bluuebunny/crossref_metadata_2025 huggingface dataset:
490 Toward Conserving a Threatened Orchid (Platanthera praeclara)
Authors: From Margaret , Read Paul E.
Published: February 2019

Platanthera praeclara, commonly called western prairie fringed orchid, is a showy forb native to seven states and one Canadian province. The species had resisted previous attempts at propagation. Small, isolated populations in the sandhills region of western Nebraska are disjunct and visitation by natural pollen vectors appears to be in decline. Modern cultivation practices and other habitat encroachment factors, including urban development, recreational activities, and natural fluctuations in seasonal water availability all have the potential to exert pressure on current populations. Federal and state permits have allowed a limited hand-pollination study to be conducted on federal land. Hand-pollinated plants showed a greater fruit production compared to control plants receiving no human pollination assistance. Germination studies were conducted using aseptic in vitro techniques. The microscopic seeds possess testa that are extremely hard and resistant to liquid absorption, which presents challenges to germination in vitro. These challenges will be discussed. Alternating cold treatments with room temperatures appeared necessary to promote protocorm development after germination. Three media tested produced varying germination responses. Juvenile plants produced through micropropagation can offer propagules for possible future reintroduction efforts of this protected species.
492 Storage of Abelia R. Br. Pollen
Authors: Scheiber S.M. , Robacker C.D. , Dirr M.A.
Published: February 2019

The genus Abelia contains ≈30 species, but A. × grandiflora, its cultivars, and A. `Edward Goucher' are the primary taxa grown. The nursery industry has stated that Abelia R. Br. taxa are important economically, and new selections or cultivars with increased cold hardiness, richer pink-rose flower colors, unique foliage colors, and compact habits are desired. Breeding and selection work in the genus is very limited due in part to limited access to germplasm. Pollen storage enables breeders to cross taxa with incongruent flowering cycles, save time and resources by eliminating the need to grow vast amounts of plant material, and incorporate otherwise unavailable germplasm into a breeding program. An experiment was conducted to determine the optimum levels of temperature and humidity for the long-term storage of A. chinensis and A. × grandiflora `Golden Glow' pollen. Temperature and humidity levels were analyzed by incubating undesiccated pollen of a given taxon at four humidity levels (0%, 50%, 80%, and 100%) for 72 h at 5 °C. Following incubation, the pollen was stored in glass vials at each of the following temperatures: 5, -20, and -70 °C. All combinations of temperature and humidity were tested. Pollen viability was assessed after 60 days by in vivo germination tests on styles. Abelia chinensis pollen germinated following storage at all temperature and humidity levels. Pollen of A. × grandiflora `Golden Glow' pollen germinated following all treatments except storage at -20 °C.
498 School Gardens: Do They Affect Children's Food Preferences and Eating Behaviors?
Authors: Lineberger Sarah , Zajicek J.M.
Published: February 2019

Nutrition plays an important role in the life of a child because of the impact it has on growth, development, and the ability to learn. One part of proper nutrition is consumption of five fruits and vegetables a day. Currently, children eat an average of 2.5 fruits and vegetables a day, which is only half of the recommended servings. Education is needed to help increase consumption. School gardens are one education tool that can provide active hands-on activities in supportive environments. Through gardening, children learn not only what they should eat but also obtain a greater appreciation for how their food is grown. The main goals of this study were to provide teachers with a guide book for teaching nutrition through horticulture activities and school gardens and to test the effect of gardening on food preferences and eating behaviors of children. A curriculum guide, “Nutrition in the Garden”, was developed for teachers to use with their garden containing background information in horticulture and nutrition. Each lesson includes three to four related activities that can be completed with a garden or in the classroom. A pretest/posttest instrument developed by Tom Baranowski, Professor of Behavioral Science, Univ. of Texas MD Anderson Cancer Center, was used to determine students' attitudes toward fruits and vegetables. A 24-hour recall food journal was used to determine eating behaviors. Results examine the effects of school gardens on nutritional attitudes and behaviors.
508 Ascorbic Acid Content in Tomato and Bell Pepper Fruit during Development, Maturation, and Senescence on the Plant and Relation with Ascorbate Oxidase and Polyamines
Authors: Yahia E.M. , Contreras-Padilla M. , Gonzalez-Aguilar G.
Published: February 2019

Plants were grown in a greenhouse in controlled hydroponic conditions, and fruit were harvested at different intervals from 18 to 94 days from fruit set (DFFS). AsA was higher in pepper than in tomato fruit. In pepper fruit, it increased very fast and reached a maximum at 50 DFFS and then decreased suddenly and reached a minimum about 60 DFFS. AsA in tomato fruit increased slowly and reached a maximum after about 75 DFFS and then declined slowly. The decrease in AsA is correlated with the initiation of ripening and with an increase in the activity of AAO. There was more putrescine in pepper than in tomato fruit. There were no major changes in spermine and spermidine in pepper and spermidine in tomato fruit. However, putrescine in pepper fruit and spermine in tomato fruit increased very early until about 30 to 38 DFFS and then decreased in a manner similar to the decrease in AsA. Putrescine in tomato fruit increased consistently and did not decrease even during the senescence of the fruit. We conclude that AsA decreases in tomato and pepper fruit after 75 and 50 DFFS, respectively, and this decrease is related to an increase in AAO and a decrease in putrescine in pepper and spermine in tomato fruit.
509 A Glycine-rich Protein from Tomato Involved in Pollen Wall Formation
Authors: Smith Alan G. , McNeil Kenneth J.
Published: February 2019

The sporophytic tissue of the anther and, in particular, the tapetum, a cell layer surrounding the pollen sac, is know to be essential for the production of pollen. The isolation and characterization of the gene 92B from tomato that encodes an extracellular glycine rich protein (GRP) has been used to further elucidate the role of the tapetum in pollen development. RNA from the 92B gene accumulates exclusively in the tapetum. Polyclonal antibodies raised against the 92B GRP detect four proteins in stamens with microspores beginning meiosis. In pollen extracts, the antibodies detect a single protein. Expression of the tomato 92B gene in transgenic tobacco indicates that the four protein products are derived from only the 92B gene. The 92B GRP is localized to the tapetum, the callose wall of microspore mother cells, the exine (outer wall) of mature pollen, and orbicules. Orbicules are globular bodies derived from tapetal material that form on the tapetum wall and line the exterior of the pollen sac. Expression of 92B antisense RNA resulted in a significant decrease of 92B RNA and protein levels in transgenic tomatoes. This reduction was correlated with a decrease in pollen germination and an abnormal exine morphology. The function of the 92B protein in pollen development and function will be discussed.
512 Copia-like Retrotransposon Sequences in the Ipomoea batatas Genome
Authors: Villordon Arthur , La Bonte Don , Jarret Robert
Published: February 2019

The presence of copia-like retrotransposon sequences in sweetpotato [Ipomoea batatas (L.) Lam.] was investigated. PCR-based amplification using primers to highly conserved copia-like reverse transcriptase sequences produced several products corresponding to the expected target size (≈300 bp) that were subsequently isolated and cloned. A random sample of the clones were sequenced and all six reading frames were translated into their corresponding amino acid sequences. Sequence analysis revealed the presence of 22 copia-like reverse transcriptase sequences corresponding to various subfamilies. The presence of several sequence families in the genome is indicative of past or recent transposition activity. Southern blot analysis suggested that these copia-like sequences were present in several hundred copies in the sweetpotato genome. Data also showed retrotransposon insertion polymorphisms between a limited sample of virus-tested and virus-infected sweetpotato clones, indicating putative activity and mobility. This investigation documented the presence of copia-like retrotransposon sequences in the sweetpotato genome. This is an important step in clarifying the possible association between mobile genetic elements and the unusually high incidence of somatic mutations that may result in clonal decline in sweetpotato and other asexually propagated crops. Data presented provides information on the possible use of retrotransposons as genetic markers for sweetpotato crop improvement.
522 Study on the Effect of GA4+7, GA3, and Dimethoate on Russeting of `Golden Delicious' Apple
Authors: Talaie A. , Mojtahed J.
Published: February 2019

Skin russet in apple fruit, which causes a considerable decrease in marketing and exporting potentials, is one of the major problems in the word fruit markets. In this project, the effect of GA4+7, GA3, and dimethoate on russeting of `Golden Delicious' apple was examined. A complete randomized-block design with 13 treatments and four replications was used. In all treatments, the trees had the same size and medium growth and were homogeneous. The distances between trees were 6 x 6 m and the age was 18 years. The total number of trees, including controls, was 52. The 12 treatments were GA4+7 and GA3 with 10 ppm and 20 ppm concentrations in one and two times of spray in petal fall (PF) and PF + 10 days. Dimethoate at a concentration of 0.03% and 0.05% in one and two times of spray in PF and PF + 10 days. Fruit russeting was reduced in all treatments except with GA3. The largest decrease of russeting was caused by GA4+7, especially with 20 ppm and also dimethoate with a significant decrease in russeting. Seed number also decreased significantly with GA4+7 and GA3, but dimethoate had no significant effect on TSS, while ACD ratio was decreased significantly by GA4+7 and dimethoate, but GA3 had no significant effect. Compared with the control, the treatment did not show differences with the other characteristics.
527 A Highly Efficient in Vitro Cranberry Regeneration System using Leaf Explants
Authors: Qu Luping , Polashock James , Vorsa Nicholi
Published: February 2019

We have established a very efficient cranberry regeneration (shoot organogenesis) system from leaf explants using a basal medium consisting of Anderson's salts and Murashige and Skoog (MS) organics supplemented with 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea (TDZ) and N6-(-??-dimethyallylamino) purine) (2ip). Characteristics examined include combinations of varying levels of three plant growth regulators (TDZ, 2ip, and naphthaleneacetic acid (NAA), explant orientation (adaxial or abaxial side in contact with the media), and leaf position relative to the distal end of the shoot. Genotypes (`Early Black', `Pilgrim', `Stevens', `Ben Lear', and US#35) differed significantly in regeneration capacity, and there were no genotype by treatment interaction effects. Regeneration occurred on more than 95% of the explants with `Early Black' and `Pilgrim' producing as many as 100 shoot tips per explant with one particular treatment. Emerging adventitious shoots were always observed on the adaxial side of the leaves regardless of explant orientation. However, regeneration was much greater when the adaxial side was in contact with the media. Regeneration efficiency was not significantly affected by leaf position (10 leaves). Elongation of shoot tips began about 2 weeks after the regenerating explants were transferred to the basal medium without hormones and continued for several months. Elongated shoot cuttings rooted readily.
529 Relationship of Soil Temperature, pH, and Organic Carbon Content to Nitrogen Release in Cranberry Soils
Authors: Davenport Joan R. , DeMoranville Carolyn
Published: February 2019

Soluble nitrogen (ammonium and nitrate) is released when soil organic matter is mineralized. The amount of N released by this process depends on the amount of organic matter present and soil temperature. Cranberry (Vaccinium macrocarpon Ait.) grows in acidic soils with a wide range in organic matter content. To evaluate how soil N release is affected by soil temperature, intact soil cores were collected from sites that had received no fertilizer and placed in PVC columns. Four different soil types, representing the range of cranberry soils (sand, sanded organic soil, peat, and muck), were used. Each column was incubated sequentially at six different temperatures from 10 to 24 °C (2.8 °C temperature intervals) for 3 weeks at each temperature, with the soils leached twice weekly to determine the amount of N release. The total amount of N in leachate was highest in organic soils, intermediate in the sanded organic soil, and lowest in the sands. The degree of decomposition in the organic soils was important in determining which form of N predominated. In the more highly decomposed organic soil (muck), most of the N was converted to nitrate. The data from this study resulted in the development of two models—one predicting the N mineralization and the other predicting the proportion of N in each of the two forms. Key factors for N release rate were soil temperature, percentage of clay, and organic carbon content. For predicting the proportion of N as ammonium vs. nitrate, key factors were soil temperature, soil pH, and the distribution of mineral matter in the silt and sand fractions.
532 Lovastatin Inhibits α-Farnesene Synthesis without Affecting Ethylene Production during Fruit Ripening in Apples
Authors: Ju Zhiguo , Curry Eric A.
Published: February 2019

At harvest, internal ethylene was >0.5 mL·L–1 and α-farnesene concentrations were below detectable levels in `Golden Supreme', `Delicious', and `Granny Smith' apples. After 30 days of storage at 20 °C, control fruit produced high levels of internal ethylene and α-farnesene. Lovastatin at 100 to 1000 mL·L–1 did not affect ethylene synthesis, but significantly inhibited α-farnesene production. In `Golden Delicious', ethephon treatment increased ethylene synthesis in lovastatin-treated fruit but did not stimulate α-farnesene production. In lovastatin-treated fruit peel of `Delicious' and `Granny Smith', mevalonate (MAL) and farnesyl pyrophosphate (FPP) induced α-farnesene production, but hydroxymethylglutaric acid (HMG) did not. The induction of α-farnesene synthesis by MAL and FPP was concentration-dependent. Precursor feeding did not affect ethylene production in fruit peel. When high level of α-farnesene was detected in fruit peel (5 mm thick), it was not found in outer (adjacent to peel) and inner cortex (mid of flesh) tissues. Adding HMG, MAL, and FPP induced α-farnesene biosynthesis in both cortex tissues. When lovastatin was added to the feeding solution, MAL and FPP induced α-farnesene production but HMG did not.
535 The Potential Benefits of 1-Methylcyclopropene (1-MCP) for Regulating the Ripening and Extending the Storage Life of Avocados
Authors: Jeong Jiwon , Huber Donald J. , Sargent Steven A.
Published: February 2019

Ethylene is integrally involved in the ripening of climacteric fruit. The ability to prevent ethylene action, or manipulate fruit sensitivity to ethylene, would provide a powerful means of extending postharvest storage life of these fruit, particularly for those that ripen rapidly and/or that are not tolerant of low-temperature storage. In this study, 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action, was used to investigate ripening, respiration, and ethylene production in avocado fruit. `Monroe' avocados were treated with 1-MCP (Ethylbloc®) for 24 h at 20 °C. The fruit were subsequently stored at 13 or 20 °C. Some fruit were exposed to 100 ppm ethylene at 13 and 20 °C before or after MCP treatment. As evaluated by flesh firmness, respiration rate, and ethylene evolution, 1-MCP completely inhibited the ripening of avocado fruit stored at 13 and 20 °C and 85% relative humidity. Ethylene evolution and respiration rates were dramatically depressed, greater than 95% and 52%, respectively, by 1-MCP. Whereas firmness of control fruit decreased from over 100 N to 10 N in as few as 7 days, fruit treated with 1-MCP remained firm (>45 N) for periods of up to 3 weeks at 13 °C. Treatment of avocado fruit with 100 ppm ethylene at 20 °C for 12 h did not overcome the influence of MCP treatment. Similarly, treatment with ethylene before MCP exposure did not circumvent the effects of the cyclic olefin on ripening. Current studies are addressing the effects of MCP concentration and exposure time on avocado ripening.
539 Firmness of Blueberry Fruit Following Storage in Air or Controlled Atmospheres
Authors: Forney Charles F. , Nicholas Kumudini U.K.G. , Jordan Michael A.
Published: February 2019

Factors affecting the firmness of `Burlington', `Coville', and `Jersey' highbush blueberries (Vaccinium corymbosum L.) during storage in controlled atmospheres or air were characterized. Fruit were stored for up to 9 weeks in 6-ounce plastic clamshells at 0 or 3 °C. Fruit firmness was measured as grams per millimeter of fruit deformation using a FirmTech1 firmness tester (Bioworks, Stillwater, Okla.). Blueberry fruit held in sealed chambers in 0% CO2/15% O2 did not soften during storage. At 0 and 3 °C, fruit firmness of all cultivars increased an average of 30% after 9 weeks of storage. Changes in fruit firmness varied between cultivars and ranged from no change in `Coville' fruit held at 3 °C to an increase in firmness of 9 g·mm–1 per week in `Burlington' fruit held at 3 °C. CO2 inhibited the postharvest firming of blueberry fruit and at higher concentrations induced softening. At 0 °C, fruit firmness decreased below initial values when held in concentrations of CO2 >12% for `Burlington' and >10% for `Coville' and `Jersey'. At 3 °C, fruit were more tolerant to CO2 and softening occurred at CO2 concentration >17% for `Burlington', and >12% for `Coville' and `Jersey' fruit. CO2-induced softening was enhanced by increased storage time. CO2 also was effective in reducing fruit decay. After 9 weeks, 2% and 36% of fruit held in air at 0 and 3 °C, respectively, were decayed. However, all fruit held in 10 to 25% CO2 had <1% decay. Controlled atmospheres of 10% to 15% CO2 reduced decay while maintaining fruit firmness.
546 Quantifying the Dose Response of Several Basic Chemicals on pH of Soilless Media
Authors: Bishko A.J. , Fisher P.R.
Published: February 2019

Our objective was to systematically quantify the dose response from applications of several basic materials recommended for raising pH in acidic media. A peat (70%)/perlite (30%) medium was mixed with a pre-plant nutrient charge, a wetting agent, and 0, 0.3, 0.6, 0.9, 1.2, or 1.5 kg dolomitic hydrated lime/m3, resulting in a range in initial pH from 3.4 to 6.4. Five rates of flowable dolomitic limestone, five rates of potassium bicarbonate, two rates of potassium hydroxide, a supernatant of calcium hydroxide and a distilled water control were applied as single drenches. The medium was irrigated with distilled water when it dried to 50% container capacity as determined by weight. Media pH and EC of four replicates were tested at 1 day and 1, 2, 3, and 4 weeks after application as a saturated media extract. Flowable limestone and potassium bicarbonate both significantly raised medium pH by up to 2 units compared with the control, depending on concentration. As initial medium pH increased, the effect of the basic chemicals on medium pH decreased. For example, flowable lime applied at 0.5 L·100 L–1 of distilled water increased pH by 2 units at an initial medium pH of 3.4 and by 0.4 units at an initial pH of 6.4. Potassium hydroxide and calcium hydroxide drenches did not significantly raise pH. Potassium bicarbonate was easier to apply than the suspension of flowable limestone, however both chemicals provide practical methods for raising pH of soilless media.
549 Imidacloprid Applications for Whitefly Control on Poinsettia Using Ebb-and-flow Systems
Authors: van Iersel Marc , Oetting Ron
Published: February 2019

Ebb-and-flow systems can be used to apply systemic pesticides to greenhouse crops without worker exposure or runoff. However, there is little information on the efficacy of pesticides applied with ebb-and-flow systems. We are using silverleaf whitefly (Bemisia argentifolii) control on poinsettia (Euphorbia pulcherrima) with imidacloprid as a model system to study pesticide efficacy in ebb-and-flow systems. The objective of this study was to determine the effect of the amount of insecticide taken up by the pot on the efficacy of whitefly control. Different amounts of imidacloprid uptake were obtained by not watering the plants for 0, 1, 2, or 4 days before the imidacloprid application. The imidacloprid (132 g·L–1) was applied once when the roots of the cuttings had reached the side of the pots. These treatments were compared to an untreated control on ebb-and-flow and a standard drench application (100 mL) to hand-watered plants. Pots in the different subirrigation treatments absorbed 12 to 175 mL of imidacloprid solution. Four days after the application, leaf tissue of the hand-watered plants contained 8 to 20 times more imidacloprid than the subirrigated plants. Efficacy was determined from the percentage of surviving mature whiteflies after 2 days on the plants and by counting the number of immatures after 2 weeks. Surprisingly, imidacloprid efficacy was better in the subirrigated imidacloprid treatments than in the hand-watered treatment. Whitefly control in all subirrigated imidacloprid treatments was excellent, irrespective of the amount of imidacloprid solution taken up by the pots.
553 Nutrient Content of a Model System of Rapid-cycling Brassica oleracea Responds to Increasing Sodium Selenate
Authors: Kopsell Dean A. , Randle William M. , Mills Harry A.
Published: February 2019

Brassica species are important economic vegetable crop, and it is possible to enrich them with selenium (Se) to supplement human diets. The health benefits associated with increased Se consumption include cancer suppression, reduced heart disease, and immune system enhancement. Vegetables enriched with Se can serve as excellent delivery systems of organic Se forms, which are more beneficial than traditional Se supplements. The vegetable Brassicas are consumed not only for their flavor, but also for their nutritional content. A heterogeneous population of rapid-cycling B. oleracea was used as a model system to study the effects of added selenate-Se on other plant micro- and macronutrients. Plants were grown in nutrient solutions amended with sodium selenate at 0.0, 3.0, 6.0, and 9.0 mg·L–1. Leaf tissues were then analyzed for nutrient content. Boron (P = 0.001) and iron (P = 0.01) content decreased, while selenium (P = 0.001), sulfur (P = 0.001), and potassium (P = 0.001) increased with increasing selenate-Se. Significant quadratic responses were found for calcium (P = 0.02), copper (P = 0.05), magnesium (P = 0.01), and molybdenum (P = 0.01). No differences in leaf fresh or dry weight were detected. Changes in plant nutrient content can be expected when Brassicas are enhanced for delivery of beneficial organic Se.
554 Sequentially Eliminating Sulfate during Onion Growth Affects Its Flavor Characteristics
Authors: Randle William M. , Snyder Rachel
Published: February 2019

Mild onion consumption is increasing in the U.S. The ability to produce mild onions depends on selecting proper cultivars and growing them in an appropriate environment. A major decision in producing onions with mild flavor is determining when to stop applying sulfate to the crop. While adequate sulfur is necessary for good early onion growth, high levels of sulfur increase bulb pungency. A study was conducted where sulfate was eliminated from the fertility program at biweekly intervals during onion growth and development. Mature bulbs were then analyzed for flavor precursors and their biosynthetic intermediates, and pungency. Pungency linearly increased from 3.7 to 5.1 μmols pyruvic acid from the earliest cut-off date to the latest cut-off date, respectively. While total milligrams of flavor precursors did not significantly change in response to sulfate elimination, the methyl cysteine sulfoxide: 1-propenyl cysteine sulfoxide ratio did. Methyl cysteine sulfoxide concentration decreased in a quadratic manner while 1-propenyl cysteine sulfoxide linearly increased as sulfate fertility was extended in the growing season. Changes in individual precursors will significantly affect flavor perception as well as flavor intensity.
559 Isolation of an ETR1 Ethylene Receptor Homologue from Peach [Prunus persica (L.) Batsch]
Authors: Bassett Carole L. , Artlip Timothy S.
Published: February 2019

During the past several years, we have been interested in genes and gene-products involved in various aspects of ripening and maturation in peach (Prunus persica) fruit. The ethylene biosynthetic and signal transduction pathways are of particular interest due to the role of this hormone in such processes. Recently, we isolated a cDNA encoding a homologue of the ethylene receptor ETR1 from a near fully ripe (20–60N) peach fruit cDNA library. This cDNA clone, PpETR1, is nearly 2300 bp in length, with a 5' untranslated region of 268 bp, a 3' untranslated region of 150 bp, and an ORF of 1881 bp, encoding a protein of 70 kDa. The cDNA is most closely related to an ETR1 homologue from apple (Malus domestica), i.e., 95% identity at the amino acid level, but shows considerable similarity to Arabidopsis thaliana ETR1, as well. A comparison of the similarity among cloned ETR1 genes from a range of plant species will be presented.
564 The Influence of Preharvest Treatments with ReTain™ (An Ethylene Biosynthesis Inhibitor) on the Fruit Maturation and Quality of `Royal Gala' Apple in New Zealand
Authors: White M.D. , Tustin D.S. , Foote K.F. , Volz R.K. , Stokes J. , Campbell J. , Marshall R. , Howard C.
Published: February 2019

ReTain™ is a plant bioregulator containing the active ingredient aminoethoxyvinylglycine (AVG), which inhibits the ethylene biosynthesis pathway. In 1997, the first efficacy studies on `Royal Gala' apple with ReTain™ were conducted under New Zealand conditions in Hawkes Bay. ReTain™ was applied 4 weeks before the anticipated start of harvest on `Royal Gala' at 850 and 1700 g·ha–1 with or without adjuvants. ReTain™ application delayed the onset of `Royal Gala' fruit maturation between 1 and 2 weeks, resulting in enhanced fruit size and fruit flesh firmness at harvest. The optimum response for delaying the onset of fruit maturation was achieved using ReTain™ at 850 g·ha–1 if applied in combination with a wetter. Fruit were also graded for fruit quality and air-stored at 0.5 °C. Fruit after 10 weeks of storage showed no difference in fruit flesh firmness, but all ReTain™ treatments had fruit with less yellow background colour compared with untreated fruit. In 1998, efficacy studies were undertaken in three geographical locations on `Royal Gala'. ReTain™ was applied at a rate of 830 g·ha–1 in combination with Silwet L-77 at 0.1%. All trees with the exception of `Royal Gala' grown in the Hawkes Bay had not received any ReTain™ previously. In all regions, seasonal changes in background color and starch pattern index were delayed by ReTain™ treatment. A concurrent delay of an increase in soluble solids concentration and retention of higher flesh firmness were also induced by ReTain™ treatment.
566 Induction of Defenses Against Pathogens of Fruit and Vegetables by Elicitors
Authors: Reddy M.V. Bhaskara , Arul Joseph
Published: February 2019

Fruit and vegetables are highly perishable and postharvest pathogens are one of the major causes in the early termination of their shelf life. Although synthetic fungicide are effective against postharvest pathogens, they face imminent problems. One alternate approach is the induction of host resistance against postharvest diseases. We tested the efficacy of chitosan, Milsana®, and Bion® on carrot, tomato, potato, green pepper, and strawberries against postharvest fungal and bacterial rots. Chitosan was not only antimicrobial but also induced resistance against postharvest infections of Alternaria, Botrytis, and Erwinia in tomato, green pepper, carrot, and potato. Preharvest sprays of chitosan induced resistance against postharvest infection of Botrytis cinerea in strawberries and improved the storage quality. Ultrastructure and cytochemical investigations showed that chitosan not only induced several morphological alterations in B. cinerea and Alternaria alternata inhibiting the production of pathogenic factors by the fungi, but also stimulated various host defense reactions, such as papilla formation and induction of defense enzymes, phytoalexins, and phenols. Application of Milsana®, a plant extract, and Bion®, an activator of host defenses, protected carrots from postharvest decay by B. cinerea. Milsana® was effective at 4 °C, while Bion® was effective at both 4 and 13 °C storage temperatures. Thus, there is great potential for defense inducers in postharvest disease control of fruit and vegetables.
567 Effects of Mancozeb, NOVA, GA, and Yeast-like Fungi on Stylar-end Russeting of Navel Orange
Authors: Stover E.W. , Myers M. , Sonoda R.M. , Guo Z.
Published: February 2019

Stylar-end russetting (SER) is a cosmetic defect of Florida citrus fruit most frequently associated with navel orange. SER is evident as spots or streaks of corky tissue that often form a network of intersecting lines. Occurrence of SER is reported to vary widely from year to year, but some orchards have a history of severe SER, with fruit culled annually for this defect. Growers report that SER is typically first evident in August. The cause of SER has not been determined. Reports of yeast-like fungi inducing russet in pome fruit suggest that similar organisms may be implicated in SER. Yeast-like fungi were isolated on acid PDA from navel oranges in an orchard with frequent severe SER. Strains were selected with a wide range of colony morphology, but were not identified taxonomically. These strains, and strains of Aureobasidium pullulans and Rhodotorula glutinis that caused russetting in pome fruit, were grown in liquid suspension and sprayed on navel orange trees with three repeated applications during July and Aug. 1998. No increase in SER was observed on strain-inoculated trees compared to controls. Two broad-spectrum fungicides were sprayed on other navel orange trees to further explore the possibility that fungi may be involved in SER. GA (gibberellic acid) was also applied in this experiment because it can reduce russetting in apples. All applications were made five times at 3-week intervals in June through Sept 1998. SER was assessed in fruit harvested late Sept. 1998. The proportion of fruit with less than 10% of the surface exhibiting SER was 51% for controls, increased to 69% where myclobutanil was applied at 74 mg a.i./L and increased further to 93% where manganese ethylenebisdithiocarbamate was applied at 1775 mg a.i./L. GA did not significantly influence SER.
572 Cold Hardiness of Summer and Fall Flowering Evergreen Azalea Hybrids
Authors: Lindstrom Orville M. , Florkowska Malgorzata A.
Published: February 2019

To date, few summer and fall flowering azaleas exist. Recently, Rhododendron oldhamii, a summer-flowering species, was hybridized with several commercial hybrids. These crosses produced various sizes and colors of flowers that bloom throughout the summer until frost, and again in the spring. However, the cold hardiness level of these azaleas is unknown. Therefore, we evaluated their cold hardiness during several months of the fall and winter. Laboratory cold hardiness tests revealed that there was a range of cold hardiness levels among the new hybrids. `Fashion' and hybrids 02003 and 4003 tended to acclimate earlier than the others, maintain a good level of midwinter cold hardiness, and retain their hardiness into the early spring. Hybrid 15001 acclimated early and had good midwinter cold hardiness, but lost its cold hardiness in the late winter, while 04003 and 09004 acclimated late in the fall and did not attain a high level of cold hardiness in the winter. `Lee's Select' and hybrid 08002 seemed to fall between the groups previously mentioned showing intermediate cold hardiness throughout the winter season. The laboratory cold hardiness results were similar with field observations.
573 Seed Vigor Testing for Small-seeded Flower Species using Computer-aided Image Analysis
Authors: Oakley Kay , Geneve Robert , Kester Sharon , Wonprasaid Patchara
Published: February 2019

Standardized seed vigor tests must be developed for greenhouse-grown flower species. Current vigor tests used to evaluate large-seeded agronomic crops are generally not useful for evaluating smaller-seeded flower species. One alternative is to use radicle length in seedlings grown under controlled environments as an indicator of seed vigor. For that purpose, a seed vigor test was developed that uses digital images taken using a flat bed scanner to measure radicle length in small-seeded flower species. A novel, cellulose substrate was used for germinating seeds. It provided similar moisture-holding properties to standard germination blotters used by commercial seed analysts, but is clear. This has allowed for quick image acquisition without removing seedlings from the petri dish. Correlations were made between seedling growth (radicle length, total seedling length, and total seedling area) with other vigor tests (saturated salts accelerated aging) and greenhouse plug flat emergence. For several seed lots of impatiens that varied in initial seed quality, radicle length after 4 days showed good correlations (>R2 = 0.79) with other measures of seed vigor for describing seed quality. This system is an improvement over other attempts to use computer-aided assessment of digital images because it provides digital images that do not vary due to external lighting; it uses software that can evaluate radicle length in a petri dish assay that does not require a slant-board for straight radicle growth; it relies on standard germination technics used by every seed lab; it uses a clear substrate to replace the opaque blotter to allow digital images to be taken within the petri dish; and accurate measurements of seedling parts is performed in under 2 min per petri dish.
575 Greenhouse Specialty Cut Flower Production Using Bedding Plant Flats
Authors: Dole John M.
Published: February 2019

Three cut-flower species, Ageratum houstonianum `Tall Blue Horizon', Antirrhinum majus `Spring Giants Mix', and Helianthus annuus `Sunrich Orange' were grown in 806, 1801, or 1001 bedding plants flats resulting in 32 (85), 86 (280), and 156 (620) cm2 (mililiter medium)/plant, respectively. Plants were sown Sept. 1997 (fall), Dec. 1997 (winter), or Mar. 1998 (spring). Increasing area per plant decreased number of stems harvested but increased percent of stems harvested for all species. Increasing area per plant increased stem length and selling price for Antirrhinum and Helianthus; no significant difference was noted for Ageratum. Days to anthesis decreased with later planting for Antirrhinum and Helianthus; however, for Ageratum winter planting had the longest crop time and spring planting the shortest. Gross profit per square meter and square meter per week increased with decreasing area per plant for Ageratum and Helianthus; no significant difference was noted for Ageratum. Gross profit per square meter per week increased with later planting for all species. With all species 806 flats or spring planting required frequent irrigation, which would best be supplied by an automated irrigation system. Experiment was repeated in 1998/1999 using Carthamus tinctorius `Lasting Yellow', Celosia argentea `Chief Mix', Cosmos bipinnatus `Early Wonder', Helianthus annuus `Sunbright, Tagetes erecta `Promise Orange' and `Promise Yellow', and Zinnia elegans `Giant Deep Red' and `Oklahoma Mix'.
576 Strawberry Yields of Normal vs. “J” Root Plants
Authors: Bendixen Warren E.
Published: February 2019

Many factors contribute to the reduction of strawberry yields. Field surveys in previous years have shown that the lack of plant vigor associated with poor crown and root systems was the result of “J” root plants. A 1998 strawberry trial was established on 7 Nov. 1997 to evaluate the fruit yield of “J” root plants in comparison with normal roots. A “J” root plant occurs when the workers place the crown at the soil surface, while the other hand then pushes the center of the root into the slotted area, leaving the lower roots near or above the ground surface. The workers used a trowel to plant the normal root plants, place the roots straight down. The variety Camarosa was planted on 64-inch-wide beds. Each plot was one bed wide and 30 feet long and replicated four times. The strawberry plants were spaced 14 inches apart within the rows and the rows 10 inches apart. Strawberry yields of normal vs. “J” root plants showed the “J” roots reduced yields more early in the season. The March, April, and May yields were harvested as fresh fruit. The normal plants yielded 33,653 lb/acre, compared to 28,411 lb/acre for the “J” roots. The June and July yields were harvested as freezer fruit. The yields for normal plants were 36,421 lb compared to 32,941 for “J” root plants. The season total yields were 70,074 lb/acre for the normal roots compared to 61,352 lb for the “J” roots, or a 14.2% yield reduction. In 1998, 10 commercial strawberry fields were surveyed to evaluate the number of “J” root plants. The results showed an average of 54% of the plants were “J” root plants, with the fields ranging from 25% to 77.5%.
581 Selection and Evaluation of Macadamia Nut (Macadamia integrifolia) Varieties and Hybrids in the Highlands of Kenya
Authors: Wasilwa L.A. , Ondabu N. , Watani G.W. , Mulli H. , Kiiru S. , Nyagah A. , Kagiri
Published: February 2019

Several outstanding macadamia trees (Macadamia integrifolia Maiden and Betche, M. tetraphylla L. S. or hybrid of these two species) were selected from orchards established in the 1960s in the central and eastern highlands and evaluated over a period of 10 years. In the thrid year of these evaluations, clones from 30 high-yielding trees (40 to 90 kg) were propagated by grafting and trials were established in the central and eastern highlands. Three to five Hawaiian varieties were included as controls. Each trial consisted of five to 10 trees of each clone. Trees were evaluated for vigor, flowering, age of bearing, and yield. From these tests, a subset of 10 of the most outstanding clones were selected and evaluated in 25 field trials located in the Kenyan highlands. Most these clones started to bear 3 years after transplanting. Three distinct flowering patterns have been observed. Ten years after transplanting, yields ranged between 30 to 60 kg nuts/tree. The macadamia hybrids and M. tetraphylla performed best at the higher elevations (1700–1850 m), M. integrifolia clones performed best at elevations of 1500 to 1750 m. Only two Hawaiian varieties performed well and have been used in the breeding program. Most of the cultivated macadamia trees in Kenya are either M. integrifolia or hybrids. Cultivation of M. tetraphylla in Kenya is no longer recommended.
583 Field performance of Grafted Chestnut Cultivars and their Seedlings
Authors: Byard Rachel , Merwin Ian A.
Published: February 2019

We planted grafted and seedling chestnuts of six cultivars in Lansing, N.Y., in April 1995 to evaluate performance of the different cultivars in our region and to compare grafted and seedling trees. We used the following cultivars: the Chinese chestnut cultivar Mossbarger (Castanea mollissima) and five interspecific hybrid cultivars [Douglas 1A (C. mollissima × C. dentata), Eaton [C. mollissima × (C. crenata × C. dentata)[, Skioka (C. mollissima × C. sativa), Layeroka (open-pollinated daughter of `Skioka'), and Grimo 142Q (an open pollinated daughter of `Layeroka')]. Growth was not significantly different between cultivars. There were no notable correlations between trunk cross-sectional area at planting and any measurement after the first year. Significant differences between cultivars were found for mortality, yield, and yield efficiency. `Eaton' had the lowest mortality rate (2%) of all cultivars. `Grimo 142Q' and `Layeroka' had the highest dry weight yields and the greatest yield efficiencies, although `Grimo 142Q' had significantly larger nuts than `Layeroka'. In 1998, the largest nuts (5.2 g) were harvested from `Mossbarger' and `Eaton trees'. `Skioka' had the highest mortality (48%), lowest yield, lowest yield efficiency, and smallest nut size. In the first 2 years, most grafted trees showed significantly higher yields and greater yield efficiency than seedling trees. By the third year, differences in yield between grafted and seedling trees were no longer significant for most cultivars. Over the 3 years most grafted trees revealed higher mortality and slower growth than seedlings of the same cultivar. Seedlings did not show more variability in measurements than grafted trees of the same cultivar.
588 Photosystem II Efficiency and CO2 Assimilation in Response to Light and CO2 in Leaves of Deciduous Tree Fruit
Authors: Cheng Lailiang , Fuchigami Leslie H. , Breen Patrick J.
Published: February 2019

Photosystem II (PSII) efficiency and CO2 assimilation in response to photon flux density (PFD) and intercellular CO2 concentration (Ci) were monitored simultaneously in leaves of apple, pear, apricot, and cherry with a combined system for measuring chlorophyll fluorescence and gas exchange. When photorespiration was minimized by low O2 (2%) and saturated CO2 (1300 ppm), a linear relationship was found between PSII efficiency and the quantum yield for CO2 assimilation with altering PFD, indicating CO2 assimilation in this case is closely linked to PSII activity. As PFD increased from 80 to 1900 μmol·m–2·s–1 under ambient CO2 (350 ppm) and O2 (21%) conditions, PSII efficiency decreased by increased nonphotochemical quenching and decreased concentration of open PSII reaction centers. The rate of linear electron transport showed a similar response to PFD as CO2 assimilation. As Ci increased from 50 to 1000 ppm under saturating PFD (1000 μmol·m–2·s–1) and ambient O2, PSII efficiency was increased initially by decreased nonphotochemical quenching and increased concentration of open PSII reaction centers and then leveled off with further a rise in Ci. CO2 assimilation reached a plateau at a higher Ci than PSII efficiency because increasing Ci diverted electron flow from O2 reduction to CO2 assimilation by depressing photorespiration. It is concluded that PSII efficiency is regulated by both nonphotochemical quenching and concentration of open PSII reaction centers in response to light and CO2 to meet the requirement for photosynthetic electron transport.
590 Growth and Physiological Characteristics of Diploid and Tetraploid Citrus Rootstock Seedlings Grown at Elevated CO2
Authors: Syvertsen J.P. , Grosser J.W , Lee L.S.
Published: February 2019

We grew three diploid (2X) Citrus rootstock seedlings and their autotetraploids (4X) at elevated CO2 to obtain insights into limitations on growth and net gas exchange that have been associated with tetraploidy. Well-nourished Volkamer lemon (Volk), Troyer citrange (Troy), and Cleopatra mandarin (Cleo) were grown in greenhouses at ambient or twice ambient CO2 for 3 months. We measured plant growth, water relations, mineral nutrition, and net gas exchange characteristics of leaves. Overall, tetraploid roots were thicker as 4X had lower root length: dry weight ratio or specific root length (SRL) than 2X roots. Tetraploid plants were smaller and had higher root/shoot ratios, shorter fibrous roots, and lower whole plant transpiration than 2X. Tetraploids also had lower leaf N and P concentrations on a dry weight basis. Since 4X leaves had thicker leaves (more dry weight per area) than 2X leaves, these nutrient differences disappeared when expressed on an leaf area basis. Elevated CO2 increased plant growth but decreased leaf N, P, and K apparently by a growth dilution effect. Elevated CO2 also increased fibrous root thickness, leaf thickness, and net assimilation of CO2 (ACO2) but decreased stomatal conductance and transpiration such that leaf water use efficiency increased. There was no effect of ploidy level on ACO2 but 4X Volk and Troy had lower rates of ACO2 than their diploids at elevated CO2. Hydraulic conductivity of intact root systems (measured in a pressure pot) was correlated to total plant growth but variability obscured effects of CO2 or ploidy on root conductivity. The low SRL of tetraploids were correlated with lower rates of water use and lower leaf nutrient concentrations, which may be operative in determining the growth characteristics associated with tetraploidy.
592 Use of Infrared Thermometry and Heat-pulse Technique for Detection of Water Stress in Apple Trees
Authors: Lombardini L. , Flore J.A.
Published: February 2019

The recent development of small portable infrared thermometers has made canopy temperature an easily measured characteristc in the field. Our objective was to correlate a reduction of soil water with foliage temperature and to compare it with other indicators of plant stress (Pn, E, gs, leaf expansion, sap flow). During Summer 1998, we evaluated the responses of potted apple rootstocks (cultivars Budagowski 9, M9, and Mark) to soil water deficit. Irrigation was withheld for 7 days, and the canopy temperature (Tc) was measured daily with an infrared camera. Tc was always higher than air temperature (Ta). Tc between control and stress plants began to differentiate from day 3. In Mark, this difference was maintained until the end of the experiment. However, gas exchange in Mark seemed to be less affected by the stress than in the other two cultivars. At day 7, midday stomatal conductance (gs) was 38.0, 32.3, and 72.0 mmol·m–2·s–1 in Budagowski 9, M9, and Mark, respectively (control values varied between 161.6 and 164.3 mmol·m–2·s–1 for all the cultivars). Heat-pulse sapflow sensors installed on Mark indicated that the speed of the xylem sap was affected by the stress from day 4 (19-26 cm/h for the controls vs. 15–21 cm/h for the stressed plants). Specific details on the physiological data will be presented.