bluuebunny/crossref_metadata_2025 huggingface dataset:
Progress in Prunus Mapping and Application of Molecular Markers to Germplasm Improvement
Authors: Baird Vance
Published: February 2019

Prunus, which includes peach/nectarine, almond, apricot, cherry, and plum, is a large and economically important genus in the family Rosaceae. The size and long generation time of these tree crops have hampered improvement through classical breeding and long-term selection programs. With the advent of DNA-based molecular diagnostics, an exciting era in germplasm improvement has dawned. Efforts are underway, notably in the United States (e.g., California, Michigan, North Carolina, and South Carolina) and the European Community (e.g., England, France, Italy, and Spain), to apply the tools of molecular mapping and marker-assisted selection to this important genus. The objective of these projects is to develop molecular linkage maps of sufficient marker density to tag phenotypic trait loci of agronomic importance. These include traits controlled by single genes (e.g., flower color, compatibility, flesh color, pest resistance), as well as more-complex, quantitative traits (e.g., cold hardiness, tree architecture, sugar content). An immediate outcome of these mapping efforts has been the development of DNA “fingerprints,” allowing for the discrimination of cultivars—both scion and rootstock. The maps will be used by breeders and molecular biologists to monitor gene introgression from wild species into elite lines, for marker-assisted selection of desired trait combinations, and for map-based cloning of specific genes. The molecular markers used in these mapping projects include RFLPs, RAPDs, and microsatellites. Each has their appropriate applications and advantages depending upon the resources at hand and the project's specific goals.
Preharvest Factors Affecting Postharvest Stone Fruit Quality
Authors: Crisosto Carlos H. , Johnson R. Scott , Day Kevin , DeJong Ted
Published: February 2019

Studies on the influences of “orchard factors” such as cultivar, harvest time, crop load, fruit canopy position, irrigation, and nitrogen regimes were investigated for plums, nectarines, and peaches at the Kearney Agricultural Center (San Joaquin Valley, Calif.a). These preharvest factors affected internal browning and mealiness incidence differently. More-reliable benefits of treatments to eliminate or reduce internal breakdown may be accomplished by using outer canopy fruit. Optimum quality expression and subsequent consumer satisfaction for each cultivar can be achieved by understanding the role of preharvest factors and harvest time on fruit quality and potential postharvest life.
Foliage Removal Influences Sweetpotato Biomass Yields in Hydroponic Culture
Authors: David P.P. , Trotman A.A. , Mortley D.G. , Bonsi C.K. , Loretan P.A. , Hill W.A.
Published: February 2019

Greenhouse studies were conducted to determine the effect of harvesting sweetpotato [Ipomoea batatas L. (Lam.)] foliage tips (terminal 15 cm) on storage root yield, edible biomass index (EBI), and linear growth rate. Plants were grown hydroponically from 15-cm vine cuttings planted in 0.15 × 0.15 × 1.2-m growth channels using a recirculating nutrient film technique system. Nutrients were supplied from a modified half-strength Hoagland solution with a 1 N: 2.4 K ratio. Foliage tips were removed at 14-day intervals beginning 42 days after transplanting. Final harvest was at 120 days after planting. At the end of the growing season, harvested foliage tips totaled 225 g/plant (fresh mass). Foliage removal significantly reduced storage root yield, shoot biomass, and linear growth rate expressed on a canopy cover basis. The EBI was higher for plants with foliage removed than for the control.
Prairie Remnant Soil as a Source of Mycorrhizal Inoculum
Authors: Kemery Ricky D. , Dana Michael N.
Published: February 2019

Soil from four native prairie remnant sites was used as inoculum in pot culture to achieve vesicular–arbuscular mycorrhizal (VAM) infection of Sudangrass [Sorghum sudanense (Piper) Stapf]. The prairie sites varied in their management histories and degradation levels. Sudangrass plants that became infected with VAM grew better than those grown in standard pasteurized greenhouse mix or those grown in a pasteurized greenhouse–prairie soil mix. Soil from prairie remnants may serve as a beginning source of inoculum that can be increased via Sudangrass pot culture for inoculation of prairie plant seedlings in nursery production.
Leaf Age Affects Gas Exchange in Okra
Authors: Whitehead W.F. , Singh B.P.
Published: February 2019

Two studies were conducted to assess the effects of leaf aging on gas exchange in okra [Abelmoschus esculentus (L.) Moench] leaves. Gas exchange was measured at 6- to 10-day intervals starting 15 days after leaf emergence (DFE) and continuing until senescence at 50 DFE. Rates of transpiration (E), stomatal conductance (gs) and CO2 exchange (CER) increased as leaves matured up to ≈25 DFE, about full leaf expansion. Transpiration rate, gs, and CER declined after 25 DFE and as leaves aged further. Internal leaf CO2 concentration (Ci) was higher in old than young leaves. This study suggests that the most efficient okra canopy would maximize exposure of 25-day-old leaves to sunlight.
Susceptibility of Selected Grape Cultivars and Tree Fruit to Silverleaf Whitefly (Bemisia argentifolii) Colonization
Authors: Summers Charles G. , Newton Albert S. , Hansen Kyle R.
Published: February 2019

Six table grape (Vitis vinifera L.) cultivars and 10 species of tree fruit were evaluated in cage tests to determine their susceptibility to colonization by the silverleaf whitefly (Bemisia argentifolii Bellows and Perring). The table grape cultivars Thompson Seedless, Perlette, Flame Seedless, Ruby Seedless, Christmas Rose, and Redglobe were all colonized. In a field nursery, with naturally occurring silverleaf whitefly populations, `Zinfandel', `Sirah', and `Chardonnay' were more heavily colonized than were `Merlot', `Thompson Seedless', or `Redglobe'. The tree crops `Kerman' pistachio (Pistacia vera L.), `Calimyrna' fig (Ficus carica L.), `Nonpareil' almond [Prunus dulcis (Mill.) D.A. Webb], and `Fuyu' persimmon (Diospyros kaki L.) were colonized in cage tests. Silverleaf whitefly failed to establish colonies on caged `O'Henry' peach [Prunus persica (L.) Batsch.], `Fantasia' nectarine [P. persica (L.) Batsch. var. nectarina (Ait.f.) Maxim.], `Casselman' plum (P. salicina Lindl.), `Tilton' apricot (P. armeniaca L.), `Granny Smith' apple (Malus domestica Borkh.), and `Hayward' kiwifruit [Actinidia delicoisa (A. Chevalier) C.F. Liang et A.R. Ferguson].
Fragaria Resistance to Spider Mites at Three Locations in the United States
Authors: Shanks Carl H. , Chandler Craig K. , Show Edgar D. , Moore Patrick P.
Published: February 2019

Eleven clones of Fragaria spp. were tested for resistance to the twospotted spider mite, Tetranychus urticae Koch, at Dover, Fla.; Watsonville, Calif.; and Vancouver, Wash. Ten clones, which had been selected previously as being mite-resistant, had generally the same relative resistance when compared to susceptible `Totem' at all three of the widely separated locations. It appears that Fragaria clones selected for resistance to spider mites at one location likely will be resistant elsewhere, in spite of environmental differences.
Ethylene-induced Abscission of Easter Cactus Phylloclades for Vegetative Propagation
Authors: Han Susan S. , Nobel Jennifer
Published: February 2019

The study was conducted to determine if ethylene or ethephon, an ethylene-releasing compound, can be used to induce abscission of phylloclades of four cultivars of Easter cactus [Rhipsalidopsis gaertneri (Regel) Moran] to increase efficiency in vegetative propagation. Abscission occurred within 24 hours after commencement of the ethylene treatments. Phytotoxicity, as exhibited by water soaking, transparency, and darkening of the phylloclades, as well as percent abscission, increased with increasing concentrations of ethephon (0 to 10,000 μl·liter–1). Ethylene released from ethephon, not the acidity of the solution, was determined to be the cause of the phytotoxicity. In three out of the four cultivars, vegetative and root growth from propagated phylloclades was significantly restricted by treatments with ethephon. In comparison, vegetative growth from phylloclades treated with ethylene at 20 μl·liter–1 was the same as from those treated with air. Root growth of the ethylene-treated phylloclades was not studied. The acidity of the ethephon solutions likely affected the growing regions, resulting in a reduction in growth. The study shows that treatment with ethylene gas or the use of pH-adjusted ethephon solutions may be an alternative to the labor-intensive procedures associated with vegetative propagation of Easter cactus. Chemical name used: 2-chloroethylphosphonic acid (ethephon).
Imidacloprid Does Not Enhance Growth and Yield of Muskmelon in the Absence of Whitefly
Authors: Palumbo J.C. , Sanchez C.A.
Published: February 2019

Imidacloprid is a new, chloronicotinyl insecticide currently being used to control sweetpotato whitefly [Bemisia tabaci Genn, also known as silverleaf whitefly (Bemisia argentifolii Bellows and Perring)]. Large growth and yield increases of muskmelon (Cucumis melo L.) following the use of imidacloprid have caused some to speculate that this compound may enhance growth and yield above that expected from insect control alone. Greenhouse and field studies were conducted to evaluate the growth and yield response of melons to imidacloprid in the presence and absence of whitefly pressure. In greenhouse cage studies, sweetpotato whiteflies developed very high densities of nymphs and eclosed pupal cases on plants not treated with imidacloprid, and significant increases in vegetative plant growth were inversely proportional to whitefly densities. Positive plant growth responses were absent when plants were treated with imidacloprid and insects were excluded. Results from a field study showed similar whitefly control and yield responses to imidacloprid and bifenthrin + endosulfan applications. Hence, we conclude that growth and yield response to imidacloprid is associated with control of whiteflies and the subsequent prevention of damage, rather than a compensatory physiological promotion of plant growth processes. Chemical names used: 1-[(6-chloro-3-pyridinyl)methyl]-4,5-dihydro-N-nitro-1-H-imidazol-2-amine (imidacloprid); [2 methyl(1,1′-biphenyl)-3yl)methyl 3-2-chloro-3,3,3-trifluoro-1-propenyl]-2,2-dimethylcyclopropane carboxylate (bifenthrin); 6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodiaxathiepin 3-oxide (endosulfan).
Gibberellic Acid-induced Fruit Set of Rabbiteye Blueberry following Freeze and Physical Injury
Authors: NeSmith D. Scott , Krewer Gerard , Rieger Mark , Mullinix Ben
Published: February 2019

In a series of experiments, gibberellic acid (GA3) was applied to rabbiteye blueberries (Vaccinium ashei Reade) under field and greenhouse conditions to determine if fruit set could be improved following physical or freeze injury to flowers. In field experiments, physically damaged flowers (i.e., corollas and styles removed, styles only removed, or ovaries lanced) of `Climax' and `Tifblue' treated with GA3 (4% ProGib at 250 mg·liter–1) set substantially more fruit than nontreated, damaged flowers. Under green-house conditions, GA3 applied postfreeze to `Tifblue' and `Brightwell' resulted in increased fruit set compared to unsprayed control plants of the same cultivars. Freeze-damaged plants had substantially reduced fruit set overall but to a much lesser extent for GA3-treated plants than for those not treated with GA3. Individual fruit weight was reduced by GA3 applications, as was berry seediness. Results from these greenhouse and field trials suggest that GA3 can be used to salvage a blueberry crop following a moderate freeze during bloom.
Chilling Exposure and Hydrogen Cyanamide Interact in Breaking Dormancy of Grape Buds
Authors: Dokoozlian N.K. , Williams L.E. , Neja R.A.
Published: February 2019

An experiment was conducted to examine the interaction between chilling exposure (0, 50, 100, 200, 400, and 800 hours at 3C) and hydrogen cyanamide (H2CN2) concentration [0%, 1.25%, and 2.50% (v/v)] on the budbreak of dormant grape buds (Vitis vinifera L. `Perlette') collected in late fall before the onset of temperatures ≤13C. Budbreak at 22C was most rapid for cuttings exposed to 800 chill hours and least rapid for cuttings that received no chilling. Budbreak of cuttings receiving 50 to 200 hours of chilling was similar and lagged behind that of cuttings exposed to 400 or 800 hours. Maximum observed budbreak improved with increased chilling exposure. Hydrogen cyanamide hastened the growth of all chilling treatments and increased the percent budbreak of cuttings receiving ≤400 chill hours. When cuttings were not treated with H2CN2, the number of days required for 50% budbreak declined sharply as chilling exposure increased from 0 to 400 hours. In contrast, this interval was reduced only slightly as chilling increased from 400 to 800 hours. Hydrogen cyanamide-treated buds exhibited a more gradual decline in the number of days required for 50% budbreak with increased chilling exposure. In this study, the physiological efficacy and economic benefits of H2CN2 applications diminished with increased chilling exposure.
Identification of Citrus Chimeras by RAPD Markers
Authors: Sugawara Kuniaki , Oowada Atsushi , Moriguchi Takaya , Omura Mitsuo
Published: February 2019

Random amplified polymorphic DNA (RAPD) markers were used to detect chimerism of citrus cultivars. Polymerase chain reaction conditions suitable for discriminating citrus chimeras were determined. Primers that produced consistent and repeatable bands that differed between the parental cultivars were chosen to create discriminating band patterns. Our results show that selected 12-mer primers can be useful for identifying the four citrus chimeras tested using RAPD technology.
Relationships of Seed Size and Shape with Polyembryony and the Zygotic or Nucellar Origin of Citrus spp. Seedlings
Authors: Bowman Kim D. , Gmitter Frederick G. , Hu Xulan
Published: February 2019

We examined the relationship between seed size and shape in Citrus and the number and type of seedlings produced by individual seeds for each of three citrus cultivars. Seed size and shape were related to the number of seedlings produced and the likelihood of recovering a zygotic seedling. The relationship between seed size and shape and the likelihood of recovering a zygotic seedling most often was connected with weight and thickness of a seed. This relationship might be of sufficient strength to use in some aspects of cultivar development. However, the relationship did not appear strong enough to be of practical value for application in commercial production of purely nucellar rootstock seedlings.
Mechanical Topping Mitigates Alternate Bearing of `Kerman' Pistachios (Pistacia vera L.)
Authors: Ferguson L. , Maranto J. , Beede R.
Published: February 2019

The effects of four mechanical pruning treatments [hedging, topping, hedging/topping, and hand-pruning (control)] on nut yield, nut quality, alternate bearing, and growth of 14-year-old female `Kerman' pistachio trees on Pistacia atlantica L. rootstocks were assessed. A single pruning was done before an “off,” or low-crop, year followed by retopping of those treatments incorporating topping the first year. Over 7 years, yields of hedged/topped and topped trees were equal to those of control trees, while hedged trees produced significantly less. The incidence of nonsplit shells and blank nuts were not affected by pruning. Nuts weighed more all years for hedged/topped and topped trees than for the others. Alternate-bearing indices within 7 years were lower for pruning treatments incorporating topping. Topping mitigated the fluctuating annual vegetative growth pattern and resulted in 27% of the shoots retaining buds through three successive alternate-bearing cycles after the year of treatment. Hedged/topped and topped trees had significantly less alternation in annual girth growth than control or hedged trees. These results demonstrated that two successive seasons of mechanical topping, started before the off year, produced changes in shoot growth, trunk growth, and bud retention that mitigated alternate bearing through three biennial cycles, without decreasing yield. Thus, severe annual hand-pruning could be used to prevent or minimize alternate bearing of pistachios.
Rooting Characteristics of Buffalograsses Grown in Flexible Plastic Tubes
Authors: Marcum Kenneth B. , Engelke M.C. , Morton Sharon J.
Published: February 2019

Rooting characteristics of 22 buffalograss [Buchloë dactyloides (Nutt.) Engelm.] genotypes were determined by growing plants in clear, sand-filled polyethylene tubes in a glasshouse. Differences were observed among entries for average maximum root depth, total root weight, root count and weight at increasing 100-mm depth increments, and total shoot weight. Average maximum root depth was positively correlated with total root weight (r = 0.59) and with root count at each 100-mm root profile depth. Root count and weight across all vertical root profile sections were highly correlated (r = 0.81). Total shoot weight was weakly correlated with average maximum root depth but not at all with total root weight. Grasses with superior rooting characteristics (deeply rooted, with larger root mass and count in the lower root profile sections) included AZ-143, NTDG-1, and `315' (NE84-315).
Germination of sh2 Sweet Corn following Seed Disinfestation, Solid-matrix Priming, and Microbial Seed Treatment
Authors: Hartz T.K. , Caprile J.
Published: February 2019

Sweet corn (Zea mays L.) cultivars carrying the sh2 mutation show poor seed vigor under stressful field conditions, requiring higher seeding rates to ensure stand establishment. The effects of sodium hypochlorite seed disinfestation, solid matrix priming (SMP), and seed-coating with Gliocladium virens Miller, Giddens & Foster to enhance emergence of sh2 sweet corn in controlled-environment cold stress tests and field trials were investigated. In combination with a chemical fungicide seed treatment (captan, thiram, imazalil, and metalaxyl), SMP significantly improved the percentage and rate of seedling emergence of `Excel' and `Supersweet Jubilee' in a cold stress test (in soil for 7 days at 10C, then 15C until emergence) but was inconsistent under field conditions, improving emergence in only one of four field trials. Sodium hypochlorite disinfestation was ineffective. Compared to a film-coated control, coating seeds with G. virens strain G-6 was highly effective in increasing emergence in two of three cultivars tested in cold stress tests in two soils, while strain G-4 was generally ineffective. In field trials, G-6 treatment significantly increased emergence over that of nontreated seed but was inferior to conventional fungicide treatment and conferred no additional benefit in combination with fungicide treatment. Overall, no seed treatment evaluated was an economically viable alternative for or supplement to chemical fungicide treatment. Chemical names used: cis-N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide (captan); tetramethyl-thiuram disulfide (thiram); 1-[2-(2,4-dichlorophenyl)-2-(2-propenyloxy)ethyl]-1H-imidazole (imazalil); N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-alanine methyl ester (metalaxyl).
Pitting of Grapefruit that Resembles Chilling Injury
Authors: Petracek Peter D. , Wardowski Wilfred F. , Brown G. Eldon
Published: February 2019

A postharvest peel disorder, morphologically similar to chilling injury (CI), was detected on nonchilled `Marsh' white grapefruit (Citrus paradisi Macf.). Like CI, the disorder was characterized by pitting of the peel caused by the collapse of oil gland clusters. This disorder is distinguished from CI in that pitting developed within the first 10 days of postharvest storage on fruit held at high (21.0C), but not low (4.5C), temperatures and on waxed fruit, but not unwaxed fruit. Pathogens isolated from pitted fruit were similar to those of nonpitted fruit. No preharvest pitting or visual clues of fruit susceptibility were observed.
Deleterious Effects of Sucrose in Preservative Solutions on Leaves of Cut Roses
Authors: Markhart Albert H. , Harper Mark S.
Published: February 2019

Leaves on cut stems of commercially grown Rosa hybrida cv. Kardinal placed in preservative solutions containing sucrose developed necrotic dry patches that began interveinally and progressed toward the major veins until the entire leaf was dehydrated. Ultrastructural observations of initial damage showed disorganized protoplasm and plasmolyzed cells. Leaves on cut stems pretreated with abscisic acid for 24 hours and transferred to preservative solution containing sucrose remained healthy. We propose that sucrose accumulates in the mesophyll cell wall, thus decreasing apoplastic osmotic potential, leading to cell collapse and tissue death.
In Vitro Propagation of Eucomis autumnalis, E. comosa, and E. zambesiaca by Twin-scaling
Authors: Ault James R.
Published: February 2019

Shoot formed in vitro from twin-scale explants of Eucomis autumnalis (Mill.) Chitt., E. comosa (Houtt.) Wehrh., and E. zambesiaca Bak. cultured on Murashige and Skoog (MS) basal medium containing 0.0, 4.4, 11.1, or 22.2 μm BA and 0.0 or 5.4 μm NAA. In all three species, shoot proliferation was obtained from single-shoot explants subcultured on medium supplemented with 4.4, 11.1, or 22.2 μm BA and 0.0 or 5.4 μm NAA. Shoots of all three species rooted readily on MS medium supplemented with 0.0, 2.7, 5.4, or 10.8 mm NAA. Overall rooting percentages were 95%, 98%, and 100% for E. autumnalis, E. comosa, and E. zambesiaca, respectively. Plant survival for rooted shoots of all three species was 100% following transfer to a 1 perlite: 1 peat (v/v) medium in the greenhouse. Chemical names used: 6-benzyladenine (BA); 1-naphthaleneacetic acid (NAA).
Chromosome Numbers of Rubus Cultivars at the National Clonal Germplasm Repository
Authors: Thompson Maxine M.
Published: February 2019

Chromosome numbers were counted for 90 Rubus cultivars and selections maintained at the U.S. Dept. of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository, Corvallis, Ore. To my knowledge, 37 of the counts are new, including five that are corrections of previously published counts, 30 that are confirmations of numbers that were previously published but assumed from their parentage rather than actually counted, and 23 that are confirmations of previous counts. The basic number was 7, and 2n numbers ranged from 2x to 14x, including odd-ploids and aneuploids.
A Marker Gene in Southern Dewberry (Rubus trivialis Michx.)
Authors: Gupton Creighton L.
Published: February 2019

Anthocyanin-deficient dewberries in Mississippi were evaluated for possible use as a source of marker genes for blackberries. Ratios of normal to anthocyanin-deficient plants from test crosses suggested single-locus control of stem color, with anthocyanin deficiency a recessive trait. Its simple inheritance and easy identification in seedlings provide potential for anthocyanin deficiency (t) to be used as a marker gene in blackberry genetic studies.
Growth Response of 20 Seed Geranium Cultivars to Three Day–Night Temperature Regimes
Authors: Strefeler Mark S.
Published: February 2019

The influence of temperature and genotype on plant height, internode length, and morphological development of 20 cultivars of Pelargonium ×hortorum Bailey were determined by growing plants under one of three day–night temperature regimes (18/18C, 18/24C, and 24/18C). Temperature regime influenced internode length and plant height regardless of plant genotype. Internode length and plant height increased as the day–night temperature differential (DIF) increased from –6 to 6C. Average internode length increased from 5.3 ± 0.2 mm for –6C DIF to 6.3 ± 0.2 mm for +6C DIF. Genotypes differed for average internode length (4.2 to 8.7 mm) and plant height (54 to 95 mm). Node count increased as average daily temperature (ADT) increased. Node counts were 11.2 at 18/18C (ADT = 18), 11.9 at 24/18C (ADT = 20.3), and 12.1 at 18/24C (ADT = 21.8). Genotype × temperature interactions were not significant for the recorded traits. This study demonstrates that DIF is an effective height control strategy, regardless of geranium genotype, and that DIF combined with the selection of genetically short cultivars may eliminate the need for chemical height control in the commercial production of geraniums.
Seasonal Growing Environment Affects Quality Characteristics and Postproduction Longevity of Potted Miniature Roses
Authors: Kyalo Titus M. , Pemberton H. Brent , Zajicek Jayne M.
Published: February 2019

To assess the effects of summer-like [high-temperature long-day (HTLD)] vs. winter-like [low-temperature short-day (LTSD)] growing conditions on production quality and postproduction longevity of potted miniature roses, plants of Rosa L. `Meirutral' and `Meijikatar' were grown in growth chambers using a short-cycle production schedule (potted liners grown until root establishment, pinched, and flowered). Plants grown under the HTLD environment [30C day/21C night plus 725 μmol·m–2·s–1 photosynthetic photon flux (PPF) for 14 hours per day] had more flowering shoots than those grown under the LTSD environment (21C day/16C night plus 725 μmol·m–2·s–1 PPF for 10 hours per day). The difference is attributable to fewer blind shoots (shoots with aborted growing terminals) under HTLD, because plants in both environments had the same total number of shoots at flowering. Plants in the HTLD chamber also flowered faster, were shorter, and had smaller and lighter-colored flowers than plants in the LTSD chamber. In addition, plants under HTLD exhibited greater poststorage floral longevity and whole-plant shelf life than plants grown under LTSD conditions, regardless of cultivar, simulated shipping (storage) treatment (4 days at 16C), or stage of floral development at harvest. These results suggest benefits from summer production of potted miniature rose plants and the possibility of using a higher-temperature forcing regimen than is normally recommended for winter production.
Identification of Peach Rootstock Cultivars by RAPD Markers
Authors: Lu Zhen-Xiang , Reighard G.L. , Baird W.V. , Abbott A.G. , Rajapakse S.
Published: February 2019

Eighteen peach rootstock cultivars, most of Prunus persica (L.) Batsch, were screened for diagnostic random amplified polymorphic DNA (RAPD) markers using synthetic decamer oligonucleotide primers. Twenty of the 80 primers were informative, and 40 amplified DNA bands from the informative primers were selected as RAPD markers. Based on combined banding patterns, all 18 rootstock cultivars were identified with only six of the 20 informative primers. Cluster analysis of the 18 peach rootstock cultivars using 40 RAPD markers produced a dendrogram of genetic relatedness in good agreement with their putative pedigrees. The first major bifurcation in the dendrogram divided these rootstock cultivars into two groups according to their resistance or susceptibility to root-knot nematodes [Meloidogyne incognita (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood].
Fall-planted Cover Crops Support Good Yields of Muskmelons
Authors: Singogo Wilfred , Lamont William J. , Marr Charles W.
Published: February 2019

Four cover crops {alfalfa (Medicago sativa L. `Kansas Common'), hairy vetch (Vicia villosa Roth), Austrian winter pea [Pisum sativum subsp. arvense (L.) Poir], and winter wheat (Triticum aestivum L. `Tam 107')}, alone and in combination with feedlot beef manure at 5 t·ha–1 were evaluated for 2 years to determine whether sufficient N could be supplied solely by winter cover cropping and manure application to produce high-quality muskmelons (Cucumis melo L. `Magnum 45') in an intensive production system using plastic mulch and drip irrigation. Among the legumes, hairy vetch produced the most biomass (8.9 t·ha–1) and accumulated the most N (247 kg·ha–1). Winter wheat produced more biomass (9.8 t·ha–1) than any of the legumes but accumulated the least N (87 kg·ha–1). Melon yields produced using legume cover crops alone were similar to those receiving synthetic N fertilizer at 70 or 100 kg·ha–1. Melons produced on plots with cover crops combined with beef manure did not differ significantly in yield from those produced on plots with only cover crops. Legume cover crops alone, used with plastic mulch and drip irrigation, provided sufficient N for the production of high-quality muskmelons.
Branching of Chrysanthemum Cultivars Varies with Season, Temperature, and Photosynthetic Photon Flux
Authors: Schoellhorn Richard K. , Barrett James E. , Nell Terril A.
Published: February 2019

Effects of photosynthetic photon flux (PPF) and temperature on quantitative axillary budbreak and elongation of pinched chrysanthemum [Dendranthema ×grandiflorum (Ramat.) Kitamura] plants were studied in three experiments. In Expt. 1, 12 commercial cultivars were compared under fall and spring environmental conditions. Spring increases in lateral shoot counts were attributable to increased PPF and air temperature. Cultivars varied from 0 to 12 lateral branches per pinched plant and by as much as 60% between seasons. There was a linear relationship between lateral branches >5 cm at 3 weeks after pinching and final branch count (y = 0.407 + 0.914(x), r2 = 0.92). In Expt. 2, air was at 20 or 25C and the root zone was maintained at 5, 0, or –5C relative to air temperature. With air at 20C, lateral branch counts (3 weeks after pinch) declined by ≤50% with the medium at 15C relative to 25C. At 25C, lateral branch count was lower with medium at 30C than at 20C. Cultivars differed in their response to the treatments. Experiment 3 compared the interactions among temperature, PPF, and cultivar on lateral branch count. Depending on cultivar, the count increased the higher the PPF between 400 and 1400 μmol·m–2·s–1. Air temperature had no effect on lateral branch count. PPF had a stronger effect on lateral branch count than air temperature, and cultivars differed in their response.
Thermal Analysis of Dormant Buds of Two Muscadine Grape Cultivars and of Vitis labrusca L. `Mars'
Authors: Clark John R. , Wolf Tony K. , Warren M. Kay
Published: February 2019

Thermal analysis was used to determine if muscadine grape (Vitis rotundifolia Michx.) buds supercool and to determine the seasonal cold hardiness of several grape cultivars grown in Arkansas. Buds of the muscadine cultivars Carlos and Summit, sampled from vines grown at Clarksville, Ark., produced low-temperature exotherms consistent with the number of buds tested. Apparent hardiness of the buds increased from 5 Nov. 1993 through 7 Jan. 1994. Mean low-temperature exotherms (MLTE) were lowest on 7 Jan. and were –21.5C for `Carlos' and –23.4C for `Summit'. `Mars' buds, sampled at Clarksville, Ark., and Winchester, Va., were included in the study and increased in hardiness during the same period. MLTE for `Mars' from Arkansas were similar to those of the muscadine cultivars on 7 Jan.; however, `Mars' attained lower MLTE temperatures with vines grown in Virginia than with those in Arkansas. Location differences in hardiness of `Mars' are conjectural.
Storage Temperature Affects Sexual Potato Seed Dormancy
Authors: Pallais Noël , Santos-Rojas José , Falcón Rosario
Published: February 2019

Sexual potato (Solanum tuberosum L.) seeds require many months of afterripening in dry storage to completely lose dormancy and germinate readily at >25C. We examined the relationship between storage temperature and seed dormancy, as assessed by the percentage of germination after 4 days. Two F1 hybrid lots of `Desiree' × 7XY.1 were used; one seed lot was produced by carefully removing half of the developing tubers from the mother plant during seed development, and the control remained undisturbed. Seeds were stored with 3.4% moisture (dry-weight basis) at 10, 20, 30, 40, and 50C and were tested eight times during 29 months for daily germination at 27/40C (21/3 h) for the first 8 days, followed by 6 days at 17C. After 29 months of storage, final germination was <97% only when control seeds were stored at 50C, in which germination was 72%. Germination after 4 days increased curvilinearly with increasing storage temperature, and both seed lots similarly lost dormancy (germination >90%) after 10 months at 40C. Optimum germination levels were maintained after 29 months at 40C. Seeds stored at 50C never completely lost dormancy, and after 7 months of storage, germination at 4 days gradually decreased to zero. Dormancy was eventually lost after 29 months in most seeds stored at <40C, and differences between seed lots suggest that removing tubers from the mother plant increased dormancy. We conclude that dry potato seeds can be safely afterripened at temperatures up to 40C; lower temperatures slow the rate of dormancy loss, and higher ones are detrimental to seed quality.
Increasing Cell Size and Reducing Medium Compression Enhance Lettuce Transplant Quality and Field Production
Authors: Nicola Silvana , Cantliffe Daniel J.
Published: February 2019

`South Bay' lettuce (Lactuca sativa L.) seedlings were grown in a greenhouse during winter, spring, and fall to investigate the effect of cell size and medium compression on transplant quality and yield. Four Speedling planter flats (1.9-, 10.9-, 19.3-, 39.7-cm3 cells) and two medium compression levels [noncompressed and compressed (1.5 times in weight)] were tested. The two larger cell sizes and compression of the medium led to increased plant shoot growth. Conversely, root weight ratio [RWR = (final root dry weight ÷ final total dry weight + initial root dry weight ÷ initial total dry weight) ÷ 2] was highest with the smaller cells without medium compression. Lettuce transplants were field-grown on sand and muck soils. The larger cells delayed harvest by >2 weeks for plants grown on muck soil, but yield was unaffected. When grown on sandy soil, earliness was enhanced from plants grown in 19- and 40-cm3 cells, but head weights were not affected in the spring planting. In fall, heads were heavier for plants grown in 11-, 19-, or 40-cm3 cells compared with those from 2-cm3 cells. On sandy soil, harvest was delayed 13 days in spring and 16 days in fall for plants grown in the smallest cell size. Using the two smaller cell sizes saved medium and space in the greenhouse and increased the root growth ratio, but it led to reduced plant growth compared to using the bigger cells. Yield and earliness were more related to season and soil type than to transplant quality. On sandy soil, plants grown in 2- and 11-cm3 cells matured later, and yield was significantly decreased (8.6%) in fall by using plants from the 2-cm3 cells compared to the other sizes. From our results, compressing the medium in the cells was not justified because it is more costly and did not benefit yield in the field.
In-row Plant Spacing Affects Growth and Yield of Pepperoncini Pepper
Authors: Motsenbocker Carl E.
Published: February 2019

Pepperoncini pepper (Capsicum annuum var. annuum L. `Golden Greek') was grown at in-row spacings of 7.5, 15, 22.5, 30, and 45 cm to determine the effect of plant population on growth and fruit yield in a 2-year field study. In 1992, pepper plants grown at the 15-cm in-row spacing had the lowest plant, stem, and leaf dry weights, while plants at the lowest density (45-cm spacing) had the highest plant, leaf, and stem dry weights and the largest leaf area (LA). Of plants grown at the 7.5-cm spacing, the total yield and fruit count per hectare were higher than at the other spacings; however, fruit yield per plant was lowest. In 1993, the lowest plant and leaf dry weights and LA and highest LA index (LAI) were from plants at the 7.5-cm in-row spacing. Plants at the 45-cm spacing had the highest plant and leaf dry weight and LA and the lowest LAI. Pepper plants grown at the narrowest spacing produced the lowest early and total fruit yield per plant but the most fruit per hectare. In general, plants grown at the narrowest spacings produced the smallest plant, leaf, and stem biomass but resulted in the highest fruit yields and counts per hectare and the lowest fruit yields per plant.
Economic Responses of Broccoli and Cauliflower to Water and Nitrogen in the Desert
Authors: Sanchez C.A. , Roth R.L. , Gardner B.R. , Ayer Harry
Published: February 2019

Field studies were conducted to develop water and N response surface models for broccoli and cauliflower (Brassica oleracea L., Botrytis Group) produced in the low desert of the southwestern United States and to estimate profit maximizing combinations of water and N over a range of realistic price situations. Marketable broccoli and cauliflower yields were increased by water and N inputs in all experiments. Generalized response equations indicate maximum broccoli yields with 43 cm of water and N at 267 kg·ha–1 and maximum cauliflower yields with 65 cm of water and N at 338 kg·ha–1. Least-cost combinations of water and N changed with the costs of these inputs for yield levels below the economic maximum. However, profit maximizing N and water rates changed little regardless of input or crop prices investigated.
Stimulation of Root Formation by Thiol Compounds
Authors: Auderset Guy , Moncousin Charles , O'Rourke Jane , Morré D. James
Published: February 2019

Root formation in shoot cuttings of soybean (Glycine max L. `Williams'), mungbean (Phaseolus aureas Mdlbg.), English ivy (Hedera helix L.), and apple (Malus ×domestica Borkh. `Jork 9') was stimulated by dithiothreitol and reduced glutathione in the presence and absence of auxin (IAA) shock. In soybean, in the absence of auxin, root formation was stimulated to about the same extent by glutathione alone as with auxin alone. The roots induced by thiol compounds were longer than roots induced by auxin shock and were completely normal in appearance. Roots produced with auxin shock alone were short and exhibited characteristic auxin-induced deformations. With a combination treatment of auxin shock and thiol compounds, roots were more numerous than with either alone, somewhat longer than with auxin alone, and exhibited fewer of the usual deformations characteristic of roots grown in the presence of external auxins. The thiol compounds also were beneficial for rooting Malus shoots propagated from callus in vitro. The thiol compounds were most beneficial with older cuttings where auxin shock was often insufficient to obtain roots. In shoots where rooting was stimulated by thiol agents, shoots grew more rapidly than in those where rooting was induced by auxin shock alone. These findings suggest a use for thiol compounds alone or in combination with auxin shock to induce differentiation of root primordia as well as for stimulation of root growth. Chemical name used: indole-3-acetic acid (IAA).
Genetic and Morphological Factors Influence Mummy Berry Blight Resistance in Highbush Blueberry Cultivars
Authors: Ehlenfeldt M.K. , Stretch A.W. , Brewster V.
Published: February 2019

The resistance of 48 highbush blueberry cultivars and selections to the blight phase of mummy berry disease, incited by the fungus Monilinia vaccinii-corymbosi (Reade) Honey, was examined in relation to percent Vaccinium angustifolium Ait. ancestry, season of fruit maturity, and shoot growth during the primary infection phase. Correlations of percent blighting with percent V. angustifolium ancestry were significant across 3 years, but correlations with fruit maturity were significant in only 2 of 3 years. Correlations of percent blighting with early shoot growth were significant in both years measured, with r values of 0.54 in 1994, 0.83 in 1995, and 0.83 across years. A multiple regression found only shoot growth highly significant for susceptibility and rendered V. angustifolium ancestry and season of fruit maturity nonsignificant. Resistant cultivars exhibiting early shoot elongation suggest that resistance can be either biochemically or escape based.
Genotype and Parental Combination Influence Efficiency of Cybrid Induction in Citrus by Electrofusion
Authors: Moriguchi Takaya , Hidaka Tetsushi , Omura Mitsuo , Motomura Toshiaki , Akihama Tomoya
Published: February 2019

Interspecific hybridizations by electrofusion of embryogenic callus cells from `Seminole' tangelo (Citrus reticulata Blanco × C. paradisi Macf.), `Hazzara (Abohar)', or `Ohta' ponkan (C. reticulata Blanco) and leaf cells from `Lisbon' lemon [C. limon (L.) Burm. f.] or rough lemon (C. jambhili Lush.), respectively, were performed. Electrofusion of `Seminole' tangelo and `Lisbon' lemon, `Hazzara (Abohar)' and rough lemon, and `Ohta' ponkan and rough lemon resulted in 33, 43, and 36 plants, respectively. Seven to 10 plants in each combination were selected randomly and used to investigate nuclear and cytoplasmic genomes. Regenerated plants derived from electrofusion of `Seminole' tangelo and `Lisbon' lemon, and `Hazzara (Abohar)' and rough lemon possessed the same restriction fragment pattern for nuclear rDNA as that of the mesophyll parents and the same mitochondrial DNA (mtDNA) restriction pattern as that of the respective suspension parents, indicating that they were cybrids. In contrast, all the plants resulting from a combination between `Ohta' ponkan and rough lemon were confirmed by nuclear rDNA and mtDNA analysis to be somatic hybrids. The analysis of chromosome number supported the results of Southern blot hybridization. The results suggest that specific cell lines, parental combinations, or both can increase the efficiency of inducing cybrids in Citrus by electrofusion.
A NEW APPROACH TO VEGETABLE VARIETY EVALUATIONS FOR THE HOME GARDEN
Authors: Bitner Wade , Goodspeed Jerry , Drost Dan , McDaniel Rick
Published: February 2019

Conducting varietal evaluations for the home vegetable garden are time-consuming, labor-intensive, and costly. As a result, most are done on an observational basis only. In 1991, a horticultural training program modeled after the highly successful Master Gardener program began at the Utah State Prison, Draper, for the prison inmate population. In 1994, 12 broccoli, 20 pepper, and 30 tomato varieties commonly used in the home garden were evaluated for growth and yield at the Prison Farm. Inmates raised, tended, harvested, and compiled the trial's data and participated in all evaluations of the varieties. Extension personnel provided the instruction and regular visits to conduct the trial. The project provides instruction on vegetable production and cultivar evaluations to the inmates while providing the public with needed cultivar information for the home garden. In addition, the partnership with the inmate population limits the time inputs necessary to conduct the trials by extension staff. This project will continue and greatly expand in 1995.
RESOURCE CONSERVATION AUDITS AND OUTDOOR CLASSROOMS DECREASE WATER USAGE
Authors: Call Robert E.
Published: February 2019

The San Pedro River has been impacted by continued growth of Fort Huachuca Military Base. The San Pedro River, a riparian-migratory area, has had continuous water flow but now has intermittent water flow. The cause is cones of depression in the aquifer due to domestic well pumping. The aquifer is recharge with water from the river. Cooperative Extension has implemented Resource Conservation Audits for landowners in the lower San Pedro Valley. Also, outdoor classrooms are being constructed at three schools to educate children and community members. The goal of these programs is to educate landowners on water conservation through the use of native and adapted drought-tolerant plants, xeriscaping, irrigation efficiency, water harvesting, soil erosion, and composting. Site visits help landowners identify opportunities to reduce water use. Research-based informational brochures have been produced so landowners can plan and implement water-saving techniques on their properties. This program has been implemented using six members of the Border Volunteer Corp., part of Americorp program.
DNA FINGERPRINTING TECHNOLOGY FOR PLANT BREEDER'S RIGHTS
Authors: Luk Victor , Carlson John
Published: February 2019

DNA fingerprinting is a potentially powerful molecular genetic technique that can be used to distinguish subtle differences in genome structure among closely related genotypes, such as many horticultural varieties. A DNA fingerprinting project is currently in progress at the Univ. of British Columbia (UBC) Biotechnology Laboratory to produce a set of DNA markers and an easy, reliable, and legally recognized analysis protocol that will enable the UBC Botanical Garden Plant Introduction Scheme (PISBG) to unambiguously identify any of their released varieties, even in dormant or juvenile form, wherever it is being propagated or sold. High-quality genomic DNA was isolated from the leaf samples of six PISBG species (Anagallis monellii, Artemesia stelleriana, Clematis, Genista pilosa, Microbiota decussata, and Penstemon fruticosa) using a modified CTAB DNA isolation protocol, and further purified by cesium chloride/ethidium bromide gradient. Samples of these genomic DNA preparations (10 ng) were then amplified by a 45-cycle polymerase chain reaction (PCR) protocol using 1.5-μm 10-nucleotide primers of arbitrary nucleotide sequence that amplify a variety of sites distributed across the genome. Following the amplification, PCR products [random amplified polymorphic DNA (RAPD) markers] were separated by agarose gel electrophoresis and visualized by ethidium bromide staining. More than 70% of the 51 primers tested so far generated distinctive banding patterns (2–11 bands) with DNA samples from each species. Subtle changes in the genome or differences between genotypes can be detected by screening a series of such primers against DNA samples from the genotypes in question. Once a RAPD primer has been identified that consistently generates a different banding pattern between genotypes, it can be used as an identification tool for discriminating between those genotypes at any time in the future.
Cranberry Evapotranspiration
Authors: Hattendorf M.J. , Davenport J.R.
Published: February 2019

Cranberry (Vaccinium macrocarpon Ait.) evapotranspiration (ET) has not been documented. Micrometeorological techniques based on canopy temperature minus air temperature were used to estimate ET on `Stevens' and `Crowley' cranberry at Long Beach (lat. ≈46°20′N, long. 124°W) and Grayland (lat. ≈46°47′N, long. 124°W), Wash., in 1991 and 1992, respectively. Cranberry ET was 55% of Priestley–Taylor reference ET and ranged from <0.5 to >4 mm·d–1. The Priestley–Taylor reference ET was a very good predictor of cranberry ET (r2 = 0.795). Running 7-day cumulative ET ranged from 7 to 17 mm·week–1.
Delaying Harvest Improves Bell Pepper Yield
Authors: Russo V.M.
Published: February 2019

Delaying or limiting the number of harvests could improve yield and reduce inputs in bell pepper (Capsicum annuum var. annuum L.) production. Fruit were harvested in a variety of timing methods, which include three times over 14 days with the second and third harvests occurring 7 and 14 days after the first. Fruit from other plants were harvested once at either 7 or 14 days after the first harvest from plants that had several harvests. Fruit length was not affected by time of harvest. Number of marketable fruit, fruit width at the shoulder, endocarp thickness, and fruit volume were increased in fruit from plants harvested once. Marketable yields from plants with a single harvest were, on average, 1.5-fold higher than those from plants with several harvests. Delaying harvests improved fruit quality and quantity. Limiting number of harvests would reduce passes through the field and the associated costs, possibly improving net income.