bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal Interactions Among Genotype, Root Regeneration Potential, and Field Performance of Transplanted Container-grown Sycamore
Authors: Shoemake Larry J. , Arnold Michael A.
Published: February 2019

Seven half-sib families of Platanus occidentalis L., either genetically improved selections (TFS-09, TFS-24, WV-10, WV-14) or non-improved selections (Brazos-C, Brazos-D, Putnam), were grown outdoors in 2.3-L to 9.1-L containers, then transplanted in fall, spring, or summer to assess root regeneration potential (RRP) and initial (2 year) post-transplant landscape growth. TFS-09, TFS-24, Brazos-C, and Brazos-D were Texas selections, while WV-10, WV-14, and Putnam were from Tennessee and Kentucky. Generally, local half-sib families grew more rapidly than geographically distant families and some genetically improved selections grew more rapidly than non-improved selections, both in the landscape and nursery. Rapid growth of new roots and transplanted root dry matter were more consistently associated with successful transplant establishment across families than other measures of RRP. Survival was reduced after summer vs. spring or fall transplant.
Blackberries and Raspberries in Southern United States: Yesterday, Today, and Tomorrow
Authors: Moore James N.
Published: February 2019

Blackberries have long been a popular fruit in the southern U.S., and they are widely grown there, with excellent potential for expanded production. Raspberries are also well-liked, but not widely grown, due to lack of adapted cultivars. Great progress has been made, particularly in the past four decades, in improving blackberry cultivars for the South, but little effort has been given to raspberry improvement. Germplasm exists within Rubus to provide great advances in conventional cultivar improvement in both subgenera and for creating new types of fruits through interspecific hybridization. Germplasm and breeding strategies will be discussed that would result in new cultivars to serve as the foundation on which to build much expanded blackberry and raspberry industries in the southern United States.
Progress in Breeding for Sweetpotato Weevil Resistance
Authors: Thompson Paul G. , Graves Boyett , Schneider John C.
Published: February 2019

A breeding program to develop improved sweetpotato genotypes with increased sweetpotato weevil resistance was started in 1990. Germplasm, including plant introductions, cultivars, and breeding lines with reported insect resistance, was field tested for injury levels by applying low numbers of weevils. Low levels of resistance were found and `Regal' was among the highest. Top performing lines were selected and intermated. After 2 selection cycles the most highly resistant selection produced 89% uninjured roots compared to 28% in `Regal'. Severity of injury score was 16 times lower in the most resistant selection (0.15) compared to `Regal' (2.40).
Management Practices for Carnival-season Production of Immature Field Corn in Trinidad and Tobago
Authors: Spaner D. , Mather D.E. , Brathwaite R.A.I.
Published: February 2019

Immature field corn (Zea mays L.) grown for pre-lenten carnival festivities in Trinidad and Tobago can be a profitable cash crop. Hybrid and local unimproved open-pollinated corn were grown with two levels of weed control and fertilizer application late in the rainy season at two locations each on Trinidad and on Tobago. The Trinidad locations were situated on more productive agricultural land than those on Tobago. The hybrid `Pioneer 3098' yielded more edible corn than the local variety at all locations and at all treatment levels. Manual weed removal at the four- to five-leaf stage was sufficient to allow corn to out-compete the weed canopy, and an additional field operation would not be justifiable. On Tobago, the application of fertilizer just before tasselling, in addition to an earlier application of urea, increased the number and yield of edible ears. Few boiling-quality, marketable ears were produced on Tobago. On Trinidad, the additional fertilizer did not alter yield. For commercial carnival-season production of immature field corn on productive soils in Trinidad, the purchase of imported hybrid seed is economically justifiable, but high inputs into weed control and fertility management may not be needed.
Improved Nuclear Staining of Asparagus Microspores for Cytological Analysis
Authors: Ziauddin Asma , Peng Mingsheng , Wolyn David J.
Published: February 2019

Clear visualization of asparagus (Asparagus officinalis L.) microspore nuclei with common stains such as acetocarmine or DAPI is difficult, hindering cytological analyses. The addition of saturated aqueous ferric chloride solution to Carnoy's I fixative (30 μL·mL-1) resulted in clear visualization of nuclei. A distinct nucleus was observed in uninucleate cells and the vegetative and generative nuclei were clearly visible in binucleate microspores. This method can be used reliably for determination of asparagus microspore developmental stage. Chemical name used: 4′,6-diamidino-2-phenylindole-2HCL (DAPI).
Rapid Freeze Acclimation of Poncirus trifoliata Seedlings Exposed to 10 °C and Long Days
Authors: Tignor Milton E. , Davies Frederick S. , Sherman Wayne B. , Davis John M.
Published: February 2019

Poncirus trifoliata (L.) Raf. seeds were germinated in perlite under intermittent mist at about 25 °C and natural daylight in a greenhouse. Two-week-old seedlings were then transferred into a growth chamber at 25 °C and 16-hour daylength for 1 week. Tissue samples were collected at 0, 6, 24, 168, and 504 hours after temperature equilibration at 10 °C. Freezing tolerance at –6.7 °C, as determined by electrolyte leakage, and stem (leaves attached) water potential (ψx), measured using a pressure chamber, was recorded for a subset of seedlings for each time interval. Red coloration (apparently anthocyanin) developed at the petiole leaflet junction and buds after 48 hours at 10 °C and gradually occurred throughout the leaves during further exposure. Complementary DNA clones for phenylalanine ammonia lyase (PAL), 4-coumarate: coA ligase (4CL), and chalcone synthase (CHS) were used to probe RNA isolated from the leaves. No increase in steady-state messenger RNA level was detected. Increases in freeze hardiness occurred within 6 hours in the leaves, and continued for up to 1 week. Water potential initially decreased from –0.6 to –2.0 MPa after 6 hours, then returned to –0.6 MPa after 1 week. Thus, Poncirus trifoliata seedlings freeze-acclimate significantly after only 6 hours at 10 °C.
Postharvest Dip in a Natural Lipid, Lysophosphatidylethanolamine, May Prolong Vase Life of Snapdragon Flowers
Authors: Kaur Navjot , Palta Jiwan P.
Published: February 2019

We investigated the use of lysophosphatidylethanolamine (LPE) for prolonging vase life of snapdragon (Antirrhinum majus L.). Freshly cut snapdragon spikes were set into a LPE solution at 25 mg·L-1 for 24 h and then transferred to deionized water. The vase life was enhanced by LPE. The flowers on spikes treated with LPE showed symptoms of wilting or browning 4 or 6 days later than those on the spikes given deionized water in inbred or `Potomac White', respectively. All the spikes were of marketable quality for 5 to 7 days after harvest when treated with LPE, whereas in the control only about half of the flowers were of marketable quality at 2 days after harvest. LPE treatment also delayed fresh mass loss, lowered endogenous ethylene production, and reduced ion leakage. These results suggest that LPE has commercial potential in enhancing vase life of snapdragons.
Evaluation of U.S. Honeydew-type Melons for Resistance against Downy Mildew and Alternaria Leaf Blight
Authors: Thomas C.E. , Caniglia E.J.
Published: February 2019

Seventeen U.S. honeydew-type cultivars of melon (Cucumis melo L.) and three control cultigens were evaluated in replicated, artificial inoculations under controlled conditions for resistance against downy mildew and Alternaria leaf blight. All cultivars tested were susceptible to downy mildew. However, all of the tested cultivars were significantly more resistant to Alternaria leaf blight than the susceptible control. Twelve of these cultivars were not significantly more susceptible to Alternaria leaf blight than the two resistant controls. These cultivars may provide useful sources of Alternaria leaf blight resistance for incorporation into other commercial melon types.
Spatial and Temporal Distribution of Ripe Muskmelon Fruit
Authors: Edan Yael , Simon James E.
Published: February 2019

The spatial distribution patterns of five melon cultivars (Cucumis melo L. var. reticulatus) were evaluated by measuring XY coordinates of ripe fruit locations in the field. Fruit ripeness distribution over time was also evaluated for three cultivars by measuring the number of ripe fruit, fruit mass, and location over time. Spatial distribution curves for distances between fruit clusters and individual fruit from cluster centroids varied between clusters and were derived for each cultivar from the best fit curves based on chi-square analysis from the two-dimensional spatial fruit distribution. These equations can be used for predicting actual fruit locations in the field. Ripeness distribution patterns indicated that, while the exact duration of the effective harvesting period is cultivar-dependent, the ripeness trend for each of the cultivars was similar. Spatial distribution patterns vary among melon cultivars and must be recognized in the design of automated harvesting systems.
Root Restriction Effects on Growth and Development of Salvia (Salvia splendens)
Authors: van Iersel Marc
Published: February 2019

Container size can affect the growth and development of bedding plants. The effects of widely differing container sizes on growth and development of salvia (Salvia splendens F. Sellow ex Roem. & Schult.) were quantified. Plants were grown in a greenhouse in 7.3-, 55-, 166-, and 510-mL containers. Container volume affected plant growth as early as 18 days after planting. Growth was positively correlated with pot size and differences increased throughout most of the growing period. Growth of the plants in the 7.3-mL cells was reduced because of a low net assimilation rate (4.34 g·m-2·d-1), compared to the plants in the 55-, 166-, and 510-mL pots (≈5.44 g·m-2·d-1). Plants in 510-mL containers grew faster than those in 55- and 166-mL containers because of a higher leaf area ratio. Both lateral branching and leaf expansion were suppressed by root restriction and flowering was delayed. The growth rate of plants in 166-mL pots declined after the onset of flowering, and final plant size was comparable for plants in 55- and 166-mL pots. Although water deficit stress or nutrient deficiencies cannot be excluded as contributing factors, these were probably not the main reason for observed differences.
Hormonal Changes after Compatible and Incompatible Pollination in Theobroma cacao L.
Authors: Baker R. Paul , Hasenstein Karl H. , Zavada Michael S.
Published: February 2019

In order to characterize the self-incompatibility system in Theobroma cacao, the levels of ethylene, indole-3-acetic acid (IAA), and abscisic acid (ABA) were determined after pollination with compatible and incompatible pollen and in unpollinated flowers. Pollen tube growth rates after incompatible and compatible pollinations were identical, and the majority of the pollen tubes reached the ovules between 12 and 20 hours after pollination. ABA levels rose in incompatibly pollinated flowers, and fell in compatibly pollinated flowers, prior to pollen tube—ovule contact. Ethylene evolution remained stable in compatibly pollinated flowers and rose in incompatibly pollinated flowers. IAA concentrations increased in compatibly pollinated flowers, and remained stable in incompatibly pollinated flowers after pollination and subsequent to pollen tube—ovule contact.
Response of `Spineless Beauty' Zucchini (Cucurbita sp.) to Nitrogen, Phosphorus, and Potassium Fertilization
Authors: Morales-Payan J. Pablo
Published: February 2019

Field trials were conducted in Nigua, San Cristobal, Dominican Republic, to determine the yield response of `Spineless Beauty' zucchini (Cucurbita sp.) to nitrogen (N), phosphorus (P), and potassium (K) soil applications in a loamy clay soil containing 4.3% organic matter, 3 parts per million (ppm) of P, and 155 ppm of K. Zucchini was direct-seeded at a distance of 1 m between rows and 0.5 m within rows. Except for N, P, and K fertilization, the crop was grown according to recommended practices. A factorial design (4 × 4 × 4) with four replications was utilized. Rates of N, P, and K were 50, 100, 150, and 200 kg·ha–1, applied as a side dressing 7 days after zucchini emergence. Zucchini fruit harvest started 40 days after crop emergence and every other day thereafter during 20 days. Analysis of variance was performed on the resulting data. Results indicate that there were significant interactions of N, P, and K fertilizer rates on `Spineless Beauty' fruit yield; therefore, nutrient combinations were considered as individual treatments. Significantly superior (lsd 5%) fruit yield was obtained with 150, 150, and 50 kg·ha–1 N, P, and K, respectively.
Colonization Potential of Ornamental Plants by Three Vesicular–Arbuscular Mycorrhizal Fungi
Authors: Trépanier Martin , Rioux Jacques-André
Published: February 2019

Roots of majority of natural shrubs are colonized by many species of vesicular–arbuscular mycorrhizal (VAM) fungi. These kinds of fungi form a symbiosis with the root system of the plant and give a better water and mineral absorption (P, Zn, N, Cu, etc.), and a better root disease resistance to the plant. However, the media usually used in ornemental plants nursery contain no or few mycorrhizal fungi. For now, new commercial inoculum are available and could be used to get the advantages provided by VAM fungi. In order to evaluate the potential of ornamental plants to be colonized, we have inoculated the rooting media with three VAM fungi (Glomus intraradices Schenk & Smith, Glomus etunicatum Becker & Gerdemann, and Glomus mosseae Nicol. & Gerd.; Premier Tech, Rivière-du-Loup, Québec). The inoculum proportion used contained about 1500 propagules/L. After 16 weeks, near 80% of the 200 species and cultivars tested have shown a colonization by at least one of the fungi. We shall present here a list of the results.
Identifying Native Prairie Grass Seedlings
Authors: Gaynor Virginia A. , Meyer Mary Hockenberry
Published: February 2019

There is great interest in prairie gardens and prairie restorations in the central United States. Small prairie gardens are often established with plugs, but most restorationists and landscape contractors use seed for large plantings. If initial establishment is poor, restorations are often interseeded the second or third season. However, to evaluate early establishment and determine if interseeding is necessary, contractors must be able to identify native grasses in the seedling and juvenile stages. In this study we investigated vegetative characteristics of native prairie grass seedlings. Seven species of native prairie grass were grown in the greenhouse: Andropogon gerardii (big bluestem), Sorghastrum nutans (Indian grass), Panicum virgatum (switch grass), Schizachyrium scoparium (little bluestem), Bouteloua curtipendula (sideoats grama), Elymus canadensis (Canada wildrye), and Bromus kalmii (Kalmís brome). Every 2 to 3 weeks after germination, seedlings were photographed, pressed, and mounted. Additional photographs were taken through the dissecting scope at key stages of development. Ligules and auricles were found to be useful in distinguishing species, and our close-up photographs highlight these structures. Hairiness and color were variable within a species and could not be used reliably in identification. A seedling identification key will be presented for the species studied.
Temperature Effects during Endodormancy Induction on Subsequent Anthesis and Growth of Peach Trees
Authors: Seeley Schuyler D. , Rojas-Martinez Raymundo , Frisby James
Published: February 2019

Mature peach trees in pots were treated with nighttime temperatures of –3, 6, 12, and 18 °C for 16 h and a daytime temperature of 20 °C for 8 h until the leaves abscised in the colder treatments. The trees were then chilled at 6 °C for 40 to 70 days. Trees were removed from chilling at 40, 50, 60, and 70 days and placed in a 20 °C greenhouse under increasing daylength, spring conditions. Anthesis was faster and shoot length increased with longer chilling treatments. Trees exposed to –3 °C pretreatment flowered and grew best with 40 days of chilling. However, they did not flower faster or grow better than the other treatments with longer chilling times. There was no difference in flowering or growth between the 6 and 12 °C pretreatments. The 18 °C pretreatment resulted in slower flowering and very little growth after 40 and 50 days of chilling, but growth was comparable to other treatments after 70 days of chilling.
Influence of Storage Period on the Postharvest Characteristics of Five Mango (Mangifera indica L.) Cultivars
Authors: Zambrano Judith , Materano Willian , Briceño Sagrario
Published: February 2019

Five mangos cultivars (Mangifera indica L., `Palmer', `Keitt', `Spring Field', `Kent', and `Anderson') were harvested at the preclimacteric stage. Fruits were selected for study that were uniform and free of visual defects and stored for 18 days at 10 °C, 90% to 95 % RH. Fruits were evaluated every 3 days for pulp and peel color, total soluble solids, titratable acidity, ascorbic acid content, and total and reducing sugars. Pulp and peel color parameters (lightness, hue, and chroma) were significantly different among cultivars. The soluble solids content, ascorbic acid, and starch content changed significantly during storage and were significantly different among cultivars. Total and reducing sugars content did not change significantly after 10 days of storage. Results of this study indicated that these five mango cultivars have good storage potential.
Low Temperatures and High CO2 Atmospheres Best Maintain the Quality of Fresh-cut Jicama (Pachyrhizus erosus)
Authors: Cantwell M. , Aquino-Bolaños E.N. , Mercado-Silva E. , Peiser G.
Published: February 2019

The jicama is a chilling-sensitive specialty root vegetable used fresh for its crisp sweet-starchy pulp. Our objective was to evaluate a range of storage temperatures and controlled atmospheres potentially useful to preserve the quality of minimally processed jicama. Jicama root pulp was cut into 1.8 × 4-cm cylinders, washed in chlorinated water, drained, and stored in glass containers at a range of temperatures from 0 to 15 °C in air, or at 5 and 10 °C in controlled atmospheres (0.3, 3, and 21% O2 with 0, 5%, 10%, or 20% CO2). Pieces were evaluated after 0, 4, 8, 12, or 16 days for visual quality, color, texture, and composition (soluble solids, ethanol, acetaldehyde). Total aerobic plate counts were determined on samples from some atmospheres. At temperatures >5 °C, browning was the most significant cause of quality loss. High CO2 atmospheres retarded the development of brown discoloration at 10 °C. During storage at 0 or 5 °C in air, quality loss was principally due to yeast and bacterial growth. The 10% CO2 atmospheres helped maintain the white color and crisp texture of the pieces and retarded microbial growth. Atmospheres with 20% CO2 damaged jicama stored longer than 8 days. Atmospheres of 3% O2 or air with 10% CO2 resulted in acetaldehyde and ethanol concentrations 4 and >10 times those of air-stored pieces after 8 days at 5 °C. Although the jicama root is chilling-sensitive, our results demonstrate that the quality of the minimally processed product is best maintained with low temperatures in combination with high CO2 atmospheres.
In Ovule Culture in Peach: Embryo Perforation, Duration of Culture, and Media Effects on Seed Growth and Seedling Survival
Authors: Byrne David H. , Rizzo Marissa , Porter Katrina , Ramming David , Anderson Natalie , Sinclair Jonathan
Published: February 2019

In the breeding of early maturing peach and nectarine cultivars, the use of embryo rescue techniques is invaluable since the embryos of these materials are not mature by the time the fruit is mature. Thus the seed does not germinate under normal stratification/germination procedures. Peach embryos between 3 and 6 mm in length were cultured in ovule on WPM under treatments that varied in sucrose levels (4% and 6%),the use of vitamins (casein hydrosylate, ascorbic acid, and panthotenic acid) and hormones (BAP and GA3), and the duration of the treatment (7, 14, 21, and 28 days). A five-seed sample was measured for length, fresh weight, and dry weight before and after treatment. The treated embryos were then cultured in a embryo rescue media (WPM, 3% sucrose) at 5 °C for 45 days in the dark and then brought out to room temperature under lights (12-h day). After 2 to 4 weeks the embryos were rated for germination, size, and root number. Embryo perforation treatment resulted in larger embryos but not in better germination than the smaller unperforated embryos. Among the embryos cultured without perforation, the addition of vitamins and hormones caused the production of plants with more roots and shoots but not necessarily with better survival. Both levels of sucrose worked reasonable well. As the time of in ovule treatment increased, embryo growth and plant survival was enhanced.
Transformation of `Bosc' Pear (Pyrus communis L.) with the rolC Gene from Agrobacterium rhizogenes and Characterization of Transgenic Plants
Authors: Scorza Ralph , Bell Richard L. , Srinivasan Chinnathambi , Webb Kevin
Published: February 2019

Pear production in the United States relies on a few major cultivars, including `Bosc'. While there is a need for new cultivars, genetic improvement of the existing major cultivars through genetic transformation could have a major impact on the industry. We have developed a system for regeneration and transformation of pear. While the major objective of the transformation project is to improve resistance to fire blight (Erwinia amylovora) in major pear cultivars, tree size control is also one of the objectives in the genetic improvement of pear that may be approached through transformation. Traditionally, manipulation of tree size and vigor in established cultivars has been achieved through the use of size-controlling rootstocks. There are no completely satisfactory size-controlling rootstocks for pear. Genetic transformation provides an approach to developing new size-controlling rootstocks and also to directly affect the growth of the transgenic scion cultivar using genes that affect plant growth such as the rolC gene isolated from the bacterium A. rhizogenes, the causal agent of “hairy root” disease. This gene has been shown to alter growth and development in a number of plant species. To investigate the potential utility of the rolC gene in altering the growth of pear trees, `Bosc' pear was transformed with A. tumefaciens EHA101 carrying a pGA482-based plasmid containing the NPTII and GUS genes, and the rolC gene under the control of its native promoter. Four clones were isolated that were kanamycin-resistant and GUS-positive. PCR assays and DNA blots indicated the presence of the rolC gene in these clones. Each transgenic clone has been multiplied in vitro and planted in the greenhouse where transgene expression and plant growth are being evaluated.
Interaction Between Powdery Mildew and N and K Fertility in Begonia
Authors: David Monica A. , Swiader John M. , Eastburn Darin M. , Williams Kimberly A.
Published: February 2019

Nine fertility treatments, consisting of a 3 × 3 factorial arrangement of three N rates (30, 120, 240 μg·ml–1) and three K rates (30, 120, 240 μg·ml–1), were applied by constant liquid feed to cuttings of Hiemalis begonia `Hilda' grown in 15-cm plastic pots containing 7.5 peat: 2.5 perlite medium. Prior to transplanting, one-half of the plants were naturally inoculated with Erysiphe cichoracearum to induce powdery mildew infection; while the remaining plants received weekly application of Bayleton (Triadimefon). Shoot growth in fungicide-treated plants increased with increasing rates of both N and K, with highest dry matter production (≈8.0 g/plant) with either 120N–240K or 240N–120K. Disease development in plants treated with fungicide was slight, averaging < 7% of the total leaf surface area infected with mildew, irrespective of N and K rates. Shoot dry weights in inoculated plants were markedly repressed, averaging 3.1 g/plant, as disease occurrence was extensive in all treatments. Significant interactions between N and K fertility affected mildew development in inoculated plants. At the high rate of N, K nutrition had little effect on mildew rating, whereas at 30N and 120N, mildew counts decreased with increasing K rate up to 120 K.
Ethylene Influences α-Farnesene Biosynthesis of Apples
Authors: Rupasinghe H.P.V. , Paliyath G. , Murr D.P.
Published: February 2019

Ethylene (C2H4) production or ripeness of fruit at harvest have been shown to influence α-farnesene accumulation and superficial scald development of apples. Effects of a 15-hr treatment with 500 ppm C2H4 and 7.5 ppm 1-methylcyclopropene (1-MCP), or 10-min dip in 200 ppm aminoethoxy vinyl glycine (AVG) on C2H4 production rate (EPR), hexane-extractable α-farnesene content in the skin, head-space α-farnesene evolution using solid phase micro extraction (SPME), and in vivo α-farnesene synthase activity of `Delicious' apples stored for 2 months at 0 °C were investigated. Compared to untreated fruits, AVG and 1-MCP treatments reduced EPR by 95% and α-farnesene content in the skin by 75% at day 6. C2H4-treated fruits evolved over 50% higher α-farnesene, but had reduced α-farnesene content in the skin and head-space. However, enzyme activity was marginally increased in C2H4-treated fruits.
Root Development of Bean (Phaseolus vulgaris L.) is Affected by Trifluralin Herbicide
Authors: Wyatt Jim E.
Published: February 2019

The objectives of this study were to investigate the effects of trifluralin (TRI) herbicide on plant vigor and lateral root growth of snap beans. Lexington silt loam soil, which had not been treated with herbicides for at least 3 years, was used in this study. TRI herbicide was mixed with appropriate amounts of soil in a cement mixer to provide a constant rate of 560 g ai/ha TRI. To simulate TRI herbicide incorporation, bands of treated and untreated soil were layered into 30 × 30 × 15 cm (vol 13,500 cm3) bottomless wood boxes. Treatments were 1) control, 2) 2.5-cm treated band placed 2.5 cm below soil surface (BSS), 3) 2.5 cm treated band placed 5.1 cm BSS, 4) top 5.1 cm with treated soil, or 5) top 7.6 cm with treated soil. `Benton' snap beans were planted in each box and grown in the greenhouse for 25 days. Plant measurements made included plant height, leaf area, and fresh and dry weight. The root system of each plant was washed and roots arising from the hypocotyl, transition zone, and primary roots were counted. All roots from each box were combined, dried overnight at 100C and weighed. Plant top weight and leaf area were not affected by TRI treatments. Plants were shorter in all TRI treatments except where placement was banded at 5.1 cm BSS. More adventitious roots were produced on hypocotyls when TRI was applied in a 2.5-cm band at 2.5-cm BSS or in the top 5.1 cm of soil. Total root weight was lower and fewer lateral roots developed in all soil bands treated with TRI.
Growth, Morphology, and Physiology of Intsia bijuga Trees Under Varied Light Conditions
Authors: DeMeo Robin A. , Marler Thomas E.
Published: February 2019

Six studies were conducted with Intsia bijuga seedlings to determine the methods and extent of shade tolerance for this species. Growth differences were minimal among plants receiving varied light exposure, although treatments ranged from 19% to 100% sunlight exposure. Light saturated photosynthesis of leaves on plants receiving 24% sunlight was achieved at a photosynthetic photon flux (PPF) of about one-fourth of that for the leaves on plants receiving 100% sunlight exposure. However, photosynthesis under conditions of extremely low PPF was higher for shade-grown plants than for full-sun plants. Shaded plants exhibited lower dark respiration, light compensation point, and light-saturated photosynthesis than full sun plants. Leaflet thickness, palisade layer number, and stomatal density of leaves of shaded plants were reduced compared with full sun plants. At seedling emergence and for several months thereafter, the plants responded to shade primarily with obligate sun plant characteristics. After the plants were established, however, responses to the varied light conditions indicated facultative structural and physiological characteristics.
Reproductive Efficiency in Muscadine Grapes
Authors: Gupton C.L.
Published: February 2019

To determine the berry production efficiency of selected muscadine grape cultivars, pollen production, size, and viability; time of pistil receptivity; mode of pollination; number of flower per cluster; and percentage fruit set were studied. Each of 17 hermaphroditic cultivars except `Noble' produced a high percentage of viable pollen grains. Pollen size averaged 32 and 51 μm in 2 years. Even at this small pollen size, our observations suggest insects rather than wind as the primary means of pollen transfer to pistillate flowers. Pistils were not receptive until the calyptra dehisced, thereby ensuring that pollen can reach the pistil when it is receptive. `Carlos' produced 68.5 and `Black Beauty', `Doreen', `Fry', `Sweet Jenny', and `Supreme' produced from 38 to 46 flowers per cluster. Percentage fruit set ranged from a high of 22 to 34 for `Fry', `Sweet Jenny', `Doreen', and `Supreme', and a low of 12 to 14 for `Carlos' and `Black Beauty'. These results suggest that pollination may not be a problem in present muscadine cultivars. Variation in yield among cultivars apparently relates to genetic differences in cluster number and berry weight.
Meiotic Behavior in an Amphidiploid Rose and Its Hybrid Progeny
Authors: Ma Yan , Byrne David H.
Published: February 2019

The amphidiploid rose 86-7 (Rosa wichuraiana × R. rugosa rubra) and its hybrids with the tetraploid breeding selection 82-1134 were analyzed for meiotic configuration frequencies and meiotic abnormalities. Genomic relationships in these hybrids were interpreted with the aid of a model of meiotic chromosome association in tetraploids. The optimized solutions to this model indicated a pattern intermediate between the “211” pattern, with one pair of closest genomes, and the “ring4” pattern, in which one of three possible pairing arrangements is strongly suppressed. The same configuration frequencies could also reflect a “4:0” pattern of equally similar genomes with more than two independent pairing and chiasma-forming domains per chromosome. The observed meiotic abnormalities included chromosome stickiness and asynchronous chromosome contraction within cells. Pollen stainability varied independently of meiotic irregularity or multivalent frequency.
Screening for Ploidy Variation in Collections of Malus (Apple) Species by Flow Cytometry
Authors: Benson Laura L. , Wheeler Nancy , McFerson James R.
Published: February 2019

Flow cytometry was used to determine the ploidy levels in three subsets of the apple germplasm collection held by the USDA–ARS Plant Genetic Resources Unit. C-values ranging from diploid to pentaploid DNA content have been reported in the genus Malus, but cytogenetic information is often not available for specific trees. Diploid, triploid, and tetraploid clones were found in the core collection, a diverse group of Malus species and hybrids. Ploidy level may vary within and between Malus species in the wild. The progeny of 38 M. sieversii trees sampled from a natural population near Targabatai, Kazakstan were screened with flow cytometry. All the tested progeny had diploid C-values. Gigas characters such as larger leaves and fruit are sometimes associated with elevated ploidy levels. Ten elite scions of large-fruited M.sieversii were evaluated. All 10 had C-values in the diploid range. While flow cytometry of nuclei liberated from leaf tissue gave the expected DNA content for cultivars with previously known ploidy levels, this technique could not distinguish a known 2-2-4-4 periclinal chimera from diploid individuals.
Evaluation of Three Soil-applied Insecticides for Root Weevil Control in Container-grown Nursery Crops
Authors: Rosetta R.L. , Svenson S.E. , Bell N.C.
Published: February 2019

To determine efficacy of insecticides for adult root weevil control in container-grown plants, adult stages of black vine root weevil, Otiorhynchis sulcatus, were established in two container-grown plant species, arborvitae (Thuja occidentalis `Emerald') and rhododendron (Rhododendron `Vulcan') in May 1997. Seven root weevil adults were placed onto the soil surface of each 1-gal plant and covered with a damp paper towel. Insecticides were applied during daylight hours on 20 May 1997. Foliar treatments were applied using a manually pressurized backpack sprayer. Baits and granular treatments were applied by hand to the soil surface. On rhododendrons, treatments consisted of: 1) an untreated control; 2) Topcide (lamda-cyhalothrin, 1.2 oz/100 gal); 3) Topcide (lamda-cyhalothrin, 4.8 oz/100 gal); 4) Pinpoint 15G (acephate, 16.5 lb/a); 5) Pinpoint 15G (acephate, 33.0 lb/a); 6) Cryolite (Sodium aluminofluoride-based bait, 30 lb/a); and 7) Gowan 1885 (30 lb/a). There were five blocks per treatment, each containing five plants. At 1 and 7 days after treatment, root weevils were collected from each container and evaluated for moribundity and mortality. Treatments 1, 3, 5, and 6 were applied to arborvitae and evaluated 1, 3, and 8 days after treatment. Cryolite, Gowan 1885, and Pinpoint 15G (high rate) had the highest mortality (70% to 79%) compared to untreated (11% to 17%) or Topcide-treated plants. Pinpoint 15G and both sodium aluminofluoride bait treatments may provide an effective, viable option for adult root weevil control when pesticides cannot be applied in the evening or when reduction of risks from foliar cover sprays to non-target organisms is desirable.
Effect of Flower Age on Ethylene Synthesis in Big Bend Bluebonnet, Lupinus havardii
Authors: Vasquez Katherine L. , Mackay Wayne A. , Wall Marisa M. , Davis Tim D.
Published: February 2019

Endogenous ethylene production of an advance breeding line and an unimproved population of L. havardii was measured to determine at what age open flowers begin to synthesize ethylene. Twenty to 30 immature flower racemes from greenhouse-grown plants were randomly selected and tagged in each plant population. Every 24 h, the uppermost open flower was tagged on the selected racemes. On the 10th day, tagged racemes were harvested from each population group. Flowers were removed from the raceme, placed into 10-ml vials (six flowers/vial), and incubated at room temperature (25 ± 2 °C). Ethylene was analyzed using a gas chromatograph. Detectable ethylene levels were most prevalent in 3- to 4-day old flowers. Mean ethylene rates were 1.7 nl/g per h and 1.1 nl/g per h for 4-day-old flowers of the advance breeding line and unimproved population, respectively. Senescing flowers (10 days old) of the advanced breeding line and unimproved population had ethylene rates of 7.9 and 6.7 nl/g per h, respectively.
Changes of Lipid Components During Dormancy in Blackberry Cultivars
Authors: Izadyar Amir B. , Wang Shiow Y.
Published: February 2019

Changes in phospholipids, galactolipids, and fatty acid were determined in two cultivars of blackberries, `Triple Crown' and `Hull Thornless', during dormancy and budbreak. Under field conditions, `Triple Crown' required lower chilling units (CUs) than `Hull Thornless' to overcome dormancy. `Triple Crown' and `Hull Thornless' achieved full budbreak after receiving 600 and 1000 CUs, respectively. Under cold-temperature treatments, `Triple Crown' needed 400 CUs, while `Hull Thornless' needed 600 CUs at 4 °C to obtain 100% budbreak. The shoots kept at intermittent 6/24 °C (6 °C for 16 h, and 24 °C for 8 h) did not reach full budbreak even after receiving 1000 CUs. An increase in phospholipids and glycolipids was observed during the termination of dormancy. The increase in phospholipids occurred earlier than the increase in glycolipids. The percentage of 18:2 fatty acid decreased while 18:3 increased and there was approximately a five-fold increase in the 18:3/18:2 ratio observed at the time of budbreak. The increase in the 18:3/18:2 ratio could serve as an indicator of dormancy termination and growth resumption in blackberry.
Depletion Evaluation of the Available Moisture in `Mission' Olives
Authors: Fontes Adán Fimbres , Contreras Raúl Leonel Grijalva , de Jesús Valenzuela Ruíz Manuel
Published: February 2019

The area of olives in the region of Caborca has been increasing in the past years to 4500 ha. Olives in other regions do not need the application of water, but here at Caborca evaporation is greater than rainfall. Because of this, an experiment was conducted in 1997 to determine the optimum water requirements for olives (table olives) in a sandy loam soil. The results indicated that the greatest yield (22.68 kg/tree) was with 40% depletion of the available moisture (AM) in the soil, and the lowest yield (7.46 kg/tree) was with 100% depletion of the available moisture in the soil. The total water applied with the 40% depletion of the AM was of 239.81 cm (2.4 m).
Soil–Root Interface Water Potential in Sweet Corn Affected by Organic Fertilizations and Effective Microbe Applications
Authors: Xu H.L. , Umemura H. , Higa T.
Published: February 2019

We examined effects of organic fertilizations and effective microbes (EM, mainly Lactobacillus, Rhodopseudomonas, Streptomyces, and Aspergillus) applications on soil-root interface water potential Ψs-r of `Honey-Bantam' sweet corn. The contributions to Ψs-r from root amount and root activity were analyzed using the Ohm's law. Plants were grown in 1/5000 a Wagner's pots filled with Andosol and six treatments were made as follows: 1) organic materials fermented anaerobically with EM added; 2) anaerobic organic materials; 3) organic materials fermented aerobically with EM added; 4) aerobic organic materials; 5) chemical fertilizers with EM applied, and 6) chemical fertilizers. One month after sowing, as soil water decreased, Ψs-r was maintained higher in organic fertilized plants than chemical fertilized ones and also higher in plants with EM applications than those without EM. The relatively high Ψs-r was contributed by both their large root amount and high root activity. As a consequence, photosynthesis under soil water deficit conditions were also maintained relatively high in these plants. Maintenance of a high Ψs-r favored plants to resist against water deficits. Moreover, the Ψs-r analysis is a practicable additional means to examine the soil-plant water status under undisturbed conditions.
Use of RAPD Fingerprints for Verification of Synonyms and Studies of Genetic Distance in Pear Genetic Resources
Authors: Bell Richard L. , Cain Shawn
Published: February 2019

Pear cultivars and clonal selections of five related Pyrus species or subspecies were “fingerprinted” using RAPD markers. Total DNA was extracted from young leaf tissue usign a modified cTAB procedure. Twenty oligonucleotide decamers from Operon kits A and B were evaluated for repeatability and polymorphisms in an initial set of six cultivars. Nine highly polymorphic primers were selected for “fingerprinting” a larger set of 29 gentoypes. Dissimilarity indices were computed from the RAPD markers, and cluster analysis performed on these genetic distance data. `Jeribasma' and `Vodenac', cultivars collected in Serbia, and `Erabasma' collected in Poland, were verified as being synonymous genotypes. Cultivars from Eastern Europe were not uniformly grouped separately from cultivars from Western Europe. The results demonstrate the efficiency of RAPD markers for cultivar identification and studies of genetic relatedness.
Field Measurements and Simulation of Nitrogen Fate under Citrus Production
Authors: Fares A. , Alva A.K. , Paramasivam S.
Published: February 2019

Water and nitrogen (N) are important inputs for most crop production. The main objectives of nitrogen best management practices (NBMP) are to improve N and water management to maximize the uptake efficiency and minimize the leaching losses. This require a complete understanding of fate of N and water mass balance within and below the root zone of the crop in question. The fate of nitrogen applied for citrus production in sandy soils (>95% sand) was simulated using a mathematical model LEACHM (Leaching Estimation And Chemistry Model). Nitrogen removal in harvested fruits and storage in the tree accounted the major portion of the applied N. Nitrogen volatilization mainly as ammonia and N leaching below the root zone were the next two major components of the N mass balance. A proper irrigation scheduling based on continuous monitoring of the soil water content in the rooting was used as a part of the NBMP. More than 50% of the total annual leached water below the root zone was predicted to occur in the the rainy season. Since this would contribute to nitrate leaching, it is recomended to avoid N application during the rainy season.
Girdling Lemons to Improve Fruit Size and Set in Southern Arizona
Authors: Wright Glenn C.
Published: February 2019

Arizona lemon producers are often concerned with poor flowering, fruit set and fruit sizing, especially following excessively warm winter or spring weather. `Limoneira 8A Lisbon' (Citrus limon Burm.) lemons were girdled over a 3-year period to determine if girdling would improve yield or fruit size. Eight trees were girdled each month, from November through August, using a double spiral girdle and a 4.8-mm wide girdling knife. Fruit size measurements were taken throughout the growing season. Trees were harvested individually, and yield; fruit packout and fruit quality measurements were collected. For the 1995/96 harvest, trees girdled in March and May had greater early size and greater yields. Fruit quality was improved as well. For 1996/97 harvest year, trees girdled the previous November and December had significantly greater yield and fruit size. For trees harvested in 1997/98, no treatment was significantly better than the non-girdled trees. The effects of girdling on the orchard profitability will also be discussed.
Potato Lipoxygenase POTLX-3 Gene is Expressed In Response to Pathogens but Not Wounding
Authors: Kolomiets Mikhailo V. , Gladon Richard J. , Hannapel David J.
Published: February 2019

Lipoxygenases are the first committed enzymes in biosynthetic pathways that produce jasmonic acid, methyl jasmonate, traumatin, fatty acid hydroperoxides, and volatile aldehydes. These pathways often function in growth- and defense-related processes in plants. Products of lipoxygenases may be the primary cause of the hypersensitive response (HR) because lipoxygenase by-products such as organic free radicals and active oxygen species are involved in cell membrane degradation during resistance responses against pathogens. In order to study lipoxygenase involvement in defense responses against pathogens, we have isolated and characterized a potato lipoxygenase gene that we have designated POTLX-3. POTLX-3 is not expressed in any potato organs, is not induced by wounding, but is strongly induced in leaves treated with ethylene, methyl jasmonate, or inoculum of Phytophthora infestans, the causal agent of potato late blight. In response to infection, POTLX-3 transcripts accumulate more rapidly in resistant lines than in susceptible lines. In resistant lines, the greatest amount of induction preceded the visual appearance of localized necrotic lesions, consistent with possible involvement of POTLX-3 in HR development. Expression of POTLX-3 also is activated in response to inoculation with the bacterial pathogen Pseudomonas syringae pv. phaseolicola, which causes strongly expressed HR in all potato cultivars. Thus, POTLX-3 expression is not a specific response to P. infestans, but rather a common response related to HR development against a broad range of pathogens. Pattern of POTLX-3 expression indicates that it may have a specific role in defense mechanisms against pathogens.
Pathogenic Variation in Halo Blight on Common Beans
Authors: Ariyarathne H.M. , Coyne D.P. , Vidaver A.K.
Published: February 2019

Halo blight, caused by a bacterium, Pseudomonas syringae pv. phaseolicola (Psp), is one of the most important bacterial diseases of common beans (Phaseolus vulgaris L.). The objective of this study was to evaluate the pathogenic variation of Psp strains with emphasis on those collected in Nebraska. Twenty-nine Psp strains were inoculated on 20-day-old leaves of eight differential cultivars/lines and a resistant check line great northern (GN) Nebraska #1 sel. 27. Two experiments were conducted in growth chambers under 20 °C and 12-h photoperiod. A split-plot design was used with nine cultivars/lines as whole plots in a randomized complete block design (RCBD) and strains as sub-plots in an incomplete block arrangement. Data were analyzed as a split-plot with a RCB arrangement because incomplete block was not significant. Strains were classified into five races with six, 16, and two strains classified as races 1, 6, and 7, respectively. The remaining strains were designated tentatively as new races 10 and 11. GN Nebraska #1 sel. 27 was resistant to all Psp strains tested. This information is useful to breeders interested in developing germplasm and cultivars resistant to Psp.
Implementing Biointensive IPM Systems in Cling Peaches
Authors: Hasey Janine K. , Pickel Carolyn , Olson William H.
Published: February 2019

A complete mating disruption program that uses pheromone confusion technology successfully controlled oriental fruit moth and peach twig borer while eliminating most in season insecticides in cling peaches from 1995–1997 in a three-county area. During this 3-year period, 46 cooperators used this program on 580 acres. Growers applied both Oriental fruit moth and peach twig borer pheromone dispensers twice. Orchards were monitored for moths and for shoot strikes during the season. Harvest samples were taken to determine worm damage. A few orchards were sprayed once when shoot strike counts exceeded threshold levels of three to five strikes per tree. Along with mating disruption in 1997, 209 acres were sprayed with Bacillus thuringiensis during bloom to replace the dormant insecticide spray and improve efficacy of pheromone confusion. Throughout implementation, mating disruption program costs were compared with conventional spray programs. Between 1995 and 1997, the complete mating disruption program cost decreased from $243 per acre to $216 per acre respectively. Even with the decrease in cost, this is much higher than $104 per acre for the standard spray program. Some growers decreased pheromone dispenser applications in 1997 for a more economic program. This program still reduced pesticide use by 33% to 67%. While most growers using this partial program had success, some orchards had high shoot strikes indicating a potential problem. Grants from USDA-ES-Smith-Lever IPM project, EPA Environmental Stewardship Partnership, California Department of Pesticide Regulation and Farm Service Agency cost share programs aided in our ability to implement these biointensive programs; they provided the money necessary for monitoring and reducing direct costs to the grower. The main obstacle to cling peach growers adopting the complete biointensive program is the economics. Most growers will continue to spray or use a partial mating disruption program until less expensive commercial products become available.