bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms of Weed Suppression in Cover Crop-based Production Systems
Authors: Creamer Nancy G. , Bennett Mark A. , Stinner Benjamin R. , Cardina John , Regnier Emilie E.
Published: February 2019

Field and laboratory studies were conducted to investigate the mechanisms of weed suppression by cover crops. High-performance liquid chromatograph analysis and a seed germination bioassay demonstrated that rye (Secale cereale L.) can be leached of its allelochemicals, redried, and used as an inert control for separating physical suppression from other types of interference. In a field study, rye, crimson clover (Trifolium incarnatum L.), hairy vetch (Vicia villosa Roth.), barley (Hordeum vulgare L.), and a mixture of the four species suppressed the emergence of eastern black nightshade (Solanum ptycanthum Dun.). Crimson clover inhibited the emergence of eastern black nightshade beyond what could be attributed to physical suppression alone. The emergence of yellow foxtail [Setaria glauca (L.) Beauv.] was inhibited by rye and barley but not by the other cover crops or the cover crop mixture.
Relative Humidity Influences Postharvest Browning in Rambutan (Nephelium lappaceum L.)
Authors: Landrigan M. , Morris S.C. , Gibb K.S.
Published: February 2019

The effect of enzymic action, mechanical damage, and relative humidity (RH), on browning of stored rambutan was investigated. Mature rambutan fruit (`R 134') were infiltrated with known enzyme inhibitors, then either mechanically damaged or left undamaged, before storage at 20 °C with 95% or 65% RH. Fruit were visually scored for browning and weight loss was measured. All fruit at low RH browned severely. At high RH, infiltration with water, but not with the enzyme inhibitors, salicylhydroxamic acid and catalase, led to a large increase in browning. We infer that enzymes were involved in browning in damaged tissue under high RH. At low RH, inhibitors were ineffective as desiccation was the dominant causative factor of browning.
Heritability Estimates for Reaction Resistance to Sweetpotato Chlorotic Leaf Distortion Caused by Fusarium lateritium
Authors: Kim Bong-kyoo , La Bonte Don R. , Clark Christopher A. , Buteler Mario I.
Published: February 2019

Narrow-sense heritabilities for reaction to chlorotic leaf distortion (CLD), incited by Fusarium lateritium Nees: Fr., were estimated in sweetpotato [Ipomoea batatas (L.) Lam] by variance component analysis and parent–offspring regression. Visually rated severity reactions to CLD varied greatly among the 20 parents used to generate half-sib progeny from open-pollinated nurseries in 1990 and 1991. Progeny from each nursery were evaluated along with parents in a completely randomized design in two consecutive years. Narrow-sense heritability (h2) estimates based on variance components were moderate on an entry mean basis at 0.61 in 1990, 0.38 in 1991, and 0.33 for the two years combined. Slightly higher, but still moderate, estimates were obtained on an individual plant basis. Narrow-sense heritability estimates using parent–offspring regression were 0.35 in 1990, 0.33 in 1991, and 0.33 for the two years combined. Predicted next-generation response was highest using a half-sib family recurrent selection among three schemes compared at a 10% selection intensity. Our data indicate –0.63 improvement in the half-sib family CLD severity rating in one breeding cycle.
DNA Amplification Fingerprinting Used to Distinguish Series of Cutting, Seedling, and Ivy Leaf Geranium
Authors: Starman Terri Woods , Abbitt Shane
Published: February 2019

The objective was to distinguish between series of cultivars of Pelargonium xhortorum (zonal geranium), Pelargonium hybrids (seed geranium), and Pelargonium peltatum (ivy leaf geranium) using DNA amplification fingerprinting (DAF) demonstrating the utility of DAF for patent protection to prevent infringement of inventor's rights. Leaf tissue of 10 plants of each cultivar of seedling geranium was bulked for DNA extraction, and cutting and ivy geranium cultivars were bulks of five plants of each cultivar. Isolated DNA from different cultivars of a series were bulked together in their respective series. Seedling geranium series included Dynamo, Glamour, Multibloom, Orbit, Pinto, and Ringo 2000. Cutting geranium series included Designer and Showcase. Ivy geraniums were from the Guillou group. Amplification was with one of two octamer primers, followed by reamplifying with one of four different mini hairpin primers. Gels were visually scored for presence or absence of bands. The four primers generated 336 bands. The average number of bands (_1000 bp) per primer was 40. Twenty percent of bands were polymorphic and distinguished between each series of cultivars. Genetic relationships were evaluated by SAHN cluster analysis based on the distance estimator of Dice using the NTSYS-pc program (Numerical taxonomy and multivariate analysis system, version 1.8). Series were grouped according to species. Seedling geraniums were in one large group, the two cutting geraniums were grouped together and the ivy leaf geraniums were a separate branch.
Seed Germination of Atlantic White Cedar as Influenced by Stratification, Temperature, and Light
Authors: Jull Laura G. , Blazich Frank A. , Hinesley L.E.
Published: February 2019

Cones of two provenances (Wayne Co., N.C., And Escambia Co., Ala.) of Atlantic white cedar [Chamaecyparis thyoides (L.) B. S. P.], were collected Fall 1994. Cones were dried for 2 months, followed by seed extraction and storage at 4°C for 6 months. Seeds were graded and stratified (moist-prechilled) for 0, 30, 60, or 90 days. Following stratification, seeds were placed at 25°C or 8/16 hour thermoperiods of 25°/15°C or 30°/20°C with daily photoperiods at each temperature of 0, 1/2, 1, 2, 4, 8, 12, or 24 h. At the conclusion of a 30-day germination period, the Alabama provenance exhibited greater germination than the North Carolina provenance for all treatments (74% vs. 46%). There were no significant differences between 25°/15°C and 30°/20°C with regard to total percent germination for both provenances. Germination was lowest at 25°C for each provenance. In some cases, however, there were no significant differences in germination of the North Carolina provenance when stratified for 60 or 90 days and germinated at 30/20°C or 25°C (61% vs. 63%). There was a highly significant quadratic response to stratification for cumulative percent germination for both provenances. The North Carolina provenance required 90 days stratification to maximize germination (66%) in contrast to the Alabama provenance, which only needed 30 days (80%). Seeds of both provenances did not exhibit an obligate light requirement. However, photoperiods ≥1/2 h increased germination greatly over seeds in darkness (29% vs. 62%).
The Effect of Stock Plant Water Potential, Auxin Application Method, and a Polyamines on Rooting Walnut Cuttings
Authors: McKenna J.R. , Sutter E.G.
Published: February 2019

Experiments with field-grown hybrid Paradox (Juglans hindsii × J. Regia) walnut trees were conducted to assess the effects of stock plant water status, auxin application method, and the addition of spermine on adventitious root formation in stem cuttings. A 2-fold increase in rooting was noted when semihardwood cuttings were collected from dry (midday Ψw = –1.3 MPa) stock plants compared to the same trees six days later when fully hydrated (midday Ψw = –0.6 MPa). Spermine, when combined with potassium indolebutyric acid (KIBA) and applied as a quick dip, enhanced the rooting percentage in hardwood cuttings (54%) compared to controls treated with KIBA alone (18%). Spermine had no effect when it was applied together with KIBA using a toothpick application, producing 65% rooting compared to controls which had 75% rooting. By itself, spermine had no effect on rooting. The toothpick method for applying rooting compounds resulted in significantly higher rooting percentages for hardwood cuttings, but not for semihardwood cuttings. Combining spermine with KIBA had no effect on rooting of semihardwood cuttings.
Factors Causing Losses of Rooted Cuttings of Olive Propagated under Mist and Ways of Its Prevention
Authors: Talaie A. , Zarrabi M.
Published: February 2019

To study the reasons for the losses of rooted semihardwood cuttings of olive propagated under the mist method, a 2-year experiment was carried out at the Horticulture Dept. of Faculty of Agriculture of the Tehran Univ. In this experiment, semihardwood cuttings of olive (Zard cultivar) in four different media—heavy-(Al), semi-heavy(A2), medium (A3), and light (A4), all disinfected with two different concentrations of Captan—were used. Root growth stages with low, medium, and light densities in spring and fall were evaluated. The results indicate that there are the least losses in semi-heavy (A2) and medium (A3) media. This could be the result of a better ventilation conditions in these media, which activates N and Ca and finally accelerates the better growth conditions in all young rooted cuttings. On the other hand, it was clear that inadequate disinfection will result in losses of rooted cuttings, and using Captan at 2 ppm gives the best result. This research indicate that, with the higher growth rate, the first medium will have the fewer losses. The reason is the higher density and more durability and strength of the root, which control the disease-causing factors; so far that these factors do not influence the young roots. Finally, strong and dense roots show less losses. This experiment was designed in a factorial with randomized complete block and the averages were compared in a Duncan test and the results of abnormally distributed characteristics were shown by using logarithmic and sinus method.
Photoperiod of Poinsettia Stock Plants Influences Adventitious Rooting of Cuttings
Authors: Roll Michael J. , Newman Steven E.
Published: February 2019

The rooting efficiency of cuttings from three poinsettia cultivars were evaluated after regulating the photoperiod during the stock plant stage. `Freedom Red', `Monet', and `V-17 Angelika Marble' stock plants were exposed to an extended photoperiod and to natural day length during September 1995. `Freedom Red' cuttings rooted more quickly under an extended photoperiod compared to those under natural day length. Furthermore, root dry weight from these cuttings was greater than cuttings from stock plants grown under natural day length. `Monet' cuttings also rooted more quickly when the stock plants were under an extended photoperiod, and showed similar differences in root weight as `Freedom Red'. Cuttings from `V-17 Angelika Marble' were not influenced by photoperiod. Lighting stock plants to block flower initiation produces a higher quality cutting when propagation takes place after the critical day length for flowering has passed.
Benefit of Chemical and Cultural Control in Managing Pumpkin Viruses and Vectors
Authors: Precheur R. , Welty C. , Riedel R.M. , Breth M.R.
Published: February 2019

Pumpkins rank third in acreage among Ohio's fresh market vegetables. Recently, increasing incidence of insect-vectored viruses have threatened the economic potential of this crop. Studies were initiated in 1992 to obtain information on abundance of insect pests, to evaluate the effect of insecticides, reflective mulch and row covers on pest density and yield of marketable fruit. In 1994 and 1995, statewide virus surveys were conducted to determine virus types infecting the pumpkin crop. In 1992 the greatest insect injury of concern was cucumber beetle feeding on fruit rinds, Insecticides lowered pest density, but there was no effect on marketable yield. In 1993, yield of virus-infected fruit was lower were reflective mulch was used than where rowcovers or foliar insecticides were used. Marketable yield and virus incidence in 1994 were not affected by reflective mulch, rowcovers or stylet oil due to the late arrival of the virus. In 1995, aphid infestations at three locations were significantly lower on plants on reflective mulch than on plants on bare ground. Results of the 1994 virus survey showed that watermelon mosaic virus (WMV) was the most common virus in Ohio pumpkins. The watermelon mosaic developed late in the season and fruit deformity was not severe enough to affect marketable yield. There was some incidence of cucumber mosaic and squash mosaic virus but zucchini yellow mosaic virus was not detected in 1994. Results of ELISA testing of samples collected in August/September 1995 at 27 farms were 18 farms positive for watermelon mosaic virus, 5 sites positive for squash mosaic, 4 sites positive for papaya ringspot and 1 site positive for zucchini yellow mosaic.
Engineering Transgenic Eggplant (Solanum melongena L.) Resistant to the Colorado Potato Beetle (Leptinotarsa decemlineata Say)
Authors: Jelenkovic G. , Billings S. , Chen Q. , Lashomb J. , Ghidiu G.
Published: February 2019

A chimeric construct, containing the synthetic cryIIIA (Btt) gene, the NPTII selectable marker and the uidA reporter gene, was incorporated via Agrobacterium tumefaciens into eggplant, variety Hibush. The synthetic cryIIIA gene, altered at the nucleotide level without changing the amino acids of the toxic protein by J. Kemp of New Mexico State Univ., Las Cruces, is adapted for high expression in plant cells. To verify the transgenic status, GUS assays were performed on over 300 plants, from which 185 were confirmed to be transgenic. Physical incorporation of the chimeric construct was further confirmed by Southern analysis of about 30 transgenic plants; both single and multiple site incorporation of the Btt gene were found. Resistance to Colorado potato beetle (CPB) was assessed by: a) placing egg masses of CPB on leaves of plants grown in the growth chamber; b) placing first-instar larvae on detached leaves; c) observing 173 transgenic plants under field conditions. About 60% of the transgenic plants displayed a very high level of resistance to CPB. No larvae survived on the resistant plants longer than 50–60 hours after hatching. Upon selfing, the transgenic plants with a single construct segregate in the S1 generation in a Mendelian fashion.
Plant Regeneration of Hot Pepper (Capsicum annuum L.) and Expression of Mouse Adenosine Deaminase (ADA) Gene via Agrobacterium-mediated Transformation
Authors: Lim Hak-Tae , Lee Kei-youn , Yoo Yeoung-Sook , Yang Duck-Chun
Published: February 2019

Since in vitro regeneration and transformation systems in hot pepper (Capsicum annuum L.) have not been available, the application of new genetic manipulations has been limited. Here we report an efficient procedure to regenerate whole pepper plants and to generate transgenic plants expressing a foreign gene was established. High frequency of plant regeneration was observed when hypocotyl and cotyledon explants were cultured on MS/B5 medium supplemented with NAA 0.05 mg·L–1 plus zeatin 2.0 mg·L–1, NAA 0.05 mg·L–1 plus zeatin 2.0 mg·L–1, IBA 10.0 mg·L–1 plus BA 1.0 mg·L–1, IAA 0.02 mg·L–1 plus zeatin 3.0 mg·L–1. An addition of AgNO3 5–10 μm to these media improved the regeneration rate by about 10%. For plant transformation, hypocotyl and cotyledon explants of pepper were preconditioned on kanamycin-free shoot induction medium for 48 hours. Then, co-cultivation with Agrobacterium tumeaacience was done on the co-culture medium for 2 days. The explants were then blotted in sterile filter paper and placed on shoot induction and selection medium containing kanamycin sulfate (100 mg·L–1) and carbenicillin (500 mg·L–1). PCR showed that the introduced ADA gene was integrated and stably expressed in the regenerated plants. ADA enzyme activities were checked by spectrophotometric analysis.
Varietal Identification of Cyclamen and Petunia Seeds Using RAPDs
Authors: Zhang Jianhua , McDonald Miller B.
Published: February 2019

Varietal identification of cyclamen and petunia is important for flower seed production because these crops are marketed as hybrids and genetic purity determinations assure the purity of the seed lot and the success of hybridization. Random amplified polymorphic DNA (RAPD) banding patterns have been shown to be useful in identifying genotypes of various crops. This molecular biology technique was applied to five commercial cyclamen and six petunia hybrids. Using bulk seed/seedling samples, the varieties could be differentiated. However, when individual seeds of the cyclamen hybrid were tested, differing polymorphisms were observed. These variations were attributed to genetic variability in the inbred parents. We conclude that the genetic purity of cyclamen seeds can be improved and that the use of RAPDs can assist breeders of hybrid flowering crops in better monitoring seed quality.
Modifying Relative Humidity during Accelerated Aging For Impatiens Seeds
Authors: Zhang Jianhua , McDonald Miller B.
Published: February 2019

The accelerated aging vigor test subjects seeds to high temperatures (41°C) and relative humidity (about 100%) for short durations (usually 72 hours). These recommendations, however, have been developed for large-seeded agronomic crops and may be too severe for small-seeded flower crops that deteriorate rapidly during storage such as impatiens. We examined the effect of aging regime duration (48, 72, and 96 hours) and temperature (38 and 41°C) as well as relative humidity using three saturated salt solutions (KCl–87% RH, NaCl–76% RH, and NaBr–55% RH) on two commercial impatiens seed lots differing in seed vigor but not percentage germination. The greatest differences in percentage germination after 4 days were found among the treatments of 48 hours for KCl, 72 hours for NaCl, and 96 hours for NaBr. While any of these saturated salt solutions may be used in a commercial situation to determine impatiens seed vigor, we suggest that a total 7-day test period consisting of 72 hours aging at 41°C using saturated NaCl with germination being determined 4 days after aging is most convenient.
Influence of Crop Load and Cluster Microclimate on Yield and Fruit Quality in `Seyval Blanc'
Authors: Hummell Ann K. , Ferree David C.
Published: February 2019

A 2-year field study was initiated in 1994 to examine the interactions between crop load and cluster exposure and their influences on the yield and fruit quality of mature, own-rooted `Seyval blanc' grapevines. Light, moderate, and heavy crop loads were established near bloom by cluster-thinning vines planted at 2.6 × 3.0-m spacing to around 20, 40, and 80 clusters per vine, respectively. At veraison, three clusters per vine were given one of three natural shaded treatments: fully exposed, partially shaded, and densely shaded. Vines with the heavy crop load produced higher yields per vine and lower cluster and berry weights. Heavy vine clusters tended to be more green in 1994 and possessed lower pH and soluble solid concentrations in both years compared to other crop loads. Compared to densely shaded clusters, fully exposed clusters had smaller average cluster and berry weights, lower titratable acidity, higher pH and soluble solid concentrations, and more yellow coloration. In 1994, no significant interactions were found for any fruit quality or yield characteristics. In 1995, significant interactions were found for soluble solids and hue angle, but not for yield, pH, or titratable acidity. These results suggest that the crop load of the vine and microclimate around the cluster, in addition to their individual effects, sometimes interact to affect fruit quality in `Seyval blanc' wine grapes.
Evaluation of Composted Municipal Sludge and Composted Yard Waste on Strawberries
Authors: Funt R.C. , Hummell A.K.
Published: February 2019

Compost increases nutrient availability, cation exchange capacity, and micronutrients in the soil. In urban areas, yard waste consisting of grass clippings, leaves, and woody materials can be composted. The purpose of this study was to compare the effects of soil-composted municipal sludge and soil-composted yard waste mixtures on strawberry plants grown in the greenhouse. Earliglow strawberry plants were planted in pots containing a soil mix of 0%, 10%, 20%, or 40% by volume of composted municipal sludge or composted yard waste. Plants were grown in the greenhouse with supplemental lighting. Soil-compost mixes having greater the 90 mhos of soluble salts were detrimental to the plants; plant survival was reduced by 80% in the 40% composted sludge–soil mix within 2 weeks after transplanting. Plants survived and grew in all other treatments. Composted yard waste at 20% to 40% by volume increased leaf K and B, but decreased P, Ca, and Mg.
Effect of Chilling on Cyanide-resistant Respiration and Carbohydrate Status in Chilling-sensitive and -resistant Species
Authors: Reyes Eleazar , Jennings Paul H.
Published: February 2019

The effect of chilling stress on induction of the cyanide-resistant pathway was investigated using roots of 3-day-old cucumber (Cucumis sativus L.) and 5-day-old pea (Pisum sativum L.) grown at 26°C, and then chilled at 2°C for 48 or 96 hours for cucumber, and 72 or 192 hours for pea. A 24-hour post-chilling treatment at 26°C was imposed on different sets of chilled roots from both crops. Carbohydrate status was determined by gas chromatography with an autosampler using a 12.5-m cross-linked methyl silicone capillary column (0.1 mm). Exposing seedlings to 2°C, as well as to a postchilling treatment, induced differential responses in the activity of the cyanide-resistant pathway. Cucumber seedling roots exhibited an accumulation of fructose, glucose and sucrose during chilling, with a rapid decline observed during the post-chilling treatment at 26°C. Pea seedling roots maintained a constant level of carbohydrates throughout the chilling period, and exhibited a slight decrease by the end of 192 hours at 2°C. There was an increase in carbohydrate levels during the post-chilling treatment. The involvement of the cyanide resistant pathway and carbohydrate changes will be discussed.
Monitoring Peach Flower and Fruit Development with a Phenology–Heat Unit Model
Authors: Powell Arlie A. , Boozer Robert T. , Pitts James A.
Published: February 2019

Phenological studies were conducted over a 3-year period beginning in Winter 1993–94 to relate flowering and fruiting stages of peach to heat accumulation [growing degree hours (GDH)]. Mature trees of `Loring' and `Redhaven' peach in the same orchard were used annually. Some variation from year to year was apparent in GDH levels related to 50% flower and other stages of development. Major sources for this variation appear to be timing and severity of pruning, tree vigor, and shoot diameter. Temperature predict models were used successfully to properly forecast GDH accumulation and and various flowering and fruiting stages once rest was satisfied.
Isolation and Characterization of Chalcone Synthase and Chalcone Isomerase cDNAs from Grapefruit (Citrus paradisi Macf.)
Authors: Luth Diane , Moore Gloria A.
Published: February 2019

Many Citrus species accumulate large amounts of flavonoids, specifically flavanone glycosides, that impart an intensely bitter flavor to the fruit. In grapefruit, this bitterness decreases the acceptability of fresh fruit and juice; in other species, these compounds entirely prevent fruit consumption. No physiological purpose for the accumulation of these compounds has been determined; they do not function in color production or, as far as is known, in defense responses. As has been found in other plants, the accumulation of specific flavonoids in citrus appears to be under genetic control, but no definitive genetic analyses have been done. The long-term objective of this research is to determine whether the production of bitter-tasting flavanone glycosides (neohesperidosides) in citrus can be manipulated using molecular genetic techniques. As a first step, cDNAs for chalcone synthase and chalcone isomerase, the first two biosynthetic enzymes specific to the flavonoid pathway, were isolated from a grapefruit leaf cDNA library using heterologous probes. Southern analyses showed that both genes appear to be part of multigene families, as expected. Northern analyses are underway to determine steady state mRNA levels in various grapefruit tissues, and Western blots to characterize protein expression are also being attempted.
Low Light Stress Influences lower Abscission and Yield of Six Bell Pepper Cultivars
Authors: Wien H.C. , Turner A.D. , Nyankanga R.
Published: February 2019

High temperatures during flowering frequently limit yields of some bell pepper cultivars in New York fields. Previous research has shown that subjecting the plants to low light at flowering can have similar effects. To determine if cultivar differences in flower abscission and yield could be accentuated by such a shade stress, field plots of six cultivars were subjected to 1 week of low light during flowering. Shade cloth tunnels were erected over the plant rows in two experiments, reducing incident light by 80%. Nondestructive abscission counts were taken at the start, and 7 days after the end of a 7-day shade period. Mature green fruit were harvested periodically. Low light stress resulted in 68% and 86% abscission at the first three fruiting nodes in 1992 and 1994, respectively. Cultivars showed differential abscission in unshaded plots, and after shade, producing a significant cultivar: shade interaction. `Ace' showed least abscission and maintained yields with shading; `Camelot' lost nearly all flowers and buds with low light stress, and was reduced by 75% and 91% in marketable yield in 1992 and 1994, respectively. Results indicate that shade stress accentuates abscission susceptibility in bell pepper cultivars. Pepper lines selected for low light tolerance may show promise in resisting flower abscission at high temperature.
Growth Analysis of `Daliva' Chicory Grown Under Bare Soil or Straw Mulch Conditions
Authors: MacDermott Jomo , Coffey D.L.
Published: February 2019

Some chicory (Cichorium intybus L.) cultivars, especially early and extra-early cultivars, often bolt and flower the first year of growth, contrary to the expected behavior of biennials. The extra early hybrid cultivar `Daliva' was grown in the field under bare soil and straw mulched conditions to examine possible correlations between growth rates, leaf and root sizes and bolting. Plants, sown on 19 June, were harvested weekly from 4 July to 1 Oct.; a total of 14 harvests. Root variables of length and diameter were best described by linear equations but root dry weight was decidedly quadratic in response. Leaf number, area and dry weight and crown diameter data were fitted to the Richards function to describe their sigmoidal phases of growth. In most cases, when using the Richards function, the two treatments (mulch vs. no-mulch) required different parameters to fit a line to the observed points with r2 values >0.95. A statistical comparison between treatment parameters (as obtained from SAS PROC NLIN and SigmaPlot) will be discussed.
Ontogeny of Grape Somatic Embryos
Authors: Gray D.J. , Labeau K.A. , Benton C.M.
Published: February 2019

The development of grape somatic embryos (Vitis vinifera cv. Thompson Seedless) was studied using high-resolution light microscopy and scanning electron microscopy. Somatic embryos develop either from discrete embryogenic cell clusters (indirect somatic embryogenesis) or from previously formed somatic embryos (direct somatic embryogenesis). In both instances, embryo development begins when a small, isodiametric, densely cytoplasmic cell undergoes a series of organized divisions, which are identical to those observed during zygotic embryogenesis. Developing embryos pass through recognizable embryonic stages, remaining white and opaque through maturity. Upon germination, embryos begin to enlarge, become yellow, then green, and develop into morphologically correct plants. The cells of somatic embryos contain little starch, but abundant storage proteins. However, lipids comprise the primary storage compound. Some developmental abnormalities occur during embryogenesis, including overly enlarged hypocotyls and fewer or more than two cotyledons. In addition, relatively few somatic embryos grow into plants primarily due to inadequate shoot apical meristem development. These abnormalities are best attributed to inadequacies of the in vitro environment of medium in a culture vessel when compared to the in vivo environment of a seed.
The Role of Sucrose Alone and Combined with Different Cytokinin-like Compounds on in Vitro Tuberization of Potato
Authors: Kefi Servet , Read Paul E. , Pavlista Alexander D. , Kachman Stephen D.
Published: February 2019

The role of sucrose alone and in combination with different cytokinin-like compounds on the microtuberization of potato, Solanum tuberosum `Atlantic', was investigated. Single nodal segments were placed in Magenta boxes containing Murashige & Skoog medium supplemented with one of 15 treatments in a 3 × 5 factorial. Treatment factors were sucrose at 3%, 6%, or 9%, and cytokinin-like compounds at five levels [cytokinin-free; 2 mg kinetin/L; 0.1 mg thidiazuron (TDZ)/L; 1.0 mg AC 243,654/L; 0.1 mg AC 239,604/L]. Except in a few cases in kinetin and TDZ treatments, nearly all cytokinin treatments failed to induce tuberization at the 3% sucrose, noninductive level. However, all cytokinin treatments induced tuberization in the presence of 6% sucrose. By raising the sucrose level from 6% to 9%, more and larger microtubers were obtained in the cytokinin-free medium. At the 9% sucrose level, even though more tubers per box were produced by TDZ and AC 243,654 treatments, less total fresh weight of tubers per box resulted from kinetin, TDZ and AC 243,654 treatments because tubers formed were smaller. Higher sucrose concentrations (9%) favored tuberization in the cytokinin-free medium, whereas 6% sucrose was optimum for the medium containing cytokinins. Sucrose might produce a strong tuberization signal that might either change endogenous hormone levels affecting tuberization or activate a number of genes coding tuber proteins and enzymes related to starch synthesis.
Publishing Newsletters on the World Wide Web Using Database Software
Authors: Rhodus Tim
Published: February 2019

Preparing newsletters for distribution over the World Wide Web generally requires one to learn HTML (hypertext markup language), purchase an HTML editor, or convert existing wordprocessing documents through a utility program. As an alternative, an input form was developed for county agents that facilitates the direct publishing of their weekly Buckeye Yard and Garden On-line newsletter over the Internet. Using FileMaker Pro 3.0 for Macintosh and the ROFM acgi script for WebSTAR, agents cut and paste text from their word processing file into specific input boxes on the screen and then submit it to the server located in Columbus. Their newsletter articles are then made available to anyone on the Web through a searchable database that allows for searching by date or title. Preparation of the input form and corresponding search form creates two distinct advantages: county agents do not have to spend time learning about HTML coding and all their newsletters are indexed in a searchable database with no additional effort by the site manager. Modification of this procedure has been done to facilitate the creation of online term projects for students and a directory for horticultural internships.
Analyzing Web Server Statistics
Authors: Lineberger R. Daniel
Published: February 2019

The World Wide Web is regarded widely as an invaluable asset to teaching and extension programs. Data supporting this assertion can be gathered actively or passively and can be analyzed to aid decision makers in matters of personnel evaluation and resource allocation. Most Web server software applications keep a log of connections by time, location, and file size transferred. The server logs of Aggie Horticulture, the Web site of the Texas Horticulture program, are analyzed bi-weekly using WebStat 2.3.4 and the number of logins, file size transferred (total and amount per sub-site), and client domain are tabulated. The number of “hits” increased from 15,000 to 120,000 per month (mid-February to mid-March of 1995 and 1996, respectively) over the last year. The logins came from 61 Internet domains representing 56 different countries. The “net” and “com” domains exhibited the greatest increase. “Active” data acquisition through a guest register at one of the sub-sites indicated that only 9% of the visitors registered. However, the data obtained from the active registrants were useful in determining the distribution of users by state and county within Texas.
BioBLAST—A New Approach to Teach High School Biology
Authors: Lea-Cox John D. , Ruberg Laurie F.
Published: February 2019

BioBLAST is a NASA-funded multimedia curriculum supplement, targeted to enrich high school biology classes. It is modeled after the CELSS scenario and currently is being developed by the Classroom of the Future at Wheeling Jesuit College. Through innovative applications of educational technologies and interactions with active researchers in life sciences based at the various NASA centers and by incorporating alternative assessment measures, the BioBLAST project seeks to improve student learning and assist biology teachers. The studentsed life-support system, which uses biological processes to supply astronauts with recycled food, water, and oxygen. The students will be encouraged to formulate hypotheses, devise hands-on experiments to investigate key processes, and use computer simulations to investigate what systems are required to achieve stability of these life-support systems in a simulated lunar base. To succeed in their mission, students will learn basic principles in plant physiology, microbiology, human physiology, nutrition, and the interdependence of systems, and the impact of physical constraints such as temperature, light, and water availability on biological system functioning. BioBLAST will be supported by extensive interactive CD-ROM-based materials and World Wide Web and other internet resources, together with intelligent tutor, frequently asked question lists, and mentor networks that will include the ability to contact NASA and other scientists on-line. An early version of this software will be prototyped to selected schools throughout the United States in Fall 1996.
Hexanal Vapor Acts as Residueless Antifungal Agent that Enhances Aroma Biosynthesis in Apple Fruit
Authors: Song J. , Leepipattanawit R. , Deng W. , Beaudry R.M.
Published: February 2019

Hexanal vapor inhibited hyphae growth of P. expansum Link. and B. cinerea Pers. on PDA media and on apple slices. After 48 hours exposure to 100 μl·liter–1 hexanal, the hyphae growth of both fungi was ≈ 50% that of nontreated controls. At a concentration of 250 μl·liter–1, neither fungi grew during the treatment period, however, some growth of both fungi occurred 120 hours after treatment. At concentrations of hexanal vapor of ≥450 μl·liter–1, the growth of both fungi ceased, and the organisms were apparently killed, neither showing regrowth when moved to air. When fungi were allowed to germinate and grow for 48 hours in hexanal-free air, a subsequent 48-hour exposure to 250 μl·liter–1 hexanal slowed colony growth relative to controls for several days and a 48-hour exposure to 450 μl·liter–1 stopped growth completely. Concentrations of hexanal that inhibited fungal growth on PDA also retarded decay lesion development on `Golden Delicious' and on `Jonagold' apple slices. Hexanal treatment stimulated aroma volatile production in `Jonagold' and `Golden Delicious' apple slices with hexanol and hexylacetate production strongly enhanced after 20 to 30 hours of treatment. A small amount of butylhexanoate and hexylhexanoate production also was noted. Since hexanal was converted to aroma-related volatiles by the fruit, the possibility of developing a system for nonresiduel antifungal agent is promising. This possibility was examined in modified-atmosphere packages.
Screening Trifoliate Hybrid Citrus Rootstocks for Resistance to Phytophthora parasitica by in Vitro Inoculation
Authors: Bowman Kim D.
Published: February 2019

Phytophthora parasitica Dast. causes several root and trunk diseases of citrus, including damping-off, root rot, foot rot, and gummosis. Phytophthora resistance is needed in Citrus rootstocks and is available in Poncirus trifoliata (L.) Raf. and some hybrids between Citrus and P. trifoliata. Field or greenhouse tests of rootstocks require large amounts of space and time. To provide a preliminary indication of rootstock resistance to P. parasitica, nucellar seedlings of P. trifoliata selections, and Citrus × P. trifoliata hybrids were tested for response to P. parasitica by in vitro inoculation. Seeds of individual selections were germinated in sterile culture and 3-week-old shoots were excised and inoculated with a cultured isolate of Phytophthora. After 1 week of incubation, response to the disease organism was measured by length of stem discoloration. Progression of Phytophthora in the stem also was measured by plating sequential 5-mm segments of the shoot and determining presence or absence of Phytophthora in individual segments. Stem discoloration length corresponded with location of Phytophthora in the stem. Relative resistance, as measured by this technique, approximated field resistance for several common rootstock cultivars. Resistant, intermediate, and susceptible selections were found in populations of Citrus × P. trifoliata rootstock hybrids using in vitro inoculation.
Generation of a Highly Saturated Linkage Map in Peach [Prunus persica (L.) Batsch] Using AFLP and RFLP Markers
Authors: Sosinski Bryon , Baird W.V. , Rajapakse S. , Ballard R.E. , Abbott A.G.
Published: February 2019

We have developed a highly saturated genetic linkage map in peach (diploid, 2n = 16) using two separate crosses. The first population consists of 48 randomly selected F2 individuals which were generated by selfing an F1 from the cross of `New Jersey Pillar' x KV 77119. This progeny set exhibits segregation for gross morphological traits including: canopy shape, fruit flesh color, and flower petal color, size, and number. The second population contains 48 F2 progeny derived from the cross of `Suncrest' x `Bailey'. These progeny segregate for quality traits such as fruit diameter, weight, flesh color, cling vs. free stone, soluble solids, pH of juice extract, and fruit developmental period. Nine linkage groups were identified in the first cross, which cover 590 cM of the genome. In the second cross, eight linkage groups were found that contain several significant chromosomal intervals contributing to fruit quality characteristics by QTL analysis. Anchor loci present in both maps were used to join the linkage groups to create a single combined map of the peach genome. Physical mapping is currently underway to assign the each linkage group to the appropriate chromosome.
Potato Seed Piece Calcium can Influence Tuber Yield
Authors: Gunter Christopher C. , Kleinhenz Matthew D. , Palta Jiwan P.
Published: February 2019

Pathogenic bacteria (Erwinia spp.) can have a significant impact on stand establishment and sprout health. These bacteria cause soft rot of the seed piece, which is common in wet spring conditions resulting in great economic loss. Recent studies have demonstrated that the incidence and severity of soft rot can be significantly reduced by increasing tuber calcium. We investigated the influence of seed piece calcium on tuber production. Field growing potato plants were treated with supplemental calcium during tuber bulking (calcium at 168 kg·ha–1 from calcium nitrate or N-Hib) to increase the seed tuber medullary calcium levels. All three cultivars (`Superior', `Atlantic', `Dark Red Norland') responded to supplemental calcium application with increases in mean calcium contents, even though soil tests showed high native calcium levels (1000 kg·ha–1). Seed tubers were sampled for calcium by removing a longitudinal slice from the center of each tuber and planting one of the resulting halves for seed piece decay evaluation and the other for yield evaluation. Calcium nitrate-treated seed tubers produced higher yields compared to ammonium nitrate and N-Hib in `Atlantic' in `Dark Red Norland'. This trend did not hold true for `Superior'. Our results suggest that a) it is possible to increase seed piece tuber calcium levels with supplemental calcium application even in soils testing high in calcium and b) improving the calcium concentration of the seed piece can increase tuber yield in some cultivars.
Wetland Plants for Wastewater Treatment: A Tremendous Opportunity for Horticulture
Authors: Bradley Jennifer C. , Zajicek J.M.
Published: February 2019

A current trend in environmental practices concerns using constructed wetlands for wastewater treatment. The ecological values of wetlands have long been known. Wetland plants aid in the treatment of water pollutants by improving conditions for microorganisms and by acting as a filter to absorb trace metals. Wetlands now are being considered for industrial, municipal, and home wastewater treatment. Constructed wetlands are an economical and environmentally sound alternative for treating wastewater. These constructed “cells” are designed to function like natural wetlands. In constructed wetlands, water flow is distributed evenly among plants in a cell where physical, chemical, and biological reactions take place to reduce organic materials and pollutants. Increasing numbers of environmentally conscious homeowners are installing wetland wastewater treatment systems in their backyards with the aid of licensed engineers. This installation is occurring despite of the lack of educational materials to aid in site selection, selection of appropriate plant materials, and long-term maintenance. Traditional wetland plant species currently are being selected and planted in these sites, and the resulting effect is often an unsightly marsh appearance. With increasingly more homeowners opting for this alternative system, a strong need exists for educational materials directed at this audience. Therefore, educational resources that can provide information to the public regarding the benefits of wetland wastewater systems, while promoting aesthetically pleasing ornamental plant species is needed. A hands-on guide for installing constructed wetlands, a home page on the World Wide Web, and an instructional video currently are being developed at Texas A&M Univ. These technologies will be demonstrated and the values, needs, and opportunities available for the horticultural industry in the area of wetland construction will be discussed.
Gibberellic Acid Application Timing Influences the Bud Viability and Fruitfulness of Seedless Table Grape Cultivars
Authors: Dokoozlian N.K.
Published: February 2019

A study initiated in Spring 1995 examined the influence of gibberellic acid (GA3) application timing on the return fruitfulness of Thompson Seedless and Flame Seedless table grapes. Vines treated with GA3 at prebloom, bloom, or berry set were compared to vines treated at prebloom + bloom + berry set and nontreated vines. Application amounts for each cultivar and timing were based on commercial label recommendations. Nodes from each treatment were collected in mid-winter and dissected, and their viability and fruitfulness were recorded. Bud viability (shoots per bud) and fruitfulness (clusters per shoot) also were evaluated at budbreak in 1996. The results indicate that GA3 applications at prebloom and bloom are most detrimental to bud viability and cluster initiation in these cultivars.
Pectin Solubilization and Enzymic Activity of Tomato Fruit Locule Tissue Cell Wall
Authors: Cheng Guiwen W. , Huber Donald J.
Published: February 2019

Hydrolytic activities in liquefying locule tissue of mature-green tomato (Lycopersicon esculentum Mill. `Solar Set') fruit were studied in pursuing the understanding of mechanisms involved in the rheological changes occurring in this tissue. Ethanol-insoluble solids (EIS) were prepared with and without enzyme-inactivating treatment. The release of uronic acids from enzymically active EIS incubated under autolysic conditions was 5-fold higher than recoveries from inactive EIS. Uronic acid release was partially inhibited by 1 mm Hg2+. Cell-free proteins extracts from active EIS exhibited hydrolytic activity against inactive EIS. Pectins released from active EIS showed no evidence of main-chain hydrolysis. Neutral sugars recovered as 80% ethanol-soluble products of autolytic reactions included glc, gal, rha, ara, xyl, and man. Gal was recovered at significant higher levels in autolysates of active EIS. Glycosidases present at high activities in locule tissue included α- and β-galactosidases, β-mannosidase, β-arabinosidase, and β-glucosidase. The results confirm our earlier findings that the metabolism of water, chelator, and alkali-soluble pectins in tomato locule tissue involves deglycosylation with no apparent depolymeriation. These changes alone appear to be inadequate in explaining the unique rheological characteristics in locule gel tissue.
Environment and Storage Time Influence on Pungency and Sugar Profiles in Long-day Onions
Authors: Patil Bhimanagouda S. , Dean Bill B.
Published: February 2019

Sweet onions have gained global importance because of their mild flavor and tear-free properties. A field investigation with seventeen Walla Walla Sweet onion entries grown at the IAREC of Washington State Univ. were evaluated in 1994 and 1995. The flavor and quality characteristics such as pyruvic acid and total sugar (fructose, glucose, and sucrose) concentrations were analyzed by spectroscopy and HPLC respectively. The pyruvic acid concentration in bulbs stored (5 °C and 65% to 75 % relative humidity) for 0, 2, and 4 months increased as the storage time increased. During 1994 and 1995 the pyruvic acid ranges during storage were 4.8 to 7.9 and 2.9 to 9.6 mmols·g–1, respectively. Total sugar concentration in 1994 decreased as the storage period increased, while in 1995 the trend was reversed. There was a higher concentration of sucrose in 1995. In general, Walla Walla onions showed a higher sugar: pyruvic acid ratio among different entries compared to short-day (Vidalia and Texas Grano 1015Y) onions.
Evidence that Rhizospheric Calcium Level Modulates Potato Plant Response to Heat Stress
Authors: Kleinhenz Matthew D. , Palta Jiwan P.
Published: February 2019

Micropropagated `Red Norland' plants were transferred to an inert mixture of 1 perlite: 1 medium-grain quartzite (v/v) and grown 21 days at 20°C day/15°C night on a 25% Hoagland solution without Ca(NO3)2 (Ca at 10 mg·L–1 from CaCl2, N at 35 mg·L–1 from KNO3). Thereafter, Ca treatments (Ca at 0.2, 1, 5, 25, 125 mg·L–1) were imposed for 21 days with other nutrients unchanged. Day/night temperatures were 20/15°C and 35/20°C for control and stress plants, respectively. Continuous drip supply of nutrient solution in excess of demand maintained target rhizospheric Ca levels. All experiments were conducted in controlled-environment chambers with 400-μmol·m–2·s–1 light level. The following results were obtained. 1) Stress, but not control, plants grown with Ca at 0.2 and 1.0 mg·L–1 displayed reduced leaf expansion, extreme senescence, and death of the primary shoot meristem. 2) Plants grown with Ca at 5, 25 and 125 mg·L–1 grew normally under both temperature regimens, although plants responded to temperature with different biomass partitioning. (3) Total root mass at harvest was similar under all Ca–temperature combinations but low-Ca-treated plants had comparatively darker roots with fewer branches. (4) Light microscopic evaluation revealed normal staining patterns of lignified elements in leaves and stems of all plants. These data suggest that constant rhizospheric Ca levels >1 mg·L–1 are required for continued plant growth during exposure to heat stress.