bluuebunny/crossref_metadata_2025 huggingface dataset:
Eliminating Thrips From In Vitro Shoot Cultures of Apple with Insecticides
Authors: Bhagwat Basdeo , Lane W. David
Published: February 2019

The insecticides acephate, dichlorvos, and imidacloprid were assayed, using in vitro shoot cultures of apple (Malus×domestica Borkh.), to determine their phytotoxicity at several concentrations and their effectiveness for eradication of the Western Flower Thrip (Frankliniella occidentalis, Pergande) from infested apple shoot cultures. Commercial formulations of acephate (Orthene), dichlorvos (VaportapeII), and imidacloprid (Admire) and a technical grade of imidacloprid were used in the experiments. For acephate and imidacloprid, concentrations of 1 to 80 mg·L-1 a.i. in shoot culture medium were used, while for dichlorvos, a fumigant, particles of the formulated product containing concentrations of 0.7 to 6.4 mg a.i. were suspended in the head space of the 500-mL glass culture jar. Acephate, dichlorvos, and the technical grade of imidacloprid did not cause phytotoxicity and growth of shoot cultures was unaffected at all treatment concentrations tested after a 6-week treatment period. Imidacloprid (20 to 80 mg·L-1 of the commercial formulation) caused chlorosis at the end of the 6-week treatment period. None of the treatments tested resulted in the death of shoots. Thrips were eradicated by acephate or imidacloprid treatments of 5 mg·L-1 and by dichlorvos treatment of 0.7 mg per 500-mL culture jar. Shoot cultures grew normally after the treatment period. Chemical names used: O,S-dimethyl acetylphosphoramidothioate (acephate), 2,2- dichlorovinyl dimethyl phosphate(dichlorvos),1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine (imidacloprid).
Rust-spotted North American Ginseng Roots: Phenolic, Antioxidant, Ginsenoside, and Mineral Nutrient Content
Authors: Campeau Cindy , Proctor John T.A. , Jackson Chung-Ja C. , Rupasinghe H.P. Vasantha
Published: February 2019

Rusty root is a major problem in ginseng production worldwide as it reduces root quality. Full characterization of rusty root is unavailable, and necessary for development of effective control measures. A comparison of phenolics, antioxidants, ginsenosides, and mineral nutrient content of rusted and non-rusted tissue from disease-free roots is reported. Periderm and adjacent tissues of 4-year-old North American ginseng roots (Panax quinquefolius L.) had a total phenolic content of 3.05 mg·g-1 dry weight (as gallic acid equivalents), which was increased 53% by rust-spotting. Antioxidant activity increased with phenolic content and was 33% higher (3.6 vs. 2.7 mg·g-1 dry weight as ascorbic acid equivalents) in rust-spotted tissue. Total ginsenoside content was higher (139.1 vs. 119.4 mg·g-1) in healthy than in rust-spotted tissue, the latter reflecting a significant decrease in four of the major ginsenosides (Rb2, Rc, Rd, and Re). The Rg group was higher (38.0 vs. 29.9 mg·g-1) in healthy than in rust-spotted tissue. The mineral elements N, P, Ca, Mg, Zn, Mn, and Fe were higher, and K lower (21%) in rust-spotted tissue than in healthy tissue.
Rapid Excision Apparatus for Plants (REAPer): Design, Implementation, and Functionality
Authors: Wall Gerard W. , McDonnell Guy
Published: February 2019

Net primary productivity of a botanical is often determined by monitoring gas exchange rates (i.e., CO2, H2O) in a controlled-environment cuvette. Because atmospheric conditions (i.e., incident photon flux density, air temperature, and water vapor pressure) change within a day, whereas edaphic (i.e., soil-water content and nutrient availability) conditions change across days, experimental results obtained between treatment variants can often be confounded within the sample interval. Consequently, in order to obtain a “snapshot” of the CO2 and H2O flux of a botanical across treatment variants, all in situ measurements must be made within a discrete interval. One approach would be to use multiple cuvettes to measure CO2 and H2O flux across all treatment variants simultaneously. But, this would be expensive in both equipment and personnel cost. A more economical approach would be to rapidly excise a botanical from each treatment variant within a discrete interval and store them under exacting steady-state laboratory conditions for in vivo rather than in situ studies. However, this too can be problematic, because in order to excise a botanical a standard operating procedure (SOP) is required. Hence, a need exists for a Rapid Excision Apparatus for Plants (REAPer). Following the SOP of the REAPer enables personnel to excise a botanical across all treatment variants within a discrete interval, while maintaining xylem conductance, minimizing mechanical damage, and providing a uniform sample for in vivo rather then in situ studies. This work describes the design, implementation, and functionality of the REAPer, its application in basic research and development, and its potential applications in the commercial floral and horticultural industries.
Prevalence of Citrus Tristeza Virus in Florida Citrus Nurseries and Scion Groves
Authors: Powell Charles A. , Pelosi Robert R. , Rundell Phyllis A.
Published: February 2019

None of 4190 sweet orange [Citrus sinensis (L.) Osb.] nursery trees of `Hamlin', `Midsweet', `Navel', and `Valencia' sampled from five Florida citrus nurseries were infected with a decline-inducing isolate of citrus tristeza virus (CTV) as judged by enzyme-linked immunosorbent assay (ELISA) using isolate-specific monoclonal antibodies. Two of the nurseries had a relatively high level of infection (37% to 100% of composite samples containing tissue from 10 trees) with nondecline-inducing (mild) isolates of CTV, depending on the cultivar. Three of the nurseries had a lower incidence of mild CTV (0% to 22% of 10 tree composite samples). No nursery was CTV-free. ELISA of individual trees used as budwood sources by the nurseries revealed that one tree out of 260 tested contained decline-inducing CTV, and 83 contained mild CTV. These results suggest that the budwood certification program adopted in 1997 has virtually eliminated decline-inducing CTV from commercial budwood supplies.
Chromosome Homology in Tetraploid Southern Highbush × Vaccinium elliottii Hybrids
Authors: Wenslaff T.F. , Lyrene P.M.
Published: February 2019

A yellow-leaf seedling marker, r, was used to determine if there was preferential chromosome pairing in a group of tetraploid southern highbush blueberry hybrids. Plants with four copies of r (no copies of R) fail to develop anthocyanins, and cotyledons, hypocotyls, leaves, stems, and other vegetative tissues have a bright yellow-green color. In the hybrids that were studied, two genomes were from the diploid wild species, V. elliottii Chapman, and both carried the recessive marker r. The other two genomes were from southern highbush cultivars and both carried the dominant wildtype allele, R. When RRrr hybrids were intercrossed or crossed to rrrr yellow-leaf plants, the number of yellowleaf rrrr seedlings obtained usually equalled or exceeded the number predicted from nonpreferential chromosome pairing. Since rr gametes can only be produced by RRrr plants when R and r chromosomes pair at Meiosis I, there was no evidence that the chromosomes derived from V. elliottii were pairing at a higher-than-random rate.
Far-red Light Absorbing Photoselective Plastic Films Affect Growth and Flowering of Chrysanthemum Cultivars
Authors: Li Shumin , Rajapakse Nihal C. , Young Roy E.
Published: February 2019

Growth and development responses of three chrysanthemum [Dendranthema ×grandiflora (Ramat.) Kitam. (syn. Chrysanthemum ×morifolium Ramat.)] cultivars (`Bright Golden Anne', `Iridon', and `Yellow Snowdon') to photoselective plastic films with varying concentrations (0 to 0.22 g·m-2) of a far-red (FR) light absorbing dye were investigated under greenhouse conditions. Photoselective films reduced stem elongation of all three cultivars. The greater the dye concentration in the film, the greater and earlier the reduction in stem elongation. After 4 weeks, `Yellow Snowden', `Bright Golden Anne', and `Iridon' plants grown under the film with the highest dye concentration (Afr3 film) were 21%, 26%, and 26% shorter than control plants, respectively. Height reduction under photoselective films was caused by shorter internodes. Photoselective covers were most effective in reducing the stem elongation during the early vegetative period. Following transition to the reproductive stage, weekly stem elongation rates were reduced. At the time of flowering, `Yellow Snowden', `Bright Golden Anne', and `Iridon' plants grown under the film with the highest dye concentration (Afr3 film) were 12%, 7%, and 14% short9er than control plants, respectively. Photoselective covers did not affect the anthesis of chrysanthemum cultivars, but resulted in a 10% to 14% reduction in flower diameter depending on the cultivar. Although the films with higher dye concentration were more effective in reducing stem elongation of chrysanthemum, increased dye concentration reduced light transmission. Thus, photoselective covers that reduce light transmission over 25% would not be suitable for commercial production.
Plant Compounds in Pachysandra terminalis That Act as Feeding Deterrents to Prairie Voles
Authors: Curtis Paul D. , Rowland Elizabeth D. , Harribal Meena M. , Curtis Gwen B. , Renwick J. Alan , Martin-Rehrmann Mathew D. , Good George L.
Published: February 2019

Many plants have mechanisms of physical or chemical resistance that protect them from herbivores in their environment. The ornamental plant Pachysandra terminalis Sieb. and Zucc is highly unpalatable to voles, but the nature of this resistance is not fully understood. Extracts of P. terminalis were prepared to determine the extent to which chemical constituents could account for its avoidance by voles. A bioassay in which samples were mixed with applesauce showed that ethanolic extracts were highly deterrent to captive prairie voles (Microtus ochrogaster Wagner, 1842). Bioassay-guided fractionation of ethanol extracts showed that antifeedant activity was present in both polar and non-polar fractions. Further separation of each fraction by open column chromatography and high pressure liquid chromatography revealed that combinations of compounds were responsible for the deterrent activity. Preliminary ultraviolet and mass spectroscopic analyses indicated that steroidal alkaloids that are characteristic of this plant are likely to be involved.
A Simple Model for Rapid and Nondestructive Estimation of Bell Pepper Fruit Volume
Authors: Ngouajio Mathieu , Kirk William , Goldy Ronald
Published: February 2019

Nondestructive estimates of fruit volume are used for yield prediction. They are also used to study the relationship between fruit expansion rate and susceptibility to diseases or physiological disorders such as fruit cracking. A model relating bell pepper (Capsicum annuum) fruit diameter and length to its volume was derived using the equation of the volume of a sphere as the starting point. The model has the following formula: VF = KD2 Lπ/6, where VF is fruit volume, K is the shape factor that varies with fruit type, D is fruit diameter, and L is fruit length. The model is simple, easy to use in the field, and may account for variations in fruit shape. Regression analyses using actual fruit volume of bell pepper measured with the water displacement method and the volume estimated using different equations showed that accuracy of the new model is comparable to that of one of the best models previously proposed. However, because the model is less complex than previous models, it is easier to use in the field.
Peach Fruit Weight, Yield, and Crop Value Are Affected by Number of Fruiting Shoots per Tree
Authors: Marini Richard P.
Published: February 2019

Mature `Norman'peach [Prunus persica (L.) Batsch] trees were dormant pruned to retain a range of fruiting shoots per tree (71 to 250) during 3 years from 1997 to 1999. About 40 days after bloom each year, fruits on all trees were thinned to similar crop loads, so only the number of fruits per shoot varied. Fruit set and number of fruits removed by hand thinning were positively related to number of fruiting shoots retained per tree. Number of fruits harvested per tree was not related to number of shoots per tree, whereas average fruit weight at thinning and at harvest, and crop value per tree were negatively related to the number of shoots retained per tree. These results indicate that commercial peach producers should consider modifying pruning and thinning strategies. Rather than retaining a large number of fruiting shoots per tree and hand thinning to distribute fruits every 15 to 20 cm along each fruiting shoot, producers should first determine the number of fruits that trees of a given cultivar can adequately size and then perform the thinning operation to obtain the desired crop load. The number of fruiting shoots retained per tree during pruning should be one-fifth to one-seventh of the number of fruits desired per tree, so that five to seven fruits per fruiting shoot are retained after hand thinning.
Breaking Dormancy in Red Raspberries for Greenhouse Production
Authors: Dale Adam , Sample Angela , King Elizabeth
Published: February 2019

Experiments were conducted to determine the chilling temperature and length of time required to break dormancy in red raspberry (Rubus idaeus L.). Five weeks of 7 °C with no light was sufficient to break dormancy in `Autumn Britten', `Nova', `Polana', and `Tulameen', while at least 8 weeks were needed for `Titan'. Comparisons with various chilling unit models allowed a model to be developed that could account for the observed chilling variation. In this model, each chilling hour was weighted as follows: below 5.6 °C = 1; 5.7 to 8.0 °C = 0.5; 8.1 to 11 °C = 0; 11.1 to 13 °C = -0.5; and >13 °C = -1. Plants of `Nova' and `Tulameen' chilled before flower initiation occurred, broke dormancy, and the resulting lateral branches remained vegetative. When the plants were fruited in the greenhouse, we were able to produce a second crop on the fruiting canes when the lateral branches that had fruited were removed. These experiments show that raspberries can be manipulated so that plants chilled in mid-September in the Northern Hemisphere can be induced to fruit by the beginning of January.
Sensitivity and Variability of Maximum Trunk Shrinkage, Midday Stem Water Potential, and Transpiration Rate in Response to Withholding Irrigation from Field-grown Apple Trees
Authors: Naor A. , Cohen S.
Published: February 2019

The sensitivity of water stress indicators to changing moisture availability, and their variability, determine the number of measurements that should be taken in order to represent properly plant water status in a certain orchard. In the present study we examined the sensitivity and variability of maximum daily trunk shrinkage, midday stem water potential, and daily transpiration rate in their responses to withholding irrigation from field-grown drip-irrigated `Golden delicious' apple trees in a commercial orchard. Irrigation was withheld from the stressed trees for 17 days starting in mid-July, and the control trees were irrigated daily at 100% of the “Class A” pan evaporation rate. The courses of daily transpiration rate, maximum trunk shrinkage, and midday stem water potential before and 10 days after the drying period were similar in the control and the stressed trees. Highly significant differences between the stressed and the control trees in their midday stem water potentials were apparent from the early stages of the stress period. Daily transpiration rate and maximum daily shrinkage were more variable than midday stem water potential, and differences between treatments became significant only after measurements were expressed relative to the initial values before irrigation was witheld. Differences between treatments (as percentages of the values obtained for the control trees) increased after irrigation stopped where these differences were greatest for maximum daily shrinkage, which reached 90%; moderate for stem water potential (60%); and least for daily transpiration rate, for which the differences remained below 20%. Our data show that the choice of a certain water stress indicator should be based on both the sensitivity to changing moisture availability and the degree of variability. Possible reasons for the different sensitivity to moisture availability and the different variability between the water stress indicators under study are discussed.
Pigment Distribution and Epidermal Cell Shape in Dendrobium Species and Hybrids
Authors: Mudalige Rasika G. , Kuehnle Adelheid R. , Amore Teresita D.
Published: February 2019

Perianths of 34 Dendrobium Sw. species and hybrids were examined to elucidate the roles of pigment distribution and shape of upper epidermal cells in determining color intensity, perception, and visual texture. Color intensity was determined by the spatial localization of anthocyanin in tissue layers, i.e., in the epidermal, subepidermal, and mesophyll layers, as well as by distribution of pigmented cells within the tissue layer. Anthocyanins were confined to the epidermal layer or subepidermal layer in flowers with low color intensity, whereas they were also in several layers of mesophyll in more intensely colored flowers. Striped patterns on the perianth were due to the restriction of pigment to cells surrounding the vascular bundles. Color perception is influenced by the presence or absence of carotenoids, which when present, were distributed in all cell layers. Anthocyanins in combination with carotenoids resulted in a variety of flower colors ranging from red, maroon, bronze to brown, depending on the relative location of the two pigments. Four types of epidermal cell shapes were identified in Dendrobium flowers: flat, dome, elongated dome, and papillate. Epidermal cell shape and cell packing in the mesophyll affected the visual texture. Petals and sepals with flat cells and a tightly packed mesophyll had a glossy texture, whereas dome cells and loosely packed mesophyll contributed a velvety texture. The labella in the majority of flowers examined had a complex epidermis with more than one epidermal cell shape, predominantly papillate epidermal cells.
Pecan Nut and Kernel Traits Are Related to Shelling Efficiency
Authors: Thompson T.E. , Grauke L.J.
Published: February 2019

The U.S. Dept. of Agriculture, Agricultural Research Service conducts the largest and oldest pecan [Carya illinoinensis (Wangenh.) K. Koch] breeding program in the world. This program evaluates thousands of nut and kernel samples each year using a standard nut and kernel evaluation system developed and refined for more than 70 years. This report relates the effectiveness of these evaluations to commercial shelling efficiency by direct comparison of these data to commercially shelled samples from the same clone performance test. Visual ratings of shelled kernel samples (1-5, with 1 = best) were correlated with time required to hand clean kernel samples (r = 0.55). As percent kernel increased, visual ratings of shelled kernels improved (decreased) (r = -0.73). More intact halves were recovered from shelled samples with the best (lowest) visual ratings (r = -0.67). Conversely, fewer pieces of any size were present in samples with the best visual ratings. Visual ratings improved as nut density decreased (r = 0.33). Samples with the lightest kernel color also had the best visual ratings (r = 0.38). These data show that the standard U.S. Dept. of Agriculture pecan nut and kernel evaluation system needs to be refined by modifying selection pressure placed on various standard evaluation traits.
Seashore Paspalum Response to Trinexapac-ethyl and Paclobutrazol
Authors: Ferrell Jason A. , Murphy Timothy R. , Duncan Ron R. , Vencill William K.
Published: February 2019

The usage of seashore paspalum (Paspalum vaginatum Swartz) as a recreational turf has increased in recent years. On similar species, such as bermudagrass (Cynodon ssp.), plant growth regulators (PGRs) are used to decrease mowing frequency. However, no data currently exists for the use of PGRs on seashore paspalum. Therefore, field experiments were conducted over 2 years to determine the effects of trinexapac-ethyl and paclobutrazol on seashore paspalum. Paclobutrazol was non-injurious to turf when applied sequentially, 4 weeks apart, at rates as high as 0.56 kg·ha-1 of a.i. However, these same treatments failed to reduce vegetative growth. Conversely, trinexapac-ethyl treatments produced unacceptable injury (>15%) when applied sequentially, 4 weeks apart, at rates higher than 0.19 kg·ha-1 of a.i. As trinexapac-ethyl rates were reduced to ≤0.14 kg·ha-1 of a.i., injury was reduced to ≤ 12% while vegetative growth was suppressed to ≥59%, relative to nontreated seashore paspalum. Therefore, trinexapac-ethyl can serve as an effective option for those managing seashore paspalum turf areas. Chemical names used: 4-(Cyclopropyl-α-hydroxymethylene)-3,5-dioxo-cyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl); (+/-)-R*,R*-β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazol-1-ethanol (paclobutrazol).
Lead Uptake by Roots of Four Turfgrass Species in Hydroponic Cultures
Authors: Qu R.L. , Li D. , Du R. , Qu R.
Published: February 2019

Turfgrass, which is widely grown and produces a large amount of biomass, could act as a sink for industrial pollutants in urban and suburban regions. Little research has been conducted regarding heavy metal uptake by turfgrasses. The objective of this study was to evaluate root uptake of lead (Pb) in four turfgrass species. Grasses were grown hydroponically in solutions containing from 0 to 450 mg·L-1 Pb, at either pH 4.5 or 5.5, for 4 or 8 days. A significant quadratic relation existed between Pb accumulation in roots and solution Pb concentration within the tested range. The maximum Pb accumulation in roots of the four species was in the range of 20 mg·g-1 dry root weight. Tall fescue (Festuca arundinacea Schreb.) and Spartina patens survived at 450 mg·L-1 Pb solution without showing obvious damage while centipedegrass [Eremochloa ophiuroides (Munro) Hack.] and buffalograss [Buchlöe dactyloides (Nutt.) Engelm.] deteriorated or died at this concentration. This study showed that turfgrass plants can absorb heavy metals efficiently and tolerate high Pb concentration in hydroponic solutions and thus may have a potential use in environmental remediation as a biological extractor of lead.
Ultra-high CO2 Levels Enhance Loblolly Pine Seedling Growth, Morphogenesis, and Secondary Metabolism
Authors: Tisserat B. , Vaughn S.F.
Published: February 2019

The growth (fresh weight), morphogenesis (number of needles and roots and shoot length) and monoterpene (α- and β-pinene) levels were determined in Pinus taeda L. (loblolly pine) seedlings exposed to 350, 1,500, 3,000, 10,000, or 30,000 μmol·mol-1 CO2 for 30 days under greenhouse conditions. Seedlings exposed to ultra-high levels (i.e., ≥3000 μmol·mol-1 CO2) had significantly higher (P = 0.05) fresh weight, needle number, root number, and shoot lengths compared to seedlings grown under ambient air (350 μmol·mol-1 CO2). Seedling fresh weights, number of roots, shoot length, and number of needles from pine seedlings supplemented with 10,000 μmol·mol-1 CO2 increased 341%, 200%, 74%, and 75 %, respectively, when compared to seedlings grown without any CO2 enrichment. In addition, α- and β-pinene levels in seedlings increased under ultra-high CO2 levels. The dominant monoterpene, α-pinene, increased 57% in seedlings grown under 10,000 μmol·mol-1 CO2 compared to levels obtained under 350 μmol·mol-1 CO2.
Nitrogen and Phosphorus Availability and Weed Suppression from Composted Poultry Litter Applied as Mulch in a Peach Orchard
Authors: Preusch P.L. , Tworkoski T.J.
Published: February 2019

Composted poultry litter (CPL) may be applied as a mulch in fruit orchards to manage waste and to provide a slow-release nutrient source and weed control. With proper management, poultry manure and bedding (litter) can prevent environmental degradation, such as hypoxia in aquatic communities. Peach (Prunus persica L. `Sunhigh') plots all received preemergence herbicides in May and then the following treatments in June 1998: commercial fertilizer (N at 15 g·m-2), low rate CPL (N at 15 g·m-2 as CPL at 2.9 kg·m-2), high rate CPL (N at 62 g·m-2 as CPL at 11.6 kg·m-2), and no fertilizer or mulch control. Weeds were completely controlled by mulch and herbicide during 1998 but not during 1999. By Sept. 1999, the high rate of CPL had only 27% weed cover compared with 86% for the commercial fertilizer-treated plots. Soil N was highest (NH4-N and NO3-N at 16.4 and 18.6 mg·kg-1 soil, respectively) in plots treated with commercial fertilizer, 6 weeks after treatment (WAT). Soil N did not differ among the two CPL treatments and the control at any time. At the high rate of CPL, there was NH4-N and NO3-N at 3.2 and 0.7 mg·kg-1 soil, respectively, at 6 WAT. Water-extractable P (WEP) in the soil did not differ among the CPL and commercial fertilizer treatments at 6 WAT (P at §14 mg·kg-1 soil). However, at 47 WAT, plots with the high rate of CPL had significantly higher WEP, with P at 30 mg·kg-1 soil vs. 14 mg·kg-1 soil in plots treated with commercial fertilizer. High applications of CPL could elevate P in surface runoff to levels that cause environmental degradation. In general, Mehlich 1-extractable P (MEP) did not differ among the CPL- and fertilizer-treated plots (averaging P at 45 mg·kg-1 soil). MEP was lowest in control plots (averaging P at 21 mg·kg-1 soil). Results indicate that CPL could be used as a weed suppressant without adversely affecting N release to the environment; however, P concentration in soil water may be problematic.
How Well Do Critical Nitrogen Concentrations Work for Cabbage, Carrot, and Onion Crops?
Authors: Westerveld Sean M. , McKeown Alan W. , Scott-Dupree Cynthia D. , McDonald Mary Ruth
Published: February 2019

With the introduction of nutrient management legislation in Ontario, there is a need to improve the efficiency of nitrogen (N) utilization. One possibility is to use critical nutrient concentrations in plant tissue as an indicator of the N nutritional status of the crop. Plant tissue analysis was used to determine the total N and nitrate-N (NO3-N) concentrations of cabbage (Brassica oleracea var. capitata L.), carrots (Daucus carota L.), and onions (Allium cepa L.) grown in Ontario. The tissue samples were collected from plants as part of N fertilization studies from 1999 to 2001 on the organic soils in the Holland/Bradford Marsh area and the mineral soils near Simcoe, Ontario. Yield was assessed at harvest as an indicator of the N requirement of the crop. Testing the usefulness of critical NO3-N concentrations to indicate the N requirement of the crop was problematic because: 1) few published references were available to indicate a critical level of NO3-N in these crops; 2) tissue NO3-N concentrations were highly variable; and 3) field data rarely matched published references. Tissue total N concentrations from the trials corresponded to published critical N concentrations in some cases, however, the use of published critical N concentrations would have resulted in either over or under-application of fertilizer to the crops. Cultivar, soil type, and climate were shown to affect tissue N concentrations. Based on these results it was concluded that local research and field verification is required before tissue N critical nutrient concentrations become useful for determining fertilizer needs of cabbage, carrots, and onions grown in Ontario.
Biological Activities and Contents of Scopolin and Scopoletin in Sweetpotato Clones
Authors: Peterson Joseph K. , Harrison Howard F. , Jackson D. Michael , Snook Maurice E.
Published: February 2019

Periderm and cortex tissues of 14 genetically diverse sweetpotato [Ipomoea batatas (L.) Lam.] clones were grown under low stress conditions and analyzed for their content of scopoletin ((7-hydroxy-6-methoxycoumarin) and scopolin (7-glucosylscopoletin). A wide range of concentrations of both compounds was found in both tissues. The two compounds were tested in vitro for their biological activity (concentration-activity relationships) using several bio assays: germination of proso-millet (Panicum milliaceum L.) seed; mycelial growth of the sweetpotato fungal pathogens Fusarium oxysporum Schlecht. f. sp. batatas (Wollenw.) Snyd. & Hans, F. solani (Sacc.) Mart., Lasiodiplodia theobromae (Pat.) Griffon & Maubl., and Rhizopus stolonifer (Ehr. ex Fr.) Lind; and growth and mortality of diamondback moth[Plutella xylostella (L.)] larvae on artificial diet. The glycoside scopolin showed little activity, except moderate inhibition of F. oxysporum. The aglycone scopoletin inhibited seed germination and larval growth; however, at much higher concentrations than were measured in the tissues. Mycelial growth of the four pathogenic fungi, however, was inhibited at concentrations occurring in some sweetpotato clones.
Lychee Quality After Hot-water Immersion and X-ray Irradiation Quarantine Treatments
Authors: Follett Peter A. , Sanxter Suzanne S.
Published: February 2019

Hot-water immersion and irradiation quarantine treatments are used to disinfest lychee (Litchi chinensis Sonn.) of fruit flies and other pests before export from Hawaii to the U.S. mainland. In the first experiment, one day after harvest, `Kaimana' lychee fruit were subjected to 1) hot-water immersion at 49.0 °C for 20 minutes, 2) irradiation treatment at a minimum absorbed dose of 400 Gy, or 3) left untreated as controls. Fruit were then stored at 2 or 5 °C in perforated plastic bags, and quality attributes were evaluated after 8 days. Lychee fruit treated with hot-water immersion were darker (lower lightness) and less intensely colored (lower chroma) than irradiated or untreated fruits at both storage temperatures. Fruit stored at 2 °C were darker (lower lightness) than fruit stored at 5 °C, but fruit held at 5 °C had greater weight loss. External appearance of fruit treated with hot-water immersion was rated as unacceptable, whereas irradiated and nontreated fruit were rated as acceptable. Taste of fruit was rated as acceptable in all treatments. In the second experiment, lychee fruit were subjected to 1) hot-water immersion at 48, 48.5, or 49 °C for 20 minutes or 2) irradiation at 400 Gy, or 3) left untreated as controls. Fruit were then stored at 4 °C in perforated plastic bags, and external appearance of the pericarp was evaluated after 1, 2, 5, 7, 8, and 9 days. Pericarp darkening was more rapid for lychee fruit treated with hot-water immersion than irradiated or control fruit, and the degree of quality loss increased with increasing hot-water immersion temperature. Overall, under these experimental conditions, irradiation was superior to hot-water immersion as a quarantine treatment on the basis of fruit quality maintenance.
Carotenoid Profiles of Potato Breeding Lines and Selected Cultivars
Authors: Nesterenko Sergey , Sink Kenneth C.
Published: February 2019

Lutein and zeaxanthin are becoming established as carotenoids beneficial for protection against common age-associated eye diseases. Thus, 15 potato (Solanum tuberosum subsp. tuberosum L.) breeding lines, cultivars Atlantic, Spunta, and Yukon Gold; and orange flesh OR-4 were surveyed for carotenoid profiles. Seven carotenoids, including violaxanthin, neoaxanthin, antheraxanthin, lutein, zeaxanthin, β-cryptoaxanthin, and β-carotene, were identified in the 19 genotypes. Violaxanthin and lutein were the prominent carotenoids detected in all genotypes studied. Neoaxanthin and antheraxanthin were found in 26% and 63% of the genotypes, respectively. β-Cryptoaxanthin, zeaxanthin, and β-carotene were found in only 5%, 10%, and 16% of the genotypes, respectively. Lutein varied from 19.8 to 119.0 μg·100 g-1 fresh weight across the 15 white- or yellow-flesh breeding lines. In contrast, zeaxanthin was detected at a low level in only one breeding line and at high level in OR-4. The three cultivars had profiles typical of yellow-flesh potatoes `Spunta' and `Yukon Gold'; while `Atlantic' had a typical white-flesh profile and a trace of zeaxanthin. The carotenoid baseline data established in this study provide information for activities to enhance potato for lutein and zeaxanthin.
Probable Qualitative Inheritance of Full Red Skin Color in Peach
Authors: Beckman T.G. , Sherman W.B.
Published: February 2019

Recently observed hybrid populations of peach [Prunus persica (L.) Batsch] provide evidence for the presence of a single gene controlling full red skin color. The fruit of seedling populations of `UFQueen' × `Springbaby', `UFQueen' × `Springprince, FL93-12C × `Springprince, FL92-22C × BY79P1945, and AP98-18 o.p. were rated for percent red skin color at full maturity. At this stage of development, “full red” phenotypes display red color over the entire surface of the fruit, including the stem cavity and portions of the fruit shaded by leaves or stems. Both crosses with `UFQueen yielded populations displaying a 1:1 segregation ration for partial red: full red. All other crosses produced populations that did not deviate significantly from a 3:1 segregation ratio. These data are consistent with the hypothesis that the “full red” phenotype is a single gene recessive trait. We propose the gene symbols of fr and Fr for the recessive full red and dominant partial red (wild-type) alleles, respectively.
Budbreak Number in Apple Seedlings as Selection Criterion for Improved Adaptability to Mild Winter Climates
Authors: Labuschagné Iwan F. , Louw J.H. , Schmidt Karin , Sadie Annalene
Published: February 2019

Absence or long delay of budbreak, also known as prolonged dormancy, is the most important symptom during incomplete dormancy. Budbreak number was evaluated to quantify seedling response to chilling and selection on excised and intact 1-year-old apple (Malus ×domestica Borkh.) seedlings under controlled and natural environmental conditions. Indices based on: 1) the number and distribution of budbreak (prolonged dormancy grade = PDG); 2) the number of buds breaking, including shoot length with increased budbreak as part of the calculation (prolonged dormancy index = PDI); and 3) budbreak number per 100-cm shoot (NB) were tested in association with budbreak time (TB). The indices expressed the effects of cold treatments that induce earlier and higher numbers of budbreak. PDI and NB, but not PDG, identified families with increased budbreak. Seedlings with high PDG and NB were also associated with families in which high chill requiring parents were used, indicating that TB as pre-selection criterion may fail to identify seedlings with increased budbreak. Response to pre-selection for increased budbreak using PDG could be verified with the PDS and NB indices in seedlings and seedling clones. The NB of intact 1-year-old shoots under natural conditions is recommended as a pre-selection criterion against prolonged dormancy in suboptimal winter conditions.
×Schimlinia floribunda (Theaceae): A New Intergeneric Hybrid between Franklinia alatamaha and Schima argentea
Authors: Ranney Thomas G. , Eaker Thomas A. , Fantz Paul R. , Parks Clifford R.
Published: February 2019

Franklinia alatamaha Bartr. ex Marshall represents a monotypic genus that was originally discovered in Georgia, but is now considered extinct in the wild and is maintained only in cultivation. Although Franklinia is very ornamental, with showy flowers and crimson/maroon fall foliage color, it tends to be short lived when grown as a landscape tree and is known to be susceptible to a variety of root pathogens. Schima argentea Pritz is an evergreen tree that is native to Asia and is valued for its glossy foliage, late-summer flowers, and broad adaptability in mild climates. Hybridization between these genera could potentially combine the cold hardiness and desirable ornamental characteristics of F. alatamaha with the greater adaptability, utility, and genetic diversity of S. argentea. Controlled crosses between F. alatamaha and S. argentea resulted in new intergeneric hybrid progeny. A morphological comparison of parents and the progeny is presented. ×Schimlinia floribunda Ranney and Fantz (mountain schimlinia) is proposed as the name for these hybrids and is validated with a Latin diagnosis.
Granulometric Characterization and Alteration during Composting of Industrial Cork Residue for Use as a Growing Medium
Authors: Carmona E. , Ordovás J. , Moreno M.T. , Avilés M. , Aguado M.T. , Ortega M.C.
Published: February 2019

This work describes the granulometry of industrial cork residue (bark of Quercus suber L.) and its possible alteration during composting to eliminate the high content of phytotoxic substances. Because of the differences in density of the different-sized cork particles, expression of the granulometric distribution in relation to volume reflected the size distribution more accurately than its expression in relation to weight. As a consequence, predictions of the physical and hydrological behavior of the substrate, deduced from its granulometry, were more accurate when this was calculated in relation to volume. Objective parameters used for textural comparison, such as the geometric mean (dg) and standard deviation of particle size (σg), which were previously used in soils, were tested. These permit the estimation of small differences in the particle size of different lots or the granulometric alteration occurring during composting. With the same purpose, a new diagram of textures for the classification of granular substrates was also studied.
Container Production of Prostrate Garden Chrysanthemums
Authors: Anderson Neil O. , Gesick Esther
Published: February 2019

The prostrate plant habit may be an important new trait for the garden chrysanthemum [Dendranthema ×grandiflora Tzvelv. (=Chrysanthemum ×morifolium Ramatuelle)] market. Fifteen prostrate and non-prostrate genotypes were evaluated in production trials, using Regular and Fast Cropping systems. At flowering, the following traits were evaluated: days to flowering (first, 50%, 100%), flowering duration, pot coverage, plant uniformity, and salability. Salability was measured with consumer evaluations. Genotypes differed significantly for days to first and 100% flowering, flowering duration, plant height, plant width, and plant uniformity. Cropping systems were significantly different for days to first and 100% flowering. `Snowscape', a semi-prostrate day-neutral cultivar, was earlier than all other genotypes for days to first flower. It also had the longest flowering duration. `Snowscape' would be the best genetic source for creating early, continual flowering cultivars. Most prostrate genotypes were as early as commercial cultivars. Genotype 90-275-27 was significantly shorter (prostrate) than all other genotypes and would be the best genetic source for prostrate plants. Genotypes 95-169-8, 92-237-9, 95-157-6, 95-169-10, 90-275-27, and `Snowscape' had the most acceptable plant width for shipping. Plant uniformity of 95-169-10 and 95-169-8 matched that of `Debonair' and `Spotlight', all of which were significantly more uniform than the other genotypes. The least uniform prostrate was 95-331-10. `Snowscape' had the highest (best) index of traits ranking and was significantly better than all other genotypes. Consumer evaluations were highest for non-prostrate cultivars.
Growth of Juniperus and Potentilla using Liquid Exponential and Controlled-release Fertilizers
Authors: Dumroese R. Kasten
Published: February 2019

Juniperus scopularum Sarg. (Rocky Mountain juniper) and Potentilla fruticosa L. `Gold Drop' (gold drop potentilla) plants grown in containers had similar or better morphology, higher nitrogen concentrations and contents, and higher N-use efficiency when grown with liquid fertilizer applied at an exponentially increasing rate as compared to the same amount of N applied via controlled-release fertilizers. More importantly, plants grown with a half-exponential rate were similar to those grown with controlled-release fertilizer but with a higher N-use efficiency, indicating that this type of fertilization may be a method for reducing the amounts of applied nutrients in nurseries and subsequent nutrient discharge.
Epidermal Segments: A Useful Model System for Studying Water Transport through Fruit Surfaces
Authors: Harz Martin , Knoche Moritz , Bukovac Martin J.
Published: February 2019

Water conductance of the cuticle of mature fruit of apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf., `Golden Delicious' Reinders/`Malling 9' (M.9)], sweet cherry (Prunus avium L., `Sam'/`Alkavo'), grape (Vitis vinifera L.), pepper (Capsicum annuum L. var. annuum Fasciculatum Group, `Jive'), and tomato (Lycopersicon esculentum Mill.) was de ter mined using excised epidermal segments (consisting of epidermis, hypodermis, and some cell layers of parenchyma) and enzymatically isolated cuticular membranes (CM) from the same sample of fruit. Segments or CM were mounted in diffusion cells and transpiration was monitored gravimetrically. Conductance (m·s-1) was calculated by dividing the flux of water per unit segment or CM area (kg·m-2·s-1) by the difference in water vapor concentration (kg·m-3) across segments or CM. Transpiration through segments and through CM increased with time. Conductance of segments was consistently lower than that of newly isolated CM (3 days or less). Conductance decreased with increasing time after isolation for apple, grape, or sweet cherry CM, and for sweet cherry CM with increasing temperature during storage (5 to 33 °C for 4 days). There was no significant effect of duration of storage of CM on conductance in pepper or tomato fruit. Following storage of CM for more than 30 days, differences in conductance between isolated CM and excised segments decreased in apple, grape, and sweet cherry, but not in pepper or tomato. Use of metabolic inhibitors (1 mm NaN3 or 0.1 mm CCCP), or pretreatment of segments by freezing (-19 °C for 18 hours), or vacuum infiltration with water, had no effect on conductance of apple fruit segments. Our results suggest that living cells present on excised segments do not affect conductance and that epidermal segments provide a useful model system for quantifying conductance without the need for isolating the CM. Chemical names used: sodium azide (NaN3); carbonylcyanide m-chlorophenylhydrazone (CCCP).
Inheritance of Male Sterility in Japanese Apricot (Prunus mume)
Authors: Yaegaki H. , Miyake M. , Haji T. , Yamaguchi M.
Published: February 2019

Pollen fertility and inheritance patterns of male sterility were analyzed in various cultivars and selections of Japanese apricot (Prunus mume Sieb. et Zucc.). Male sterility segregated differently in two types of crosses. In pairings of male-sterile and male-fertile parents, progenies were either all male-fertile, all male-sterile, or mixed. Crossing two male-fertile plants resulted in offspring that were either all male-fertile or mixed. Male sterility in Japanese apricot appears to be of the gene-cytoplasmic type. The genotypes of 10 cultivars and three selections are determined.
Efficacy and Persistence of Paclobutrazol Applied to Rooted Cuttings of Rhododendron Before Transplant
Authors: Gent Martin P.N.
Published: February 2019

Efficacy of paclobutrazol was determined when applied to rooted cuttings before transplant. Cuttings of large-leaf Rhododendron catawbiense Michx. were treated with paclobutrazol applied as a 40-mL drench. In 1998, concentrations of 0, 1, 2, 10, or 20 mg·L-1 were applied to liners before root development was complete in February, or after cuttings were root-bound in May. The same volume of solution was applied to other plants at concentrations of 0, 5, 10, or 20 mg·L-1 in July 1998, after transplant to 1-gal pots. In 1999, a 40-mL drench of paclobutrazol at 0, 1, 2, 5, 10, or 20 mg·L-1 was only applied to liners in April. All cuttings were transplanted to 1-gal pots and set in the field. The elongation of stems was measured after each of three flushes of growth. Plants were far more responsive to paclobutrazol when it was applied before, rather than after transplant. There was a saturating response to paclobutrazol concentration and the half-maximal response occurred at 2 to 4 mg·L-1 (0.08 to 0.16 mg/plant). At low rates, later flushes of growth were affected less than earlier flushes. However if paclobutrazol was applied at 10 or 20 mg·L-1, later flushes of growth were inhibited more completely than early flushes. Flowering was enhanced by paclobutrazol. Paclobutrazol at 2 mg·L-1 applied to rooted cuttings before transplant was sufficient to inhibit growth of rhododendron, but not to the point where later flushes of growth were excessively short. Chemical name used: 2RS,3RS-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-l-yl)-pentan-3-ol (paclobutrazol).
Creating a Short Life Site for Prunus Rootstock Evaluation on Land with No Innate Mesocriconema xenoplax Population
Authors: Nyczepir A.P. , Okie W.R. , Beckman T.G.
Published: February 2019

Peach tree short life (PTSL) is associated with the presence of ring nematode, Mesocriconema xenoplax, and poor orchard management practices. Finding a noncommercial field site to evaluate rootstocks for PTSL resistance is increasingly difficult. The time needed to create a PTSL test site was investigated. In 1994, a site not planted in peaches for >80 years was identified in Byron, Ga. Analysis of preplant soil samples revealed that there were no M. xenoplax on the site. One-third of the land was planted to peach and infested with 1600 ring nematodes per tree in Spring 1994 (P2) and another one-third in Spring 1995 (P1). The remaining one-third of the land received no trees or ring nematode and served as the control (F2). In Fall 1995, trees were removed from P1 and P2 plots and all treatments were replanted to peach in 1996. In 1997, tree death resulting from PTSL occurred only in P2 (7%). By 2000, PTSL tree death reached 41% in P2, 16% in P1, and 4% in F2 plots. Nematode populations were higher (P < 0.05) in P1 (649 ring nematode/100 cm3 soil) than in F2 (221 ring nematode/100 cm3 soil) plots, whereas populations in P2 (300 ring nematode/100 cm3 soil) plots did not differ from those in P1 or F2 plots. Establishing a PTSL screening site was possible 3 years after M. xenoplax introduction; PTSL development among treatments in the subsequent planting was dependent upon cumulative population exposure of trees to M. xenoplax.