bluuebunny/crossref_metadata_2025 huggingface dataset:
A Community Service Approach for a Landscape Design Course: Design and Installation of a Habitat for Humanity Residential Landscape
Authors: Davis Gregory L.
Published: February 2019

Landscape design courses typically include real-life projects in which students integrate design principles and selection of plants and materials. Such projects also allow students to sharpen their graphical and interpersonal communication skills; they draw plans to satisfy a client. For one project in our course, students do all of that work plus contribute to the off-campus community via the Habitat for Humanity program. Students gain not only the traditional experience of designing a residential landscape on a strict budget but also the experience of competing to create the plan to be chosen by a committee of decisionmakers. The students gain further practical hands-on experience because they install the landscape. This type of community service project allows horticulture students to earn the satisfaction of seeing a site evolve from an empty lot to a finished landscape, knowing they are enhancing a homeowner' s and the community's environment.
The Use of Sap Flow Gauges for Estimating Transpiration
Authors: Rose Mark A.
Published: February 2019

New electronic biosensors that directly monitor plant physiological and morphological processes are now being developed for use in research and commercial applications. Although methods for measuring sap flow by applying heat to stems have been used for more than 20 years, they have usually been intrusive, required empirical calibrations and conversions, and been too fragile for rugged commercial environments. A more-promising method for monitoring sap flow is balancing the thermal fluxes into and out of a stem segment using heat sources wrapped around a stem. Constant heat-balance sap-flow gauges have been used for the direct, accurate, non-invasive, and continuous measurement of sap flow rate in many herbaceous and woody plants, including forest and fruit trees, vines, landscaping shrubs, and numerous agronomic plants. The performance of sap-flow gauges has steadily improved as they have been used in a wider range of basic and applied research. Research is now being conducted to use these gauges as on-line sensors to schedule irrigations, monitor plant stress, and even control the greenhouse environment.
Composted Poultry Litter as a Low-cost Media Amendment
Authors: Welch Matt , Creech D.L.
Published: February 2019

The poultry industry is a $1 billion industry in Texas, with most production centered in eastern Texas. The nursery industry is a $600 million industry, with 25% of the producers located in eastern Texas. With hundreds of millions of birds produced each year, and each bird producing ≈2 lb of manure, waste disposal is a growing problem. Composted poultry litter was mixed with composted pine bark to create five media with varying percentages of poultry litter as a component: 0%, 5%, 10%, 20%, and 40%. A randomized complete-block design was used with poultry litter rates as main plots and plant species tested as subplots. Five species included: tomato, marigold, Cortaderia selloana, Asian jasmine, and Salvia leucantha. Prior to planting, all 1-gal containers were leached with 1000 ml of water, the leachate collected, and tested for conductivity. Plant growth measurements to be presented include plant height and dry weight. The results of media and leaf tissue nutrient analysis will be presented.
Cotton Fiber as a Substitute for Agar Support in Tissue Culture
Authors: Moraes-Cerdeira Rita M. , Krans Jeffrey V. , McChesney James D. , Pereira Ana M.S. , Franca Suzelei C.
Published: February 2019

Cotton fibers were tested as a substitute for agar in tissue culture. The cost of agar has prompted us to search for an alternative more economical medium support. Effectiveness as a medium support was evaluated in terms of callus maintenance and shoot organogenesis using Artemisia, Agrostis, and Taxus. Taxus and Agrostis calli cultivated on liquid media with cotton fiber as medium support (25 ml of medium per gram of cotton) grew better than calli on agar (0.8% w/v). There were no significant differences in shoot organogenesis of Artemisia and Agrostis grown in 25 ml of medium per gram of cotton from those grown in agar medium.
Chlorophyll Fluorescence as a Potential Indicator of Controlled-atmosphere Disorders in `Marshall' McIntosh Apples
Authors: DeEll Jennifer R. , Prange Robert K. , Murr Dennis P.
Published: February 2019

Chlorophyll fluorescence was evaluated as a rapid and nondestructive technique to detect low-O2 or high-CO2 stress in apples (Malus domestica Borkh.) during storage. `Marshall' McIntosh apples were held for 5, 10, 15, 20, or 25 days at 3C in 1) standard O2 (2.5% to 3%) and low CO2 (<1%), 2) low O2 (1% to 1.5%) and low CO2 (<1%), 3) standard O2 (2.5% to 3%) and standard CO2 (4% to 4.5%), or 4) standard O2 (2.5% to 3%) and high CO2 (11% to 12%). Only 10% of the apples had skin discoloration after 5 days in 1% to 1.5% O2; 80% developed skin discoloration after 20 days in low O2. Small desiccated cavities in the cortex, associated with CO2 injury, developed in 10% of the apples after 20 days in 11% to 12% CO2. Five days in 1% to 1.5% O2 or 11% to 12% CO2 caused variable fluorescence (Fv) of apple fruit to decrease compared to those held in standard atmospheres. Additional exposure did not significantly affect Fv in either the low-O2 (1% to 1.5%) or high-CO2 (11% to 12%) treatment. Our results suggest that chlorophyll fluorescence techniques can detect low-O2 and high-CO2 stress in apples before the development of associated disorders.
Leader Management and Soil Fumigation Affect Branching and Precocity of Young Apple Trees
Authors: Parker Michael L. , Young Eric
Published: February 2019

Apple (Malus domestica Borkh.) cultivars Spur Galagored (#42) (`Gala'), Jonagored (`Morren's'), and Red Fuji (B.C. #2) (`Fuji') on Mark rootstock and `Gala' on Malling 26 EMLA (M.26) and Malling 9 EMLA (M.9) were planted in the four major apple-production regions of western North Carolina. Three leader management techniques, weak leader renewal, snaked leader, and heading with partial terminal leaf removal (H + PTLR), were applied to five-tree plots beginning the spring after planting. Leader management techniques, weak leader renewal or H + PTLR, which involved dormant pruning or vegetation removal and an interruption in vegetative vigor, reduced total branching and yield during the third year. Fumigation with methyl bromide increased lateral branching and yield in the third year. No significant yield differences were detected for `Gala' grown on M.9, M.26, or Mark rootstocks. Trees grown in the most western region of the state, Haywood County, had smaller trees and reduced yields compared to the other three regions due to a shorter growing season.
Tree Form and Heading Height at Planting Affect Peach Tree Yield and Crop Value
Authors: Marini Richard P. , Sowers Donald S. , Marini Michele Choma
Published: February 2019

`Sweet Sue' peach (Prunus persica L. Batsch) trees were subjected to a factorial arrangement of treatments. At planting, trees were headed at 10 or 70 cm above the bud union and trees were trained to an open-vase or central-leader form. For the first 4 years, high-headed trees were larger than low-headed trees. After 7 years, open-vase trees had larger trunk cross-sectional area, tree spread, and canopy volume than central-leader trees. Open-vase trees had higher yield and crop value per tree, but lower yield and crop value per unit of land area or unit of canopy volume than central-leader trees. Crop density and yield efficiency were similar for all treatments.
Growth of Budded, Containerized, Citrus Nursery Plants when Photosynthesis of Rootstock Shoots Is Limited
Authors: Williamson J.G. , Maust B.E.
Published: February 2019

Two experiments were conducted to determine the effects of rootstock shoot defoliation or shading on growth during the first two scion flushes of budded, containerized, citrus nursery trees. Both experiments were conducted in a greenhouse with Cleopatra mandarin (Citrus reticulata Blanco) and Swingle citrumelo [C. paradisi (L.) Osb. × Poncirus trifoliata (L.) Raf.] seedlings budded with `Hamlin' orange [C. sinensis (L.) Osb.]. Scion buds were forced by cutting off the rootstock shoots above the bud union or by bending the rootstock shoots and tying them to the base of the plants (bending). In one experiment, shoots from both rootstocks that were forced by bending received one of four defoliation treatments: treatments were 0%, 40%, 60%, or 85% (based on leaf area) defoliation for Cleopatra and 0%, 30%, 60%, or 100% defoliation for Swingle. In the second experiment, rootstock shoots of plants forced by bending were subjected to a maximum photosynthetic photon flux (PPF) of 820, 225, 90, or 30 μmol·m–2·s–1. Growth of Cleopatra plants declined linearly with increasing levels of rootstock shoot defoliation. When rootstock shoot defoliation was ≤40%, whole-plant (minus rootstock shoot) dry weights were higher for plants forced by bending than for those forced by cutting off rootstock shoots. For Swingle, most growth responses to rootstock shoot defoliation were curvilinear. Higher levels of rootstock shoot defoliation resulted in less growth than lower defoliation levels. Low PPF reduced whole-plant (minus rootstock shoot) and root dry weights for both rootstocks compared to high PPF. For Cleopatra, whole-plant and scion dry weights were highest at the highest PPF. For Swingle, whole-plant and scion dry weights were highest at 225 μmol·m–2·s–1. For both rootstocks, plants forced by bending had higher dry weights at 820 and 225 μmol·m–2·s–1 than plants forced by cutting off the rootstock shoots. For Swingle, most of the reduction in scion growth from rootstock shoot defoliation occurred during the first scion flush. Our results suggest that recently produced rootstock shoot photosynthates are the primary source of greater plant growth achieved by bending compared to cutting off rootstock shoots.
Bioavailable Herbicide Residues in Turfgrass Clippings Used for Mulch Adversely Affect Plant Growth
Authors: Bahe Anita R. , Peacock Charles H.
Published: February 2019

Grass clippings may comprise a minimum of 35% of yard waste. We investigated whether bioavailable herbicide residues in grass clippings used as mulch would be toxic to desirable plants. In each of three experiments, tall fescue (Festuca arundinacea Schreb.) was treated with a mixture of 2,4-D + dicamba + MCPP at 0.5 g total a.i./m2. Clippings were collected at 1-, 5-, 10-, and 15-day postspray intervals. Clippings at gram equivalent weights relative to desired mulching depths were applied to tomato (Lycopersicon esculentum L.), cucumber (Cucumis sativus L.), salvia (Salvia splendens F.), and marigold (Tagetes tenuifolia Cav.) grown in pots. Plant dry-weight comparisons were made at two destructive harvest intervals, from 2 to 5 weeks after mulching. No mulch and nontreated mulch treatments were used as controls. Growth of tomato and marigold was enhanced when nontreated grass mulch was used compared to no mulch, but growth of cucumber and salvia was not enhanced. The bioavailable residues relative to the postspray interval (1 to 15 days) influenced growth of all species. Mulching depth affected growth of all species, except salvia. Herbicide-treated mulch reduced dry weight by ≤80% for cucumber, 73% for tomato, 65% for marigold, and 34% for salvia compared to controls. Herbicide residues apparently increased with mulching depth, resulting in a cumulative effect inhibiting plant growth. Chemical names used: 2,4-dichlorophenoxyacetic acid (2,4-D); 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP); and 3,6-dichloro-o-anisic acid (dicamba).
Aluminum Amendment of Potting Mixes for Control of Phytophthora Damping-off in Bedding Plants
Authors: Benson D.M.
Published: February 2019

Control of preemergence damping-off caused by Phytophthora parasitica Dastur was investigated on three bedding plant species in a 1 peat: 1 vermiculite medium (v/v) limed at 3 kg·m–3 and drenched with aluminum at 10, 25, or 50 meq Al/100 cm3 medium. Aluminum as Al2(SO4)3 was applied as a drench at 0.75, 1.9, or 3.75 g/150 ml water to the surface of infested medium in 650-cm2 plug trays (1300-cm3 tray volume). All concentrations of aluminum were effective in controlling preemergence damping-off of snapdragon (Antirrhinum majus L.) and vinca (Catharanthus roseus G. Don, Madagascar periwinkle), but only 50 meq Al+3/100 cm3 medium was effective for petunia (Petunia ×hybrida Hort. Vilm.-Andr.). At 4 days after seeding and drenching with aluminum sulfate, exchangeable aluminum was 0, 0.5, and 2.03 meq Al+3/100 g medium, respectively, for the three concentrations used. Control of damping-off of snapdragon and vinca with 10 meq Al+3/100 cm3 medium with no detectable exchangeable aluminum 4 days after application suggests that P. parasitica was suppressed by aluminum early in the host–pathogen interaction, whereas petunia was susceptible to damping-off for a longer period before seedling emergence. Aluminum was not phytotoxic to vinca, snapdragon, or petunia grown in a limed medium.
Chromosome Numbers of Rubus Species at the National Clonal Germplasm Repository
Authors: Thompson Maxine M.
Published: February 2019

The U.S. Dept. of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), Corvallis, Ore., maintains Rubus germplasm representing worldwide diversity of the genus. Chromosome numbers were counted for 201 plants representing 124 taxa (species and varieties). There are new reports for 42 taxa, confirmation for 72 previously reported, and 10 counts for plants unidentified to species. The basic chromosome number was seven, and ploidy levels ranged from 2x to 12x.
Isozyme Variation in Cymbidium Species (Orchidaceae)
Authors: Obara-Okeyo P. , Fujii K. , Kako S.
Published: February 2019

Eight enzyme systems were used to study electrophoretic variability among 12 species of Cymbidium Swartz and to assess phylogenetic relationships among them. The species could be easily distinguished by two enzyme systems, malate dehydrogenase (MDH) and phosphoglucose isomerase (GPI), although other enzyme combinations were also diagnostic. Genetic similarity index data indicated considerable genetic variability among the 12 species. Isozyme data supported the current taxonomic placement of the investigated species. The terrestrials [Cymbidium goeringii (Rchb. f.) Rchb. f., Cymbidium ensifolium (L.) Swartz, and Cymbidium sinense (Jackson) Wild.], which are all members of the subgenus Jensoa (Rafin.) Seth & Cribb., were the most closely related.
Seed Production in Watermelon: A Comparison between Two Commercially Available Pollinators
Authors: Stanghellini M.S. , Ambrose J.T. , Schultheis J.R.
Published: February 2019

The number of honey bees (Apis mellifera L.) continues to decline due to parasitic mite pests and other factors. Honey bees and bumble bees (Bombus impatiens Cresson) were therefore compared for their effects on the seed set of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] in a 2-year field experiment. The experiment was a 2 x 4 + 2 factorial, comparing bee type (honey bee or bumble bee) at four visitation levels (1, 6, 12, and 18 bee visits) to pistillate flowers, with two controls: a no-visit treatment and an open-pollinated treatment. Bee visitation level had a strong positive influence on seed set (P ≤ 0.0001). All flowers bagged to prevent insect visitation aborted, demonstrating the need for active pollen transfer between staminate and pistillate watermelon flowers. Flowers visited by B. impatiens consistently contained more seed than those visited by A. mellifera, when compared at equal bee visitation levels (P ≤ 0.0001). We conclude that bumble bees have great potential to serve as a supplemental pollinator for watermelon when honey bees available for rental are in limited supply.
Effect of Nitrogen Fertilization on Yield and Quality of Some Salad Crops
Authors: Abdalla M.I. , Abdalla M. M.A. , Abdel-Aal S.A. , Farag I.A.
Published: February 2019

The present experiments were carried out at the Assiut Univ. Experimental Farm during two winter seasons, 1994/1995 and 1995/1996, to study the effect of nitrogen source and level on growth, yield, and quality of salad crops (lettuce, parsley, and roquette). Nitrogen sources were urea, ammonium nitrate, and ammonium sufate. Three nitrogen levels, namely 20, 40, and 80 kg N/feddan, in addition to organic manure (2.028% N), in addition to the control, were used. Plant height, number of leaves (parsley and roquette), number of non-edible leaves (in lettuce) were significantly increased with urea followed by ammonium nitrate. Plant fresh weight, weight of edible part (in lettuce), and total yield/feddan were significantly higher with urea than ammonium nitrate or ammonium sulfate. The lowest content of nitrate and nitrite in leaves of the salad crops was obtained with ammonium sulfate followed by ammonium nitrate, while urea gave the highest values. Application of organic manure produced plant height, number of leaves per plant, plant fresh weight, total yield, dry matter content almost equal to that obtained from 40 or 20 kg N/fed. Nitrate and nitrite content were at their lowest value when organic manure was used. Plant height, number of leaves, non-edible leaves, weight of plant and total yield/feddan were significantly increased with increasing nitrogen rates from 0 to 80 kg/feddan. Using 80 kg N/fed. gave the highest dry matter, nitrate, and nitrite content.
Light Quality Regulation of Gene Expression in Chrysanthemum
Authors: Zhang L. , Rajapakse S. , Ballard R.E. , Rajapakse N.C.
Published: February 2019

A major part of Clemson light quality research program focuses on understanding the mechanisms of plant growth alteration under spectral filters. We have extended this research to understand the molecular basis for plant height control by spectral filters. From the whole plant research we have found that gibberellins (GA) play a key role in height control under spectral filters. However, it is not clear whether an alteration of endogenous gibberellin levels or a change in sensitivity to gibberellins is causing the observed effects. Since gibberellins are a key hormone in cell expansion and flower development, an understanding of gibberellin regulation and metabolism under spectral filters is critical for the control of height and flowering of plants grown under these filters. For the molecular study, we have selected the gene that code for enzyme GA 20-oxidase, one of the key enzymes involved in producing functional GAs in the mevalonic acid pathway. GA 20-oxidase is thought to be a site of regulation of GA synthesis by the environment. We are currently studying the regulation of the expression of this gene by light quality using Northern analysis. Results from temporal and tissue specific regulation of chrysanthemum plants grown under CuSO4 filters will be presented.
The Influence of Temperature and Low Light on Fruit Set and Chemical Thinning of Apple Trees
Authors: Byers R.E.
Published: February 2019

Fruit trees grown in the eastern U.S. environment are typically exposed to low light conditions from cloudy/rainy periods that can reduce PAR to 10% to 15% of full sun for 2 to 3 days. To magnify or concentrate the effect of temperature during low light stress, fruit trees were moved from the field into total darkness for 2 to 4 days at various temperatures and then returned to the field. This provided low light stress while eliminating the need for treatments involving various levels of light and temperature during the day on photosynthesis. To reduce transplanting shock, bearing apple trees used were grown in the field in 25-cm-diameter root bags and were on M.27 rootstock. After initial fruit set (at about 15 mm fruit diameter) trees were dug and transplanted into 5-gal buckets and moved for short periods of time (2 to 4 days) into various dark environments or sprayed with various thinning chemicals and placed in growth chambers at 5, 10, 16, and 21 °C in the dark. Immediately after dark treatments, trees were returned to the field and placed in the original holes. In 1995, we found that Elstar/M.27 apple trees placed in the dark for 3 or 4 days and returned to natural sunlight conditions abscised all of their fruit at 21 °C dark temperature but were retained at 5 °C. In 1996, we found that Braeburn/M.27 apple trees placed in the dark for 2 days and returned to natural sunlight conditions abscised all of their fruit at 16 and 21 °C dark temperature, but were retained if the dark period was 5 °C. These data indicated that the dark period temperature was very important for fruit retention. In addition, trees sprayed with Carbaryl+Accel 3 h before placing in the growth chambers caused the development of more pigmy fruit at all temperatures. Pigmy fruit also appeared to be related to the combined effects of digging trees, treating with Carbaryl + Accel, and colder temperatures. In 1997, we found that Stayman/M.27 apple trees placed in the dark for 2 days and returned to natural sunlight conditions abscised most of their fruit at 21 °C dark temperature, but were retained if the dark period was 5 °C. Fruit thinning occurred at 10 and 16 °C. Additional fruit thinning was significantly promoted by Carbaryl or NAA + Regulaid over the range of temperatures (5 to 21 °C), but thinning appeared to be most promoted at 21 °C dark temperature. Unexpectedly, ethephon caused fruit thinning at all temperatures from 5 to 21 °C, and thinning did not appear to be affected by temperature (ethephon defruited all trees at all temperatures). We suspect that higher dark temperatures caused either higher respiration rates or higher natural ethylene production, which promoted fruit abscission whether treated with a thinner or not. In one field experiment, Carbaryl sprays were applied at 2-h intervals beginning at 6 a.m. until 8 p.m. to Empire/Mark trees. Similar fruit thinning occurred when applied at temperatures ranging from 18 to 36 °C. These data suggest that no differences in thinning were related to daytime temperature.
A Study on the Recovery Following Freeze–Thaw Injury in Onion and Chrysanthemum
Authors: Jiang Yiwei , Lim Chon C. , Arora Rajeev
Published: February 2019

Onion (Allium cepa L. cv Sweet Sandwich) and Chrysanthemum (Dendranthema grandiflora `Sunny Denise') tissues were used to investigate protein changes associated with recovery from freeze–thaw injury. Medium-sized onions were slowly frozen to either –4 or –9 °C, subsequently thawed, and divided in two halves. One half was used immediately for ion leakage (IL) measurements and total and microsomal protein extraction, whereas the other half was allowed to recover at 6 to 8 °C in the dark for 4 to 5 days. Chrysanthemum leaves were frozen to –3.75 °C, and allowed to recover first at 6 to 8 °C in the dark (1 d) and then under 12-h photoperiod at 18 °C (3–4 d). Results indicate a 1.4- and 2.5-fold higher IL, compared to control, from onion tissues frozen to –4 or –9 °C, respectively. IL in –4 °C-treated tissues was the same as respective control following recovery; however, it was further enhanced to 3.6-fold in –9 °C-treated samples. Chrysanthemum leaf tissue exhibited a 1.6-fold increase in ion leakage following injury, but completely recovered to control levels after 4 to 5 d. SDS-PAGE profiles revealed an absence of a 25-kDa microsomal protein in the injured onion tissues but, its up regulation during recovery only in reversibly injured tissues. Data also indicated an accumulation of 36-kDa soluble protein in chrysanthemum leaf tissues during recovery. Experiments are underway to further characterize these protein changes.
Changes in Lipid Peroxidation and Antioxidant Status in Ripening Muskmelon (Cucumis melo var. reticulatus) Fruit
Authors: Conner Patrick J. , Ng Timothy J
Published: February 2019

Muskmelons are perishable fleshy fruits with a shelf life of less than 14 days. This short timespan is a serious limitation to marketing of the fruits and reduces the profitability of the crop. Variation exists within and between melon types for postharvest storage ability, indicating a breeding program aimed at introducing longer storage times into muskmelon might be successful. However, there is a fundamental lack of knowledge of the underlying physiological processes that determine longer storage ability. Disruption of cellular membranes appears to be a persistent feature of plant senescence. Melon fruit tissues show a progressive decrease of membrane integrity, as measured by membrane permeability, as the fruit matures. Loss of membrane integrity may hasten tissue breakdown due to a loss of cellular compartmentalization and altered expression of membrane-bound enzymes. This project examines melon fruit during their development and postharvest storage. Fruit were collected at 20, 30, and 40 days post-anthesis, and after 10 days of storage. Fruit tissue was examined for evidence of lipid peroxidation which may contribute to the loss of membrane integrity. In addition status of the key antioxidants glutathione (GSH), ascorbate, and vitamin E was assayed to determine the possible breakdown sight of the cellular protection system. This information may be directly useful in providing selection criteria for a breeding program aimed at increasing muskmelon postharvest storage life.
Curing Influences Sugar Metabolizing Enzyme Activity in Sweetpotato
Authors: Huang Yuehe , Picha David H. , Johnson Charles E. , Kilili Anthony W.
Published: February 2019

Sweetpotato roots (`Beauregard', `Hernandez', and LSU breeding line 9496) were cured (30 °C and 90% RH) for 10 days immediately after harvest to determine the effect of curing on several sugar-metabolizing enzymes. Free sugars and activities of invertase, sucrose synthase (SS), and sucrose phosphate synthetase (SPS) were assayed. Total sugars for the three genotypes ranged from 132.5 to 177.9 mg sugar/g DW at harvest, and from 162.3 to 204.3 mg sugar/g DW after curing. Enzyme activity at harvest averaged over the three genotypes ranged from: 154 to 251 mol sucrose DW/h for invertase; 18.6 to 23.1 mol sucrose DW/h for SS, and 7.4 to 15.7 mol sucrose DW/hr for SPS. Enzyme activity after curing averaged over the three genotypes ranged from: 251 to 288 mol sucrose DW/h for invertase; 20.3 to 25.8 mol sucrose DW/h for SS, and 11.3 to 17.3 mol sucrose DW/h for SPS. The increase in invertase activity during curing was highest in `Hernandez' and lowest in the breeding line 9496. The increase in invertase activity correlated to the increase in reducing sugar content for `Hernandez' and `Beauregard'. Curing also shifted the pH optima of invertase in `Hernandez' from pH 5.2 to 7.6.
Weed Seed Banks in Established Strawberry Fields
Authors: Propsom Faye , Hoover Emily
Published: February 2019

Weed control in strawberries, either in a new planting or one that is established, is a major source of problems for growers in Minnesota. To control weeds, growers need to know which weeds are a problem, which weeds are deleterious, and which weeds have the potential to become a problem. Weeds present, soil type, and weed seed bank information are needed in order to predict potential weed problems. With different weed control practices applied between and within the rows, we assumed weed seed bank populations would vary. In addition, we were interested in seeing if the seed banks differed between soil types and individual farmer's cultural practices. Soil samples were collected from 13 commercial strawberry fields located around the Twin Cities metro area. In 1996, samples were taken after renovation and before mulch was applied. In 1997, they were taken after mulch was removed and prior to renovation. The soil samples for each date, treatment, and farm were dried, and organic matter was separated from inorganic. The weed seeds were removed from the remaining organic matter, identified and counted. Soil types and cultural practices were used to compare the differences among the farms.
Influence of Cover Crop on Soil Quality in Strawberry
Authors: Summers Jillene , Nonnecke Gail , Cambardella Cynthia , Schultz Richard , Isenhart Thomas
Published: February 2019

Traditional cover crops, such as perennial ryegrass (Lolium perenne), and sorghum-sudan grass (Sorghum sudanense), commonly are used in rotation with strawberry in the midwestern United States to improve soil quality and suppress weeds. The objective of the field study was to investigate the effects of various cover crops on soil quality and weed populations. The experiment was established in 1996 at the Iowa State Univ. Horticulture Station, Ames, in plots that previously were planted continuously in strawberry for 10 years. Nine treatments were arranged in a randomized complete-block design with three replications. Treatments included cover crops of Indian grass (Sorghastrum avenaceum), switch grass (Panicum virgatum), big bluestem (Andropogon gerardii), black-eyed susan (Rudbeckia hirta), marigold (Tagetes erecta `Crackerjack'), sorghum-sudan grass, perennial ryegrass, strawberry (Fragaria xananassa `Honeoye'), and bare soil (control). Of the prairie plants, Andropogon gerardii was the most difficult to establish and thus had the highest percentage weed cover. Macroaggregate mass of the soil at 0- to 15-cm depth was least in the bare-soil treatment and in the other annual-plant treatment, Tagetes erecta `Crackerjack'.
In Vitro Shoot Regeneration from Callus Derived from Marubakaido Apple Rootstock under Different Aluminium Concentrations
Authors: de Oliveira Marisa F. , de L. Fortes Gerson R. , da Silva João B.
Published: February 2019

The aim of this work was to evaluate the organogenesis of Marubakaido apple rootstock under different aluminium concentratons. The explants were calli derived from apple internodes treated with either 2,4-dichlorophenoxyacetic acid or pichloram at 0.5 and 1.0 μM and under five different aluminium concentrations (0, 5, 10, 15, 20 mg/L). These calli were then treated with aluminium at 0, 5, 10, 15, and 20 mg/L. It was observed shoot regeneration only for those calli previously treated with pichloram. There were no significant difference among the aluminium concentrations.
Use of Microsatellites for the Identification of Potato Somatic Hybrids
Authors: Johnson Alexander A.T. , Veilleux Richard E.
Published: February 2019

Somatic hybrid plants were obtained through protoplast fusion of monoploid potato. Of three separate fusions, two were interspecific between Solanum phureja and S. chacoense, whereas one was intraspecific between two S. phureja clones. Microsatellites, or SSRs, were employed to distinguish true somatic hybrids from somaclones of unfused protoplasts. Primers flanking eight different SSR loci obtained from GenBank accessions for potato were developed for PCR amplification. Microsatellites consisted of di-, tri-, and tetra-nucleotide repeat units that varied from 4 to 20 repeats per locus. The majority of microsatellites were highly polymorphic between the S. phureja and S. chacoense clones and the presence of both parental alleles in fusion regenerants indicated their interspecific hybrid nature. One interspecifc somatic hybrid could be identified at three of the four examined loci (two tri- and one di-nucleotide repeat loci). The parents were monomorphic at the remaining di-nucleotide repeat, thereby rendering it unsuitable for hybrid identification. A similar result was obtained for another interspecific hybrid, with four of five loci appearing polymorphic between the parents and in the somatic hybrid. Less polymorphism was observed between the parents of an intraspecific S. phureja somatic hybrid, with only one locus (a tetra-nucleotide repeat) of five examined showing polymorphism. Results indicate that SSRs are a consistent and reliable means for somatic hybrid identification in potato. In order to reduce the cost and time of maintaining numerous calluses through a lengthy tissue culture regeneration phase, a technique was developed to screen calluses prior to regeneration. Using SSRs and a rapid DNA extraction method, hybrid and nonhybrid calluses could be distinguished rapidly without adversely affecting subsequent regeneration of shoots from the callus.
Derivation and Comparison of Androgenic and Gynogenic Monoploid Potato Families
Authors: Cutright Rebecca J. , Veilleux Richard E.
Published: February 2019

Monoploid potato (2n = 1x = 12) can be derived either paternally through anther/microspore culture or maternally through crossing with a haploid-inducing pollinator. Evidence from other genera suggests that androgenic and gynogenic haploid populations derived from the same parent may differ due to gametic selection and/or epigenetic factors. Our objectives were to derive androgenic and gynogenic monoploid populations from each of two diploid (2n = 2x = 24) Solanum phureja clones and compare their phenotypic characteristics in a greenhouse study. A haploid-inducing pollinator, S. phureja IVP101, was crossed to two selections of S. phureja (PP5 and BARD1-3). A total of 185 fruit was obtained from PP5 and 398 from BARD1-3, resulting from 85% and 65% fruit set, respectively. Seed lacking the dominant embryo spot marker carried by IVP101 were selected and germinated in vitro. From 29,300 PP5 × IVP101 seeds, 278 were spotless, resulting in 27 monoploids. Approximately 35 monoploids were obtained from the 99,500 BARD1-3 × IVP101 seeds, of which 500 were spotless. In anther culture, PP5 and BARD1-3 yielded 0.16 and 1.67 embryos per anther, respectively, of which 51% and 44% of the regenerants were monoploid. A total of 32 anther-derived monoploids has been obtained from PP5 and 130 from BARD1-3. Rooted cuttings of 21 androgenic and 21 gynogenic PP5 monoploids were established in a greenhouse in each of three randomized complete blocks. Data were collected on height, vigor, and stem number. Although the gynogenic monoploids appeared slightly more vigorous, there were no significant differences between the androgenic and gynogenic populations for vigor and stem number (P > 0.05). Mean height of the gynogenic monoploid population (13 cm) was significantly greater at 4 weeks than the androgenic monoploid population (9 cm); P < 0.05.
Cumulative Yield, Tree Growth, and Yield Efficiency of 18 Asian Pear Cultivars
Authors: Larsen Fenton E , Higgins Stewart S.
Published: February 2019

Eighteen Asian pear cultivars on Pyrus betulaefolia rootstocks were planted in 1990 at Washington State University's Royal Slope Research Unit in central Washington State. Annual trunk diameters have been measured since planting, and annual harvest records have been kept since 1995. The six cultivars with the largest trees, ranked in decreasing order of trunk cross-sectional area, were `Daisui Li' (144 cm2), `Ishiiwase', `Huhoot Li', `Shin Li', `Shinsui', and `Yoinashi' (123 cm2). The six cultivars with the smallest trees were `Twentieth Century' (91 cm2), `Chojuro', `Shinseiki', `Shinko', `Yakumo', and `Tarusa Crimson' (38 cm2). `Tarusa Crimson' was significantly smaller than all other cultivars. The six highest-yielding cultivars, ranked in decreasing order of cumulative yield, were `Daisui Li' (183 kg/tree), `Shinseiki', `Shin Li', `Shinko', `Chojuro,' and `Olympic' (107 kg/tree). `Daisui Li' had significantly higher cumulative yield than all other cultivars. The six lowest-yielding cultivars were `Yoinashi' (71 kg/tree), `Huhoot Li', `Tarusa Crimson', `Yakumo', `Shinsui', and `Nangon Li' (19 kg/tree). The six highest-ranking cultivars for cumulative yield efficiency were `Shinseiki' (1.6 kg·cm–2), `Shinko', `Chojuro', `Daisui Li', `Tarusa Crimson', and `Olympic' (1.2 kg·cm–2). The six least-efficient cultivars were `Ishiiwase' (0.7 kg·cm–2), `Yakumo', `Yoinashi', `Huhoot Li', `Shinsui', and `Nangon Li' (0.2 kg·cm–2). `Daisui Li' and `Tarusa Crimson' had similar, relatively high, cumulative yield efficiencies, but for different reasons. `Daisui Li' produced high yields on large trees while `Tarusa Crimson' produced low yields on small trees. In contrast, the relatively high efficiencies of `Shinseiki', `Shinko' and `Chojuro' resulted from high yields produced on small trees.
Co-blended Composts for Production of Potted Chrysanthemum
Authors: Ku Catherine S.M. , Bouwkamp John C.
Published: February 2019

Blending polymer dewatered biosolids (PDB), poultry litter (PL), and yard wastes (YW) composts improved the usefulness of these composts as potting substrate. This study was to evaluate the optimum blending ratio of these three composts for potted chrysanthemum production. `Boaldi', `Yellow Boaldi', and `Red Akron' were planted in six compost blends at compost levels of 75% and 100% and two commercial substrates. The PDB, PL, and YW composts were blended on a 2:1, 1:1, and 1:2 ratios (v/v); Sunshine mix 1 and Pro Gro 300S were the control. All treatments were replicated five times. Plants were fertilized with 150 or 300 mg·L–1 N from 21N–2.2P–16.6K once weekly. Plants grown in blends at the 75% compost level and 300 mg·L–1 N treatment produced greater number of branches, flower buds, plant height, plant width, and plant grade than those at 100% compost level and 150 mg·L–1 N treatment. The PDB + YW blends at the 75% compost level and high-fertility treatment produced premium-quality plants that were better than any of the control plants.
Effect of Fertilizer Concentration on Growth of Variegated and Non-variegated Double Impatiens
Authors: Whipker Brian E. , Dasoju Shravan K. , Dosmann Michael S. , Iles Jeffery K.
Published: February 2019

Double impatiens (Impatiens wallerana) `Blackberry Ice' (variegated-leaf type) and `Purple Magic' were grown on flood benches and irrigated with 50, 100, 200, or 300 mg·L–1 N to study the effect of fertility on growth and development. Leaf, stem, bud, and total shoot dry mass exhibited a quadratic concentration effect with maximum growth for both cultivars occurring at 100 mg·L–1 N. Tissue concentrations of N, P, and K exhibited a quadratic concentration effect and increased with fertilization concentration, however, levels were higher for `Blackberry Ice' than `Purple Magic' over all fertilization concentrations. Tissue Mg levels also increased with fertilization concentration, but levels were higher for `Purple Magic'. Tissue Ca concentrations were similar for both cultivars and levels decreased as the fertilizer concentration increased. For maximum shoot growth and flower bud production, growers should apply 100 mg·L–1 N when growing double impatiens on flood benches.
Toxicity of Minor and Micronutrients in Cranberry
Authors: Roper Teryl R. , Krueger Armand R.
Published: February 2019

Cranberry showed significant yield response to applied fertilizer. Some growers apply large quantities of some minor and micronutrients in an effort to increase yields. Tissue levels for nutrient sufficiency and excess have been determined in cranberry, but toxicity levels have not been determined. We exposed rooted cuttings of `Stevens' cranberry (Vaccinium macrocarpon Ait.) to high concentrations of individual nutrients in solution culture and then aeroponics. Shoot boron concentration rose rapidly, but not root concentration. At 300 ppm boron, leaf necrosis appeared and dry weight accumulation slowed. Copper and zinc accumulated in roots, but not in tops and thus will be difficult to diagnose. Shoot growth slowed with elevated root copper. Sulfur accumulated quickly in shoots and reduced growth when it exceeded 0.65%. These tissue levels are far higher than historical results from grower samples.
Horticultural Perspective: History of White Pine Blister Rust
Authors: Hummer Kim E.
Published: February 2019

White pine blister rust, Cronartium ribicola J. C. Fischer, requires a pine (Pinus L.) and a Ribes L. as obligate alternate hosts. The center of diversity for this rust is east of the Ural Mountains, where the organism evolved with P. cembra L and R. nigrum var. sibericum L over several million years. Susceptible Pinus strobus L from North America was imported into England in 1710 and was transplanted throughout eastern Europe. In 1865, rust was first reported on these introduced pines in Eastonia. In the late 1800s, the white pine nursery industry continued to develop in Europe, but was declining in the United States. American foresters began importing white pines from Europe. Rust was found on cultivated currants in New York in 1906 and U.S. inspectors began examining for the disease. In 1910, infected white pines were imported from France into Vancouver, British Columbia; in 1911, infected pines were found in New Hampshire, Vermont, Massachusetts, Connecticut, Pennsylvania, Indiana, Ohio, Ontario, and Quebec. Additional rust-infected imported pines were found in nurseries in Wisconsin in 1913, and Minnesota in 1914. Rust spread to native pines in New York by 1915 and to Idaho by 1927. A summary of the blister rust control program, the recent spread of the disease, and the present state regulations will be presented.
Identification of a RAPD Marker Closely Linked to Fruit Color in Muscadine Grapes (Vitis rotundifolia)
Authors: Ren Zhongbo , Lu Jiang , Lamikanra Olusola
Published: February 2019

The major fruit color phenotypes in grapes are either white (including green, yellow, bronze etc.) or red (including pink, reddish) and black (including purple). Like other fruits, anthocyanin (Acy) pigments in the berry skin contribute to the colors of grapes. These water-soluble pigments are phenolic compounds as secondary metabolite and accumulated essentially in the epidermal cells of fruits. Seedling screening can be performed if a genetic marker for the fruit color is available. A F1 population of 82 progenies derived from a cross of two muscadine grape (Vitis rotundifolia) cultivars, `Summit' × `Noble', was used for tagging the gene determining the fruit color. `Noble' is a red grape while `Summit' is white. Segregation of berry color in the F1 population indicated that the red color is controlled by a single dominant gene. RAPD (Random Amplified Polymorphic DNA) technique and Bulk Segregant Analysis (BSA) was used for tagging the fruit color trait. A total of 350 oligonucleotide 10-mers were screened for polymorphisms between the red- and white-colored DNA pools (each pool was consisted of seven individual DNA samples). Two RAPD fragments linked to the target gene were identified and one of them, a 650-bp fragment completely co-segregated with the 56 progenies of red berries, while the white fruit progenies were absent of the RAPD fragment. The cosegregation data clearly indicated that the 650-bp RAPD fragment is tightly linked to the red fruit trait. The marker DNA was isolated from the agarose gel, cloned, and sequenced. A pair of 18-mers and 20-mers flanking the RAPD fragment were designed based on the sequencing information. The RAPD marker was reamplified in red-fruited muscadine grapes with this pair of universal primers.
Agronomic Evaluation of Different Watermelon Varieties (Citrullus vulgaris Sch.) with Fertigation and Plastic Mulch
Authors: Radillo-Juárez F. , Farias-Larios J.
Published: February 2019

The cultivation of watermelon is profitable for producers because of its high price and demand in the export market to United States and Canada. The crop profitability depends on the suitable management and agronomic practices and the selection of variety of the plant based on its productive capability. This characteristc is a cornerstone for the success in the establishment and yield of the crop. The present study was conducted to determine the vegetative growth and production of variety improvement of watermelon under irrigation conditions and plastic mulch. The experiment was established in a muddy-sandy soil with 7.6 pH. The varieties evaluated were: Charleston Gray, Peacock Improved, Peacock WR-60, Tatum, Sunshade, Jubilee, and Chilen Black. Results show that all varieties in relation to yield and quality of fresh fruit presented similar yield, Sunshade and Jubilee registred heightest production with 39.9 and 37.3 ton/ha, respectively, of fresh fruit with characteristics for export and for national consumption of 19.5 and 15.1 ton/ha. They have higher economic value. In relation to agronomic characteristics, the results show that `Tatum' was earlier to flowering at 36 days and begin the ninth node flower. The greater longitude of the main sprout was in `Peacock Improved', with 4.8 m; in size of fruit in `Charleston Gray', and `Tatum' had the greater longitude and diameter of fruit, with 45.6 and 21.4 cm, respectively. The varieties presented a similar yield of fresh fruit; although there exists an economically significant difference for quality of fruit, presenting the greater profitability. `Sunshade' and `Jubilee' are the most promising varieties to improve the economy of the producers.
Muskmelon (Cucumis melo L.) Responses to Floating Row-cover
Authors: Elattir Hassan , Derouich Mohamed , Hanafi Abdelhaq
Published: February 2019

Two groups of Cucumis melo L. cv. Galia F1 were seeded on 10 Jan. 1994. The first group was direct-seeded in a loam sandy soil and covered at the same time with perforated polyethylene floating rowcover. The other group was seeded in a nursery and the muskmelon seedlings were transplanted and covered by perforated polyethylene in 7 Feb. 1994. The experiment was conducted in the Complexe Horticole experiment station located 17 km southeast of Agadir in a randomized block design with four treatments and four replications. Floating rowcover increased minimal and maximal air temperatures by 0.92 to 2.43 °C and 3,71 to 6.99 °C, respectively. Ten centimeters deep, soil temperatures of covered treatments were higher by 0.35 to 0.57 °C and 0.71 to 1 °C at 7 AM and 4.30 PM respectively. Plant early yield recorded in the four treatments: transplanted muskmelon with floating rowcover, direct seeded muskmelon with floating rowcover, transplanted muskmelon without cover and direct seeding without cover was 2003.9 g, 1219.2 g, 500.9 g, and 60.6 g respectively.
Banded Cucumber Beetle (Diabrotica balteata LeC.) Injury during Sweetpotato Development
Authors: Jett Lewis W. , Story Rick N. , Hammond Abner M.
Published: February 2019

Banded cucumber beetle (Diabrotica balteata LeC.) larvae can cause significant injury to the sweetpotato [Ipomoea batatas (L.) Lam.] by boring small holes in the storage root. Often, these holes expand with development to produce crater-like scars. The objective of this research was to characterize the effects of Diabrotica injury to storage roots by simulating the injury through development. Deep (i.e., penetrating the vascular cambium) and shallow (i.e., not penetrating the vascular cambium) injuries were inflicted at 10-day intervals on `Beauregard' sweetpotato commencing 35 days after transplanting (DAT) through 85 DAT in 1996 and 1997. Visual evaluation indicated significant healing of deep injury through 55 DAT, with the diagnostic cratered appearance more prevalent on storage roots injured at 35 and 45 DAT. Moreover, deep injury in early development (35, 45 DAT) significantly expanded in diameter and depth, reducing marketable yield. Significant healing of shallow injury was observed through 75 DAT. The results of this research can be used by growers and researchers to assess the stage of development in which Diabrotica injury occurred.