bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Heated Water in Prevention of Chilling Injury in Tomatoes
Authors: Hakim Abdul , Voipio Irma
Published: February 2019

Mature green tomatoes (Lycopersicon esculentum Mill. cv. Vibelco) were immersed in 38, 42, 46, 50, and 54C for 90 min prior to storage at 2C for 2, 4, or 6 weeks in paper bags. After storage, they were kept at 20C. Fruits immersed in heated water showed lower ethylene production, rate of respiration, electrolyte leakage, and visible chilling injury than nontreated fruits. During storage and after removal at 20C, hot-water-treated fruits ripened faster than nontreated fruits The increase in water temperature from 38 to 46C resulted in declined ethylene production, rate of respiration, electrolyte leakage, and visible chilling injury, but, with further increase in water temperature (46 to 54C), they increased. Of all the pretreatments, the treatment at 42 or 46C were most effective in enhancing fruit color changes. Inhibition in ethylene production, rate of respiration, electrolyte leakage, and visible chilling injury was highest on fruits immersed at 42 and 46C.
Relationship between Sugar Content in Raw, Baked, and Microwaved Sweetpotato Roots during Storage
Authors: Romaine Durel J. , LaBonte Don R.
Published: February 2019

Seven compositionally diverse sweetpotato lines were examined for changes in individual sugar concentrations at harvest (green), after curing (7 days at 90% RH and 29.5C), and after 4 and 8 weeks of cold storage (16C) to determine the relationship between raw and cooked root sugar composition. Raw root sucrose concentrations at harvest in two dessert types, `L91-80' and `Heart-O-Gold', were at least 22% higher than other dessert types, such as `Beauregard' and `Jewel', and 26% higher than white starchy types (`Rojo Blanca' and `White Star'). The sucrose concentration remained correspondingly higher for these two lines when baked or microwaved. Total sugar concentration was not significantly correlated between raw vs. baked or microwaved roots. The major sugar in most baked and microwaved roots was maltose, accounting for 18% to 93% of the total sugars. `L91-80' behaved differently from other lines during microwaving, where sucrose was the major sugar. The total sugar concentration of `L91-80' and `Heart-O-Gold' were not statistically greater after baking and microwaving for all dates, including the white, starchy types. These results suggest the need to further evaluate the relative importance of individual sugar concentrations on consumer preference.
Effect of Preharvest Conditions on Chilling Susceptibility of Tomato Fruit
Authors: Dodds G.T. , Trenholm L. , Madramootoo C.A. , Stewart K.
Published: February 2019

In a 2-year study, tomato plants (Lycopersicon esculentum Mill. cv. New Yorker), grown in field lysimeters, were subjected to water table levels (WTD) of 0.3, 0.6, 0.8, and 1.0 m from the soil surface, factorially combined with five K–Ca combinations, and replicated four times. Four mature green fruit per plant were stored at 5C for 21 days, and fruit color (L*,a*,b*) was measured daily. Fruit were then ripened at 21C for 10 days, and the surface area with chilling damage and the ripening stage noted for each fruit. In 1993, a dry year, the 1.0 m WTD showed the greatest color change, the 0.3 m WTD the least. The 1.0 m WTD showed the least damaged area and least delay in ripening, the 0.3 m WTD the most. In the wet year, 1994, differences by WTD were not significant. K and Ca fertilizer effects were not significant in either year. The number of hours below 15C, precipitation, and crop evapotranspiration in the week prior to harvest appeared to be of lesser importance than WTD in subsequent chilling response. Preharvest plant water relations appear to have some bearing on postharvest chilling sensitivity.
Remote Sensing Techniques Coupled with Leaf Spectroscopy to Evaluate the Severity of Dogwood Anthracnose
Authors: Hayes Tara H. , Beyl Caula A.
Published: February 2019

Flowering dogwoods. (Cornus florida L.) have been attacked by dogwood anthracnose. In vivo leaf reflectance values of infected leaves from Summer 1993, Fall 1993, and Fall 1994 were obtained using a spectroreflectometer at wavelengths from 300 to 2500 nm to determine what wavelengths could best detect differences between dead and healthy leaves. At -those wavelengths, a mathematical expression was devised and used to calculate the predicted reflectance value for that percent disease severity (Rexp50%). The predicted reflectance values were compared with actual mean reflectance values (Rmean) obtained from leaves with up to 50% disease severity achieving correlations of 0.95, 0.66, and 0.84, for the Summer and Fall 1993, and Fall 1994, respectively. For Fall 1994, actual disease severity values were obtained by scanning and image analysis to compute an expected reflectance for these actual percentages (Rreal%) for a correlation value of 0.98.
Technical Feasibility of Pneumatic Control on Colorado Potato Beetle
Authors: Lacasse Benolt , Laguë C. , Yelle S. , Roy P.M. , Khelifi M.
Published: February 2019

A front-mounted prototype designed to pneumatically remove Colorado potato beetles (CPB) from potato plants was tested in the field. Effects of different combinations of airflow velocities, nozzle widths, and travel speeds were investigated. Results showed that capture and dislodging of CPBs were better for adults and big larvae (L3 & L4). On the other hand, neither the airflow width and velocity nor the travel speed affected significantly the dislodging and the collection of small larvae. Field trials on the removal of larvae under the effect of different travel speeds showed that, the slower the prototype moved, the better was the collection of L3-L4 larvae. This study demonstrates the potential of pneumatic control of adult and L3-L4 CPBs.
The Effect of the Fungicides Metalaxyl and Fosetyl-Al on Root Rot (Phytophthora cactorum) of American Ginseng (Panax quinquefolium) in the Greenhouse
Authors: Medina M.V. , Gray A.B. , Ju H.Y
Published: February 2019

Ginseng seedlings were inoculated with Phytopthora cactorum by dipping their roots for 5 min in a suspension of 105 zoospores/ml. Inoculated plants were repotted and grown under shade in the greenhouse. In various experiments, fungicides were applied 1 week before inoculation, at the time of inoculation, 2 days after inoculation, or a combination of the first two of these. Treatments included fosetyl-Al applied as a foliar spray until run-off at a concentration of 2.5, 5.0, or 10 g a.i./liter of water or as a soil drench containing 0.25, 0.5, or 1.0 g a.i./100 ml water per plant and metalaxyl applied as a soil drench containing 5 or 10 mg a.i./100 ml of water per plant. The treatments with fosetyl-Al as a spray did not reduce root rot ratings, but fosetyl-Al applied as a drench significantly reduced root rot ratings at all three concentrations when applied at inoculation. The best control was achieved using metalaxyl at either 5 or 10 mg a.i./plant applied either at inoculation or both 1 week before inoculation and at inoculation.
Toxicological Assays in Bemisia tabaci (Genn.) from Cabbage Plots in La Paz, Baja California Sur, Mexico
Authors: Servín Rosalía , Martínez Jos L. , Troyo-Diguez E. , Ortega A.
Published: February 2019

The sweetpotato whitefly [Bemisia tabaci (Gennadius)] has become a high-risk insect pest in Mexico as well as in other countries, causing serious damage to several crops. Control of whitefly in Baja California Sur, ,Mexico, is usually done by intense insecticides applications, either alone or in mixtures of several kinds. The aim in this work was to determine its susceptibility to cypermethrin, endosulfan, methamidophos, and methyl-parathion. LC50 was obtained to identify the resistant and susceptible populations. A group of 20 whiteflies were introduced in a 20-ml scintillation vial coated in the inner surface with a known concentration of the insecticide. Mortality readings were obtained 3 h after exposing the insects to the residual activity at five concentrations. Five replications and control were run in different consecutive days for each bioassay. Results indicated that cypermethrin was the most toxic to B. tabaci and metamidophos the least. Data will be considered for further evaluations.
Evaluation of Onion Lines for Resistance to Onion White Rot and Onion Maggot
Authors: McDonald M.R. , Lewis T. , Goldman I.
Published: February 2019

Onion lines were evaluated for resistance to Allium white rot (Sclerotium cepivorum Berk.) and onion maggot [Delia antigua (Meig.)] in field plots established on organic soil in the Bradford Marsh, Ontario. White rote valuations were conducted on 20 lines in 1992–1994, with follow-up laboratory trials in 1995. Onion maggot screening was conducted on these same lines in 1993 and 1994. Plots were arranged in a randomized complete-block design with four replications per line. Significant differences in susceptibility to white rot were found in 1992 and 1993, while differences in onion maggot resistance were identified in 1993 and 1994. Commercial cultivars Norstar and Fortress had relatively low levels of onion maggot damage and Fortress demonstrated some tolerance to white rot. Other lines with low levels of white rot infection were 1292-91, 1564-91, 124-93, 116-93, and 117-93, from the breeding program at the Univ. of Wisconsin. Line 1292-91 also had low levels of onion maggot damage. The horticultural characteristics of the onion lines will be discussed.
A Question for the Class: Why Do Roses Die?
Authors: Knee Michael , McMahon Peg , Carey Glenn
Published: February 2019

An undergraduate class in postharvest physiology observed a number of factors in the senescence of cut roses, which had been studied separately in the literature. They assessed the relative importance of the factors in determining vase life. `Samantha' roses were held at 20C in distilled water or a floral preservative. Ethylene treatment caused petal distortion and premature senescence. Floral preservatives stimulated ethylene production, although vase life was extended relative to flowers in water. Higher sugar contents and respiration were maintained in preservative than in water. Water uptake by roses was almost constant, but stem resistance to water flow increased faster in water than in preservative. In the 2nd week of vase life, transpiration exceeded water uptake, particularly for roses in water. As much of this water was lost through leaves as through the flower. The results suggest that a complex interaction of several factors determines vase life.
The Effect of GA3 Concentration on Germination of Trillium grandiflorum (Michx) Salisb.
Authors: Solt Stephanie , Perry Leonard
Published: February 2019

In the wild, Trillium seeds are reported to take 2 years to germinate, producing the radicle the first year and the cotyledon the second year. The accepted treatment has been to stratify the seeds using a temperature sequence of 3 months cold–3 months warm–3 months cold–3 months warm. It also has been reported that Trillium seeds treated with GA3 will germinate with no temperature treatment. The objective of this experiment was to determine the effects and optimum concentration of GA3 on the seed of Trillium grandiflorum. Seeds were soaked for 12 h in concentrations of GA3 K-salts at 500, 1000, 2000, or 4000 ppm dissolved in distilled water with five replicate petri dishes of 20 seeds each (100 seeds per treatment) in a randomized complete-block design in a growth chamber (zero light). Results were analyzed using ANOVA.
Effects of Controlled Water Tables on Yield and Marketability of Field Tomatoes
Authors: Trenholm L. , Dodds G.T. , Madramootoo C.A. , Stewart K.
Published: February 2019

In a 2-year study, tomato plants (Lycopersicon esculentum Mill., cv. New Yorker), grown in a sandy loam in field lysimeters, were subjected to controlled water table treatments (CWTT) of 0.3, 0.6, 0.8, and 1.0 m from the soil surface, factorially combined, in a central composite design, with 5 K–Ca fertilization combinations, replicated four times. Final shoot mass, no. fruit/plant (yield), percent marketability, fruit dimensions, and the incidence and severity of catfacing and sunscald were measured. In the first, drier year, the two higher, better-irrigated CWTT (0.3 and 0.6 m) gave higher yields, larger fruit, and higher final shoot mass, whereas in the second, wetter year, the two lower, better-drained CWTT (0.8 and 1.0 m) were best. In the dry year, the best-yielding CWTT showed the poorest marketability, while, in the wet year, the best-yielding CWTT showed the best marketability. Severity of catfacing and sunscald did not show consistent variations with CWTT. Fertilizer effects were generally not significant. Results will be discussed in the context of the use of subirrigation in field tomato production.
Stability and Effectiveness of Wetting Agents in Stored Growing Media
Authors: Mane Santakumari , Turner James , Kostka Stanley
Published: February 2019

Three soilless media of different composition (peat: vermiculite, bark: peat: vermiculite, peat: vermiculite: polystyrene) received one of three wetting agent treatments (AquaGro 160 at 60 ml or 120 ml·m–3; or AquaGro L at 120 ml·m–3) and were subsequently analyzed for wettability after storage for up to 4 months. The respective untreated media served as the controls. All media were stored in closed bags at 24 ± 4C. Water retention was greater in wetting agent-treated media than in controls. Both wetting agents facilitated uniform distribution of water in the media. Control media became more difficult to wet over time, whereas wetting agent treatments maintained uniform wettability of media throughout the storage period. Wetting agent chemistry, treatment rate, and media composition influenced wetting characteristics during media storage. All three wetting agent treatments improved wetting of the peat: vermiculite over the 4-month test period. In bark media, AquaGro 160 applied at 120 ml·m–3 enhanced wetting throughout the study. Media containing polystyrene were difficult to wet. AquaGro 160 applied at 120 ml·m–3 improved wetting for up to 2 months.
Heritability of Resistance to Root-knot Nematode (Meloidogyne hapla Chitwood) in Carrot (Daucus carota L.)
Authors: Wang Min , Goldman I.L.
Published: February 2019

The root-knot nematode (M. hapla Chitwood) poses a threat to carrot (Daucus carota L.) production in the United States. Little information is available concerning the genetic control of nematode resistance in carrot. Crosses between two inbreds, a resistant genotype (R1) and susceptible genotype (S1) identified in previous screening tests of carrot were studied in the F2 and BC1 generations to determine the heritability of resistance to the root-knot nematode. Seedlings of F2 (R1/S1), BC1S1, and BC1R1 generations were evaluated for their responses to infestation of M. hapla Chitwood based on gall number per root, gall rating per root, and root rating per root in a greenhouse experiment conducted during 1994. Narrow-sense heritabilities were calculated according to the method of Warner (1952). Narrow-sense heritability was 0.16 for resistance based on gall number, 0.88 for resistance based on gall rating, and 0.78 for resistance based on root rating. This information may be of importance to geneticists and carrot breeders for the development of nematode-resistant carrot cultivars.
Simple Sequence Repeats (SSRs) in Watermelon (Citrullus lanatus L.)
Authors: Jarret R.L. , Kresovich S. , Holms T. , Evans Janelle , Liu Z.
Published: February 2019

Simple sequence repeats (SSRs) were isolated from a size-fractionated genomic DNA library of watermelon (Citrullus lanatus L. cv. New Hampshire Midget). Screening of the library with five oligonucleotide probes, including (GT)11, (AT)11, (CT)11, (GC)11, and (TAA)8, detected the occurrence of 96 positive colonies among ≈8000 recombinants. Automated DNA sequencing revealed the presence of SSRs. PCR primer pairs homologous to the regions flanking the SSR loci were synthesized commercially and used to screen 56 watermelon genotypes for the occurrence of SSR polymorphisms. Amplification products were separated using nondenaturing PAGE. Eighty percent of the primer pairs produced amplification products of the expected size and detected polymorphisms among the genotypes examined. The use of SSRs for watermelon germplasm characterization is discussed.
Ipomoea Accession Closely Related to Sweetpotato
Authors: Bohac J.R. , Rajapakse S.
Published: February 2019

An Ipomoea accession from Indonesia, originally classified as I. trifida, was found to segregate in flower morphology. It was hypothesized to be either a very close relative of I. batatas (6x sweetpotato), or a hybrid between I. batatas (6x) and I. trifida (2x). Twelve seedlings of this accession were grown and precise measurements of sepal angle, corolla shape, and root morphology were taken. Samples were also compared on the DNA level using molecular markers. Based on morphological measurements, it was found that some individual seedlings of the unknown Ipomoea accession were not significantly different than I. batatas; others were not significantly different than I. trifida. The control I. batatas and I. trifida lines were significantly different from each other. DNA flow cytometry was used to determine that all seedlings were diploids with the same amount of DNA per cell. Overall plant morphology and molecular analysis confirmed that all of the seedlings were very closely related and the segregation in flower morphology was not due to a seed mixture. This data is consistent with the hypothesis that the accession is a hybrid between I. batatas and I. trifida.
Simple Sequence Repeats (SSRs) in Sweetpotato [Ipomoea batatas (L.) Lam.]
Authors: Jarret R.L. , Bowen N. , Kresovich S. , Liu Z.
Published: February 2019

Simple sequence repeats (SSRs) were isolated from a size-fractionated genomic DNA library of sweetpotato [Ipomoea batatas (L.) Lam.]. Screening of the library with five oligonucleotide probes, including; (GT)11, (AT)11, (CT)11, (GC)11, and (TAA)8, detected the occurrence of 142 positive colonies among ≈12,000 recombinants. Automated DNA sequencing revealed the presence of simple, compound, perfect, and imperfect SSRs. Five homologous PCR primer pairs were synthesized commercially and used to screen 30 sweetpotato clones for the occurrence of SSR polymorphisms. All primer pairs produced an amplification product of the expected size and detected polymorphisms among the genotypes examined. The potential for the use of SSRs as genetic markers for sweetpotato germplasm characterization is discussed.
Use of Sod Competition in Peach Production
Authors: Glenn D.M. , Welker W.V.
Published: February 2019

Planting sod beneath peach trees to control excessive vegetative growth was evaluated from 1987 to 1993 in three field studies. Peach trees were established and maintained in 2.5-m-wide, vegetation-free strips for 3 years, and then sod was planted beneath the trees and maintained for 5 to 7 years. Reducing the vegetation-free area beneath established peach trees to a 30- or 60-cm-wide herbicide strip reduced total pruning weight/tree and weight of canopy water shoots in many years. Fruit yield was reduced by reducing the size of the vegetation-free area in some, but not all, years; however, yield efficiency (kg yield/cm2 of trunk area) was not reduced in two studies, and in only 1 year in the third study. Planting sod beneath peach trees increased available soil water content in all years and yield efficiency based-evapotranspiration (kg yield/cm soil water use + precipitation) in some years compared to the 2.5-m herbicide strip. Reestablishing sod beneath peach trees has the potential to control vegetative growth and may be appropriate for high-density peach production systems where small, efficient trees are needed.
Growth and Production of `Bing' and `Schmidt' Sweet Cherries on East Malling or Mazzard × Mahaleb Rootstocks
Authors: Larsen Fenton E. , McCamant Virginia S. , Higgins Stewart S.
Published: February 2019

`Schmidt' and `Bing' sweet cherries were planted in 1982 at the W.S.U. Royal Slope orchard near Othello, Wash. `Schmidt' was on Mazzard × Mahaleb (M × M) rootstocks 39, 97, 14, and Mazzard seedling. `Bing' was on East Malling (E.M.) cherry rootstocks 38, 15, 21, 16, 50, and Mazzard and Mahaleb seedling. Yield of `Schmidt'/M × M 39 was greater than all other rootstocks. Trunk diameters of `Schmidt' were greatest on Mazzard and M × M 39. If a standard-size tree is desired, M × M 39 may be useful. `Bing' trees on the E.M. rootstocks tended to be larger than on Mazzard or Mahaleb and are, therefore, not of great interest.
A Decision Support System for Designing the Spatial Characteristics of Field Plantings at Any Global Location to Optimize Available Canopy Insolation during Any time Period
Authors: Burcaw Jeffrey W. , Wood Bruce W. , Poole Michael W.
Published: February 2019

A decision support system (DSS) is described that quantitatively analyzes certain important light climate characteristics of crops planted in discrete canopy, hedgerow, or trellis cropping systems. The DSS facilitates rapid and efficient calculation of the theoretical maximum shading (or, conversely, the theoretical minimum level of insolation) for use in determining the planting pattern that minimizes canopy shading during user-specified temporal intervals. It addresses canopy shading in field plantings within a wide variety of geometric patterns, interplant spacings, canopy sizes and forms, global latitudes, pattern orientations, site reliefs and aspects. Calculations describe insolation characteristics during any hour(s) of the day or day(s) of the year within the range of planting parameters. The DSS functions as a systems tool, or module, for design of the spatial subsystem component of a particular cropping strategy where horticulturally important traits are regulated by the light climate.
Sensitivity of Seedling Radicles to Chilling and Heat-shock-induced Chilling Tolerance
Authors: Rab Abdur , Saltveit Mikal E.
Published: February 2019

Chilling sensitivity increased as the radicle of germinating corn (Zea mays L. `Jubilee' hybrid), cucumber (Cucumis sativus L. `Poinsett 76'), mung bean (Phaseolus aureus Roxb. `Berkin'), and tomato (Lycopersicon esculentum Mill. `Rio Grande') seeds increased in length from 1 to 7 mm. In contrast, radicles of germinating okra (Hibiscus esculentus L. `Clemson' spineless) seeds exhibited similar levels of chilling sensitivity at all radicle lengths. The degree of chilling sensitivity varied among the species in relation to time required to elicit a significant response and the magnitude of the elicited response. Based on subsequent radicle elongation, okra and cucumber were the most sensitive species to chilling at 2.5C for 96 h; tomato and corn were relatively less sensitive, and mung bean was the least sensitive. This pattern of sensitivities changed when other criteria were used to evaluate chilling sensitivity. The development of lateral roots decreased with prolonged chilling in all species, except for corn in which the apical tip remained viable even after 192 h of chilling. Heat shock (0 to 10 min at 45C) induced chilling tolerance in all species, except okra. In okra, neither increasing the heat shock temperature nor decreasing the severity of chilling (i.e., temperature and duration of exposure) resulted in a significant reduction in chilling injury. The differential induction of heat shock proteins in okra and the other species is discussed.
Thermal Analysis of Dormant Muscadine Grape Buds
Authors: Clark John R. , Wolf Tony K. , Cook M. Kay
Published: February 2019

Thermal analysis was used to determine if muscadine grape (Vitis rotundifolia Michx.) buds supercooled and to determine the seasonal cold hardiness of several grape cultivars. Buds of the muscadine cultivars `Carlos' and `Summit', sampled from vines grown at Clarksville, Ark., produced low-temperature exotherms consistent with the number of buds tested. Apparent hardiness of the buds increased from 5 Nov. 1993 through 7 Jan. 1994. Mean low-temperature exotherms (MLTE) were lowest on 7 Jan. and were –21.5C for `Carlos' and –23.4C for `Summit'. Mars (V. labrusca L.) buds, sampled at Clarksville and Winchester, Va., were included in the study, and increased in hardiness during the same period. MLTE temperatures for `Mars' from Arkansas were similar to those of the muscadine cultivars on 7 Jan.; however, `Mars' attained lower MLTE temperatures with vines grown in Virginia compared to those in Arkansas. Location differences may be due to cultural conditions, sample handling, environment or other reasons.
Cabium Browning of Cold-damaged Peach Trees in the Nursery
Authors: Deyton D.E. , Sams C.E. , Cummins J.C. , Lockwood D.W.
Published: February 2019

One-year-old peach trees in nurseries at McMinnville, Tenn., were exposed to –11C on 5 Nov. 1991 before digging. The nursery owners were concerned about the relationship of tree cambium browning to potential tree performance after planting. A color scale [0 = nondamage (white) to 6 = severely damaged (brown)] showing discolored cambium of peach nursery trees was developed to rate damage. Browning was rated at 8 cm above graft union. Five trees each of nine cultivars with chill hour requirements ranging from 175 to 1050 were rated. Cultivars with <500 chill hour requirement had higher ratings. Ten `Harbite' trees from each of six size grades were rated. Trees in grades of 30- to 90-cm height had less cambium browning than trees in grades of 90 to 152 cm height. In Dec. 1992, 1-year-old `Red Globe' trees were exposed to –6 (minimum field temperature), –15, –18, –24, –30, or –35C in a programmable freezer. A subsample of five trees per treatment was rated for browning 1 day after treatment and a second subsample rated in mid February. Trees in a third subsample were grown in a nursery the following summer. Slight browning (rating = 1.6) was evident soon after exposure to –24C; however, severe browning was evident on trees exposed to –30 or –35C. Trees exposed to temperature more than –24C did not differ in height, trunk diameter, or dry weight at the end of the growing season, however trees exposed to –30 or –35C did differ. In a similar experiment, `Juneprince' trees exposed to –18C had slight cambium browning (rating = 1.2) but trees died.
Stem Elongation Response of `Stargazer' Oriental Lily to Bulb Dips in Uniconazole
Authors: Liu Bin , Heins Royal D.
Published: February 2019

Shoot elongation of `Stargazer' lily is rapid during the first 15 to 20 days after planting (1 to 2 cm·day–1 is common). Lower stem leaves are small, separated by long internodes. We determined if dipping `Stargazer' bulbs in uniconazole (5-, 10-, 20-, or 40-ppm solutions for 1 min) before planting would slow initial stem elongation, decrease final height, and improve appearance. Emergence, visible bud, anthesis dates, and flower bud count were recorded. Plant height was measured three times per week until anthesis. Uniconazole did not affect time to emergence, visible bud, anthesis, or flower bud count. Compared to the final height of 48 cm (untreated plants), height was reduced 7, 17, 22, and 30 cm (5%, 35%, 46%, and 62%) at anthesis for plants in the 5-, 10-, 20-, and 40-ppm treatments, respectively. The uniconazole bulb dips did not affect stem elongation rate for the first 10 days after treatment or from 45 days after treatment through anthesis (day 65). Relative to untreated plants, stem elongation rate of treated plants decreased linearly from 10 to about 35 days after treatment, with a maximum reduction of 55%, 75%, 85%, and 100% for plants in the 5-, 10-, 20-, and 40-ppm treatments, respectively.
Use of Ethephon as a Controlled Abscission Agent on Paprika Pepper
Authors: Motes James E. , Kahn Brian A. , Maness Niels O.
Published: February 2019

Our objective was to increase the percentage of marketable red fruit at harvest time on paprika pepper (Capsicum annuum L.) plants intended for mechanical harvest by using ethephon [(2-chloroethyl)phosphonic acid] to remove late-developing blooms and green fruit. We conducted three experiments on field-grown plants in southwestern Oklahoma. We tested ethephon solutions of 0, 1000, 2000, 3000, and 4000 μl·liter–1 as a one-time foliar application on various dates. Total dry weight of harvested fruit decreased linearly with ethephon rate in all three studies. Marketable fruit as a percentage of total harvested fruit weight increased linearly with ethephon rate in two studies. There was no consistent effect of ethephon on the intensity of red pigment extracted from dehydrated marketable fruit. With proper timing, as little as 1000 μl ethephon/liter was enough to alter the distribution of total harvested fruit weight toward marketable fruit and away from green fruit. A target spray “window” of the last 10 days in September seemed appropriate for southwestern Oklahoma, and the recommended rate of ethephon was between 2000 and 3000 μl·liter–1.
Chemical Growth Regulation of Landscape Groundcovers
Authors: Paulsen Pamela J. , Hensley David
Published: February 2019

Landscape maintenance in Hawaii occurs year round. Many popular groundcovers are pruned monthly, some twice monthly. This increases labor costs and creates large amounts of waste. Several rates of five commercial growth regulators (cimectacarb, flurprimidol, mefluidide, paclobutrazol, and uniconazole) were applied to several groundcovers commonly grown in Hawaii. Species used include Cuphea hyssopifolia, Evolvulus glomeratus, Lantana montevidensis, Myoporum spp., and Wedelia trilobata. Studies were conducted in the shadehouse with potted plants and in the field with established plants. Rates, response, and method of application (spray or soil drench) for each product were evaluated. Growth, length of control, and phytotoxicity were measured. Flurprimidol, paclobutrazol, and uniconazole showed the greatest control for the most species. Flurprimidol and paclobutrazol controlled growth for the longest time, up to 4 months for some species. However, these materials resulted in the greatest amount of damage, even at low rates. Cimectacarb controlled growth of fewer species, while mefluidide caused the least growth reduction for all species.
Chemical Fruit Thinning with Armothin® Sprays to Reduce Fruit Set in `Loadel' Cling Peach
Authors: Southwick Stephen M. , Yeager James T.
Published: February 2019

Hand-thinning is required every season to ensure large fruit size of `Loadel' cling peach in California. Hand-thinning is costly. Chemical thinning could help to lower costs of hand-thinning. Armothin® {[N,N-bis2-(omega-hydroxypolyoxyethylene/polyoxypropylene)ethyl alkylamine], AKZO-Nobel, Inc., Chicago; AR} was sprayed at 80% of full bloom (FB), FB and FB + 3 days. The spray volume was 935 liters·ha–1. Concentrations of AR were 1%, 3%, and 5% AR applied at FB. No damage to fruit was noted. Leaf and fine shoot phytotoxicity were seen at 5% AR. The amount of time needed and number of fruits thinned were reduced by those same treatments. Salable yield and fruit size after AR treatments equaled those found on hand-thinned controls. Armothin® shows promise for chemical thinning of peach when used as a bloom spray that damages flowers, thereby reducing fruit set. An experimental use permit was issued for use of AR for stone fruit thinning in California during 1995.
Shading and DCPTA Interactively Influence Shoot Growth of Hypoestes
Authors: Svenson Sven E.
Published: February 2019

The objective of this study was to determine if shading and DCPTA application interactively influence seedling emergence and shoot growth of Hypoestes phyllostachya Bak. seedlings. Hypoestes `Carmine Red' seeds were soaked for 6 h in distilled water, and then soaked 6 h in solutions containing' 10 mg DCPTA/liter (30 mM) and 0.1% Tween-80, 0.1% Tween-80, or distilled water. Date of seedling emergence was recorded after sowing (0.5 cm) in 9-cm (460 ml) pots filled with 440 ml of a 5 pine bark: 4 Florida sedge peat: 1 sand medium. Forty pots from each of the three seed-soak treatments were grown under 30%, 63%, or 84% shading, provided by saran-type shadecloth, using natural photoperiods (completely randomized design). Shoot heights and dry weights were recorded 75 days after sowing. Neither shading nor DCPTA influenced total seedling emergence or seedling emergence rate (time to 50% emergence). Under 30% shading, seedlings from DCPTA-treated seeds were taller and had more shoot dry weight than seedlings from surfactant- or water-treated-seeds; however, DCPTA did not influence seedling height or shoot weight under 63% or 84% shading.
Agricultural Applications of Ethephon
Authors: Murray Mike , Beede Bob , Weir Bill , Williams Jack
Published: February 2019

Physiological effects on plant growth caused by the plant hormone ethylene have been noted for many years. More than 100 years ago, workers noted that illuminating gas or broken gas mains had deleterious effects on surrounding trees or plants. It was not until the 1960s that scientists documented that plant growth may be manipulated by applying ethylene. Some of the biological effects since noted include premature defoliation, fruit maturation ripening, induction of flowering, stimulation of sprouting or germination, and shortening of plant height. These effects are noted on a wide variety of agricultural crops, including vegetables, field crops, tree crops, and ornamentals. Ethylene is a gas and dissipates rapidly, and, thus, does not lend itself to field application. In the 1960s, the product ethephon [(2-chloroethyl)phosphonic acid] was developed. When taken up by the plant, ethephon is converted to ethylene in the cells and becomes available for physiological interactions. Because ethephon precipitates a wide variety of biological reactions, application technology becomes extremely important. Factors such as plant growth stage, plant stress status, plant foliage spray coverage, ethephon rates, and environmental conditions determine the responses obtained. An example is provided by processing tomatoes, where the desired response is to maximize fruit maturity enhancement and minimize premature defoliation—both ethylene responses. We have selected five agricultural applications of ethephon as examples of how plant growth may be altered. These are: increased boll opening in cotton; enhanced pistillate flower induction in hybrid squash seed; accelerated fruit maturity in processing tomatoes; enhanced hull splitting in walnuts; and reduced lodging in wheat. Each of these applications, and others, are common in California agriculture. Brevity necessitates providing only a summary of relevant applied research activities, which are not intended to be complete or thorough. Details on specific ethephon applications may be obtained from that particular researcher.
Genetic Variation and Mapping of the Carrot Nuclear and Chloroplast Genomes
Authors: Sampath Vivek , Simon Philipp
Published: February 2019

Studies of genetic variation at the DNA level in the genus Dacus have been very limited. Molecular markers based on restriction fragment length polymorphism (RFLP) have been highly useful and efficient gene markers in other plant species. We have evaluated the chloroplast genome of 19 Dacus species and inbreds cut with 10 restriction enzymes and probed with 14 petunia chloroplast clones. A phylogenetic tree generated to date shows three major groupings of these accessions as seen with data generated by an earlier study using nuclear RFLPs. However, D. glochidiatus and D. guttatus are in different groups. Details of the chloroplast study will be discussed. Also, a genetic linkage map of carrot will be constructed. The map will be used to determine the genomic regions conditioning traits such as pigmentation root and core diameter, and root length.
Identification of Simple-sequence Repeats in Malus (Apple)
Authors: Szewc-McFadden Amy K. , Bliek Sharon , Alpha Christopher G. , Lamboy Warren F. , McFerson James R.
Published: February 2019

Simple-sequence repeats (SSRs) are efficient and informative DNA markers with great potential for germplasm characterization. When used to characterize large arrays of accessions, such as the core subset of the USDA/ARS Malus collection, SSRs may be more effective than other approaches, such as restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD). For example, SSRs can be PCR-amplified and fluorescence-based detected; they also appear to be abundantly disbursed throughout plant genomes and yield abundant polymorphisms in most taxa studied. We are conducting an extensive screening of a size-fractionated library of Malus ×domestica cv. Golden Delicious to identify and characterize selected SSR loci. We are applying genetic information revealed by SSR loci in combination with passport and horticultural data to better comprehend genetic identity and relatedness in Malus germplasm collections and help develop the Malus core subset. Ultimately, application of molecular marker data will permit improved conservation and use of genetic resources.
Linkage and Correlation Analysis of Some Traits in Peach
Authors: Weber C.A. , Sherman W.B. , Moore G.A.
Published: February 2019

Segregating F2 peach populations in the Univ. of Florida breeding program were analyzed to determine linkage relationships among five qualitative traits: flower type, Sh/sh, flesh type, M/m; flesh color, Y/y; leaf gland type, E/e; and pubescence, G/g. Independent segregation was confirmed between flesh color and leaf gland type, between pubescence and flesh color, and between flower type and pubescence. Previously undocumented independent segregation was found between leaf gland type and flesh type and between pubescence and leaf gland type in our populations. The relationship between these latter characteristics should be investigated in other breeding populations. No correlation was found between fruit development period and flesh type. Also, no correlation was found between chilling requirement and flesh type.
Controlled Release Urea Fertilizers Affect the Growth and Quality of Selected Foliage Plants
Authors: Murakami Paul K. , Rauch Fred D.
Published: February 2019

Three formulations of an encapsulated urea product and one sulfur-coated urea were evaluated at 0 to 4 times the recommended rate on Chomaedorea elegans, Chomaedorea seifrizii, Chrysalidocarpus lutescens, Spathiphyllum `Tasson', and Rhapis excelsa against a standard controlled-release fertilizer at equal N rates. Each plant species responded differently to the fertilizer sources. Chomaedorea seifrizii and Spathiphyllum `Tasson' did not exhibit preferences for fertilizer source from top-growth measurements. Chomaedorea elegans, Chrysalidocarpus lutescens, and Rhapis excelsa growth measurements indicate that fertilizer source affected growth and quality of the plants. The general recommendation for foliage plant production is an equal ratio of ammoniacal to nitrate nitrogen sources. Economically, this ratio makes the fertilizer more expensive than other traditional fertilizers. The use of a controlled-release urea fertilizer has the benefit of being a cheaper source of N and would lower the cost of production, but results on the selected foliage plants indicate that the fertilizer composition is important in plant production.
Whole-plant Response of Six Poinsettia Cultivars to Three Fertilizer and Two Irrigation Regimes
Authors: Schuch U.K. , Redak R.A.
Published: February 2019

Six cultivars of poinsettia (Euphorbia pulcherrima Willd. `Angelika White', `Celebrate 2', `Freedom Red', `Lilo Red', `Red Sails', and `Subjibi Red') were grown for 9 weeks under three fertilizer treatments (80, 160, or 240 mg N/liter constant feed) and were either well-watered or water deficient between irrigations. Plant height decreased with decreasing fertilizer and with low vs. high irrigation treatments. Dry weight of all shoot components were reduced by deficit irrigation. For well-watered plants, leaf area and leaf dry weight increased from low to medium and decreased from medium to high fertilizer treatment. For plants under deficit irrigation, these variables were similar for low and medium fertilizer and increased at the 240 mg N/liter. Stomatal conductance and transpiration decreased with increasing fertilization level and deficit irrigation. Leaf chlorophyll content at week 5 was 40% and 49% higher for plants fertigated with 160 or 240 mg N/liter compared to 80 mg N/liter, while 2 weeks later these differences decreased to 20% and 26%. Irrigation had little influence on leaf chlorophyll content.
Preplant Superphosphate Amendment and Leaching Fraction on Growth of Potted Poinsettia
Authors: Ku Catherine S.M.
Published: February 2019

Earlier study indicates that greenhouse crop production may be an overlooked point source of P pollution. A potential strategy to reduce P leaching may be to eliminate superphosphate amendment in soilless medium. Single-pinched `Amy' poinsettias (Euphorbia pulcherrima) in 15-cm pots were grown in a soilless medium of 3 peat: 1 perlite: 1 vermiculite (by volume). A treatment combination of preplant, finely ground, single superphosphate (SSP) (0N–8.8P–0K) amendment at 0 or 172 mg/pot and leaching fractions (LFs) of 0 and 0.2 were evaluated in a completely randomized design during a 10.5-week study. Plants received constant liquid fertigation with 7.8 mg P/liter and 210 mg N/liter from modified Hoagland solution #1. The total P applied via fertigation ranged from ≈38 mg at 0 LF to ≈50 mg at 0.2 LF. The leachate P concentration ranged from 4 mg/liter to 38 mg/liter. There was no significant difference in yield due to SSP and LF. Across all treatments, mean fresh mass was 36 g, mean dry mass was 5.9 g, mean leaf area was 980 cm2, and mean bract area was 1900 cm2.
The Effect of Nutrient Regime on Biomass Allocation and Nutrient Accumulation in Red Oak Seedlings
Authors: Larimer Jill C. , Struve Dan
Published: February 2019

ln Spring 1993, red oaks (Quercus rubra) were propagated from seed. From June through October, plants were fertilized twice daily with 1.4 liters of 20N–10P–20K water-soluble fertilizer solution at concentrations of 0, 25, 50, 100, 200, or 400 ppm N. Destructive harvests were conducted six times at intervals from June through Dec. 1993. Leaf area, stem height, root length, root area, and dry weights of roots, stem, and leaves of harvested plants were measured and tissue nutrient concentrations were analyzed. There was no relationship between whole-plant N concentration and total plant biomass (r = 0). However, there were some linear relationships between total plant N and total plant biomass for an individual fertilizer treatment. Biomass allocation between root, stems, and leaves was very consistent across all fertilizer levels at any one harvest. Percent total N in roots, stems, and leaves also was fairly consistent across fertilizer levels. This was true at each harvest, except the first two, in which a greater percentage of total N was partitioned to the leaves and a smaller percentage was partitioned to the roots in the high (100, 200, 400 ppm N) fertilizer treatments. Whole-plant K concentrations increased with increasing fertilizer level, but decreased over time. Whole-plant P concentrations increased linearly with whole-plant dry weight in the higher (100, 200, 400 ppm N) fertilizer treatments.
Cornus florida Floral Development
Authors: Maluea K.R. , Holton R.W , Schlarbaum S.E. , Graham E.T. , Triaiano R.N.
Published: February 2019

Cornus florida L. floral development was monitored using standard paraffin histological techniques and light microscopy. Terminal buds (putative floral buds) were collected over 6 weeks from mature landscape trees located on The Univ. of Tennessee Agricultural Campus, Knoxville. Examination of samples taken at 3- to 7-day intervals revealed variations in development representing 1- to 2-week differences between florets in a single inflorescence, florets on the same tree and florets from different trees. Floral initiation occurred before July 19th in the 2 years of this study. Floral development followed typical angiosperm stages. Florets, although small, appeared morphologically mature by early September in both years.
Phytochrome-A as a Strategy to Control Internode Elongation in Crops Grown in Crowded Conditions
Authors: Tennessen D.J.
Published: February 2019

Increased plant density can reduce the per-plant cost of ornamental and vegetable crop production, but also reduces the quality of the crop produced. Plants grown under these conditions exhibit internode elongation and yellow leaves. This response generally is described as a shade-avoidance response. Genetically transformed tobacco that express oat Phytochrome-A (Phy-A) grew short in white light but grew as tall as the nontransformed control (10 cm) in red light. When a mixture of red and 5% far-red (700 to 750 nm) was used, transformed tobacco remained short (5 cm) and dark green, whereas nontransformed grew taller (27 cm). The concept of masking the shade avoidance response was tested in transformed lines of tomato (Boylan and Quail 1989) that express elevated oat Phy-A. Transformed plants remained short and dark-green in shade-light. Phy-A may be a useful strategy to mask the shade-avoidance response.
A Simple Method for Measuring Crop Canopy
Authors: Smith Janice , Raczkowski Charles , Kamp-Glass Marihelen
Published: February 2019

Crop canopy cover data is used to study canopy structure and crop growth analysis. This study was conducted to determine the easiest and most reliable method of calculating crop canopy cover. Using Decagon Sunfleck Ceptometer was compared with the traditional method (tape measure) of retrieving crop canopy cover data. Data was collected on silage corn (Zea mays) and soybeans (Glycine max L.). The method of collecting data using the ceptometer was simple and quick compared to the traditional method. The ceptometer, even with human variability, was found to be ≈99% accurate. The traditional method was found to have >10% variability. The ceptometer is a much quicker and more reliable tool to use. It appears to decrease the variability in the collection of crop canopy cover data.
Use of Pre-sidedress Nitrate Test and SPAD Meter to Evaluate Nitrogen Needs of Peppers
Authors: Mangan Francis X. , Howell John , Herbert Stephen
Published: February 2019

Hot cherry peppers were grown after incorporation of the following three winter cover crop regimes in Summer 1994—hairy vetch (Vicia villosa) plus winter rye (Secale cereale), hairy vetch alone, and no cover crop. For each main effect there were three N rates applied to peppers in three applications over the course of the season: 0, 85, and 170 kg·ha–1. The pepper yield was significantly higher with hairy vetch plus rye than rye alone or no cover crop. There was also no significant yield increase with the addition of N fertilizer to the peppers grown with hairy vetch. Soil nitrate–N levels taken just prior to N sidedress were significantly higher in plots that had hairy vetch plus rye compared to other treatments. There was also a significant linear relationship of the soil nitrate–N levels among the three N rates. Based on the results of this study, sidedressing peppers would be recommended when soil nitrate levels are above the 25 ppm that is the current threshold for other crops. SPAD readings were taken several times during the season. There was a high correlation of SPAD readings to pepper yield very early and very late in the season. The correlation of SPAD readings to pepper yield was poorest when taken at the time of N sidedress.