bluuebunny/crossref_metadata_2025 huggingface dataset:
287 Total Biomass and Ion Accumulaton of Eucalyptus camaldulensis, Hybrid Populus, and Robinia pseudoacacia Irrigated with Saline Municipal Wastewater
Authors: Jessen Brenda L. , Picchioni Geno A. , Mexal John G.
Published: February 2019

A field study was conducted in 1997 and 1998 in Ojinaga, Chihuahua, Mexico, to compare biomass production potential and ion uptake capacity of seven tree species and clones, Eucalyptus camaldulensis (4016, 4019, and 505), hybrid Populus (029, 197, and 367), and seedlings of Robinia pseudoacacia irrigated with saline municipal wastewater. Total dry biomass production was greatest with poplar clone 367 (657 g) and eucalypt clone 4019 (643 g). Both clones also provided the most aboveground biomass (463 and 528 g, respectively), essentially because of their greater stem biomass (274 and 234 g, respectively). Poplar clone 367 had the highest lateral branch biomass (84 g), followed by eucalypt clone 4019 (75 g). The clones with the greatest leaf biomass were eucalypt clone 4019 (179 g), followed by eucalypt clone 505 (148 g) and poplar clone 367 (145 g). In all tree selections, Cl concentration was highest in the leaves with poplar clone 197 having the highest concentration (>2%), but the lowest subsequent winter survival at just 55%. The tree with the second lowest survival rate, poplar clone 029 (76%), also had the second highest Cl concentration in its leaves, almost 1.5% Cl. Eucalypt clones 4019 and 4016 accumulated the most total Cl in its tissues (327 and 236 g per tree, respectively) followed by poplar clone 029 (216 g per tree). Eucalypt clone 4019 accumulated the most Na in its tissues (109 g per tree) followed by poplar clone 367 (74 g per tree). In conclusion, poplar clone 367 and eucalypt clone 4019 seem to be sufficiently salt-tolerant for these saline conditions, having high survival, growth, and biomass capacity and perform well under high biomass-generating, short rotation conditions. Eucalypt clone 4019 is also an effective accumulator of Cl and Na ions and may be the most suitable tree for the remediation of salt-affected land in these experimental conditions.
302 Accel and Carbaryl Affect Apple Thinning
Authors: Ouma George , Matta Frank
Published: February 2019

Experiments were conducted in 1995 and 1996 to investigate the effect of Accel and Carbaryl on apple fruit on three apple cultivars (Empire, Jon-A-Red, and Braeburn) at the Mississippi State Univ. Aricultural Experiment Station, Pontotoc. The treatments consisted of Accel 25 ppm, Accel 50 ppm, Accel 75 ppm, Carbaryl 0.05%, Carbaryl 0.2%, and an unsprayed control. Trials conducted over 2 years showed that Accel and Carbaryl consistently reduced the fruit set of three apple cultivars. There were interactions between the bioregulators and cultivars only in 1996. In all the bioregulators, treatments reduced fruit set, while in 1996, Carbaryl and Accel at all concentrations except Accel 25 ppm reduced the fruit set of `Empire', `Jon-A-Red', and `Braeburn'. Carbary 0.2% and Accel 75 ppm were the most-effective concentrations in `Empire', `Jon-A-Red', and `Braeburn', respectively, in 1996. The treatments generally increased yield and sugar content, while pH was either not affected, increased or decreased, depending on the apple cultivar.
313 Iron-chelate Photodegradation in Lab-prepared Nutrient Solutions Alters Root Physiology and Causes Mn Toxicity in Marigold
Authors: Albano Joseph P. , Miller William B.
Published: February 2019

Our objective was to determine the effects on plant growth and physiology that a photodegraded Fe-chelate containing lab-prepared nutrient solution would have when used in plant culture. Plants grown hydroponically in the irradiated Fe-DTPA containing nutrient solution had ferric reductase activity 2.2 times greater, foliar Fe level 0.77 times less, and foliar Mn level 1.9 times greater than in plants grown in an identical but non-irradiated solution, indicating that plants growing in the irradiated solution were responding to Fe deficiency stress with physiological reactions associated with Fe efficiency. The youngest leaves of plants that were grown in the irradiated solution had symptoms of Mn toxicity. Restoration of the irradiated solution by removing the precipitated Fe by centrifugation and adding fresh Fe-chelate resulted in plants that were, in general, not different from those grown in the non-irradiated solution (control).
314 Effects of Mycorrhiza Fungi and Phosphorous on Growth and Nutrient Uptake of Micropropagated Prickly Pear Cactus Plantlets (Opuntia amyclaea Tenore cv. Reyna)
Authors: Estrada-Luna Andrès A. , Davies Fred T.
Published: February 2019

Micropropagated cactus pear plantlets (Opuntia amyclaea Tenore) cv. Reyna were colonized with a Mexican endomycorrhiza isolate, ZAC-19 (containing Glomus etunicatum and two unknown Glomus spp.) and fertilized with two phosphorous levels (0 and 11 μg P/ml) to study their effect on plant growth and nutrient uptake. After 7 months of greenhouse culture, there was 100% survival of the micropropagated cactus pear plants. Evidence of mycorrhizal colonization was observed 5 days after inoculation, with the development of internal hyphae in root cortices. At the end of the study, high colonization occurred (48% to 54%) with no differences in P treatments. Plantlets transferred to soil began to actively grow with no lag phase. However, plant growth rate was significantly affected by treatments. Absence of P supply and lack of colonization resulted in lower dry mass and surface area of prickly pear cactus plants. In contrast, the combination of supplementary P and mycorrhizal colonization significantly increased plant growth.
319 Flowering Phenology of Mamey Sapote [Calocarpum sapota (Jacq.) Merr.] in Florida
Authors: Davenport Thomas L. , O'Neal James T.
Published: February 2019

Flowering and fruit set characteristics were examined in the popular commercial cultivar Magaoa in an effort to elucidate the reproductive phenology of mamey sapote, Calocarpum sapota (Jacq.) Merr. [syn. Pouteria sapota (Jacq.) H.E. Moore and Stearn]. Flowers opened during the night with anthesis beginning around sunset. The length of floral opening varied according to season, ranging from 6 days in winter to a single day in summer. Bursts of new flowers generally appeared in cycles of about 7 days in declining numbers of flowers per burst until all the floral buds of a particular floral bud flush had flowered. Floral buds flowered randomly along a branch with only a few flowers open at any one time. Flower position around the branch was a factor in fruit set. Flowers and small fruitlets encircled horizontal branches in great numbers, but immature fruit most often developed from flowers located on the upper branch quadrant. The lower quadrant contained the fewest immature fruit. As fruit matured, however, more upper quadrant fruit abscised until by harvest, most mature fruit were found on the lower quadrant. The observations provide new insights into the reproductive phenology of mamey sapote.
662 Genetics and Physiology of Postharvest Cut Flower Longevity
Authors: Stimart Dennis P. , Schroeder Kenneth R.
Published: February 2019

Efforts to improve postharvest longevity of fresh-cut flowers has only recently turned toward selection and breeding. Conventional methods to extend keeping longevity of cut flowers depend on use of chemical treatment placed in holding solutions. Postharvest longevity studies were initiated with Antirrhinum majus L. (snapdragon) to determine: if natural genetic variation existed for cut-flower longevity, the inheritance of the trait, heritability, and associated physiology. Evaluation of commercial inbreds held in deionized water revealed a range in cut-flower longevity from a couple of days to 2.5 weeks. The shortest- and longestlived inbreds were used as parents in crosses to study the aforementioned areas of interest. Information will be presented on inheritance of cut flower longevity based on populations evaluated from matings for generation means analysis and inbred backcross method. Also presented will be information on stomata, transpiration, carbohydrate, fresh-weight change, and forcing temperature relative to postharvest longevity.
Sensory Profiles of Carrot (Daucus carota L.) Cultivars Grown in Georgia
Authors: Gills L.A. , Resurreccion A.V.A. , Hurst W.C. , Reynolds A.E. , Phatak S.C.
Published: February 2019

Descriptive analysis was used to compare sensory color, flavor, and textural attributes of Georgia-grown carrots. The relation between °Brix, total sugar, and intensity perception of sweetness was also studied. Significant differences existed in the perception of sweet taste and of color, and in levels of °Brix and percentage of sugar among all cultivars, but perceived intensity of sweetness was not related to the levels of °Brix or percentage of sugar. No significant differences were found among cultivars in harsh carroty, green, astringent, and earthy flavors, and in the perception of sour taste. Intensity ratings for perceived hardness were nonsignificant in either study. Differences in sensory profiles existed among all cultivars, but no trend was evident in the relation of sweetness to harsh flavor.
Fumigating `Crimson Seedless' Table Grapes with (E)-2-Hexenal Reduces Mold during Long-term Postharvest Storage
Authors: Archbold Douglas D. , Hamilton-Kemp Thomas R. , Clements Ann M. , Collins Randy W.
Published: February 2019

Seedless table grapes (Vitis vinifera L.) cv. Crimson Seedless were exposed to (E)-2-hexenal vapor during cold storage to determine its potential as a fumigant for long-term control of postharvest mold. Fruit were fumigated with 0.86 or 1.71 mmol (100 or 200 μL neat compound, respectively) (E)-2-hexenal per 1.1-L container for 2 weeks during 2 °C storage. Containers were moved to 20 °C storage after 4, 8, and 12 weeks for determination of mold incidence and berry quality over 12 days. The headspace concentration of (E)-2-hexenal, measured by gas chromatography, reached a maximum of 2.5 and 4.2 μmol·L–1 for 0.86 and 1.71 mmol per container, respectively, after 1 day and declined to <1 μmol·L–1 for both treatments by 14 days. Upon removal from cold storage at 4, 8, and 12 weeks, the incidence of mold was significantly lower for (E)-2-hexenal–treated fruit. Control of mold by (E)-2-hexenal fumigation persisted through 12 days of 20 °C storage, even though mold generally increased in all treatments. The two levels of (E)-2-hexenal were similar in their suppression of mold. Fumigation did not affect O2 or CO2 concentrations within the containers, nor were fruit firmness or soluble solids content affected. Postharvest fumigation of seedless table grapes with the natural volatile compound (E)-2-hexenal shows promise for control of mold.
Insect Resistance in Sweetpotato Plant Introductions
Authors: Thompson Paul G. , Schneider John C. , Graves Boyett , Sloan R. Crofton
Published: February 2019

One hundred U.S. sweetpotato [Ipomoea batatus (L.) Lam.] plant introductions (PIs) and four control cultivars were screened for insect injury in 1993. Of the least injured by insects, 56 and 31 were tested again in 1994 and 1995, respectively. Among control cultivars, the most highly resistant was `Regal' (moderately resistant), followed by `Beauregard' (susceptible), `Centennial' (susceptible), and `Jewel' (susceptible). Stem and root injury by the sweetpotato weevil (SPW) [Cylas formicarius elegantulus (Summers)] and root injury by the wireworm (Conoderus sp.)–Diabrotica sp. (cucumber beetle)– Systena sp. (flea beetle) (WDS) complex were measured. SPW stem injury was less severe (P ≤ 0.05) in 1994 and 1995 in PIs 508523, 531116, and 564107 than in control cultivars. PIs 508523 and 531116 also suffered less SPW root injury than did `Regal'. In the six PIs with least SPW root injury, PIs 538354, 564149, 508523, 538286, 531116, and 564103, 70% to 85% of the roots were not injured compared with 36% in `Regal' and 6% in `Jewel'. SPW root injury scores (0 = no injury; 5 = severe injury) in those PIs averaged 0.5 vs. 2.3 for `Regal'. Only in PI 538286 was WDS injury to roots less than in `Regal' over 2 years. However, eight additional accessions suffered less WDS injury than `Regal' in 1995 and four of those were among the six with least SPW injury. The lower levels of combined insect injury found in these four PIs (compared to `Regal') show that PIs have potential use for increasing insect resistance in sweetpotato improvement programs.
Parthenocarpy in Summer Squash
Authors: Robinson R.W. , Reiners Stephen
Published: February 2019

Summer squash (Cucurbita pepo L.) cultivars were compared for ability to set parthenocarpic fruit. Some cultivars set no parthenocarpic fruit and others varied in the amount of fruit set when not pollinated. The degree of parthenocarpy varied with season, but the relative ranking of cultivars for parthenocarpy was generally similar. Cultivars with the best parthenocarpic fruit set were of the dark green, zucchini type, but some cultivars of other fruit types also set parthenocarpic fruit. A summer squash cultivar was developed that combines a high rate of natural parthenocarpy with multiple disease resistance. Yield of summer squash plants grown under row covers that excluded pollinating insects was as much as 83% of that of insect-pollinated plants in the open.
Aminoglycoside Antibiotics Inhibit Shoot Regeneration from Siberian Elm Leaf Explants
Authors: Kapaun James A. , Cheng Zong-Ming
Published: February 2019

Four aminoglycoside antibiotics were evaluated for their effects on shoot regeneration from leaf explants of Siberian elm (Ulmus pumila L.) seedlings and their potential use as selective agents in genetic transformation with the neomycin phosphotransferase II gene as the selective marker gene. Kanamycin at 100 mg·L–1 or higher concentration reduced shoot regeneration, with complete inhibition at 225 mg·L–1, and was considered a suitable selective agent. Neomycin completely inhibited shoot regeneration at 450 mg·L–1, but all explants remained green; therefore, it may also be used as a selective agent. Geneticin significantly inhibited shoot formation at 1 mg·L–1 and completely killed the explants at 4 mg·L–1 after 1 week. Geneticin was too toxic for direct selection, but may be useful in a delayed selection scheme or for confirmation of transformation. Paromomycin was least effective in inhibiting shoot formation; 13% of explants still regenerated shoots on the medium with the highest concentration tested (400 mg·L–1). Both neomycin and paromomycin precipitated in media containing Phytagel as a gelling agent if antibiotic stock solutions were added to the medium without adjusting their pH. Precipitation was prevented by adjusting the pH of the stock solutions from 6.2 (neomycin) or 6.9 (paromomycin) to above 9, or by using agar as a gelling agent. The precipitation was not affected by the concentrations of salts in the media.
Genetic Variability in Flower Attractiveness to Honeybees (Apis mellifera L.) within the Genus Citrullus
Authors: Wolf S. , Lensky Y. , Paldi N.
Published: February 2019

Fruit and seed set in insect-pollinated agricultural crops rely primarily on honeybees because of their ease of management and transportation. In many fruit and vegetable crops, the number of bee visitations can be the limiting step in obtaining optimal yield. Increasing the attractiveness of flowers to honeybees could, therefore, provide a useful means of improving fruit yield and seed production. Genetic variability in attractiveness to honeybees was found within the genus Citrullus. The number of daily visits per flower ranged from six to 12 among cultivars. Moreover, most of the visits to the more attractive cultivars occurred in the first hour of bee activity, whereas visits to the less attractive cultivars started later in the morning. A positive relationship was found between the frequency of bee visitations and seed number per fruit. Analyses of floral attributes indicated no genetic variability in flower size, amount of pollen grains, or nectar volume; however, differences were observed in the concentration of sucrose and total sugars in the nectar. A positive relationship was found between attractiveness to bees and nectar sugar concentration, suggesting that this characteristic is one of the parameters responsible for variability in attractiveness to honeybees.
Sources of Resistance for Two Differentially Pathogenic Strains of Xanthomonas fragariae in Fragaria Genotypes
Authors: Maas John L. , Hartung John S. , Gouin-Behe Cristina , Hokanson Stan C.
Published: February 2019

Bacterial angular leafspot disease (BALD) of strawberry (Fragaria sp. and F. ×ananassa Duchesne cultivars) has become increasingly destructive to strawberry fruit and plant production in Canada and the United States, as well as in other countries. The disease, caused by Xanthomonas fragariae Kennedy and King, was first documented in Minnesota in 1960, and has become of worldwide concern because of the economic impact of BALD in strawberry fruit and nursery-plant production and the lack of adequate disease control strategies. We tested 81 Fragaria genotypes, including representatives of F. ×ananassa, F. chiloensis (L.) Duchesne, F. virginiana Duchesne, and F. vesca L., for resistance to two pathogenic strains of X. fragariae. Two genotypes, a native F. virginiana from Minnesota and an F. virginiana × F. ×ananassa hybrid, were found to resist infection by both bacterial strains and may be potential sources of resistance to other strains of X. fragariae.
Seasonal Variation in the Response of `Valencia' Orange to Two Abscission Compounds
Authors: Hartmond U. , Whitney J.D. , Burns J.K. , Kender W.J.
Published: February 2019

Two field studies were conducted to evaluate the effect of metsulfuron-methyl and 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole) on abscission of `Valencia' orange [Citrus sinensis (L.) Osbeck] during the 3-month harvest season. Solutions of metsulfuron-methyl at 0.5, 1, and 2 mg·L-1 active ingredient (a.i.) were applied at 10-day intervals beginning on 13 Feb. and ending 18 May 1998. Early in the harvest season, 1 or 2 mg·L-1 metsulfuron-methyl significantly reduced fruit detachment force (FDF) 14 days after application. Metsulfuron-methyl was less effective during a 4- to 6-week period following bloom (“less-responsive period”). After this period, metsulfuron-methyl regained the ability to loosen fruit. Applications of 2 mg·L-1 a.i. were more effective than 1 mg·L-1 in reducing FDF and causing leaf drop, but 0.5 mg·L-1 a.i. had little or no effect on FDF. Flowers and leaflets on developing shoots and young fruit completely abscised with 1 and 2 mg·L-1 a.i. Defoliation and twig dieback was extensive at all concentrations and spray dates, eliminating metsulfuron-methyl as a commercially viable abscission agent for citrus. In a separate experiment CMN-pyrazole at 50 and 100 mg·L-1 a.i. and metsulfuronmethyl at 0.5 mg·L-1 a.i. were applied to `Valencia' trees to determine fruit removal with a trunk shake and catch harvesting system. Application of both abscission materials before and after the “less-responsive period” resulted in a 10% to 12% increase in fruit removal when compared to control trees. Less than a 35% reduction in FDF was sufficient to significantly increase fruit removal. Only 100 mg·L-1 a.i. CMN-pyrazole significantly increased fruit removal when applied during the “less-responsive period.” Chemical names used: Methyl-2-(((((4-Methoxy-6-Methyl-1,3,5-Triazin-2-yl)-Amino)Carbonyl) Amino)Sulfonyl)Benzene (Metsulfuron-methyl); 5-Chloro-3-methyl-4-nitro-1-H-pyrazole (CMN-pyrazole).
Prestorage Heat Treatment and Poststorage Quality of Mango Fruit
Authors: Ketsa Saichol , Chidtragool Sugunya , Lurie Susan
Published: February 2019

Freshly harvested mango fruit (Mangifera indica L. cv. Nam Dok Mai), were heated at 38 °C for 3 days or heated and then stored at 4 °C for 3 weeks before ripening at 25 °C, then compared with nonheated fruit for quality changes. When not refrigerated, heated and nonheated fruit ripened within 7 days to a comparable quality, although titratable acidity remained higher in heated fruit. The peel of heated fruit was initially yellower in cold-stored fruits, and soluble solids content was initially greater, whereas firmness and titratable acidity were less than that of nonheated fruit during ripening at 25 °C. After cold storage and ripening, heated fruit had a lower incidence of disease and developed less chilling injury than nonheated fruit. Nonheated fruit stored at 4 °C also developed off-flavors whereas the heated fruit did not. Heat treatment did not inhibit ripening but did ameliorate low-temperature injury.
042 Efficient Transformation of Elite Aspen Hybrids
Authors: Dai Wenhao , Cheng Zong-Ming , Sargent Wayne
Published: February 2019

A high-efficiency regeneration/transformation system was developed for three elite aspen hybrids (Populus tremuloides × P.tremula, P.tremuloides × P.davidiana, and P. × canescens × P. grandidentata). On both modified MS medium for aspen (MSA) and Woody Plant Medium (WPM) supplemented with zeatin (2.0 mg/L) and NAA (1.0 mg/L), nearly 100% leaf explants formed calli, of which 80% to 100% regenerated into shoots on both media with 2.0mg/L zeatin and 0.01 mg/L TDZ. Bacterial concentration, pH value of the co-cultivation medium, and acetosyringone were evaluated for enhancing transformation efficiency. Agrobacterial concentration at 1.0 Absorbance at OD600 was better than at 0.1, 0.5 Abs, yielding 80% and 75% of callus induction rates from agrobacterium harboring CaMV35s and Heat shock promoter constructs, respectively. The pH of co-cultivation medium, ranging 5.0 to 5.9, did not have any effect on transformation frequency. Acetosyringone was added to the co-cultivation medium and/or to the callus induction medium, the induction of kanamycin-resistant callus increased from 70% to 80% to 90% to 100%, and the size of callus also increased. Acetosyringone had no effect on shoot regeneration from kanamycin-resistant calli. Regenerated aspen shoots were screened on the kanamycin-containing medium, and confirmed by GUS histochemical assay. The GUS-positive plants were further confirmed by polymerase chain reaction, showing that the nptII, uidA, and rolB genes were integrated into the aspen genomes.
068 Development of the Bacterial Disease Resistant Potatoes by Introduction of Shiva Gene
Authors: Yi Jung-Yoon , Seo Hyo-Won , Kim Kwan-Soo , Cho Hyun-Mook , Park Kuen-Woo
Published: February 2019

Antimicrobial peptide gene (shiva) under the promoter of tomato phenylalanine ammonia-lyase (tPAL5) was transformed into potato (Solanum tuberosum L.) plants. Antimicrobial peptide gene was isolated originally from giant silk moth (Hyalophora cecropia) and modified its nucleotide seqnence to increase antimicrobial activity. Phenylalanine ammonia lyase 5 (PAL5) gene was known to express highly by wounding, irradiation, and infection by pathogens. It also expresses specifically on vessel tissues of young roots, stems, and leaves. The vector with shiva and CaMV35S promoter was also introduced into potatoes. The efficiency of regeneration was maximized at the medium containing Zeatin 2 mg/L, NAA 0.01 mg/L, GA3 0.1 mg/L. Putative transgenic potato plants were cultured on the media containing kanamycin 50 mg/L. From the tissue extracts of putative transgenic plants, GUS activity was assayed using 4-methylumbellyferyl glucuronide (MUG) as a substrate for GUS enzyme. In several transformant, GUS activity was 20- to 40-fold higher than non-transformants. Especially, one clone with CaMV35S promoter expressed ≈400-fold higher GUS activity than nontransformants. For histochemical in situ localization of GUS activity, chromogenic substrate 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide(X-gluc) was used for staining. GUS was highly expressed in the whole tissue of the transformants under CaMV35S promoter, but the other side GUS was expressed especially in the vascular tissues of stems and leaves of transformants with tPAL5 promoter. PCR was carried out at 94 °C for 20 s, 52 °C for 20 s, and 72 °C for 60 s with 45 cycles, using NPTII gene-specific primer set. PCR amplification by NPTII-specific primers confirmed 0.5-kb band in most transformants.
080 Genetic Transformation of Grapefruit (Citrus paradisi) and Sweet Orange (C. sinensis) With the Coat Protein Gene of CTV
Authors: Palacios-Torres Elvia C. , Gutièrrez-Espinosa M. Alejandra , Moore Gloria A. , Mora-Aguilera Gustavo , Ochoa-Martínez Daniel L. , Villegas-Monter Angel
Published: February 2019

Citrus Tristeza Closterovirus (CTV) induces mild and/or severe symptoms on Citrus species. It may cause death of trees if the rootstock-scion combination is susceptible. It has been found in other plant/virus combinations that transformation with partial or complete viral genes (e.g., coat protein genes) can confer resistance to the resulting transgenic plants. We previously reported A. tumefaciens mediated transformation and production of two sour orange (C. aurantium L.) plants expressing the coat protein gene of CTV, which was the first report of production of transgenic Citrus using a viral gene. However, in order to properly evaluate resistance, it is necessary to obtain as many transgenic Citrus plants from single transformation events as possible. Therefore, we are currently transforming grapefruit (Citrus paradisi) `Marsh' and `Star Ruby' and sweet orange (C. sinensis) `Valencia' with CTV coat protein genes. These species are susceptible to CTV and more amenable to transformation than sour orange. Epicotyl segments of etiolated seedlings were inoculated with A. tumefaciens strain EHA101 harboring binary plasmid pGA482GG containing the coat protein gene of mild Florida CTV strain T30 (CP-T30) or severe Florida strain T36 (CP-T36). Putatively transformed shoots were regenerated on selection medium containing kanamycin. Regenerated shoots were evaluated with GUS assays; those shoots positively identified by GUS were then evaluated with PCR. We have currently identified 17 `Marsh' grapefruit, 20 `Star Ruby' grapefruit, and seven sweet orange putatively transformed plants.
086 A Willow-leaf Mutant of Peach
Authors: Okie W.R. , Scorza R.
Published: February 2019

Willow-leaf peaches, reported by Lesley (1957) as a product of inbreeding but also mentioned as far back as 1887 (Hedrick, 1917), are characterized by a narrow leaf shape. We received willow-leaf germplasm from Wayne Sherman (Univ. of Florida, Gainesville), who selected a peach seedling with unusually narrow leaves from a group of seedling rootstocks. His original willow-leaf tree bore very small, poor-quality fruit. In 1983, it was used in breeding at the USDA-ARS breeding program at Byron to develop willow-leaf peaches with improved fruit types. After four generations, current selections are approaching commercial fruit standards in size, color, firmness, and attractiveness. Inheritance studies indicate the character is at least partially dominant and is expressed in some F1 seedlings of crosses with wild-type parents. However, the precise mode of inheritance remains unclear as the ratios do not fit common patterns. Progeny show a range of leaf narrowness, complicating characterization of genotype. The character may be useful in standard-type trees to enhance spray penetration, speed drying of the foliage to reduce disease, improve light penetration and photosynthetic efficiency, and make the fruit more visible to speed picking.
099 Browning Inhibition of Fresh-cut `Anjou' and `Bartlett' Pears
Authors: Abbott Judith. A. , Buta J.G.
Published: February 2019

A treatment to inhibit browning and maintain quality of fresh-cut `Anjou' and `Bartlett' pears (Pyrus communis L.) was developed. Slices of ŒAnjou, and ŒBartlett, pears with a range of initial firmness values were dipped in mixtures of 4-hexylresorcinol, isoascorbic acid, potassium sorbate, and N-acetylcysteine before refrigerated storage. Browning, as indicated by visual observation and by colorimeter readings, was inhibited for 14 d. Pears receiving the antibrowning treatment maintained firmness as well or better than the control slices.
130 Response of Anaerobic Metabolism to Delaying Controlled Atmosphere Storage in Braeburn Apples
Authors: Gong Yiping , Toivonen Peter M.A. , Lau O.L. , Wiersma Paul A.
Published: February 2019

Apple fruits (Malus domestica Borkh. cv. Braeburn) harvested from two orchards (A and B) on the same day were stored in air or pretreated in air for 0, 2 (2dCA) or 4 weeks (4dCA) before moving into controlled atmosphere (CA) storage with 1.5% O2 + 5% CO2. During storage at 1 °C for 9 weeks in air and/or CA, changes of pyruvate decarboxylase (PDC) activity, alcohol dehydrogenase (ADH) activity, acetaldehyde (AA) and ethanol (EtOH) concentrations in flesh tissue were assayed in addition to the incidence of Braeburn browning disorder (BBD). Immediate introduction to CA conditions induced the development of BBD with the highest incidence 62.2%, however delaying application of CA for 2 and 4 weeks reduced the incidence of BBD to 38.5% and 27.0%. The development of disorder in grower B was less than in grower A. 2dCA and 4dCA treatments did not influence PDC activity compared with treatment of CA. However, ADH activity and the accumulation of AA and EtOH in treatments of 2dCA and 4dCA were markedly lower than those in CA. The accumulation of AA in grower B was lower than grower A. The results of this study suggest that the delayed application of CA reduced BBD and this may be due to reduced anaerobic metabolism of fruits in the delayed CA.
132 Semi-commercial-scale Ultra-low Oxygen Storage for Disinfestation of Mexican Fruit Fly in Grapefruit
Authors: Shellie Krista C. , Rodde Ken
Published: February 2019

A treatment schedule for disinfesting grapefruit of Mexican fruit fly with refrigerated (14 °C) storage for 21 days in ultra-low oxygen (0.05 kPa) was tested using a fully loaded, 24-ft sea freight container. The objective of this research was 3-fold: 1) evaluate the ability of a free standing Electronic Oxygen Control system to maintain 500 ppm of oxygen for 21 days inside the sealed container, 2) evaluate the mortality of third instar Mexican fruit fly larvae stored for 21 days inside the sealed container, and 3) evaluate fruit market quality after 21 days inside the container. The container was loaded with 17 pallets of red-fleshed, `Rio Star' grapefruit. Three boxes from each pallet were evaluated for fruit quality (decay (%), visible disorders (%)) after 21 days of treatment and again after 14 additional days of storage in air at 10 °C. Four cartons, each containing 24 fruit infested with third instar, Mexican fruit fly larvae, were each placed on top of a pallet in four different container locations. Upon completion of treatment, larvae were evaluated for survival. In the first replication, no fruit fly larvae survived the low oxygen treatment. In the second replication, oxygen concentration was less controlled, and 60 pupae survived the treatment. Treated and control grapefruit had similar incidence of decay when the treatment was terminated, however no sporulation was observed in fruit stored under ultra-low oxygen. Grapefruit exposed to ultra-low oxygen had a higher incidence of visible disorders, consisting of darkened, sunken areas on the fruit surface. It is unclear whether this damage is attributed to fluctuating levels of oxygen, deleterious volatiles produced during treatment, or a sensitivity of the fruit to low oxygen.
133 Watermelon Lycopene Content Varies with Cultivar and Maturity Stage
Authors: Perkins-Veazie P. , Collins J.K. , Pair S.
Published: February 2019

The red flesh of watermelon contains the fat-soluble carotenoid pigment lycopene. A high level of lycopene in human blood serum has been correlated with a reduced incidence of several cancers. This experiment was done to determine the variation in lycopene content among watermelon cultivars and ripeness stages. Ten melons per cultivar of hybrid, open-pollinated, and triploid (seedless) types were selected from field plantings at Lane, Okla. Additionally, 20-melon, quarterly shipments of hybrid or triploid types were used from commercial growers. Melons were cut transversely and a 100-g sample of heart tissue was removed from the center, frozen at –80 °C, extracted with a hexane–acetone–ethanol mixture and pigment quantified at 503 nm. Unripe melons (about 3 to 5 days from fully ripe) had 18% less lycopene than ripe melons. The average lycopene content of all ripe melons sampled (open-pollinated, hybrid, triploid) was 47.82 μg/g (n = 247 melons), while that of ripe hybrid and triploid melons was 54.76 μg/g (n = 209 melons). Lycopene content of ripe melons varied among cultivars, from as little as 33.96 μg/g in `Crimson Sweet' to as much as 75.72 μg/g in `Scarlet Trio'. These results indicate that fresh watermelon has a naturally high level of lycopene and that potential for enhanced lycopene content is already present in the germplasm of commercial cultivars.
214 Hydrogen Peroxide Reduces Hypoxia in Germinating Bean Seeds
Authors: Baek Kwang-Hyun , Rajashekar C.B.
Published: February 2019

Effects of hypoxia on germinating bean seeds (Phaseolus vulgaris cv. Tendergreen) were examined by imbibing them in water for various lengths of time. Hypocotyl elongation under hypoxic conditions and recovery from hypoxia in bean seeds were determined. Oxygen concentration in the water began to decrease sharply after 12 h of seed imbibition and had declined by more than 63% after 3 days of seed imbibition. When seeds were germinated on 0.8% agar after 24 h of imbibition, the hypocotyl elongation was reduced by about 70% compared to the seeds with no hypoxia, and longer imbibition resulted in poor or no germination. Exogenous hydrogen peroxide (20 mm) in water increased the oxygen concentration from 250 to 350 mm in the presence of seeds and was considerably higher after 3 days of seed imbibition than that in the control. Hypocotyl elongation occurred in seeds submerged in water containing hydrogen peroxide up to 72 h while none was observed in water. This was comparable to hypocotyl elongation under non-hypoxic conditions. Hypoxia in imbibing seeds was overcome by the high oxygen levels in the medium resulting from reaction of hydrogen peroxide with seed catalase and catalytic metal ions. Considerable catalase activity was detected in germinating seeds and the use of a catalase inhibitor, aminotriazole, suggests that the enzyme plays an important role in the release of oxygen into the medium. Of the catalytic metals, the seed content of iron was dominant and was about 6 folds higher than that of either copper or manganese.
215 Influence of Promalin Spray and Drench on Fern Numbers of Asparagus
Authors: Johnson Clarence
Published: February 2019

Asparagus (Asparagus officinalis)plants were sprayed and drenched with different concentrations of Promalin (0, 250, and 500 ppm) The varieties for the spraying experiment were `Mary Washington', `Emeral', `UC-157-F1', and `UC157F2'. Six replications for each treatment were used in a randomized complete-block design. The drenching experiment used two varieties (Mary Washington and UC-157-F2) with six replications of each treatment in a randomized complete-block design. Pots were numbered and labeled for each experimental unit. Plants (ferns) were counted and recorded in order to obtain the initial number of ferns before or after the spraying or drenching. In the spraying experiment, the plants were sprayed to run-off using a hand sprayer whereas; in the drenching experiment, 1000 mL or 1 L of the solution was used to drench each plant. The response to the chemical was measured in two ways: weekly stimulation of emergence of new-shoots and percent increase in final number of shoots over the initial number. In the spraying treatments differences were not found among the treatments used. In the drenching experiment with `Mary Washington' variety, a lower initial number of ferns at 250 ppm as compared to the 0 ppm of Promalin (8.82 to13.00) was observed. Differences for `Mary Washington' variety was not found for cumulative number of ferns on weeks 1, 2, and 3. However, the percent increase in number of ferns was higher for the 250 ppm as compared to the 0 ppm (174.55% to 78.14%). `UC-157-F2' showed no difference among the different concentrations. This indicates a difference in varietal response.
227 Rate of Root Growth of Three Woody Ornamental Species
Authors: Wright Amy N. , Warren Stuart L. , Blazich Frank A.
Published: February 2019

Root growth is a critical factor in landscape establishment of container-grown woody ornamental species. Kalmia latifolia (mountain laurel) often does not survive transplanting from containers into the landscape. The objective of this experiment was to compare rate of root growth of mountain laurel to that of Ilex crenata `Compacta' (`Compacta' holly) and Oxydendrum arboreum (sourwood). Six-month-old tissue-cultured liners (substrate intact) of mountain laurel, 1-year-old rooted cutting liners (substrate intact) of `Compacta' holly (liner holly), 6-inch bare root seedling liners of sourwood, and 3-month-old bare-root rooted cuttings of `Compacta' holly were potted in containers in Turface™. Prior to potting, roots of all plants were dyed with a solution of 0.5% (w/v) methylene blue. Plants were greenhouse-grown. Destructive harvests were conducted every 2 to 3 weeks (six total harvests). Length, area, and dry weight of roots produced since the start of the experiment, leaf area, and dry weight of shoots were measured. Sourwood and liner holly had greater rate of increase in root length and root dry weight than mountain laurel and bare root holly. Rate of increase in root area was greatest for sourwood, followed by (in decreasing order) liner holly, mountain laurel, and bare-root holly. Increase in root length and root area per increase in leaf area was highest for liner holly, possibly indicating why this species routinely establishes successfully in the landscape. Increase in root dry weight per increase in shoot dry weight was lowest for mountain laurel. The slow rate of root growth of mountain laurel (compared to sourwood and liner holly) may suggest why this species often does not survive transplanting.
269 Evaluation of Low-chilling Requirements of Apricot Selections in Northwestern Mexico
Authors: Grijalva-Contreras Raúl Leonel , López-Carbajal Arturo , Fimbres-Fontes Adán , Navarro-Ainza Cristobal , Juárez-González Rogelio , Robles-Contreras Fabián
Published: February 2019

Apricot production in México is limited; actually, the area devoted to this crop is ≈880 ha, of which 230 ha are established in Sonora State. The main cultivar used is `Canino'. The fruit yield ranges from 15-20 t·ha-1. The present study tested 20 low-chilling (300 to 400 chill hours) requirments of apricot selections; `Nemaguard' was the rootstock used. On the 4rth production year from the 20 apricot selection tested, 7-23, 1-81, and 15-1 yielded 31.8, 20.2. and 15.5 Ton.Ha-1, respectively; all of these selections showed higher yields than the Canino cultivar (14.6 t·ha-1). The fruit of these apricot selectiosn ripened by mid-May, exhibiting all the tested selection a similar fruit quality (size, flavor, color, and °Brix). We have not recorded any important insect pests or diseases during this trial.
271 Gibberellic Acid Effects on `Hamlin' Orange Peel Quality are Reduced by Wash-off Sprays
Authors: Fidelibus Matthew W. , Davies Frederick S.
Published: February 2019

In Florida, gibberellic acid (GA3) is applied to citrus in the late summer or early fall to reduce senescence-related peel disorders of fresh fruit and to increase juice yield of processing oranges. Heavy rainfall may occur daily during this time that could reduce the efficacy of GA3 sprays. Experiments were conducted in 1998-99 and 1999-2000 to test the effect of timed “wash off” treatments on the peel color and peel puncture resistance (PPR) of `Hamlin' orange (Citrus sinensis [L.] Osb.) fruit that were previously treated with GA3. In Oct. 1998 and 1999, the canopy of 14- or 15-year-old trees were sprayed to runoff (≈10 L) with GA3 (45 g a.i./ha) and a non-ionic surfactant (Silwet, 0.05%). For the next 4 (1998-99) or 5 (1999-2000) h, three different GA3-treated trees each hour were then sprayed with ≈20 L of tap water to simulate rainfall that might remove or dilute the GA3. An additional three trees did not receive a GA3 or a washoff treatment. Fruit were harvested in Nov. 1998 and Jan. 1999 and Dec. 1999 and Jan. 2000 and evaluated for PPR and color. Data were subjected to regression analysis to determine the relationship between peel variables and time until washoff. In 1998-99, PPR and peel hue (level of green color) increased linearly with time until washoff, indicating that some GA3 uptake was still occurring after 4 h. In 1999-2000, PPR and hue increased linearly until about 3 h before washoff. Therefore, heavy rainfall within 3 to 4 h of application may reduce GA3 effectiveness, even when a surfactant is used.
309 Rapid Growth of Microbudded Citrus Planted Ultra-high Density
Authors: Skaria Mani , Tao Zhang
Published: February 2019

High-density or ultra-high-density orchards have had positive economic return up to 12 years after planting. However, an initial higher investment on more number of trees needed is a limiting factor for high-density planting. Our preliminary studies have shown that a microbudding technique that we had developed would produce less-expensive, budded citrus trees. In June 1997, several hundred microbudded citrus trees were planted in a field, under drip irrigation. The planting continued monthly until Dec. 1997. The cultivars planted were: `Marrs' orange, `Rio Red' grapefruit, `Meyer' and `Ponderosa' lemon, and satsuma mandarin. All plants were microbudded on sour orange rootstock grown in 5′′ long “conetainers.” Our objectives were to study the growth performance of small, microbudded trees planted in the field. The plants grew normally and even out-performed the conventionally budded trees in a field nursery next to the test plot. In Dec. 1999, tree height reached 60 inches. Five percent of the trees produced fruit and they were normal in shape, color, and quality.
328 Manipulation of Microtuber Yield and Size Distribution with Successive Harvests
Authors: Abdulnour J. , Donnelly D. , Barthakur N.
Published: February 2019

The effect of successive harvests on potato microtuber yield (fresh weight and number) and size distribution in stationary liquid cultures was evaluated in cultivars Norland, Bintje, and Shepody. Harvesting microtubers successively at both 33 and 65 days, compared with a single harvest at 65 days, increased the total number of microtubers but decreased the number of larger microtubers (>0.75 g). Selective removal of Shepody microtubers >8 mm (>0.5 g) at 33 days increased the combined total number of microtubers from both harvests, but decreased the number of very large microtubers (>1.5 g). Successive harvest had no effect on total fresh weight yield, but increased overall microtuber numbers and skewed the size distribution downwards.
336 A Comparison of Virus-free Versus Infected Sweetpotato Transplants for Cutting Propagation
Authors: Bush Edward W. , LaBonte Don R. , Gray Ann L. , Villordon Arthur Q.
Published: February 2019

Production of disease-free sweetpotato [Ipomoea batatas (L.) Lam.] transplants is of major importance to certified and foundation seed programs and producers. Sweetpotato roots are traditionally planted and cuttings are harvested from propagation beds. The objective of this study was to investigate the efficiency of producing cuttings in nursery containers. Virus-tested and virus-infected `Beauregard' sweetpotato transplants were harvested from planting beds for the purpose of producing cuttings for transplants. Cuttings were established in 3.7-L plastic nursery containers filled with 100% pine bark amended with either low, medium, or high rates of Osmocote 14-14-14 and dolomitic lime. Resulting transplants produced a greater number of cuttings and greater plant biomass with higher fertilizer rates. Increasing fertilizer rates also had a positive effect on cutting production and biomass. Dry weight and stem growth were similar for both virus-infected and virus-tested transplants following first and second harvests. Producing foundation cuttings in nursery containers filled with a pine bark medium proved to be an efficient method of increasing virus-tested sweetpotato cuttings.
342 Propagation of Camptotheca acuminata
Authors: Maxwell Douglas W. , Lineberger R. Daniel
Published: February 2019

Research was undertaken to optimize seed storage and vegetative propagation of Camptotheca acuminata. Camptotheca is a member of the Nyssaceae native to southern China and is important because it contains the medicinal alkaloid camptothecin. Seeds stored in polyethylene bags in a refrigerator (4 °C) or freezer (- 20 °C) maintained good germination (79% and 83%, respectively), while seeds stored at room temperature in open containers or polyethylene bags lost germination ability quickly (45% and 51%, respectively). Softwood cuttings of Camptotheca rooted readily in intermittent mist (4 s on every 6 min.) in coarse vermiculite when treated with K-IBA (indolebutyric acid, potassium salt) quick dips ranging from 1000 to 9000 ppm, with a 7000 ppm quick dip (5 s) promoting 82% rooting with little foliar damage. Actively growing shoot tip explants were tissue cultured on media containing Murashige and Skoog, Gamborg, and Woody Plant Medium (WPM) salts in factorial combinations with BA (benzyladenine). WPM containing 1.0 mg/lBA promoted excellent shoot proliferation; microcuttings were rooted, acclimated, and grown on in the greenhouse. Camptotheca is readily adaptable to modern nursery techniques for either seed or vegetative propagation.
349 Determining Nitrogen Requirements of Lettuce through Presidedress Soil Nitrate Testing (PSNT)
Authors: Hartz T.K. , Breschini S.
Published: February 2019

High rates of N fertilization of cool-season vegetables has contributed to NO3-N pollution of groundwater in the Salinas Valley of central California. Ten field demonstrations were conducted in 1999 to document the utility of presidedress soil NO3-N testing in maximizing N fertilizer efficiency in iceberg lettuce (Lactuca sativa L.). In each demonstration, a plot 36 beds wide × the entire field length was established in a commercial lettuce field. The cooperating growers applied 1 to 3 N sidedressings in these fields. Before each sidedressing the soil NO3-N concentration in the top 30 cm of the plot was determined by an on-farm quick test technique. If NO3-N was >20 mg·kg-1, no N was applied at that sidedressing; for NO3-N <20 mg·kg-1, ≈4 kg N/ha was applied for each milligram per kilogram below the 20 mg·kg-1 threshold. Plot yields, harvested by commercial crews, were compared to the yield of adjacent areas of the field that received the growers' full sidedress N regime. Across fields, seasonal sidedress N application in the PSNT plots averaged N only at 86 kg·ha-1, almost 60% less than the average N (212 kg·ha-1) applied by the growers. Yields in the PSNT plots averaged 1824 boxes/ha, compared with 1829 boxes/ha in the companion field plots. Whole leaf N concentration at heading was above published sufficiency standards in all PSNT plots. Evaluation of heads after 10 days of storage at 5 °C showed that sidedress N application rate did not affect visual quality, decay, or midrib discoloration. We conclude that PSNT can reliably be used to minimize wasteful sidedress N applications in lettuce.