Extra Fancy and 13% Fancy grade fruit. Mechanically harvesting fresh-market-quality apples from semidwarf freestanding trees was difficult and its potential limited. Cumulative yield of open-center trees was less than that of central-leader trees during the 3 years (sixth through eighth leaf) of our study. `Golden Delicious' trees generally produced higher yields than `Delicious' trees.
Graft Compatibility among Chestnut (Castanea) Species
Authors: Huang Hongwen , Norton J.D. , Boyhan G.E. , Abrahams B.R.
Published: January 2019

Graft compatibility was investigated for 15 Chinese chestnut (Castanea mollissima Bl.) cultivars, nine American chestnut [C. dentata (Marsh.) Borkh.] selections, six Japanese chestnut (C. crenata Sieb.) cultivars, and two putative Japanese hybrids on two known rootstocks of Chinese chestnut. Intraspecific grafting of Chinese chestnut resulted in 80% success after two growing seasons. An unusual anatomical structure of the chestnut stem had a significant effect on graft success. The phloem fiber bundles related to graft failure are described in the study. Interspecific grafts of seven American and five Japanese chestnut selections resulted in ≥70% success. The putative Japanese hybrids had a significantly lower success rate (<50%) regardless of rootstocks. A marked graft incompatibility was found in one Japanese/Chinese and two American/Chinese combinations. Graft incompatibility related to morphological abnormalities at the graft union was also observed in interspecific grafts. Comparisons of cambial isoperoxidase isozymes between successful and unsuccessful grafts did not support the hypothesis that peroxidase isozymes are indicators of rootstock-scion compatibility. The results suggest that genetic incompatibility is not a major cause of graft failure in Chinese chestnut.
Irrigation Requirements, Root-medium pH, and Nutrient Concentrations of Easter Lilies Grown in Five Peat-based Media with and without an Evaporation Barrier
Authors: Argo William R. , Biernbaum John A.
Published: January 2019

Subirrigated Easter lilies were grown in five commercially formulated root media using one water-soluble fertilizer applied independently to each medium based on water-holding capacity and water loss. The number of irrigations ranged from 12 to 20 and the amount of applied water ranged from 5.3 to 6.8 liters for the uncovered media treatments. When the root-medium surface was covered with an evaporation barrier, the average amount of applied water was reduced by 35% compared to the uncovered media. The largest effect on root media pH was between uncovered and covered media due to the reduced amount of water applied. Similar macronutrient concentrations were measured in the five media during the experiment with few exceptions. The greatest differences in nutrient concentrations were found within the pots. The top 2.5 cm (top layer) contained nutrient concentrations up to 10 times higher than those measured in the remaining root medium (root zone) of the same pot. Covering the root-medium surface with an evaporation barrier reduced the stratification of fertilizer salts. Root-zone soluble salt concentrations of plants in the covered pots were similar to those of uncovered plants even though 36% less fertilizer was applied to the covered plants.
Seasonal Changes in Ice Distribution and Xylem Development in Blueberry Flower Buds
Authors: Flinn Cindy L. , Ashworth Edward N.
Published: January 2019

The location of ice crystals and their relationship to xylem vessels was studied in nonacclimated and acclimated `Berkeley' blueberry (Vaccinium corymbosum L.) flower buds. Light microscopy and low-temperature scanning electron microscopy (SEM) were used to detect ice crystals in the bud scales, floret scales, and bracts of dormant flower buds that had been frozen to -15C. No evidence of ice formation was observed in rachises, pedicels, and organs in florets when buds that had been fixed while frozen at -5C were examined with conventional SEM. This indicated that dormant buds underwent extraorgan freezing as a survival mechanism. Ice formation was not uniform in nonacclimated or deacclimated buds, although it was more prevalent in both than in acclimated buds. Large ice crystals were found in the ovaries of freeze-stressed nonacclimated buds. In deacclimated freeze-stressed buds, ice was found in the petals, rachises, pedicels, and ovaries. To determine whether this ice distribution pattern was correlated with the presence of mature xylem vessels, cleared flower buds were stained with basic fuchsin, which revealed the intact network of lignified elements. In nonacclimated buds (20 Sept.), mature xylem vessels extended through the rachises, connecting the bud scales with the floret scales and through the pedicels into the corollas of the florets. Although vascular development occurred in dormant buds, the greatest proliferation of vessels in the ovaries, petals, and sepals occurred coincident to the appearance of ice in these organs and the loss of hardiness.
Ethephon Tissue Penetration and Harvest Effectiveness in Olive as a Function of Solution pH, Application Time, and BA or NAA Addition
Authors: Denney James O. , Martin George C.
Published: January 2019

Fruit removal force (FRF) and percent leaf drop (LD) of fruit-bearing olive (Olea europaea L.) shoots were examined 120 hours after being sprayed with ethephon at 600 mg·liter-1 and held under controlled-environmental conditions analogous to those found in the field in California at harvest time in mid-October. FRF was not significantly affected by solution pH, but FRF of all treated shoots was significantly lower than that of the untreated controls. Only at pH 5 was percent LD significantly greater than that of the controls, but, of the shoots treated with ethephon, the lowest percent LD occurred at pH 3. Percent LD after treatment with ethephon at pH 3 was not affected by application time, but FRF was significantly less than the controls' when shoots were treated at 7 am or 12 pm but not at 5 pm or 10 pm. Adding NAA to the ethephon solution raised FRF and adding BA lowered FRF compared to ethephon alone. Adding NAA or BA did not mitigate percent LD significantly. Adding BA advanced anthocyanin production in fruit. Ethephon penetration of rachides was ≈70% that of petioles. Correlation between ethephon penetration of petioles and percent LD was greater than that between penetration of rachides and FRF. Correlation was significant for both tissues only in the 12 pm pH 3 treatment; correlation was also significant for petiole penetration and percent LD at pH 5. Autoradiographic studies of the 14C-ethephon penetration showed no pH effect, greater penetration into petioles than rachides, and that radioactivity was limited largely to intercellular spaces, with accumulation in vascular bundles, especially xylem. Regardless of treatment, FRF and percent LD are negatively correlated (r2 = 0.615). Mean results to be expected using ethephon as an olive harvest aid under these conditions are an FRF of ≈3 N and a percent LD of ≈15%. The desired low FRF and percent LD were obtained by applying ethephon alone at pH 3 at 7 am. Raising ethephon solution pH does not increase harvest effectiveness. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon), naphthalene acetic acid (NAA), 6-benzylaminopurine (BA).
Growth and Yields of Bell Pepper and Winter Squash Grown with Organic and Living Mulches
Authors: Roe Nancy E. , Stoffella Peter J. , Bryan Herbert H.
Published: January 2019

Increasing disposal problems with polyethylene (PL) mulch and greater availability of compost prompted an investigation into the effects of using compost as a mulch on horizontal raised bed surfaces with living mulches (LMs) on vertical surfaces. Wood chips (WC), sewage sludge-yard trimming (SY) compost, and municipal solid waste (MW) compost were applied at 224 t·ha-1 on bed surfaces. Sod strips of `Jade' (JD) or `Floratam' (FT) St. Augustinegrass (Stenotaphrum secundatum Kuntze) or perennial peanut (Arachis glabrata Benth.) (PP) or seeds of a small, seed-propagated forage peanut (Arachis sp.) (SP) were established on the vertical sides of the raised beds before transplanting bell pepper (Capsicum annuum L.) into the beds. Phytophthora capsici reduced pepper plant stand in PL-mulched plots compared with organic mulch (OM) and LM. Despite the stand reduction, total pepper yields were highest in PL plots and, in the OM plots, decreased in the order SY > MW > WC. Early fruit yields and yield per plant were highest from plants in PL plots followed by SY. Among LMs, plants in SP plots produced highest early yields and FT produced the lowest. Plants in PL plots produced the largest fruit. When the same plots were seeded with winter (butternut) squash (Cucurbita pepo L.), plant stands were higher in MW than WC and SY. Squash yields were similar between PL and OM plots.
Stomatal Conductance of Lysimeter-grown Asian Pear Trees before and during Soil Moisture Deficits
Authors: Renquist A. Richard , Caspari Horst W. , Behboudian M. Hossein , Chalmers David J.
Published: January 2019

Stomatal conductance (gs) of `Hosui' Asian pear (Pyrus serotina Rehder) trees growing in lysimeters was characterized for trees in well-watered soil and after brief water deficit. The measures of water status used to interpret gs data were soil-water content, leaf water potential (ψl), and instantaneous water use (trunk sap flow by the compensation heat-pulse technique). The diurnal course and range of gs values of well-irrigated Asian pear trees were similar to those reported for other tree fruit crops. Soil moisture at the end of a midsummer deficit period was 60% of lysimeter pot capacity, and diurnal ψl reflected this deficit predawn and in the late afternoon compared to well-irrigated trees. The gs was sensitive to deficit irrigation during more of the day than ψl, with gs values <3 mm·s-1 for most of the day; these were less than half the conductances of well-irrigated trees. The reduction of gs in response to a given soil-water deficit was not as great on days with lower evaporative demand. After a water deficit, gs recovered to predeficit values only gradually over 2 to 3 days. The low gs of trees in dry soil was the apparent cause of reduced transpiration, measured by trunk sap flow, and reduced responsiveness of sap flow to fluctuations in net radiation.
Field Evaluation and Selection for Resistance to Aster Yellows in Carrot (Daucus carota L.)
Authors: Gabelman W.H. , Goldman I.L. , Breitbach D.N.
Published: January 2019

Aster yellows, an insect-vectored disease caused by a mycoplasma-like organism (MLO), is a destructive vegetable plant disease in the upper midwestern United States. A breeding effort was initiated in 1982 to develop aster yellows resistance in carrot. An aster yellows synthetic (AYSYN) population composed of four standard open-pollinated cultivars and five inbred lines was assembled in 1982. Inbred lines were extracted from the AYSYN population using a variety of methods. Selection in naturally and artificially infested field sites was carried out from 1982 to 1989. Twenty-three carrot germplasm lines inbred for a minimum of five generations and three hybrids were developed from the AYSYN population during the selection process. Replicated field experiments were conducted in 1990, 1991, and 1993 to determine the relative aster yellows resistance of these 26 selected lines compared with six commonly grown carrot cultivars. Susceptibility was based on the presence of disease symptoms on carrot shoots. Data were collected as percent aster yellows infection based on the presence or absence of crown shoots on each plant. Averaged over years, significant differences were detected for percent aster yellows infection among carrot genotypes. Breeding lines selected for resistance ranged from 2.5% to 35.3% infected plants per plot averaged over years, while standard cultivars ranged from 12% to 42% infected plants per plot. Significant reductions in aster yellows infection were observed in many selected lines compared to standard cultivars. Results demonstrate the effectiveness of inbreeding and selection for aster yellows resistance. This breeding effort represents the first report of aster yellows-resistant carrot germplasm.
Estimating Nuclear DNA Content in Peach and Related Diploid Species Using Laser Flow Cytometry and DNA Hybridization
Authors: Baird W. Vance , Estager Agnes S. , Wells John K.
Published: January 2019

Using laser flow cytometry, nuclear DNA amounts were estimated for 12 Prunus species, representing three subgenera [Prunophora (Prunus), Amygdalus, and Cerasus (Lithocerasus)], two interspecific hybrids, four cultivars, and a synthetic polyploid series of peach consisting of haploids, diploids, triploids, and tetraploids (periclinal cytochimeras). Peach nuclear DNA content ranged from 0.30 pg for the haploid nuclei to 1.23 pg for the tetraploid nuclei. The diploid genome of peach is relatively small and was estimated to be 0.60±0.03 pg (or 5.8×108 nucleotide base pairs). The polyploid series represented the expected arithmetic progression, as genome size positively correlated with ploidy level (i.e., DNA content was proportional to chromosome number). The DNA content for the 12 diploid species and two interspecific diploid hybrids ranged from 0.57 to 0.79 pg. Genome size estimates were verified independently by Southern blot analysis, using restriction fragment length polymorphism clones as gene-copy equivalents. Thus, a relatively small and stable nuclear genome typifies the Prunus species investigated, consistent with their low, basic chromosome number (× = 8).
Selection Criteria for Drought-resistance Breeding in Turfgrass
Authors: Zhao Yuguang , Fernandez George C.J. , Bowman Daniel C. , Nowak Robert S.
Published: January 2019

Cumulative evapotranspiration (ETcum) patterns of 10 commercially available cool-season turfgrass species and cultivars were evaluated under progressive water stress in the semi-field conditions using a gravimetric mass balance method in three studies. At the end of water stress, the cultivars were visually scored for green appearance on a 0 (no green) to 10 (100% green) scale. A Gompertz nonlinear model gave a best fit to ETcum vs. days adjusted for pan evaporation variation. Two of the ETcum attributes (ti, the time during which the rate change in ET is zero, and ETmax, the maximum ET rate) estimated from the Gompertz model appeared to reflect efficient water-use attributes in the turfgrass. Among the physiological screening techniques studied, electrolyte leakage, relative water content, and the difference between canopy and air temperature appeared to separate cultivars by drought resistance and water use efficiency (WUE). These physiological attributes were also relatively easy to measure and had high correlations with color score and WUE. Biplot display is a graphical technique in which the interrelationships between the cultivars and water-use attributes can be displayed together. Based on ti, ETmax, color score, and physiological attributes, `Wabash' and `Bristol' Kentucky bluegrass (Poa pratensis L.), `Aurora' hard fescue (Festuca ovina var. duriuscula L. Koch.), and `FRT-30149' fine fescue (F. rubra L.) were identified as cultivars with higher WUE.
Evaluation of the Initial Season for Implementation of Four Tomato Production Systems
Authors: Steffen Kenneth L. , Dann Michael S. , Harper Jayson K. , Fleischer Shelby J. , Mkhize Sizwe S. , Grenoble' Doyle W. , MacNab Alan A. , Fager Ken , Russo Joseph M.
Published: January 2019

During the initial season of implementation, four tomato production systems differing in soil management, pest control practices, and level of inputs, such as labor, materials, and management intensity were evaluated. These systems were CON, a low input (no mulch, no trellising, overhead irrigation, preplant fertilization, scheduled pest control), conventional agrichemical system; BLD, a high input [straw mulch, trellising, trickle irrigation, compost fertility amendment, integrated pest management (IPM)], ecologically-oriented system that emphasized the building up of soil organic matter levels and used no agrichemicals to supply fertility or for pest control; BLD+, a system similar to BLD, except that agrichemical pesticides were used; and ICM, a high input system (black polyethylene mulch, trellising, trickle irrigation, fertigation, IPM pest control) that used agrichemicals to supply fertility and for pest control. Soil characteristics and fertility levels in the BLD and BLD+ systems were modified with extensive amendments of spent mushroom compost and well-rotted cattle manure. Levels of agrichemical NPK calculated to meet current crop needs were supplied to the CON and ICM systems, with 75% of fertility in the ICM system supplied through the trickle irrigation lines (fertigation). The BLD system had a greater soil water holding capacity and sharply reduced irrigation requirements. During a wet period, fruit cracking and evidence of water-mold root rot were significantly higher in the ICM system than the BLD and CON systems. Defoliation by Alternaria solani was greatest in the BLD system and least in the ICM system. The BLD and ICM systems resulted in a 1 week earlier peak yield compared to the CON system. The yield of No. 1 fruit was 55% to 60% greater in the BLD+ system than the other three systems, which were comparable in yield. Net return was highest in the BLD+ system, although the benefit/cost ratio was greatest in the CON system. This multidisciplinary study has identified important differences in the performance of diverse production systems during the unique transitional season.
Stigmatic Receptivity Limits The Effective Pollination Period In Kiwifruit
Authors: González Maria Victoria , Coque Manuel , Herrero Maria
Published: January 2019

The effective pollination period was determined in kiwifruit [Actinidia deliciosa (Chev.) Liang and Fergusonl and the factors affecting it were evaluated. The effective pollination period, measured as the capability to set fruit after hand-pollinating flowers of different ages, was 4 days; 5 days after anthesis fruit set decreased and 2 days later it was nil. Pollen tube growth did not appear to he a limiting factor since pollen tubes grew quickly and reached the base of the style 2 days after pollination and reached the ovules 1 day later. Ovules appeared viable for the 7 days following anthesis, and visibly degenerated within the following 3 days. Stigmatic receptivity was determined by the ability to sustain pollen germination after hand pollinating flowers of different ages. The duration of stigmatic receptivity closely fit the effective pollination period determined through fruit set. Thus, it appears that stigma receptivity is the main factor responsible for the short effective pollination period.
Scanning Electron Microscopy, Video-image Analysis, and Confocal Imaging of Changes Occuring during Peach Fruit Abscission
Authors: Tirlapur Uday K. , Costa Guglielmo , Malossini Carlo , Vizzotto Giannina , Cresti Mauro
Published: January 2019

`Redhaven' peach (Prunus persica L. Batsch) fruit abscission has been investigated using scanning electron microscopy, computer-assisted video-image analysis, and confocal laser scanning microscopy in conjunction with chlorotetracycline and ethidium bromide as fluorescent probes for membrane Ca2+ and nuclear DNA. This enabled us to document the morphological changes of the cells, distribution patterns of membrane Ca2+ in the constituent cells of the abscission zone, and the nuclear morphology with accompanying changes in nuclear DNA. The digitized images of CTC-fluorescence emissions revealed that the membrane Ca2+ levels in the pre-abscission zone (control) is uniform and similar to that present in the cells of the spongy proximal region of the peduncle and that of the fruit parenchyma. However, with the induction of abscission, 2 days after embryoctomy, there was a significant increase in membrane Ca2+ in the cells of the abscission zone compared to the neighboring cells of the fruit and the peduncle. Thereafter, with the gradual separation of the cells and the concomitant vacuolation, the membrane Ca2+ level decreased substantially. Confocal imaging of EB labeled cells of the abscission zone before induction invariably revealed a well-organized nucleus. However, during cell separation, significant changes in the cellular and nuclear morphology occured, including 1) rounding of cells, 2) reduction in the nuclear volume, and 3) concomitant fragmentation of nuclear DNA. The possible role of Ca2+ during the process of peach fruit abscission and nuclear DNA fragmentation leading to cell death is discussed. Chemical names used: chlorotetracycline (CTC), ethidium bromide (EB).
Origin and Inheritance of Dwarfing by the Citrus Rootstock Poncirus trifoliata `Flying Dragon'
Authors: Cheng Frank Suozhan , Roose Mikeal L.
Published: January 2019

`Flying Dragon' Poncirus trifoliata L. Raf. is a dwarfing rootstock for citrus. Inheritance of dwarfing ability was studied in a population of open-pollinated seedlings of `Flying Dragon'. Molecular marker genotypes suggest that all seedlings originated from selfing. Progeny seedlings were budded with `Cutter Valencia' orange and planted in the field to evaluate the dwarfing effect of the seedling rootstock. At 5 years after planting, rankit analysis of the frequency distributions of trunk cross-sectional area and canopy volume suggested the presence of two overlapping distributions of 34 dwarf trees and 7 nondwarf. This ratio is consistent with inheritance of rootstock dwarfing as a single dominant gene for which `Flying Dragon' is heterozygous. Two morphological characteristics of `Flying Dragon', curved thorns and twisted trunk growth, were closely linked to, or pleiotropic effects of, the dwarfing gene. Bulked segregant analysis was used to identify three RAPD markers linked to the dwarfing gene. `Flying Dragon' was identical to nondwarfing cultivars of trifoliate orange at 40 homozygous and heterozygous isozyme and RFLP markers; therefore, it is likely that `Flying Dragon' originated as a mutant of a nondwarfing genotype and has not undergone sexual recombination since this event.