bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlled-atmosphere Storage of Shredded Carrots
Authors: Izumi Hidemi , Ko Nathanee P. , Watada Alley E.
Published: February 2019

Quality and physiology of carrot shreds were monitored during storage in air, low O2 (0.5%, 1%, and 2%), or high CO2 (3%, 6%, and 10%) at 0, 5, and 10C to evaluate the response to controlled-atmosphere (CA) storage. Oxygen uptake and CO2 production from respiration were reduced under low-O2 or high-CO2 atmosphere, the reduction being greater at lower O2 and higher CO2 levels. The respiratory quotient was about 1 with samples in air, more than 1 in low-O2, and less than 1 in high-CO2 atmosphere during storage at all temperatures. No differences were found in ethylene production, which were less than 0.2 μl·kg–1·h–1 with all samples. The CA containing 0.5% O2 and 10% CO2 reduced weight loss and formation of white-colored tissue and decreased pH, but did not affect microbial count and texture at all temperatures. Off-odor and black root rot were not detected in both CA and air atmospheres.
Transgenic Resistance to Virus Diseases in Squash and Cantaloupe
Authors: Clough George H. , Hamm Philip B.
Published: February 2019

Three transgenic yellow crookneck squash (Cucurbita pepo var. melopepo) and five transgenic cantaloupe (Cucumis melo, Reticulatus group) lines were field-tested in 1993 and 1994, respectively, for resistance to Zucchini Yellow Mosaic Virus and Watermelon Mosaic Virus II. During both years, non-transgenic plants were inoculated with virus before transplanting to provide a high virus threat to the transgenic plants. Before and after transplanting, serological (ELISA) testing was used to obtain baseline information on transformed plants and to confirm field virus infection. In both years, plant disease development was rated weekly; yield was assessed during 1993. Disease progression, yield, and end-of-season ELISA indicated a significant reduction in frequency of disease incidence in the transgenic lines. Total squash yields did not differ between the transformed and unchanged lines, but the transgenic lines yielded more marketable fruit than the non-transgenic line.
Antiplatelet Activity is Positively Correlated with Pungency and Solids in Onion (Allium cepa L.)
Authors: Kopelberg M. , Goldman I.L. , Debaene J.E.P. , Schwartz B.S.
Published: February 2019

Onion (Allium cepa L.) and other vegetable Alliums have long been recognized for the antiplatelet properties. Consumers may benefit from the medicinal value of onions because they are commonly eaten raw in salads and the antiplatelet factor is destroyed by heat. Recent work indicates antiplatelet activity in Allium sp. may be due to the presence of native organosulfur compounds. The concentration of organosulfur compounds correlates positively with pungency, varies with onion cultivar, and is influenced by environmental factors. Bulb dry matter content, or solids, is positively correlated with pungency. Because antiplatelet activity may also be based on the activity of organosulfur compounds, it is possible these three factors are significantly correlated. The objective of this investigation was to examine the relationship among pungency, solids, and antiplatelet activity in four diverse onion genotypes. Replicated trials consisting of two mild and two pungent genotypes were conducted at four locations in 1994. Onion bulbs were harvested and analyzed for all three traits. Results from this investigation indicate significant positive correlations between antiplatelet activity, pungency, and solids in onion.
Effects of Varying Sulfate Concentrations on Growth and Mineral Nutrition of the Greenhouse Tomato
Authors: Lopez J. , Parent L.E. , Tremblay N. , Gosselin A.
Published: February 2019

In hydroponic recirculating systems, sulfate ions can accumulate to excessive levels and interfere with other nutrient ions. The objective of this research was to determine the effects of four sulfate concentrations on growth and mineral nutrition of greenhouse tomato plants (Lycopersicon esculentum Mill. cv. Trust). Tomato seeds were sown in flats and subsequently transplanted into rockwool slabs. Ten days after transplanting, plants were given four sulfate concentrations in nutrient solutions (S0 = 0.1, S1 = 5.2, S2 = 10.4, and S4 = 20.8 mM). The plots were arranged in a randomized complete-block design with four replications. Treatment S0 reduced dry weight of the top portion of the plant. A sulfate shortage in the nutrient solution decreased S concentrations in the leaf and decreased fruit number. Activities and concentrations of major ions in solutions expressed in mM or as row-centered logratios were correlated with corresponding foliar concentrations expressed in grams of nutrient per kilogram of dry matter or as row-centered logratios. Data were presented in this manner in order to explore interactive models describing relationships between mineral composition of both nutrient solutions and plant tissues. High concentrations of sulfate ions in the nutrient solution up to 20.8 mM did not affect tomato growth or yield. Tomato plants appeared prone to sulfate deficiency, but tolerant to sulfate concentrations up to 20.8 mM in the nutrient solution.
Improving Nitrogen Management of Vegetable Crops Through Intensive Monitoring
Authors: Hartz T.K. , Costa F.J.
Published: February 2019

The production of cool-season vegetable crops in California's coastal valleys is characterized by high N input (typically 200–300 kg·ha–1 per crop), with two crops per year the norm. N. removal in harvested biomass seldom exceeds 100 kg·ha–1, suggesting a high degree of inefficiency in N management. A project was conducted on a commercial farm in Santa Maria to document the utility of intensive monitoring of soil and plant N status on improving N management. Eight fields were monitored through successive cropping cycles. Slow-release N fertilizer was applied preplant at 110–250 kg·ha–1 in subplots in each field to provide a reference of known N sufficiency against which to compare field productivity; these reference plots also received the same in-season fertilizer N applied in the balance of the field. N monitoring techniques included: in situ and controlled-environment soil incubation to estimate net N mineralization, soil NO3-N analysis by a “quick test” technique using colormetric test strips, and petiole sap analysis by NO3-N selective electrode. It was consistently demonstrated that, for lettuce, cauliflower, and broccoli, maximum crop productivity was obtained with seasonal N applications 50–100 kg N/ha less than the industry norm and that fertilizer cost savings more than offset the cost of crop and soil monitoring.
Nonstructural Carbohydrates and Mesocarp Development as a Result of Blossom Thinning in Peach
Authors: Mrosek Janet S. , Myers Stephen C.
Published: February 2019

The relationship between cell division, nonstructural carbohydrates and fruit size was investigated using 5-year-old `Encore' peach [Prunus persica (L.) Batsch]. The trees, which were trained to two opposing scaffolds, were selected for uniformity based on tree size and floral bud density. One-year-old shoots ranging in size from 20 to 30 cm were tagged from throughout the canopy. At anthesis, one entire scaffold was thinned of 75% of its flowers, leaving 25% in the mid-section of each shoot. The opposing scaffold served as the control. Samples were taken at three intervals for histological analysis: Anthesis, 30 days, and 45 days after full bloom. Nonstructural carbohydrates were analyzed on samples taken at five intervals: Anthesis, 10, 20, 30, and 45 days after full bloom. Volumetric size increased 29% by 30 days after full bloom, and 64% by 45 days after full bloom. Final fruit size (volumetric) was increased 8% by harvest.
Determining the Juvenile Phases of Coreopsis grandiflora, Gaillardia grandiflora, Heuchera sanguinea, and Rudbeckia fulgida
Authors: Yuan Mei , Carlson William H. , Heins Royal D. , Cameron Arthur C.
Published: February 2019

Most plants have a postgermination juvenile phase in which flower induction will not occur. Some species require a cold period for flower induction and will not respond to the cold treatments during the juvenile phase. We determined juvenile phases of Coreopsis grandiflora `Sunray', Gaillardia grandiflora `Goblin', Heuchera sanguinea `Bressingham', and Rudbeckia fulgida `Goldsturm'. Plants were exposed to 5C for 0, 10, or 15 weeks when Coreopsis had 0, 2, 4, 6, 8, or 10 leaves (>1 cm); Gallardia, 4, 8, 12, or 16 leaves; Heuchera, 8, 12, 16, or 20 leaves; Rudbeckia, 5, 10, 15, or 20 leaves. Plants were grown under a 4-h night interruption lighting (LD) or under a 9-h photoperiod (SD) after cold treatments. Based on time to flower and final leaf count, the juvenility of Coreopsis, Gaillardia, Heuchera, and Rudbeckia ended when they had about 6, 10, 12, and 15 leaves, respectively. Cold treatments were necessary for flower induction of Coreopsis and Heuchera and they increased the flowering percentage of Gaillardia and Rudbeckia. Heuhera was a day-neutral plant, Rudbeckia was on obligate LD plant, and Gaillardia and Coreopsis were quantitative LD plants.
Comparison of Molecular Marker and Morphological Data to Determine Minimum Distance among Tomato Cultivars
Authors: Villand Julie , Nienhuis James , Skroch Paul , Tivang Jan
Published: February 2019

Precise cultivar descriptions are necessary to support Plant Variety Protection and utility applications for patent protection. However, accurate discrimination among cultivars is contingent upon the dependability of the method used to delineate lines. The efficiency and reliability of Amplified Fragment Length Polymorphisms (AFLPs), Random Amplified Polymorphic DNAs (RAPDs), microsatellite polymorphisms, and phenotypic traits were studied in order to determine a method's ability to accurately predict pedigree relationships among a set of 20 California processing tomato cultivars. All molecular marker and phenotypic trait data sets were independently produced using identical cultivar seed sources. Data was reduced to a genetic distance measure and presented as a multidimensional scaling (MDS) plot. Principal component analysis using the scored quantitative phenotypic traits was computed and is compared to molecular marker data results. Experimental error, sampling variance, and independence of scored bands for each molecular marker technique are presented. These estimates should assist breeders to determine a sufficient level of characterization, determine a minimum distance considered to be unique, and defend pedigree relationships.
Comparison of Five Molecular Marker Systems in Assessing Genetic Relationships among 39 Elite Corn Belt Inbreds
Authors: Tivang J.G. , Nienhuis J. , Smith O.S. , Smith J.S.C.
Published: February 2019

The statistical properties associated with molecular markers are important when used to characterize germplasm. Evaluation of these properties are necessary for informed selection of one marker system over another. Five different molecular marker systems, Amplified Fragment Length Polymorphism (AFLPs), Arbitrary Primed Polymerase Chain Reaction (AP-PCR), Random Amplified Polymorphic DNA (RAPDs), Restriction Fragment Length Polymorphism (RFLPs), and Isozymes were used to evaluate 39 elite corn belt inbreds. Each system was characterized for fragment frequency distribution, and band correlation distribution as a measure of independence. A regression model estimating resolution and rate of information addition was constructed using the sampling variance. All marker systems were evaluated according to this model. The model facilitated genetic relationships among the inbreds to be compared at equivalent performance level among all marker systems. Four performance levels resulted in 10 comparisons. Pairwise test of significance were conducted using t tests where the null-distributions were obtained by the bootstrap procedure. The maker system were ranked, assisting breeders in selecting marker systems for germplasm organization.
Integration of RAPD Marker Genetic Linkage Maps in Phaseolus vulgaris L.
Authors: Skroch Paul , Nienhuis Jim , Jung Geunwha , Coyne Dermot
Published: February 2019

Currently, we are studying the genetics and linkage relationships of important quantitative and qualitative traits in common bean, including disease resistances, plant architecture, seed size and shape, and pod size, shape, and fiber content. Study of the genetics of these traits is being facilitated through the use of RAPD marker-based linkage maps in four RI populations. Cultivated P.vulgaris has two primary centers of diversity—Meso-american and Andean, the RI populations used for mapping are Meso x Andean (Bat93 x Jalo EEP558 and Eagle x Puebla 152), Andean x Andean (PC50 x Xan159), and Meso x Meso (BAC6 x HT7719) crosses. Maps in these four populations are being integrated through the use of cosegregating markers. Integration of maps will allow integration of the linkage relationships of relevant genes and also allow more efficient sampling of markers for future linkage studies.
Diallel Analysis for Rain Check in Tomato
Authors: Emmons Cheryld L. , Scott J.W.
Published: February 2019

To investigate the genetic control of rain check (cuticle cracking) in tomato (Lycopersicon esculentum), a full diallel cross including five parents ranging from very resistant to very susceptible was grown in late spring 1994. A randomized complete-block design with four replications was used and the proportion of fruit showing check was measured on all mature fruit from eight plants per replication at three harvests. Analysis of variance indicated significant (P < 0.0001) variation for line, harvest, and line by harvest interaction. The proportion of fruit affected increased with each successive harvest. Reciprocal differences were tested on a by-harvest basis and found to be nonsignificant. Reciprocals were combined and a Hayman's analysis was performed on a by-harvest basis on the means. Additive effects on variance were significant (P < 0.05) for all harvests. Under high environmental stress (harvest 3), dominance effects were negative and significant (P < 0.05). Narrow-sense heritability ranged from 0.54 to 0.67 and increased with increasing environmental stress. General combining ability was significant for all harvests, whereas specific combining ability was significant only for harvest 3 (P < 0.05).
Effect of Urea, Some Micronutrients, and Growth Regulator Foliar Sprays on the Yield, Fruit Quality, and Some Vegetative Characteristics of `Washington' Navel Orange Trees—Yield and Yield Components
Authors: Akl Ahmed M. , Eid Abdel-Fattah M. , Hegab Mohamed Y.
Published: February 2019

This investigation studied the effects of foliar sprays of urea (0.5%), a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulfates from 23% Zn, 28% Mn, 19% Fe, and 30% Cu, respectively, and two growth regulators (GA3 at 25 ppm and α-NAA at 10 ppm), as well as number and date of sprays, on the number of fruit/tree, average fruit weight, and yield/tree in kilograms. Spraying `Washington' navel orange trees with urea and/or micronutrients significantly increased the number of fruit/tree, average fruit weight, and yield/tree expressed in kilograms. However, the treatment including both of them was the most effective in 1991–92 and 1992–93. Application of GA3 and NAA effectively increased the value of the three traits compared with the control; however, spraying the trees with NAA was responsible for higher fruit numbers, while GA3 was more effective in increasing fruit weight. Two sprays of urea, micronutrients, and NAA (or GA3), the first applied 3 weeks before flowering and the second 4 weeks after fruit set, were more effective than spraying once at any of the two dates in producing high numbers of fruit/tree, average fruit weight and yield per tree by weight.
Gene Expression and Membrane Changes in Bermudagrass during Cold Acclimation
Authors: Wells John , Yan Jiyu , Riley Melissa , Samala Suresh , Baird Vance
Published: February 2019

Bermudagrass (Cynodon dactylon) cultivars may exhibit increased tolerance to cold following periods of exposure to moderately cold temperature (i.e., acclimation). We are evaluating biochemical changes and the regulation of gene expression in two cultivars—'Midiron' and U-3—during this acclimation period. Total membrane lipid fatty acids per unit of total lipids (MLFA/TL; μg·mg–1) increased in crowns over the 4-week exposure to chilling temperatures (8C day/2C night). Of the fatty acids comprising 95% of total MFLA, concentrations of short-chain and saturated FAs declined significantly while unsaturated longer-chain FA concentration increased. As a result, the double bond index (percent of each FA x number of double bonds in the FA) increased during the period of low temperature exposure, indicative of increasing membrane fluidity. Changes in MFLA were evident as early as 4 days following exposure to chilling temperatures. Identification of mRNA species expressed in response to low temperature utilized differential display-PCR. Initial screening with paired T11N1N 2 3'-anchor and 5'-random decamer primers has identified transcripts differentially expressed as early as 23 h post-exposure and was maintained for at least an additional 36 h. Isolation, reamplification, and cloning of these identified PCR products is in progress.
Effect of Chilling on Respiration and Induction of Cyanide-resistant Respiration in Cucumber Roots
Authors: Reyes Eleazar , Jennings Paul H.
Published: February 2019

The effect of chilling stress on induction of the cyanide-resistant pathway was investigated using roots of 3-day-old cucumber (Cucumis sativus L.) grown at 26C and then chilled at 2C, 10C, or 15C for 24, 48, 72, and 96 h. A 24-h post-chilling treatment was imposed on different sets of chilled cucumber roots at 26C. Exposing seedlings to 2C, 10C, and 15C, as well as to a post-chilling treatment, induced differential responses in the activity of the cyanide-resistant pathway. Cucumber seedling roots exhibited an increase in the cyanide-resistant pathway after a 96-h chilling treatment at 2C. The involvement of the cyanide-resistant pathway in the chilling stress response will be discussed.
The Effects of Mechanical Conditioning on Tomato Transplant Growth and Field Performance
Authors: Garner Lauren C. , Björkman Thomas
Published: February 2019

Stretching is a problem in high-density transplant production. Mechanical conditioning provides good height control for many crops, but information concerning the dosage and timing of stimulation, and possible effects on field performance are necessary for successful commercial implementation. Mechanical conditioning was applied to processing tomatoes (`Ohio 8245') grown in #288-deep flats (≈2000 plants/m2). Brushing was applied by daily gentle stroking of the plant canopy with a Styrofoam planter flat. The appropriate dose as determined by stroking 0, 10, 20, or 40 times daily back and forth. Twenty strokes provided sufficient height control with minimal plant damage. The interval between strokes was also varied, using 0.6 6, 60, or 600 s. These intervals were all equally effective in reducing the growth rate of the canopy. This broad range provides flexibility in commercial use of this technique. To test for effects on field performance, two methods of conditioning were used: brushing and impedance. Brushing was 20 continuous strokes daily. The impeded plant canopy was compressed slightly by a piece of Plexiglas suspended overnight. The treatments were applied from canopy closure until transplanting to the field. At transplanting, brushed and impeded plants were significantly shorter than control plants without a reduction in shoot dry weight. The treatments did not affect the speed at which the plants grew in the field. Within 5 weeks after transplanting, there were no significant differences between treatments in any measured parameter, including final yield. Therefore, both brushing and impedance provide a flexible and effective method for controlling tomato transplant height without adversely affecting establishment or yield.
Matriconditioning Integrated with GA to Hasten Seed Germination and Improve Stand Establishment of Pepper and Tomato
Authors: Andreoli Claudinei , Khan Anwar A
Published: February 2019

Emergence and stand establishment of pepper and tomato seeds often are slow and erratic, particularly under stress conditions. Field emergence trials sometimes have not responded to priming in pepper. In this study, we examined the combining effect of matriconditioning with GA4+7 to hasten germination and improve stand establishment of pepper and tomato seeds. The results showed that, in all cases, even under stressful conditions, the combined matriconditioning plus GA treatment was effective in improving germination and emergence of pepper and tomato seeds. Emergence was improved in 20% when seeds were treated with GA4+7 up to 200 mM. Thus, matriconditioning during which germination is suspended, provides a unique means to rapidly and efficiently digest the endosperm by GA-induced enzymes and reduce not only the mechanical restraints but also provide the energy for embryo growth.
Amphidiploids as a Source of Blackspot Resistance in Rose Germplasm Development
Authors: Byrne D.H. , Ma Y. , Black W. , Pemberton H.B.
Published: February 2019

Extensive field screening of rose (Rosa spp.) germplasm at two sites in Texas has determined that most modern roses are susceptible to blackspot [Diplocarpon rosae (Lib.) Wolf]. Fortunately, there is a high level of resistance in a number of diploid rose species, such as Rosa laevigata, R. ganksiae, R. rugosa, R. wichuraiana, and R. roxburghii. These species were used to create three amphidiploids: 84-1000 (R. roxburghii x R. laevigata), 86-3 (R. banksiae x R. laevigata), and 86-7 (R. wichuraiana x R. rugosa rubra). These were examined for fertility to determine their usefulness in a breeding program. 86-7 had the most abundant pollen production and the greatest pollen fertility, as measured by hip set (38%), followed by 86-3 (19%), and 84-1000 (13%). The female fertility of 86-3 and 84-1000 is low, and 86-7 is female-sterile. Although 86-7 showed poor female fertility, F1 hybrids exhibited a wide range of fertility, indicating that the fertility of this germplasm can be quickly increased in subsequent generations.
Effects of Continuous Lighting and Light Spectral Composition on Photosynthesis and Related Processes of Greenhousegrown Tomato and Pepper Plants
Authors: Demers Dominique-André , Dubé Sylvain , Yelle Serge , Gosselin André
Published: February 2019

Growing tomato and pepper plants under continuous light causes negative effects such as leaf chlorosis and deformities, and decreased growth and yield. Such effects are more pronounced on tomato plants. Our general objectives are to identify the physiological process(es) responsible for these negative effects and to explain the difference in sensitivity of tomato and pepper plants to continuous light. The specific objective of this experiment was to determine the effects of continuous light and light spectral composition on photosynthesis and related processes of tomato and pepper plants. Tomato and pepper plants were place on 7 June 1994 in growth chambers under photoperiod treatments of 12 h [high-pressure sodium (HPS) lamps], 24 h (HPS lamps), and 24 h [metal halide (MH) lamps]. For all treatments, FPP was 350 μmol·m–2·s–1, temperatures were 21C (day) and 17C (night), and RH was 70%. Every 2 weeks (7 June until 2 Aug.), tomato and pepper leaf samples were harvested and frozen in liquid nitrogen for subsequent measurements of starch content (Robinson et al, 1988, Plant Physiol.), sucrose phosphate synthase activities (Dali et al., 1992, Plant Physiol.) and chlorophyll and carotenoid content (determination on HPLC). A system that measured gas exchange and chlorophyll fluorescence of fresh leaf samples was used to determine the photosynthetic rate and quantum yield of CO2 fixation and electron transport. Development of the negative effects of continuous light on plants was monitored. Light spectral composition of the two types of lamps was measured using a spectroradiometer. Results show that, under continuous light, pepper plants were less-efficient than tomato plants in using light for CO2 fixation, but were more efficient in dissipating the extra energy received. This may explain why pepper plants are less sensitive to continuous light than tomato plants. MH lamps caused more-severe chloroses on tomato leaves than HPS plants. We believe that the higher proportion of UV-light provided by MH lamps may be related to this effect. Detailed results will be presented.
An Inexpensive, Whole-plant, Open Gas-exchange System for the Measurement of Photosynthesis in Potted Woody Plants
Authors: Miller David P. , Howell G. Stanley , Flore James A.
Published: February 2019

The measurement of whole-plant CO2 uptake integrates leaf-to-leaf variability, which arises from such sources as angle of incident radiation, source/sink relationships, age, and biotic or abiotic factors. Respiration of above-ground vegetative and reproductive sinks is also integrated into the final determination of whole-plant CO2 assimilation. While estimates of whole-plant CO2 uptake based on single-leaf determinations have been used, they do not accurately reflect actual whole-plant assimilation. Chambers were constructed to measure gas exchange of entire potted grapevines. The design and construction are simple, inexpensive, and easy to use, allowing for the measurement of many plants in a relatively short time. This enables the researcher to make replicated comparisons of the whole-plant CO2 assimilation of various treatments throughout the growing season. While CO2 measurement was the focus of this project, it is also possible to measure whole-plant transpiration with this system.
Chlorophyll Fluorescence as an Indicator of Low O2 or High CO2 Stress in Apples during Storage
Authors: DeEll Jennifer R. , Prange Robert K. , Murr Dennis P.
Published: February 2019

Chlorophyll fluorescence, measured using a Plant Productivity Fluorometer Model SF-20 (Richard Brancker Research, Ottawa, Ont.), was evaluated as a rapid and nondestructive technique to detect low O2 and/or high CO2 stress in apples during storage. `Marshall' McIntosh apples were held for 5, 10, 15, 20, or 25 days at 3C in the following four treatments: standard O2 (2.5% to 3%) and low CO2 (<1%); low O2 (1% to 1.5%) and low CO2 (<1%); standard O2 (2.5% to 3%) and standard CO2 (4% to 4.5%); or standard O2 (2.5% to 3%) and high CO2 (11% to 12%). Only 10% of the apples had skin discoloration after 5 days in 1% to 1.5% O2, while 80% developed skin discoloration after 20 days in low O2. Small desiccated cavities in the cortex, associated with CO2 injury, developed in 10% of the apples after 20 days in 11% to 12% CO2. Both 1% to 1.5% O2 and 11% to 12% CO2 for 5 days caused chlorophyll fluorescence [Fv = (P – T)/P] of apple fruit to decrease, as compared to those held in standard atmospheres. Additional exposure time did not significantly affect Fv in either the low-O2 (1% to 1.5%) or high-CO2 (11% to 12%) treatment. The results of this study suggest that chlorophyll fluorescence can detect low-O2 and high-CO2 stress in apples, prior to the development of associated physiological disorders.
Lipid Changes during Heat Treatment of Apple Fruit
Authors: Whitaker Bruce D. , Klein Joshua D. , Conway William S.
Published: February 2019

Postharvest heat treatment of apples maintains fruit firmness and reduces decay during storage. Four days at 38C are beneficial, but 1 or 2 days are detrimental. The cellular basis of these effects may involve changes in cell wall and membrane lipid metabolism. Lipids from hypodermal tissue of `Golden Delicious' apples were analyzed after 0, 1, 2, or 4 days at 38C. Major lipids included phospholipids (PL), free sterols (FS), steryl glycosides (SG), and cerebrosides (CB). Galactolipids (GL) were minor components. PL content fell ?10% after 1 day at 38C, was unchanged after 2 days, and began to rise again after 4 days. PL class composition did not change with heating, but fatty-acid unsaturation declined throughout. FS and CB content and composition changed little, whereas SG content cropped by ≈20% over 4 days. GL fell ≈50% during 1 day at 38C, with no change at days 2 or 4. A burst of PL catabolism followed by recovery of synthesis may in part explain the different effects of 1-, 2-, or 4-day heat treatments. GL loss (in plastids) may be related to the effect of heat on fruit color (yellowing).
Superficial Scald Development on Apples at Chilling and Nonchilling Temperatures
Authors: Bramlage William J.
Published: February 2019

`Cortland' and `Delicious' apples were stored at 0C for up to 25 weeks, and at 20C in either open boxes or non-sealed poly bags for up to 8 weeks. At 20C, lesions occurred mostly around lenticels, but with some calyx bronzing and scald-like symptoms on shaded areas. At 0C, typical scald symptoms occurred. At both temperatures, high concentrations of alpha-farnesene and conjugated trienes occurred in conjunction with symptom appearance, and both these concentrations and discolorations decreased with later harvest of fruit. Scald development appeared to be chilling-enhanced, but not chilling-dependent.
Effect of Storage Humidity and Post-storage Handling Temperature on Bruising of CA-stored `McIntosh' Apples
Authors: Prange Robert K. , Harrison Peter A. , DeEll Jennifer R.
Published: February 2019

In a 2-year study, `McIntosh' apples were stored in a CA regime of 4.5% CO2 + 2.5% O2. Within the CA cabinets there were three humidity levels: >75% RH (CaCl2 salt in the chamber), >90% RH (ambient), or >95% RH (distilled water in the chamber). After removal at 4 and 8 months, the fruit were warmed to handling temperatures of 0C, 10C, or 20C and subjected to three levels of impact bruising of 0, 10, or 20 lb with a Ballauf pressure tester with a 1.5 × 1.5-cm tip. The results showed that low-humidity CA storage decreased visible bruising. Although visible shrivel was not observed, the low-humidity treatment may increase the possibility of its occurrence. Respiration, measured as O2 consumption or CO2 production immediately after removal from CA storage, was lowest in low humidity (>75% RH) and highest in ambient humidity (>90% RH) CA storage. The humidity treatments did not affect firmness, soluble solids, titratable acids, or ethylene production. Increasing the temperature during post-storage handling decreased the amount of visible bruising without affecting other variates such as firmness, soluble solids, titratable acids, respiration, or ethylene production.
Studies on DNA Polymorphism of Silver Maple (Acer saccharinum L.)
Authors: Freire A. Virginia , Preece John E. , Lightfoot David A.
Published: February 2019

Silver maple has great potential as a biomass feedstock. We compared three clones from each of seven provenances located on east to west and north to south transects across the natural range of silver maple and one red maple. DNA extracted by a modification of the CTAB technique (Murray and Thompson, 1980) was not suitable for RAPD analysis. Using this technique, polymorphism was either not reproducible or there was poor amplification for some clones. A new DNA extraction technique using PVPP, chloroform, and cesium chloride was tested (a modification of Yoon et al., 1991). this method yielded DNA that was more suitable for PCR amplification. Both RAPD and DAF (Caetano-Anolles and Gresshoff, 1994) methods were used for amplification. Polymorphism was detected among and within provenances. DAF was more efficient than RAPDs for determination of the genetic relationship among silver maple clones.
Development of Scar Markers Tightly Linked to the CTV Resistance Gene in Poncirus trifoliata
Authors: Deng Zhan'ao , Gmitter Fred G. , Xiao Shunyuan , Huang Shu
Published: February 2019

Citrus tristiza virus (CTV) is the most-significant viral pathogen of citrus in the world. Rapid decline of trees on sour orange and stem pitting of grapefruit and sweet orange, two diseases induced by CTV, severely jeopardize citrus production worldwide. It is recognized that all future rootstocks should be resistant to this virus, and scion resistance to stem pitting stains is desirable. To facilitate introgression of the CTV resistance gene from Poncirus trifoliata and development of CTV-resistant varieties in citrus, gene mapping projects have been initiated and more than a dozen RAPD markers have been identified with tight linkage to the resistance gene. As part of our efforts to use marker-assisted selection with a large number of crosses, and ultimately to accomplish map-based cloning of the CTV resistance gene, we have been converting the most tightly linked RAPD markers into SCAR (sequence characterized amplified region) markers by cloning, sequencing the marker fragments, and designing locus-specific primers. One codominant and several dominant SCARs have been developed thus far. The updated progress and utilization of these SCARs in marker-assisted selection and possibly in characterization of a BAC library will be presented and discussed.
Calcium and Fruit Firmness in Highbush Blueberry: Natural Gradients and the Effect of Foliar Applications
Authors: Retamales Jorge B. , Accedondo Cerardo A.
Published: February 2019

Calcium gradients were established in firm (`Bluecrop' and `Blueray') and soft (`Ivanhoe') highbush blueberry (Vaccinium corymbosum L.) fruits from a 7-year-old planting at La Union, southern Chile. Manual firmness measurements established that `Ivanhoe' fruit was softer than either `Bluecrop' or `Blueray'. In all varieties, Ca concentrations were: seed > pulp > epidermis; opposite trends were found for K+Mg/Ca ratios. Seed number and Ca concentration in the pulp were negatively correlated in `Bluecrop' and `Ivanhoe', but not in `Blueray'. In a related experiment, the response of `Bluecrop' to preharvest sprays of two calcium sources (chloride and nitrate) in four doses (0, 47.5, 35, or 190 g Ca/100 liters of water) was studied; dose and source interactions were not significant. Both calcium sources affected fruit Ca concentrations similarly;l calcium applications, either as nitrate or chloride, increased Ca significantly in epidermis and seed; the highest dose was required to raise significantly Ca concentrations in the pulp. K+Mg/Ca ratios in nitrate- or chloride-treated fruit were: pulp > seed > epidermis.
Phosphorus Forms for Cranberry Production
Authors: DeMoranville Carolyn
Published: February 2019

Commercial cranberry (Vaccinium macrocarpon Ait.) soils are high in iron and calcium and have low pH. This soil chemistry causes conditions where phosphorus is tightly bound and is, to a large extent, unavailable to the cranberry plants. In theory, P forms that directly enter the plant (foliar), or that do not quickly dissolve to become rapidly immobilized (organic, slow-release, other insoluble forms) could be more efficient for cranberry production. To test this hypothesis, two separate sets of field plots, one comparing 19 kg P/ha from sole P sources (all received 22 kg·ha–1 each N and K2O as ammonium sulfate and potassium sulfate) and the other comparing “complete” N–P–K fertilizers containing P, were established at six locations on three cranberry cultivars. Experiment #1 showed that, over all locations, there were no differences in mean yield for plots fertilized with triple super phosphate (current practice), foliar, or rock phosphate. However, fruit rot levels differed by treatment. In Experiment #2, organic forms (except bone meal) gave the lowest yields, while rock phosphate plots had the greatest yields. These field studies indicated that, while some organic P sources may not be suitable for cranberry production, low-leaching P forms such as bone meal and rock phosphate were as effective for cranberry production as the more-soluble triple super phosphate.
Yield and Growth Responses of Asparagus to Between-row Spacing and Planting Depth
Authors: Loughton Arthur , Baker Randy , Allen O. Brian
Published: February 2019

Five between-row spacings of asparagus ranging from 60 to 120 cm were combined with five planting depths ranging from 15 to 30 cm, in a central composite rotatable design. After seven harvest seasons, the accumulated yields (kg·ha–1) declined linearly by 108 (+18) kg·ha–1 for each increase of 1 cm of depth. Accumulated yield also declined linearly by 6.6 (+4.5) kg·ha–1 with each increase of 1 cm in row width. Depth and row width did not interact. Effects of treatment on average spear weight were negligible. When the experiment was terminated, the final depth of all crowns, regardless of original planting depth, had floated to about 11.3 cm.
Development of Diagnostic Nutrient Sufficiency Criteria (Homeostatic Level) from High-yielding Wheat and Potato Plants
Authors: Berry W.L. , Matar A. , Mackowiak C.L. , Stutte G.W. , Wheeler R.M. , Sager J.C.
Published: February 2019

Elemental analysis of tissue is very useful in determining when plants are nutrient-stresses, but has less diagnostic value when concentrations are within the poorly defined sufficiency range. It has been postulated that, within the sufficiency range, there is a homeostatic, or equilibrium, level for each element. As a first approximation, we utilized the nutrient profiles of non-nutrient-limited, high-yielding wheat and potato crops during the vegetative growth phase. Plants were grown hydroponically (NFT) in NASA's Biomass Production Chamber (20 m2) using a complete nutrient solution with the electrical conductivity maintained at 0.12 S·m–1. These profiles were compared to critical deficiency levels found in the literature for both field- and controlled environment-grown plants. The homeostatic concentrations for the various nutrients were found to be 3 to 8 times that of their respective deficiency critical levels, suggesting that nutrient status can be defined even within the sufficiency range.
Ripening Physiology and Storability of Saskatoon Fruit
Authors: Rogiers S.Y. , Knowles N.R.
Published: February 2019

Saskatoon (Amleanchier alnifolia Nutt.) fruit were stored into nine maturity stages based on color and size. Fruit color ranged from green (stages 1–4) to pink (5 and 6) to red (7 and 8) to purple (9). Fruit diameter of `Smoky' increased linearly as maturity advanced from 1 to 9. Fresh weight increased by 46 mg/fruit for each stage between 1 and 6, and then increased by 141 mg/fruit for each stage between 7 and 9. Firmness declined linearly from maturity 1 to 5, then remained relatively constant through maturity 9. The ability of fruit of maturities 3, 5, and 7 to ripen after harvest was assessed over 6 days (23C). Color measurements of maturities 3 and 5 indicated a change from green to pink, but no further change to purple. Color of maturity 7 changed to equal that of fully ripe (purple) maturity 9 fruit. After 6 days, fruit firmness of maturities 5 and 7 was equal that of freshly harvested maturity 9 fruit; however, maturity 3 fruit were incapable of softening to the same degree as fully ripe fruit. While fruit harvested at stage 7 appear to ripen normally, a significant lower fruit fresh weight precludes harvesting at this stage. Internal C2H4 concentration of fruit, and production by fruit in an open air-flow system, were monitored for `Northline', maturities 1–9. Internal C2H4 concentration of maturity 6 fruit was about 8-fold higher than that of maturity 4 fruit. Moreover, C2H4 production rate of maturity 5 fruit increased 3-fold from 10 to 25 h after harvest and then fell, reached the initial rate by 45 h after harvest. The respiration of these fruits also increased (by ≈70%) from 15 to 30 h after harvest, and then declined. Fruit color had changed from mostly green to red by 45 h after harvest. Collectively, these results indicate that saskatoon fruit exhibit a climacteric ripening patter. Results on the efficacy of controlled-atmosphere and hypobaric storage to delay physiological and pathological deterioration of saskatoon fruits will be presented.
Ethylene Evolution, Respiration, and Mold Development Studies in Some Selected Rubus Genotypes
Authors: Cummaragunta J. , Schlimme D.V. , Walsh C.S. , Swartz H.J. , Watada A.E.
Published: February 2019

In 1993, we studied the postharvest behavior of 25 Rubus genotypes. Included in the study were named cultivars from Europe and North America, advanced selections from the Univ. of Maryland Cooperative Breeding Program, species and raspberry interspecific hybrids, with R. phenicolasius, R. pungens oldhamii R sumatranus, and R parvifolius. Wide variation exists in the ethylene production rates of these genotypes. The difference between the lowest ethylene producer, R. phenicolasius, and the highest ethylene evolver, HTCC-6t (R. lasiostylus), was four orders of magnitude. Ethylene evolution rate and percentage mold were not correlated. Ethylene production and respiration rates were also measured using a flowthrough system. No single pattern was characteristic of all genotypes. Red raspberries were the highest ethylene producers and showed an ethylene and respiratory climacteric. Blackberries were low ethylene producers. Interspecific hybrids showed varied postharvest behaviors. The behavior observed in these interspecific hybrids may explain some of the conflicting reports on the postharvest behavior of blackberries and raspberries. In general heattolerant species such as blackberry, R. occidentalis, R. parvifolius exhibited lower rates of respiration and ethylene evolution than species from cool, temperate areas like R. idaeus.
Optimum Soluble and Slow-release N Rates for Rhododendrons and the Fate of Such N Applied to Various Potting Media
Authors: Rathier Thomas M.
Published: February 2019

Two year-long, factorial experiments were conducted on Rhododendron catawbienses (cv. Roseum elegans) grown in 2.3-liter plastic pots. I) Annual N rates of 0, 0.4, 0.8, 1.6, and 3.2 g/pot were applied as NH4NO3 (SBL) or sulfur-coated urea (SR) to plants potted in a composted hardwood bark (CHB)/peatmoss (P)/sand (S) medium. Plant growth and quality was best at 0.8 g N/pot for SBL and 1.6 and 3.2 g N/pot for SR. II) Annual N rates of 0.8 (SBL) and 2.4 (SR) g/pot were chosen as optimum rates and applied to plants potted in the following media: pine bark (PB)/P/S; CHB/P/S; P/S; and PB/CHB/P/S. Plant growth and N uptake was best in PB/PS. Plant quality was best in P/S. NO3 in leachate did not differ among media, but was greater in SBL. Total N immobilized in media was greater in PB/CHB/P/S. N recovered from SR-treated pots as unused fertilizer did not differ among media. Total applied N recovered was 90% for SBL and 51% for SR.
Isozyme Variation in Lychee (Litchi chinensis Sonn.)
Authors: Zee F. , Aradhya K.M. , Manshardt R.M.
Published: February 2019

A genetic diversity analysis involving 49 Iychee (Litchi chinensis Sonn.) accessions using eight enzyme systems encoding 12 loci (Idh-1, Idh-2, Mdh-2, Per-1, Pgi-2, Pgm-1, Pgm-2, Skdh, Tpi-1, Tpi-2, Ugpp-1, and Ugpp-2) revealed moderate to high levels of genetic variability. Cluster analysis of the isozyme data from 40 genetically different accessions of the total 49 identified three groups at the 50% level of genetic similarity, the largest of which contained 32 of the 40 accessions distributed in three sub-groups. The groups including the three subgroups differed in frequency and composition of alleles at different loci. Polymorphism was observed in 77% of the loci, with an overall mean of 2.2 alleles per locus and an observed heterozygosity of 0.387. The unbiased genetic identities (I) between groups ranged from 0.809 to 0.937. Summing over all 11 polymorphic loci, 16% of gene diversity was due to differentiation between groups and 84% within groups. Comparison of isozyme fingerprints revealed that some accessions with identical names, particularly of `No mai tsz', `Kwai mi', and `Hak ip', possessed different isozyme genotypes, while other accessions with different names displayed identical isozyme genotypes. Isozyme fingerprinting will be useful in revealing and resolving questions of clonal identity, which are common in Iychee germplasm collections.
Genetic Structure of Pejibaye Heart of Palm Yield Precocity at an Ideal Site in Hawai'i
Authors: Clement C.R. , Manshardt R.M.
Published: February 2019

The pejibaye (Bactris gasipaes Kunth) is being evaluated in Hawai'i for its fresh heart of palm, a gourmet vegetable. Seven half-sib progenies of the Putumayo land race were planted in a split-plot design, with densities (3333, 5000, 6666 plants/ha) as the main plots, progenies as the sub-plots, three replications, and nine plants/plot. Precocity was defined as “days from planting to harvest”; relative growth rate (RGR) and unit leaf rate (Ea) are possible causes of precocity and were estimated for the period from 6 months after planting to harvest. Density effects were never significant, suggesting that competition is not significant before harvest. Mean precocity ranged from 610 to 712 days; Va accounted for 14% of the phenotypic variance (Vp), with h2 = 0.57, similar to fruiting precocity in African oil palm (Elaeis guineensis Jacq.). Mean Ea ranged from 1.89 to 2.21 g/m2 per day, Va accounted for 8% of Vp, with h2 = 0.33 Mean RGR ranged from 0.0086 to 0.0102 d–1; Va accounted for 9% of Vp, with h2 = 0 35 Neither RGR (r = 0.20) nor Ea (r = 0.19) are significantly correlated with precocity. Heart, edible stem, and total edible product weights did not present significant progeny effects, probably because of the criterion used to determine harvest (height = 1.3 m). Precocity is easiest to work with and should give acceptable genetic gains.
Direct Turgor Measurements in Cells of Cherry and Other Fruit and Vegetable Tissues, and Its Relation to Tissue Physical Properties
Authors: Shackel Kenneth A. , Ahmadi H. , Greve C. , Labavitch J. , Verstreken Liesbeth , Chen Paul , Thompson Jim
Published: February 2019

The pressure microprobe has been used to measure cell turgor and, in addition, to sample vacuolar tissues. In carrot, a rapid initial loss of tissue firmness (instron technique) occurred when the tissue was heater (cooked), and this could be entirely attributed to a loss in cell turgor. Turgor was well-correlated to firmness over the range of turgor measurements (0–0.8 MPa). In cherry and other fruits, turgor is typically 1 to 2 orders of magnitude lower than that expected based on cell osmotic potential, indicating the presence of apoplastic solutes. Cherry fruit firmness and cell turgor were well-correlated during the first 2 h of hydration at 20C, but, as fruit began to crack, tissue decreased, whereas turgor continued to increase.
Effect of Site Preparation on Seeding of Wildflower or Prairie Mixtures in Ontario
Authors: Cain Nancy P.
Published: February 2019

The effect of site preparation on the establishment of a perennial wildflower and a prairie mixture was compared on five highway rights-of-way in southwestern, central, and northern Ontario. The site preparation treatments of the existing perennial cover were: 1) control, 2) broadcast glyphosate herbicide application, or 3) broadcast glyphosate herbicide application plus cultivation. The sites were mown prior to drill seeding. The experiments were planted in 1990 and 1992 and evaluated for total cover, cover of seeded species, and noxious weeds. The wildflower mixture established more rapidly than the prairie mixture. The wildflower seed mixture established better with either site preparation treatment compared to the control regardless of the type of vegetation present prior to planting. By 3 years after treatment the original vegetation had reinvaded to a greater degree with the herbicide treatment, indicating that the herbicide plus cultivation provided better control of the original perennial cover. Four years after seeding, neither seed mixture had established in the control, indicating that control of perennial vegetation was crucial for establishment of these seed mixtures on existing sites.