bluuebunny/crossref_metadata_2025 huggingface dataset:
Grouping and Comparison of Container Substrates Based on Physical Properties Using Exploratory Multivariate Statistical Methods
Authors: Blythe Eugene K. , Merhaut Donald J.
Published: February 2019

Nursery growers develop container substrate blends based on factors such as cost, availability of substrate components, and the physical and chemical properties of the blends. Comparative examination of potential substrate blends typically involves comparison of measured values one variable at a time; however, multivariate methods are available that can allow simultaneous consideration of all variables. In this study, 127 container substrate blends were prepared, each blend containing two to four of 11 individual substrate components with at least one inorganic component (soil, sand, soil + sand, soil + perlite) and at least one organic component (coir, peatmoss, compost, pine bark, cedar bark, redwood shavings, fine-grade coconut husk chips, and medium-grade coconut husk chips). One blend containing only soil and perlite was an exception. Mean values for air space, container capacity, and bulk density were determined using five samples of each blend in #1 (2.84 L) containers. Among the 127 blends, air space ranged from 5.1% to 40.4% (by volume) and container capacity ranged from 24.8% to 59.4% (by volume). Bulk density among the blends ranged from 0.35 g·cm−3 to 1.00 g·cm−3 with bulk densities below and above ≈0.55 g·cm−3 represented almost exclusively by blends with and without perlite, respectively. Principal components analysis and hierarchical cluster analysis (Ward's method) were used to group the blends into eight groups based on the three physical property variables with each group distinguishable from all other groups based on simultaneous consideration of the three variables. In this study, we demonstrate that exploratory multivariate statistical techniques can be used to create groups of substrate blends, thus providing information to assist nursery growers in identifying and comparing substrate blends with similar or dissimilar physical properties among blends containing similar or different inorganic and organic components and proportions of those components.
Tolerance of Turf-type Tall Fescue Established from Seed to Postemergence Applications of Mesotrione and Quinclorac
Authors: McElroy J. Scott , Breeden Greg K.
Published: February 2019

Research was conducted to evaluate the tolerance of tall fescue to mesotrione applied during establishment from seed. Nine field studies were conducted over a 3-year period (2004–2006) near Knoxville, Tenn., to evaluate the tolerance of seedling tall fescue [Schedonorus phoenix (Scop.) Holub] to mesotrione and quinclorac. The first evaluated tall fescue tolerance to single and sequential applications of mesotrione compared with quinclorac (multiple application study). The second evaluated the timing of mesotrione application on tall fescue injury and establishment (timing study). In the multiple application study, all treatments injured tall fescue 23% or less. Quinclorac reduced tall fescue groundcover up to 17% 63 days after emergence (DAE). Mesotrione at 0.28 kg·ha−1 applied 28 and 42 DAE or 14, 28, and 42 DAE decreased groundcover only 4% and 6% 63 DAE. In the timing study, mesotrione at 0.28 kg·ha−1 applied at 7 and 28 DAE injured tall fescue 17% to 21% 7 and 14 days after application; however, injury subsided to less than 10% by 28 days after application. Only mesotrione at 0.28 kg·ha−1 applied 7 DAE resulted in delayed tall fescue groundcover at 70 DAE. Variation was observed in Fall 2005 evaluations compared with other evaluations, which may be attributable to delayed seeding date and cool, wet conditions.
Salinity Affects Quality Parameters of ‘SeaDwarf’ Seashore Paspalum
Authors: Berndt William L.
Published: February 2019

Irrigating salt-tolerant grasses with nonpotable water, like salt water, conserves fresh water resources. Advertising suggests that ‘SeaDwarf’ seashore paspalum (Paspalum vaginatum O. Swartz) is salt-tolerant and that it resists the effects of salinity on growth typically observed when irrigating other turf types with salty water. As a result, it is now being used on golf courses and home lawns in an effort to help conserve fresh water. Commensurate with the use of nonpotable irrigation, however, would be an expectation of high turf quality. This study was done to determine if the quality of ‘SeaDwarf’ seashore paspalum was affected by irrigating it with nonpotable water having high levels of salinity. Seven irrigation water sources created by blending tap water and ocean water and ranging in salinity from 0.52 to 49.40 dS·m−1 were used to flood-irrigate containerized ‘SeaDwarf’ seashore paspalum once daily for 50 consecutive days. Turf quality gradually decreased as salinity increased but improved with time except at the highest level of salinity. Effect of water source on turf quality was attributed to salinity-induced changes in quality parameters, including leaf texture, color, stolon growth, and shoot yield. The observed effect of salinity on quality parameters likely resulted from osmotic stress associated with high levels of salinity. The salt tolerance of ‘SeaDwarf’ seashore paspalum in this study was moderately good, but irrigating it with water having lower levels of salinity resulted in better quality turf.
Testing the Assumption of Normality for pH and Electrical Conductivity of Substrate Extract Obtained Using the Pour-through Method
Authors: Blythe Eugene K. , Merhaut Donald J.
Published: February 2019

The pour-through method is a simple and useful technique for on-site monitoring of pH and electrical conductivity (EC) in container nurseries, and has also been used in numerous research studies focused on substrates, plant nutrition, and plant production. Linear models, including the special cases of analysis of variance and linear regression analysis, are often used for statistical analysis of extract data and are readily available as procedures in statistical software packages. Certain assumptions, including normality of the data values or model residuals, are required to develop valid statistical inferences using linear models. This study evaluated the normality of pH and EC variables using data obtained from 100 extract samples collected weekly over 12 weeks using the pour-through method from a uniform containerized substrate (25 pine bark : 18 peatmoss : 7 sand blend amended with calcium sulfate and top-dressed with Polyon 17N–2.1P–9.1K + micros, a 365-day controlled-release fertilizer, at 10 g/container) in 2.8-L containers. Graphical techniques (histograms and QQ plots) and formal goodness-of-fit tests (tests based on the empirical distribution function, moment tests, and the Shapiro-Wilk regression test) were used to demonstrate methods for assessing normality. The variables pH and EC both exhibited relatively normal distributions. For comparative purposes, the transformed variables ln(pH), 10–pH, and ln(EC) were also evaluated. The latter two variables exhibited significant departures from normality, whereas ln(pH) did not. Average weekly EC exhibited positive correlations with time-lagged, average weekly substrate temperature, suggesting that nutrient release from the controlled-release fertilizer could be more dependent on temperature in the second to fourth weeks preceding extraction than on temperature in the week immediately preceding extraction.
‘Fiorente’ and ‘Arno’ Elm Trees
Authors: Santini Alberto , Fagnani Alberto , Ferrini Fabio , Ghelardini Luisa , Mittempergher Lorenzo
Published: February 2019

Dutch elm disease (DED) has spread through Europe since the beginning of the 20th century. Several independent genetic improvement programs for breeding DED-resistant elms have been established in Europe. The Italian elm breeding program began in the late 1970s with the goal of hybridizing susceptible European elms with resistant Asian species to select DED-resistant clones suited to the Mediterranean climate. Ulmus ‘Fiorente’ and ‘Arno’ are two new releases selected for DED resistance, superior growth rate, attractive foliage, and upright habit.
Evaluation of Genetic Purity of F1 Hybrid Seeds in Cabbage with RAPD, ISSR, SRAP, and SSR Markers
Authors: Liu Liwang , Liu Guang , Gong Yiqin , Dai Wenhao , Wang Yan , Yu Fanmin , Ren Yunying
Published: February 2019

Four molecular marker systems—RAPD (random amplified polymorphic DNA), ISSR (intersimple sequence repeat), SRAP (sequence-related amplified polymorphism), and SSR (simple sequence repeat)—were used to evaluate seed genetic purity of a hybrid cabbage cultivar ‘Zaoxia 16’. Genetic relationships of the F1 hybrids and their parents were analyzed with 157 RAPD primers, 54 ISSR primers, 84 SRAP primer combinations, and 44 SSR primers. Three RAPD primers (NAURP2006, NAURP2020, and NAURP2031), two ISSR primers (NAUISR1058 and NAUISR1062), one SRAP primer combination (NAUSR04/NAURS05), and two SSR primers (NAUSSR1011 and NAUSSR1031), which produced male and female parent-specific markers simultaneously, were selected for testing the genetic purity of the F1 seeds. A total of 210 ‘Zaoxia 16’ hybrid individuals were investigated with these eight selected primers. Of these, 12 appeared to be false hybrids. Nine of the 12 putative false hybrids, confirmed with all eight primers, exhibited similar banding patterns to the female parent, suggesting that they could be derived from selfing of the female parent. The results were in accordance with those from field evaluations. This study showed that RAPD, ISSR, SRAP, and SSR markers are highly efficient and reproducible for genetic purity testing of cabbage commercial hybrid seeds.
Sampling Damage to Tree Fine Roots: Comparing Air Excavation and Hydropneumatic Elutriation
Authors: Kosola Kevin R. , Workmaster Beth Ann A. , Busse James S. , Gilman Jeffrey H.
Published: February 2019

Air excavation is commonly used to expose structural roots of trees, but its suitability for sampling fine roots for research has not been closely examined. We compared damage and root-diameter class distribution in roots sampled by air excavation with roots sampled by hydropneumatic elutriation of soil cores. We collected samples from six different tree species with a range of fine root diameters: Amur corktree (Phellodendron amurense Rupr.), apple [Malus sylvestris var. domestica (Borkh.) Mansf.], river birch (Betula nigra L.), striped maple (Acer pensylvanicum L.), swamp white oak (Quercus bicolor Willd.), and western redcedar (Thuja plicata D. Don). Root-diameter class distributions for each species were the same for samples collected by either air excavation or by elutriation. Median root diameter was greatest for Amur corktree and western redcedar (≈0.5 mm), intermediate in striped maple and oak, and least in river birch and apple (≈0.2 mm). Root damage was primarily due to loss of root tips. Although species varied in their susceptibility to root damage and whether air excavation caused more damage than elutriation, root diameter was not a good predictor of damage during sampling. Air excavation caused ≈26% greater damage to root samples of river birch and western redcedar than did elutriation. Both sampling methods caused equivalent root damage in all other species. Root anatomy influenced susceptibility to damage during sampling. Epifluorescence microscopy revealed a root hypodermis in all species except Amur corktree and western redcedar. Without the mechanical support of this suberized layer, the cortex of Amur corktree was easily stripped from the stele, leading to extensive damage by both sampling methods. Hydropneumatic root elutriation conferred some protection to roots relative to air excavation (in two of six species); final choice of root sampling method must depend upon the requirements of the individual study and characteristics of the site.
Evaluation of Interspecific Hybrids between Lagerstroemia indica and L. speciosa
Authors: Pounders Cecil , Rinehart Tim , Sakhanokho Hamidou
Published: February 2019

Production of viable interspecific seedlings from a cross between Lagerstroemia indica L. ‘Tonto’ × L. speciosa (L.) Pers. was confirmed by comparison of morphological traits and genetic markers. Traits such as plant height and width showed marked variation within the seedling population whereas variation in other traits such as flower size and color was very limited. Seedlings were found to be functionally sterile as either male or female parents. Observed sterility prevents the maximum introgression of important complex traits such as cold hardiness by sib mating or backcrossing into clones derived from this parental combination. ‘Princess’ was confirmed to be a sterile hybrid of L. indica and L. speciosa whereas ‘Monia’ was indicated to have L. indica in its ancestry but not L. speciosa.
Oryzalin-induced Chromosome Doubling in Buddleja to Facilitate Interspecific Hybridization
Authors: Dunn Bruce L. , Lindstrom Jon T.
Published: February 2019

A protocol for producing fertile tetraploid forms of the hybrid Buddleja madagascarensis Lam. × B. crispa Benth. would enable introgression of orange flower, pubescence, and nondehiscent fruit characteristics found in section Nicodemia (Tenore) Leeuw. into B. davidii Franchet section Buddleja. Excised nodal sections of a single sterile diploid selection from that cross were treated in vitro with 3, 5, or 7 μm oryzalin concentrations for 1, 2, or 3 days or were left as an untreated control. A population of plants was generated from these cultures and transferred to the greenhouse. Treated plants were initially screened phenotypically for higher ploidy levels on the basis of stem thickness and leaf size. Those selected based on polyploidy characteristics were subjected to cytometric analysis, confirming that six tetraploid plants were generated. Nodal survival rates were dependent on oryzalin concentration and treatment duration. Significant increases in fertility accompanied polyploidy induction, because crosses between the newly developed tetraploids and B. davidii cultivars produced viable fertile plants. Chemical name used: 3,5-dinitro-N
4,N
4-dipropylsulfanilamide (oryzalin).
Genetic Diversity of White Sapote (Casimiroa edulis La Llave & Lex.) Demonstrated by Intersimple Sequence Repeat Analysis
Authors: Yamamoto Masashi , Tomita Takahiro , Onjo Michio , Ishihata Kiyotake , Kubo Tatsuya , Tominaga Shigeto , Yonemoto Yoshimi
Published: February 2019

Phylogenic relationships among 31 cultivars of white sapote (Casimiroa edulis La Llave & Lex.) were examined by intersimple sequence repeat (ISSR) analysis. Polymorphic fragments were obtained in 24 of 100 ISSR primers (UBC Set#9, 801–900). Although ‘Cuccio’ and ‘Florida’ showed identical fragment patterns, the remaining cultivars could be distinguished from each other. The present study demonstrated the usefulness of ISSR analysis for cultivar identification and phylogenic study in white sapote.
Net Photosynthesis and Growth of Three Novel Woody Species Under Water Stress: Calycanthus occidentalis, Fraxinus anomala, and Pinckneya pubens
Authors: Stewart J. Ryan , Landes Reid D. , Koeser Andrew K. , Pettay Andrea L.
Published: February 2019

Frequent episodes of water stress in managed landscapes have led the nursery industry to look for attractive woody species that perform well under extreme conditions of drought and flooding. We chose to evaluate three taxa with highly localized natural distributions in the United States, Calycanthus occidentalis (north–central California), Fraxinus anomala (northeastern Utah), and Pinckneya pubens (northeastern Florida), each of which may merit further use under cultivated conditions beyond their respective ranges. Although widespread cultivation of each taxon may not be possible as a result of limitations related to cold hardiness, we hypothesized that each species can tolerate extremes in soil moisture availability more so than their native habitats imply. Our objective was to characterize, under greenhouse conditions, how the quantity of soil water affects gas exchange of potted plants of each species. Plants were divided into five groups, each exposed to treatment conditions ranging from complete submersion to severe drought. Complete submersion killed plants of C. occidentalis and F. anomala, although in drought or severe drought conditions, C. occidentalis plants had lower net photosynthesis and less leaf area and plant dry weight than control plants. Net photosynthesis, leaf area, and plant dry weight of partially flooded plants, however, were not found to be significantly less than that of the control plants. Mean net photosynthetic levels and plant dry weights of severe drought, drought, and control F. anomala did not differ. While severe drought plants of P. pubens exhibited much lower levels of net photosynthesis, but not plant dry weights or leaf area, than the control plants, those exposed to drought, partial flood, and complete submersion were not found to differ in net photosynthesis levels from the control plants. Due to the sustained tolerance of F. anomala and P. pubens to a range of extreme soil moisture conditions, as exhibited by net photosynthetic responses, carbon accumulation, and survival, we conclude that use of these species in landscapes is warranted if invasiveness and other potential problems are not identified. Calycanthus occidentalis, however, appears unsuitable for cultivation in areas with organic soils greater than ≈66% and lower than ≈30% soil moisture content as a result of its high mortality in flooded conditions and poor physiological responses under dry conditions.
Autotoxicity in Some Ornamentals with the Means to Overcome It
Authors: Asao Toshiki , Kitazawa Hiroaki , Ushio Kazuyori , Sueda Yukio , Ban Takuya , Rahman Pramanik M. Habibur
Published: February 2019

Autotoxicity in some ornamentals was investigated. The plants were grown by hydroponics with or without the addition of activated charcoal (AC) to the nutrient solution. The AC was used to trap the exuded organics from roots. Among the 37 plants under study, growth of lily, prairie gentian, corn poppy, farewell-to-spring, rocket larkspur, and carnation was drastically reduced in the absence of AC compared with those in the presence of AC in the nutrient solution. Root exudates of some plants were analyzed and several organic compounds were detected. The strong growth inhibitors such as lactic acid in pot marigold, benzoic and p-hydroxybenzoic acid in lily, o-hydroxyphenylacetic acid in rocket larkspur, benzoic and p-hydroxybenzoic acid in sweet pea, and maleic and benzoic acid in prairie gentian were detected in the root exudates. The reduced growth of prairie gentian after prolonged cultivation in a field might be avoided by amending the soil with AC at a rate of 60 kg·10a−1.
The Occurrence of Pecan Kernel Necrosis
Authors: Smith Michael W. , Cheary Becky S. , Carroll Becky L.
Published: February 2019

Pecan [Carya illinoinensis (Wangenh.) C. Koch] kernels (cotyledon) of ‘Pawnee’ displayed a consistent malady not described previously that was designated as “kernel necrosis.” The most severe form of the problem was blackened, necrotic tissue engulfing the basal one-half to one-third of the kernel. The mildest form was darkened tissue in the dorsal grove at the basal end of the kernel. The problem was first observable during the gel stage of kernel development. No symptoms of kernel necrosis were visible on the shuck (involucre). Kernel necrosis was more prominent on ‘Pawnee’, ‘Choctaw’, and ‘Oklahoma’ than other cultivars observed. At maturity, nuts with kernel necrosis had a larger volume than nuts with normal kernels. There were few differences in elemental concentrations of normal kernels from a severely affected orchard and an orchard with little kernel necrosis, and none of the differences appeared to be associated with this disorder. ‘Pawnee’ kernels with necrosis had more phosphorus, zinc, and manganese than normal kernels. Basal segments of necrotic kernels had more boron and acetic acid-extractable and water-soluble calcium than distal segments or normal kernels. Higher elemental concentrations in basal segments of necrotic kernels did not appear sufficient to cause tissue damage.

Soil from the orchard with severe kernel necrosis had unusually high concentrations of nitrate, expressed as nitrogen (NO3-N), in the soil profile. Groundwater used for irrigation was contaminated with 34 mg·L−1 NO3-N. An experiment on ‘Pawnee’ evaluated three nitrogen (N) rates, 0, 0.8 g·cm2 cross-sectional trunk area applied in March, and 1.6 g + 1.6 g + 1.2 g·cm2 cross-sectional trunk area N applied during the second week in March, first week in June, and first week in September, respectively, on the incidence of kernel necrosis, leaf N concentration, soil NO3 concentration, yield, nut quality, and growth over 5 years. Leaf N was affected by treatment only once during the study. Nitrates accumulated in the soil, increasing 24% in 3 years when no supplemental N was applied, except in the contaminated irrigation water. Kernel necrosis was either unaffected by N treatment or during 1 year, kernel necrosis was highest without supplemental N application. Tree yield, kernel quality, and growth were unaffected by N treatment. Yield fluctuations among years were apparent demonstrating that an abundant N supply did not prevent alternate bearing. Kernel necrosis was a severe problem in one orchard and was identified in several orchards at low frequencies. The cause of kernel necrosis remains unknown.
Effects of Maleic Hydrazide Treatment on the Size and Number of Cells and Sugar Accumulation in the Fruit of Melons (Cucumis melo L.)
Authors: Kano Yasutaka
Published: February 2019

The relationships between the size and the number of cells and sugar accumulation in melon fruit have been examined. Maleic hydrazide (MH) was used to investigate the relationships. Although cell size was markedly larger in MH-treated fruit than in untreated fruit in the early stages of fruit development, the number of cells in MH-treated fruit was less than in untreated fruit in latter fruit development. Sucrose, glucose, and fructose content were higher in MH-treated fruit than in untreated fruit. It is therefore suggested that sucrose accumulation in fruit subjected to MH treatment is accelerated as a result of early cell enlargement and that sucrose content increases further as a result of the decrease in the number of cells in the fruit during late development.
Low-cost Shielding to Minimize Radiation Errors of Temperature Sensors in the Field
Authors: Tarara Julie M. , Hoheisel Gwen-Alyn
Published: February 2019

The importance of shielding temperature sensors from solar radiation is understood, but there is a lack of prescriptive advice for plant scientists to build inexpensive and effective shields for replicated field experiments. Using the general physical principles that govern radiation shielding, a number of low-cost, passively ventilated radiation shields built in-house was assessed for the measurement of air temperature against the same type of sensor in a meteorological “standard” Gill radiation shield. The base shield material had high albedo (≈0.9) and low emissivity (0.03). Aspirated shields were included for simultaneous measurements of temperature and relative humidity. Differences in air temperature (ΔT) between low-cost shields and the standard Gill were greatest for shields with open bottoms (up to +7.4 °C) and for those with poorly perforated sidewalls. Open-bottomed shields were prone to heating from reflected radiation. Tube-shaped shields appeared to require more than 30% sidewall perforation for convection by ambient wind (up to 4 m·s−1) to offset the midday radiation load of the shield. The smallest daytime ΔT were between aspirated shields and the standard Gill, averaging less than ±0.5 °C. Among passively ventilated shields, the smallest daytime ΔT consistently were produced by a shield that emulated the stacked plate design of the standard Gill for a total of U.S. $4.00 in materials and 45 min construction time. Eighty-nine percent of all daytime ΔT for the “homemade Gill” shield was 1.5 °C or less. The combination of low ambient wind speed (less than 1 m·s−1) and high global irradiance (greater than 600 W·m−2) produced the largest ΔT for all passively ventilated shields, the magnitude of which varied with shield design; stacked plate configurations were more effective shields than were tube-based configurations. Nighttime ΔT were inconsequential for all shields. Cost-effective radiation shielding can be achieved by selecting shield materials and a configuration that minimize daytime radiation loading on the shield while maximizing the potential for convective transfer of that radiation load away from the shield and the sensor it houses.
Effect of Water Deficit on Gas Exchange, Osmotic Solutes, Leaf Abscission, and Growth of Four Birch Genotypes (Betula L.) Under a Controlled Environment
Authors: Gu Mengmeng , Rom Curt R. , Robbins James A. , Oosterhuis Derrick M.
Published: February 2019

Water was withheld from 2-year-old seedlings or rooted cuttings of four birch genotypes (Betula alleghaniensis Britton, B. davurica Pall., B. nigra L. ‘Cully’, and B. papyrifera Marsh.) until the combined weight of the container and plant decreased below 40% of its original value to induce plant predawn water potential between −1.5 MPa and −2.1 MPa, after which plants were supplied with a requisite amount of water to reach 40% of its original value for 5 weeks under controlled conditions to investigate changes in gas exchange, osmotic solutes, leaf abscission, and growth compared with well-watered (WW) plants. Observations indicated that three of the four genotypes (except B. papyrifera) expressed three stages of photosynthetic response during water deficit: 1) a stress stage, 2) an acclimation stage, and 3) an adapted (or tolerance) stage. The stages were characterized by decreasing, increasing, and stabilized Pnws/ww (net photosynthesis presented as a ratio of water-deficit stressed (WS) plants to WW plants), respectively. A strong relationship between Pn and g
S observed in the WS plants of the four genotypes, suggested inhibition of Pn by stomatal closure. After exposure to water deficit for 5 weeks, Pnws/ww recovered to 70% of the initial value for B. alleghaniensis and B. nigra ‘Cully’ and 98% for B. davurica and B. papyrifera. WS plants had higher foliar concentrations of chlorophyll a and b (nmol/g) and potassium (%) than the WW plants. Increased levels of polyols (mg/g) were detected only in the WS plants of B. allegahaniensis. Increased levels of carbohydrates or organic acid under water deficit were not detected. A significant increase in leaf abscission in the WS plants of B. papyrifera compared with the other genotypes could be a morphological adaptation to water deficit conditions and facilitate recovery of Pnws/ww during the acclimation stage.
Control of Mediterranean Fruit Fly Ceratitis capitata (Diptera: Tephritidae) with the Parasitoid Muscidifurax raptor (Hymenoptera: Pteromalidae) in Vineyards
Authors: Kapongo Jean Pierre , Kevan P.G. , Giliomee J.H.
Published: February 2019

The control of Ceratitis capitata (Diptera: Tephritidae) has been mostly done with chemical insecticides and some selected natural enemies. However, these control methods are not popular because of the adverse effects of chemical controls and the unreliability of some natural enemies (Spalangia sp. and Pachycrepoideus sp.: Hymenoptera: Pteromalidae). The generalist parasitoid, Muscidifurax raptor (Hymenoptera: Pteromalidae), has been used successfully for biological control of the house fly [Musca domestica (Diptera: Muscidae)] pupae in poultry houses. Our study investigated the use of this parasitoid to control C. capitata in a vineyard. Parasitoids were released at rate of 5, 10, and 20 per m2 in a vineyard and in laboratory cages to parasitize pupae of C. capitata and M. domestica, respectively, for 2 days. The number of killed pupae of both host pests increased with the number of released parasitoids in the field. The highest rate of 20 released M. raptor resulted in 23.52% (±0.30 se) killed pupae, respectively, for house fly and fruit fly. M. raptor parasitized indiscriminately host species of pupae and the daily oviposition rate was 4.9 (±0.07 se) eggs per female. The parasitoid laid the same number of eggs as when released in poultry houses for the control of M. domestica. We conclude that M. raptor constitutes a promising biocontrol agent for the control of C. capitata in vineyards.
Silk Abscission in Two Sweet Corn (Zea mays L.) Hybrids That Differ in Susceptibility to Common Smut Infection of Ears
Authors: Pataky Jerald K. , Richter Paul M.
Published: February 2019

Host resistance is the most efficient way to control common smut (Ustilago maydis) in sweet corn, but resistance to U. maydis is not understood well. All meristematic tissues are susceptible, but infection is localized. Ear galls result from infection of ovaries. Infection and resistance can be affected by plant morphology. For example, ovaries are protected from U. maydis infection when an abscission zone forms at the base of the silk 6–24 h after a pollen tube reaches an ovary. The objective of this study was to determine if the rate of silk abscission differed between two related sweet corn hybrids that differed in susceptibility to smut infection of ears. The two hybrids, Green Giant Code 3 (GG3) and Green Giant Code 46 (GG46), were evaluated for the occurrence of infected ears in 58 paired plots at four locations near Le Sueur, MN, from 1993 to 1999. The rate of silk abscission in the two hybrids was evaluated in two field trials in Urbana, IL, in 2002 and 2004. Incidence and severity of ear smut were significantly (P < 0.05) greater and about twice as much on GG3 than on GG46. Silk abscission was more rapid on GG46 than on GG3. Although this association does not prove that decreased susceptibility of GG46 to ear infection is due to silk abscission, it is a logical basis from which to hypothesize that silk dynamics and other aspects of maize floral biology play important roles in resistance to ear infection by minimizing the time period that all ovaries on an ear are exposed to infection by U. maydis. This hypothesis is discussed in relation to the results of this and other research.
Micropropagation of the Medicinal Plant Eremanthus erythropappus (DC.) MacLeish
Authors: Rosal L.F. , Pinto J.E.B.P. , Bertolucci S.K.V. , Costa L.C.B. , Corrêa R.M.
Published: February 2019

The aim of the present work was to establish appropriate conditions for the in vitro micropropagation of Eremanthus erythropappus (DC.) MacLeish through shoot multiplication on apical and nodal bud explants. Explants were excised from in vitro-grown seedlings and incubated on Murashige and Skoog medium containing different combinations of 6-benzylaminopurine (BAP) and 1-naphthalene acetic acid (NAA) (for apical buds) and gibberellic acid and NAA (for nodal segments). Proliferation of apical shoots was successfully achieved in the presence of BAP and NAA, each at 1.0 mg L−1, while the elongation of apical shoots could only be attained on medium containing NAA at 1.0 mg L−1. Elongation of nodal shoots was induced in the presence of NAA at 2.0 mg L−1. The most suitable medium for inducing root proliferation on explants of E. erythropappus was NAA at 1.0 mg L−1.
Stable Production of Transgenic Pepper Plants Mediated by Agrobacterium tumefaciens
Authors: Ko Moon Kyung , Soh Hyunchul , Kim Kyung-Moon , Kim Young Soon , Im Kyunghoan
Published: February 2019

The aim of this study was to establish a stable transformation method for hot pepper using the hygromycin phosphotransferase (hpt)/hygromycin selection strategy. Explants from aseptic pepper seedlings were inoculated with Agrobacterium tumefaciens carrying pCAMBIA1301. A number of calli were developed on the medium containing hygromycin to discriminate the induction of “false-positive buds,” and then shoots were successfully regenerated from the hygromycin-resistant calli. Southern and Northern hybridization analysis indicated that the hpt gene was integrated and expressed in the transgenic pepper plants (T0) and transmitted to the progeny (T1) without genetic modification. Most T1 progenies derived from self-pollination revealed a 3:1 segregation ratio for hygromycin resistance, indicating that one copy of the T-DNA was integrated into the respective transgenic lines. Both uidA and hpt genes were stably expressed in the T1 generation and coinherited in the progenies. Finally, homozygous progenies were identified in the T1 generation of the transgenic peppers, and the homozygous state was maintained in all progenies tested (T2). The results show the reliability and stability of the hpt/hygromycin selection protocol for pepper transformation.
Primed Lettuce Seeds Exhibit Increased Sensitivity to Moisture Content During Controlled Deterioration
Authors: Hill H.J. , Cunningham Jesse D. , Bradford Kent J. , Taylor A.G.
Published: February 2019

The Ellis-Roberts seed viability equation is used to predict seed survival after storage at specified temperatures and moisture contents. Seed priming, which can break dormancy and accelerate germination, can also reduce seed storage life. Because primed seeds were not used in developing the Ellis-Roberts equation, the reciprocal nature of specific seed moisture content (MC, fresh weight basis) and temperatures that applies to nonprimed lettuce (Lactuca sativa L.) seeds may not apply to primed seeds. To determine how priming affects lettuce seeds in relation to the viability equation, an experiment was conducted using two cultivars, ‘Big Ben’ and ‘Parris Island Cos’. Seeds primed in polyethylene glycol 8000 (–1.45 MPa, 24 h at 15 °C) and nonprimed seeds were first adjusted to 6% and 9% moisture contents and then stored at 48 and 38 °C for up to 30 days, respectively. These storage conditions (6% MC and 48 °C; 9% MC and 38 °C) were predicted by the viability equation to result in equal longevities. Subsequent viability assays at 20 °C revealed that nonprimed seeds in both storage environments exhibited similar losses in viability over time, thus validating the Ellis-Roberts equation and the use of these conditions to apply different but equal aging stress. Primed seeds of both cultivars deteriorated faster than nonprimed seeds as expected. However, primed seeds did exhibit different rates of deterioration between the storage environments. Primed seeds stored at 9% MC and 38 °C deteriorated faster than primed seeds stored at 6% MC and 48 °C. The rate of decline in probit viability percentage was three times greater in primed ‘Big Ben’ seeds stored at 9% MC and 38 °C than for those stored at 6% MC and 48 °C (–1.34 versus –0.26 probits per day, respectively). ‘Parris Island Cos’ seeds stored at 9% MC and 38 °C had twice the rate of deterioration that those stored at 6% MC and 48 °C (–1.19 and –0.49 probits per day, respectively). The results indicate that primed lettuce seeds were more sensitive to the adverse effects of higher seed MC than were nonprimed seeds during storage at elevated temperatures.
Short-duration Water Stress Decreases Onion Single Centers without Causing Translucent Scale
Authors: Shock Clinton C. , Feibert Erik B.G. , Saunders Lamont D.
Published: February 2019

Single centeredness has become an important onion attribute for marketing because of the use of onions in food products such as onion rings. Although onion single centeredness is largely cultivar dependent, it may also be influenced by growing conditions. These trials tested the effects of early-season, short-duration water stress on onion single centeredness. The effects of the short-duration water stress were also evaluated on onion yield, grade, and translucent scale. Translucent scale is a physiological disorder thought to be influenced by water stress. Onions were drip irrigated automatically at a soil water tension (SWT) of 20 kPa and were submitted to short-duration water stress in 2003, 2004, and 2005. Onions in each treatment were stressed once at either the two-leaf, four-leaf, early six-leaf, late six-leaf, or eight-leaf stage and were compared with a minimally stressed control. Onions were stressed by interrupting irrigations until the SWT at a 0.2-m depth reached 60 kPa, at which time the irrigations were resumed. Onion single centeredness was reduced by short-duration water stress in 2003 and 2005. Onions were sensitive to the formation of multiple centers with water stress at the four-leaf to late six-leaf stages. The 2004 growing season was characterized by cool, moist conditions, and water stress did not affect single centeredness. Among all treatments and years, marketable yield was only reduced in 2005, with stress at the four-leaf and eight-leaf stages. The incidence of translucent scale was very low each year and was not related to early-season water stress.
Fertigation and Crop Load Affect Yield, Nutrition, and Fruit Quality of ‘Lapins’ Sweet Cherry on Gisela 5 Rootstock
Authors: Neilsen Gerry , Kappel Frank , Neilsen Denise
Published: February 2019

‘Lapins’ sweet cherry (Prunus avium L.) on Gisela 5 (Prunus cerasus × Prunus canescens) rootstock were subjected to a factorial combination of two crop load and eight fertigation treatments from the sixth to the eight growing seasons. Crop load treatments included full crop and dormant spur thinning to remove and maintain 50% of fruiting spurs. The eight fertigation treatments, which had been maintained since the first growing season, included low (42 mg·L−1), medium (84 mg·L−1), and high (168 mg·L−1) concentrations of N applied by sprinkler fertigation of Ca(NO3)2 annually ≈8 weeks postbloom. The medium N concentration was also applied with P fertigated in early spring or K fertigated in June. A standard N treatment involved broadcast application of NH4NO3 in early spring at 75 kg·ha−1 also followed with medium N sprinkler-fertigated postharvest in August. The medium N concentration was also supplied for 8 weeks postbloom through drip emitters. Removal of 50% of fruiting spurs decreased annual yield on average by only 10%. Average fruit size could be increased in years of high crop load (greater than 400 g fruit/cm2 trunk cross-sectional area), but in a year of low crop load (less than 100 g fruit/cm2), fruit size was very large (averaging greater than 14 g) and unaffected by crop load adjustment. Minimal effects on fruit and leaf NPK concentrations, fruit firmness, soluble solids concentration (SSC), and titratable acidity (TA) were associated with yield reductions of 10%. Fertigation treatments resulted in a large range in tree vigor and yield during the experiment. High N applications reduced tree and fruit size and fruit TA and were undesirable. Annual P and K fertigation by sprinklers was generally ineffective, having minimal effects on tree PK nutrition and fruit quality with the exception of increased fruit firmness associated with P fertigation in 2005, when yield was low. Drip-fertigated trees were small, frequently had fruit with elevated SSC, but had deficient leaf K concentrations in 2004 implying a need to fertigate K when drip-irrigating.
Effect of Fertilizer Source on Nitrate Leaching and St. Augustinegrass Turfgrass Quality
Authors: Saha Subhrajit K. , Trenholm Laurie E. , Unruh J. Bryan
Published: February 2019

As a result of the coexistence of turfgrass and ornamentals in traditional landscapes, it is often impractical to separate fertilization and irrigation management among species. Furthermore, limited information is available on effects of turfgrass fertilizer on ornamental plants and vice versa. This research studied effects of two quick-release fertilizers (QRF) and one slow-release fertilizer (SRF) on quality and growth of turfgrass and ornamental plants and nutrient leaching. ‘Floratam’ St. Augustinegrass (Stenotaphrum secundatum Walt. Kuntze) was compared with a mix of common Florida ornamentals, including canna (Canna generalis L.H. Bailey), nandina (Nandina domestica Thunb.), ligustrum (Ligustrum japonicum Thunb.), and allamanda (Allamanda cathartica L.). All plants were grown in 300-L plastic pots in Arredondo fine sand. Less nitrate (NO3
−) was leached from turfgrass than from ornamentals and more NO3
− leached from QRF 16N–1.7P–6.6K than from SRF 8N–1.7P–9.9K. Quick-release fertilizers produced higher plant quality. This controlled environment research provides preliminary data on which in situ research may be modeled. Further research is required to verify how nutrient release rate affects turfgrass and ornamental quality and nitrate leaching in an urban landscape.
Effect of Nitrogen Fertilizer on Cell Size and Sugar Accumulation in the Leaves of Cabbage (Brassica oleracea L.)
Authors: Kano Yasutaka , Nakagawa Hiroshi , Sekine Masami , Goto Hideyuki , Sugiura Akira
Published: February 2019

Head and leaf weight of cabbage plants grown using half the nitrogen fertilizer applied to control plants (hereafter referred to as the half treatment) were markedly less than those obtained for control plants to which the standard amount of nitrogen fertilizer was applied. Sugar content 33 d after sowing (DAS) did not differ between treatments, but glucose and fructose content in the half treatment 82 DAS was higher than that of the control. Although the number of cell layers in cross-section for the leaves from both treatments was ≈20, cells from the half treatment appeared smaller than those of the control. Therefore, it is suggested that the higher sugar content in leaves of cabbage plants grown on media containing less nitrogen fertilizer occurs in response to the smaller cells in the leaves.
An Analysis of Combining Ability for Height, Leaf Out, Bloom Date, and Flower Color for Crapemyrtle
Authors: Pounders Cecil , Rinehart Tim , Edwards Ned , Knight Patricia
Published: February 2019

Breeding of crapemyrtle (Lagerstroemia) in the United States has focused on developing hybrids between parents with disease or pest resistance and those with good floral characteristics. The objective of this work was to study the general and specific combining ability of several horticulturally important traits in crosses between pest-resistant parents and those with saturated flower colors. Ten crapemyrtle parents were tested in a factorial mating design including 25 of the 29 possible families. Analysis of variance revealed significant differences (P ≤ 0.05) for all traits for the general combining ability of parents. The cross between ‘Arapaho’ and ‘WHIT IV’ displayed the best specific combining ability for a desirable combination of height, leaf-out time, bloom time, and flower color based on current breeding objectives. Overall, this study revealed the importance of both additive and nonadditive genetic variability in crapemyrtle, suggesting that an integrated breeding strategy to capture both additive and dominance variance would be appropriate for producing new, improved crapemyrtle clones for the four traits evaluated.
Growth Habit Determination of Genotypes of African Bermudagrass
Authors: Kenworthy Kevin E. , Martin Dennis L. , Taliaferro Charles M.
Published: February 2019

Six African bermudagrass (Cynodon transvaalensis Burtt-Davy) genotypes, one common bermudagrass [C. dactylon (L.) Pers. var. dactylon] genotype, and ‘Tifway’ (C. dactylon × transvaalensis) hybrid bermudagrass were evaluated for shoot type, leaf angle, and shoot angle. Evaluations were conducted to determine if these measurements could be used to differentiate among upright, intermediate, and prostrate growth habits. Significant differences were found for all three techniques, but attempts to group plants together as having prostrate, intermediate, or upright growth habits was not possible. ‘Tifway’ was intermediate between the African bermudagrass genotypes and the common genotype for shoot type observations, but was more similar to upright-growing African bermudagrass for leaf angle and the more prostrate-growing common bermudagrass for shoot angle. Quantification of shoot type and leaf angle did not appear as useful as shoot angle measurements for screening germplasm to identify upright or prostrate growth habits in bermudagrass.
Potential for the Improvement of Turf Quality in Crested Wheatgrass for Low-maintenance Conditions
Authors: Robins Joseph G. , Waldron Blair L. , Johnson Paul G.
Published: February 2019

With the exception of the undesirable characteristic of summer dormancy and the accompanying low aesthetic value, crested wheatgrass has many desirable characteristics in semiarid environments, making it a promising candidate for lower water use turf. Using a population of 27 half-sib families, this study characterized the underlying genetics of turf quality (based on a 1–9 rating scale) of crested wheatgrass and compared the performance of crested wheatgrass turf with traditional control cultivars (‘Cody’ buffalograss, ‘Gazelle’ tall fescue, ‘Manhattan 3’ perennial ryegrass, and ‘Midnight’ Kentucky bluegrass) over 2 years under space-planted conditions. Heritability estimates were generally high (h2 = 0.44 to 0.84) and suggested a strong additive genetic component for crested wheatgrass turf quality throughout the summer months. Genotypic correlations among the monthly turf quality scores were very high (greater than 0.90) indicating a strong commonality for the genetics underlying turf quality during any point in the growing season. Thus, a breeding program aimed at improving turf quality in this population of crested wheatgrass would stand a good chance for success. However, primarily as a result of summer dormancy, the crested wheatgrass turf performed poorly compared with the control cultivars during late spring and early summer. Turf quality scores in early July were ≈3 for the crested wheatgrass half-sib families compared with scores between 5 and 6 for the traditional turf species. Thus, crested wheatgrass, for the near future, will likely be a viable turf candidate only in situations in which turf aesthetics are secondary to a desire for low-input requiring species.
Characterization of Watermelon (Citrullus lanatus var. citroides) Germplasm for Resistance to Root-knot Nematodes
Authors: Thies Judy A. , Levi Amnon
Published: February 2019

Root-knot nematodes (Meloidogyne spp.) cause extensive damage to watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus], and resistance to root-knot nematodes has not been identified in any watermelon cultivar. Twenty-six U.S. Plant Introductions (PIs) of Citrullus lanatus (Thunb.) Matsum. & Nakai var. citroides (L. H. Bailey) Mansf., one PI of C. lanatus var. lanatus, and three PIs of Citrullus colocynthis (L.) Schrad. were evaluated in greenhouse tests for resistances to Meloidogyne incognita (Kofoid & White) Chitwood race 3 and Meloidogyne arenaria (Neal) Chitwood race 2. Twenty-three of the C. lanatus var. citroides PIs and the C. lanatus var. lanatus PIs were previously identified as moderately resistant to M. arenaria race 1. Overall, the C. lanatus var. citroides PIs exhibited low to moderate resistance, and the C. lanatus var. lanatus and C. colocynthis PIs were susceptible to both M. incognita race 3 and M. arenaria race 2. The C. lanatus var. citroides PI 482303 was the most resistant PI with gall index (GI) = 2.88 and reproductive index (RI) = 0.34 for M. incognita race 3 and GI = 3.46 and RI = 0.38 for M. arenaria race 2 (1 = no galling; 5 = 26% to 38% root system galled; 9 = 81% to 100% root system galled). These results demonstrate that there is significant genetic variability within C. lanatus var. citroides for reaction to M. incognita and M. arenaria race 2, and several C. lanatus var. citroides PIs may provide sources of resistance to root-knot nematodes.