bluuebunny/crossref_metadata_2025 huggingface dataset:
645 Using Site-specific Approaches to Advance Potato Management in Irrigated Systems
Authors: Davenport Joan R.
Published: February 2019

Potato (Solanum tuberosum L.) is grown extensively throughout the Pacific Northwest as a high-value crop in irrigated rotations with other row crops such as wheat (Triticum aestivum L.) and corn (Zea mays L.)—both field and sweet. Center pivots are predominant irrigation systems. Soil texture ranges from coarse sands to finer textured silt loams and silts and can vary within one field, often with very hilly topography. Site-specific management is being evaluated as an approach to help to optimize inputs (water, seed, agricultural chemicals) to maintain or enhance yield and reduce the potential of negative environmental impacts in these farming systems. Currently variable rate fertilizer application technology and harvest yield monitoring equipment are commercially available for these systems. Variable rate seeding and variable rate irrigation water application technologies are developed but not fully commercialized and variable rate pesticide application equipment is in development. At the Irrigated Agr. Res. and Ext. Ctr. in Prosser, Wash., we have a team of research scientists (both university and USDA/ARS), interested individuals from local industry, and other key organizations (e.g., local conservation districts) who are working together to evaluate different site specific technologies, improve the ability to use available tools, and to improve decision-making ability by conducting research both on farm and in research plots.
652 Challenges and Opportunities for Application of Genetic Engineering to Horticultural Crop Improvement
Authors: Somers David A.
Published: February 2019

Genetic engineering offers numerous potentially useful genetic manipulations for the improvement of horticultural crops. Nevertheless, there are several impediments to the efficient integration of genetic engineering into plant improvement programs. The ability to regenerate plants from tissue cultures and, therefore, to genetically engineer most plant species is limited to specific genotypes. This may constrain introduction of genetically engineered traits into crops that have complex genetics, are highly heterozygous, or are propagated by asexual reproduction. Even in crops that are self-compatible, diploids, genotypic specificity of the transformation process often necessitates backcrossing for transfer of genetically engineered traits into elite lines and to reduce problems associated with tissue culture-induced genetic variation. This limits progress in improving other traits compared to other breeding strategies. Other challenges to applying genetic engineering exist. The major genomics initiatives currently underway for gene discovery from a broad range of organisms will provide plant improvers access to most genes. Yet there remains a dearth in tissue-specific, developmentally timed, and environmentally responsive promoters for appropriate expression of introduced genes (transgenes). Furthermore, transgene expression is not as controllable as desired due to transgene silencing. Transgene integration is a random process and further refinements of targeted DNA integration will likely enhance the stability of expression of transgenic traits. The availability of other tools, such as selectable marker genes, will become limiting as multiple transgenic traits are combined within a species. In addition to technical problems, there likely will be problems of access to proprietary technology and testing to meet federal regulations and public acceptance. While these various challenges and limitations currently may constrain progress in application of genetic engineering to horticultural crop improvement, it is foreseeable that with further improvements of genetic engineering technology and development of the appropriate molecular tools, genetic engineering will become a component of most plant improvement programs.
656 Improving Seedling Establishment of Medicinal Herbs
Authors: Grassbaugh Elaine M. , Bennett Mark A. , Evans Andrew F.
Published: February 2019

Successful crop production and optimum yields, regardless of the species, can be accomplished only when maximum stand establishment is achieved. Stand reduction after planting typically results in reduced yields and lower crop quality. Several classes of factors (environmental, edaphic, biotic) contribute to successful stand establishment in crop production and should be considered in growing medicinal plants. Environmental factors (e.g., temperature and moisture extremes) as well as pathogens and insect pests that attack seeds and seedlings may contribute to reduced stands. Soil related factors such as pH, nutrient availability, and crusting may also restrict seedling growth. Understanding the requirements for optimum seed germination and the environmental conditions into which the seed is sown is essential for uniform crop establishment. Vigor tests can aid growers in determining the optimum temperature range for seed germination. Many cultural practices may also influence soil related factors and contribute to successful stand establishment in the field. Seed vigor tests (SSAA, thermogradient results) along with seed treatments and enhancements can assess seed vigor, improve germination and lead to more reliable stands of medicinal species.
657 Relationship between Intensity of Flowering and Cropping in Fruit and Nuts
Authors: Stover E.W.
Published: February 2019

The relationship between intensity of flowering and various aspects of cropping will be reviewed for fruit and nuts. Clearly, relatively light flowering can limit yield in most fruit and nut species. This commonly occurs before mature bearing commences and in “off” years for varieties that display alternate bearing. During mature bearing, many species will carry fruit numbers that exceed commercially desired levels, resulting in excessively small fruit and accentuating alternate bearing. The economic disadvantages of excess cropload have resulted in considerable research on fruit thinning and widespread commercial application of this practice. Heavy flowering intensity in some crop species results in economic disadvantages beyond the problems of excessive cropload and resultant small fruit size. Many species flower profusely and have initial fruit set far in excess of final tree capacity, resulting in abscission of numerous flowers and fruitlets. Abscised organs can represent a substantial investment in carbohydrates and nutrients, compromising availability at critical periods in flower and fruit development. The potential implications of this process are best exemplified in navel orange, where an increase in flowering beyond intermediate intensity results in a reduction in both initial fruit set and final fruit yield at harvest. In several crops, there is evidence that fruit size may be reduced by excessive flowering, even when cropload is quickly adjusted to an acceptable level. These data suggest that further research on the advantages of controlling flowering intensity is warranted.
664 Breeding and Development of Cold-hardy Roses
Authors: Davidson Campbell G.
Published: February 2019

Without a doubt, roses have been and continue to be an important landscape and greenhouse plant. From the early records, dating back to Egyptian, Roman, and Greek times, roses have played an important societal role. Early attempts at growing roses in Prairie Canada were frequently unsuccessful. The extreme cold in winter, where temperatures of –30 to –40 °C are common, and droughts and heat in the summer greatly reduced the range of plant material, including roses that could be grown. As a result, the Morden Research Centre, part of Agriculture and Agri-Food Canada's Research Branch in southern Manitoba, initiated a series of projects on the development of hardy landscape plants including roses. Since1929, we have introduced over 130 new landscape plant cultivars to the nursery trade, including 18 cultivars of roses. One of the keys to the success of the program was the incorporation of cold tolerance originally obtained from Rosa arkansana, a prairie native. This has led to the development of the `Parkland' rose series. This group of plants flowers repeatedly, are hardy to USDA zone 3, root from softwood cuttings, and are available in a variety of colors. Highlights of these will be presented. More recently, emphasis has been placed on developing breeding strategies to improve disease resistance. Major diseases affecting roses include black spot (Diplocarpon rosea), powdery mildew (Sphaerotheca pannosa), and rust (Phragmidium sp.). Details of the current breeding protocols will be outlined as well as results from a series of trials established to elucidate the influence of environment and genotype on disease expression. Cooperative disease monitoring trials (Canada and Sweden) were established and results will be presented.
665 Selection, Domestication, and Breeding Native Herbaceous Prairie Plants
Authors: Lindgren D.T.
Published: February 2019

There has been a large increase in the use of native herbaceous prairie plants for ornamental purposes. They are also being used for cut flowers, medicinal purposes, and in restoration projects. To discuss the subject of breeding and selecting herbaceous plants for landscaping, it is convenient to divide the topic into three areas of interest: 1) selecting native ecotypes for use on specific sites; 2) selecting and breeding for nonnative/native plants for wildflower mixes; and 3) selecting, breeding and developing specific individual plants for ornamental/garden use. Native plant traits that are being evaluated at the Univ. of Nebraska West Central Center include competitiveness, pest tolerance, regional adaptation, flowering characteristics, foliage characteristics, proportionality of plants, ease of propagation, ease of establishment, and moisture requirements. In addition, research is being conducted at the West Central Center regarding genetic variation. For example, Dalea purpureum varies in height, foliage color, stems per plant, stem lodging, and time of flowering. Similar variation has been documented in Lithospermum, Calylophus, Penstemon, Liatris, and Echinacea, to name a few. Botanically, genetic variation has been documented within many native herbaceous species. However, plant breeders have done very little with these variations in genotypes, thus allowing considerable opportunity for breeding research with native herbaceous plants.
666 Trends in Floriculture Plant Breeding and the Seed Industry
Authors: Price Grace R.
Published: February 2019

This presentation describes market demands and breeding methodologies that in combination drive development of new floriculture products. In recent years, radical shifts in the direction and pace of product innovation have taken place. New product introductions and development in petunias will be reviewed to demonstrate how breeders approach these new challenges. Parameters of product performance and selection will be discussed as these apply to the midwest, as well as to the rest of the world.
673 Resistance and Resilience of Native Forests to Disturbance by Hurricane Iniki
Authors: Fownes James H. , Harrington Robin A. , Herbert Darrell A.
Published: February 2019

Two studies were established in upland native forest of northwestern Kauai before Hurricane Iniki (Sept. 1992). One study was a gradient study in Acacia koa forest in the leeward rain shadow and the second study was a replicated fertilization experiment in mesic Metrosideros polymorpha forest. Both studies escaped devastation by high-intensity microbursts. Removal of LAI (from 3% to 80%) was proportional to pre-hurricane LAI, suggesting that resistance to damage was higher in low LAI, low-productivity sites. LAI recovered to prehurricane levels within 2 years, except in plots with major limb and stem loss. In the Acacia forest, damage to overstory trees was less than to understory trees, whereas in Metrosideros forest, larger trees were more damaged than smaller trees. During 2 years of recovery, both forests lost LAI in winter storms nearly equivalent to the hurricane damage. Disturbance is more frequent than previously known, which suggests that chronic disturbance needs to be better understood as a force regulating ecosystem structure and function. In both studies, the relative rate of recovery was faster in the more productive but more disturbed plots, suggesting that ecosystem resistance and resilience were traded off. These results have application to land use planning, agroforestry systems management, and other perennial crop management decisions following damage by a tropical cyclone.
676 Overview of Phosphorus Research in Horticultural Crops
Authors: Sistrunk Laurence A.
Published: February 2019

UIsing phosphorus in horticultural crops has been researched for a long time, almost since it was discovered in 1669 by Hennig Brand in Germany. Recent advances in phosphorus application, involving using precision placement of coated fertilizers and by inoculating crops with mycorrhizae, have provided-more efficient uptake and increase in plant yields. By reviewing the key discoveries and current work going on, we can better design our future projects as nutrition scientists. While this approach will not encompass all horticultural crops, results with vegetables and ornamentals should provide concepts for work with other commodities.
677 Phosphorus Soil Transformations and Management for Vegetables
Authors: Sanchez C.A.
Published: February 2019

The amount of phosphorus (P) accumulated by vegetable crops is relatively small compared to nitrogen and potassium. However, large amounts of P fertilizer are often required for optimal yield and quality. Typically P added to soils is quickly converted to unavailable forms resulting in low crop utilization efficiencies. These low P uptake efficiencies have long been of economic concern and a major focus of agronomic and horticultural research. Additionally, in certain regions where crop production areas are hydrologically linked to wetland ecosystems, P fertilization is also of environmental concern. This presentation will summarize important P soil transformations, biotic and abiotic factors influencing the availability of P to crops, and P fertilizer management strategies for improved crop utilization efficiency and reduced environmental impact.
680 Use of Mycorrhiza for Selected Horticultural Crops
Authors: Bloodnick Ed
Published: February 2019

In undisturbed soil environments, certain bacteria and fungi help plants by transforming organic compounds, surpressing diseases, and acquiring nutrients. A strong interest has developed in the identification and culture of beneficial soil microorganisms. Complex groups of fungi, called mycorrhizae, grow in association with roots of many plant species. These fungi show promise as growth and quality enhancers for agriculture crops. However, farmlands that are subjected to excessive chemical fertilizers, pesticides, and soil fumigants contain low levels of indigenous mycorrhizae and other beneficial microorganisms. The re-introduction of endo-mycorrhizae populations has proven to be valuable for improvement of soils and vegetable crop culture. Peat-based substrates are generally used for germination and production of vegetable transplants. In this case, endo-mycorrhizae species (Glomus intraradices) was incorporated into a peat-based growing medium as a means of introducing inoculum to vegetable transplants. Bell pepper (Capsicum annuum) seeds were germinated and grown-on inoculated and non-inoculated growing medium inside of a polyhouse for a period of 8 weeks. Fertilizer applications of 50 ppm of N were given weekly. Seedlings were subsequently outplanted into field soil where incidence of root disease, fertilizer requirements, and pesticide applications were recorded. At fruit maturity, each harvest was evaluated for fruit quality and yield. At the end of the growing season, results indicated an improvement of fruit quality and a yield increase of >16%.
Cutting Apple Fruits Induces Cellulase Activity in the Abscission Zone
Authors: Ward Daniel L. , Beers Eric P. , Byers Ross E. , Marini Richard P.
Published: February 2019

Preharvest abscission of apple [Malus ×domestica (L.) Borkh.] fruits causes significant crop loss in many years. In this study, fruit cutting was used to induce abscission in August and September. Abscission zones of `Redchief Delicious' Mercier strain fruits were sampled 0, 2, 4, and 6 days after cutting. Thin-layer-plate assays were developed and used to identify hydrolytic enzymes active in the abscission zone (AZ) after induction. Increased activity of cellulase, but not polygalacturonase, was detected in the AZ following cutting. Cellulase activity was consistently high in AZs 4 days after cutting. Both AVG (652 mg·L–1) and NAA (10 mg·L–1) applied 2 or 4 days after cutting delayed drop, but NAA delayed drop 1.6 days longer than did AVG. Fruits treated with AVG dropped over a longer period than did control or NAA-treated fruits. Chemical names used: aminoethoxyvinylglycine (AVG); naphthaleneacetic acid (NAA).
Flower Bud Density Affects Vegetative and Fruit Development in Field-grown Southern Highbush Blueberry
Authors: Maust B.E. , Williamson J.G. , Darnell R.L.
Published: February 2019

Floral budbreak and fruit set in many southern highbush blueberry (SHB) cultivars (hybrids of Vaccinium corymbosum L. with other species of Vaccinium) begin prior to vegetative budbreak. Experiments were conducted with two SHB cultivars, `Misty' and `Sharpblue', to test the hypothesis that initial flower bud density (flower buds/m cane length) affects vegetative budbreak and shoot development, which in turn affect fruit development. Flower bud density of field-grown plants was adjusted in two nonconsecutive years by removing none, one-third, or two-thirds of the flower buds during dormancy. Vegetative budbreak, new shoot dry weight, leaf area, and leaf area: fruit ratios decreased with increasing flower bud density in both cultivars. Average fruit fresh weight and fruit soluble solids decreased in both cultivars, and fruit ripening was delayed in `Misty' as leaf area: fruit ratios decreased. This study indicates that because of the inverse relationship between flower bud density and canopy establishment, decreasing the density of flower buds in SHB will increase fruit size and quality and hasten ripening.
Performance of `Valencia' Orange on 21 Rootstocks in Central Florida
Authors: Wutscher H.K. , Bowman K.D.
Published: February 2019

Twenty-one selections consisting of 13 numbered hybrids, one ornamental, and seven named cultivars were tested as rootstocks for `Valencia' orange, Citrus sinensis L. Osbeck. The test included six, four-tree replications in randomized complete blocks on sandy soil typical of the center of the Florida peninsula. Trees propagated on Vangasay lemon, HRS 812 (Sunki × Benecke trifoliate orange), and HRS 942 (Sunki × Flying Dragon trifoliate orange) produced more fruit than trees on the other 18 rootstocks in the test. Trees on 10 rootstocks, including the widely used commercial rootstocks, Swingle citrumelo and Carrizo citrange, were intermediate in cumulative fruit production. Trees on five rootstocks, including Sun Chu Sha, Gou Tou #1, and Tachibana, had low yields and trees on HRS 939 (Flying Dragon trifoliate orange × Nakorn pummelo) and sour orange #2 were extremely dwarfed and were minimally productive because of tristeza virus disease. Fouryear cumulative fruit production ranged from 52 to 317 kg per tree. Fruit from trees on HRS 954 and HRS 952 (Pearl tangelo × Flying Dragon trifoliate orange) had the highest, and fruit from trees on Vangasay and Gou Tou #1 had the lowest total soluble solids concentration.
Nitrogen Fertilization to Maximize Carrot Yield and Quality on a Sandy Soil
Authors: Hochmuth George J. , Brecht Jeffrey K. , Bassett Mark J.
Published: February 2019

Nitrogen is required for successful carrot production on sandy soils of the southeastern United States, yet carrot growers often apply N in amounts exceeding university recommendations. Excessive fertilization is practiced to compensate for losses of N from leaching and because some growers believe that high rates of fertilization improve vegetable quality. Carrots (Daucus carota L.) were grown in three plantings during Winter 1994–95 in Gainesville, Fla., to test the effects of N fertilization on yield and quality. Yield increased with N fertilization but the effect of N rate depended on planting date; 150 kg·ha–1 N maximized yield for November and December plantings but 180 kg·ha–1 N was sufficient for the January planting. Concentration of total alcohol-soluble sugar was maximized at 45 mg·g–1 fresh root with 140 kg·ha–1 N for `Choctaw' carrots, whereas sugar concentration of `Scarlet Nantes' roots was not affected by N fertilization. Carrot root carotenoid concentration was maximized at 55 mg·kg–1 fresh root tissue with 160 kg·ha–1 N. Generally, those N fertilization rates that maximized carrot root yield also maximized carrot quality as determined by sugar and carotenoid concentrations.
Resin-coated Fertilizers Affect Postproduction Growth, but Not Flowering, of Potted Alstroemeria
Authors: Chiari Alessandro , Elliott George C. , Bridgen Mark P.
Published: February 2019

Seven resin-coated fertilizers (RCF) (Osmocote 19–6–12, 18–6–12, 14–14–14, 13–13–13, and 19–6–12, and Polyon 19–6–12, 17–17–17, and 13.5–13.5–13.5) were applied to marketable potted Alstroemeria hybrid FL101 plants to determine their effects on postproduction flowering and growth. The nonfertilized control produced the greatest number of floral stems, total florets, and mean number of florets per stem, but these plants were extremely chlorotic and spindly, and had the lowest fresh weight and number of vegetative stems. In a subsequent experiment, plants were fertilized with low, medium, and high concentrations of either Osmocote 19–6–12 or Sierra HighN 24–4–8. Nonfertilized controls were again chlorotic and spindly, but produced as many florets as fertilized plants. Plants fertilized with Osmocote 19–6–12 had greater fresh weight and more vegetative stems, but fewer total florets than those fertilized with Sierra HighN 24–4–8. We concluded that potted Alstroemeria do not need fertilizer for continued flowering, and fertilization favors production of vegetative stems relative to flowering stems. However, application of RCF to marketable plants prevents chlorosis, increases fresh weight, and, if low to moderate rates of formulations with N–P ratios of at least 6:1 are applied, does not inhibit flowering.
Preplant Lime and Micronutrient Amendments to Pine Bark Affect Growth of Seedlings of Nine Container-grown Tree Species
Authors: Wright Amy N. , Niemiera Alex X. , Harris J. Roger , Wright Robert D.
Published: February 2019

The objective of this study was to determine the effects of lime and micronutrient amendments on growth of seedlings of nine container-grown landscape tree species in two pine bark substrates with different pHs. Acer palmatum Thunb. (Japanese maple), Acer saccharum Marsh. (sugar maple), Cercis canadensis L. (redbud), Cornus florida L. (flowering dogwood), Cornus kousa Hance. (kousa dogwood), Koelreuteria paniculata Laxm. (golden-rain tree), Magnolia ×soulangiana Soul.-Bod. `Lennei' (magnolia), Nyssa sylvatica Marsh. (blackgum), and Quercus palustris Müenchh. (pin oak) were grown from seed in two pine bark substrates with different pHs (pH 4.7 and 5.1) (Expt. 1). Preplant amendment treatments for each of two pine (Pinus taeda L.) bark sources were: with and without dolomitic limestone (3.6 kg·m–3) and with and without micronutrients (0.9 kg·m–3), and with and without micronutrients (0.9 kg·m–3), supplied as Micromax. Seedlings were harvested 12 and 19 weeks after seeds were planted, and shoot dry weight and tree height were determined. The same experiment was repeated using two of the nine species from Expt. 1 and pine bark substrates at pH 5.1 and 5.8 (Expt. 2). Seedling shoot dry weight and height were measured 11 weeks after planting. For both experiments, pine bark solutions were extracted using the pour-through method and analyzed for Ca, Mg, Fe, Mn, Cu, and Zn. Growth of all species in both experiments was greater in micronutrient-amended than in lime-amended bark. In general, adding micronutrients increased nutrient concentrations in the pine bark solution, while adding lime decreased them. Effect of bark type on growth in Expt. 1 was variable; however, in Expt. 2, growth was greater in the low pH bark than in the high pH bark. In general, nutrient concentrations in bark solutions were higher in low pH bark than in high pH bark for both experiments. Under the pH conditions of this experiment, micronutrient additions stimulated growth whereas a lime amendment did not.
Efficient Plant Regeneration from Suspension-cultured Cells of Tall Bearded Iris
Authors: Wang Yuexin , Jeknić Zoran , Ernst Richard C. , Chen Tony H.H.
Published: February 2019

A protocol was developed for efficient plant regeneration of Iris germanica L. `Skating Party' from suspension cultures. Suspension cultures were maintained in Murashige and Skoog (MS) basal medium (pH 5.9) supplemented with 290 mg·L–1 proline, 50 g·L–1 sucrose, 5.0 μm 2,4-D, and 0.5 μm Kin. Suspension-cultured cells were transferred to a shoot induction medium (MS basal medium supplemented with 10 mg·L–1 pantothenic acid, 4.5 mg·L–1 nicotinic acid, 1.9 mg·L–1 thiamine, 250 mg·L–1 casein hydrolysate, 250 mg·L–1 proline, 50 g·L–1 sucrose, 2.0 g·L–1 Phytagel, 0.5 μm NAA, and 12.5 μm Kin). Cell clusters that proliferated on this medium differentiated and developed shoots and plantlets in about 5 weeks. Regeneration apparently occurred via both somatic embryogenesis and shoot organogenesis. A series of experiments was conducted to optimize conditions during suspension culture to maximize subsequent plant regeneration. Parameters included 2,4-D and Kin concentrations, the subculture interval, and the size of cell clusters. The highest regeneration rate was achieved with cell clusters ≤280 μm in diameter, derived from suspension cultures grown for 6 weeks without subculturing in liquid medium containing 5 μm 2,4-D and 0.5 μm Kin. Up to 4000 plantlets with normal vegetative growth and morphology could be generated from 1 g of suspension-cultured cells in about 3–4 months. Chemical names used: 2,4-dichlorophenoxyacetic acid (2,4-D); kinetin (Kin); 1-naphthaleneacetic acid (NAA).
Assisting Natural Wind Pollination of Field Tomatoes with an Air Blower Enhances Yield
Authors: Hanna H.Y.
Published: February 2019

Studies were conducted in 1994, 1995, and 1997 to determine the effect of assisting natural wind pollination using an air blower on yield and fruit characteristics of three tomato (Lycopersicon esculentum Mill.) cultivars. Tomato plants and flowers in the air blower–assisted treatment were vigorously vibrated at midday every other day on sunny days for 4 weeks. Plants and flowers in the control treatment were exposed to ambient wind only. Early yield was significantly greater in the treated plants in 2 years, marketable and total yields for all tested cultivars were significantly greater in all years, and yields of culls were significantly lower in 2 years. Fruit weight and diameter and number of seeds per fruit were increased in all years.
Drought Avoidance in Katsura by Drought-induced Leaf Abscission and Rapid Refoliation
Authors: Dosmann Michael S. , Graves William R. , Iles Jeffery K.
Published: February 2019

The limited use of the katsura tree (Cercidiphyllum japonicum Sieb. & Zucc.) in the landscape may be due to its reputed, but uncharacterized, intolerance of drought. We examined the responses of katsura trees subjected to episodes of drought. Container-grown trees in a greenhouse were subjected to one of three irrigation treatments, each composed of four irrigation phases. Control plants were maintained under well-hydrated conditions in each phase. Plants in the multiple-drought treatment were subjected to two drought phases, each followed by a hydration phase. Plants in the single-drought treatment were exposed to an initial drought phase followed by three hydration phases. Trees avoided drought stress by drought-induced leaf abscission. Plants in the multiple- and single-drought treatments underwent a 63% and 34% reduction in leaf dry weight and a 60% and 31% reduction in leaf surface area, respectively. After leaf abscission, trees in the single-drought treatment recovered 112% of the lost leaf dry weight within 24 days. Leaf abscission and subsequent refoliation resulted in a temporary reduction in the leaf surface area: root dry weight ratio. After relief from drought, net assimilation rate and relative growth rate were maintained at least at the rates associated with plants in the control treatment. We conclude that katsura is a drought avoider that abscises leaves to reduce transpirational water loss. Although plants are capable of refoliation after water becomes available, to maintain the greatest ornamental value in the landscape, siting of katsura should be limited to areas not prone to drought.
Transfer from Long to Short Photoperiods Affects Production Efficiency of Day-neutral Rice
Authors: Goldman K. Rachelle , Mitchell Cary A.
Published: February 2019

The day-neutral, semidwarf rice (Oryza sativa L.) cultivar Ai-Nan-Tsao was grown in a greenhouse under summer conditions using high-pressure sodium lamps to extend the natural photoperiod. After allowing 2 weeks for germination, stand establishment, and thinning to a consistent planting density of 212 plants/m2, stands were maintained under continuous lighting for 35 or 49 days before shifting to 8- or 12-h photoperiods until harvest 76 days after planting. Non-shifted control treatments consisting of 8-, 12-, or 24-h photoperiods also were maintained throughout production. Tiller number increased as duration of exposure to continuous light increased before shifting to shorter photoperiods. However, shoot harvest index and yield efficiency rate were lower for all plants receiving continuous light than for those under the 8- or 12-h photoperiods. Stands receiving 12-h photoperiods throughout production had the highest grain yield per plant and equaled the 8-h-photoperiod control plants for the lowest tiller number per plant. As long as stands were exposed to continuous light, tiller formation continued. Shifting to shorter photoperiods late in the cropping cycle resulted in newly formed tillers that were either sterile or unable to mature grain before harvest. Late-forming tillers also suppressed yield of grain in early-forming tillers, presumably by competing for photosynthate or for remobilized assimilate during senescence. Stands receiving 12-h photoperiods throughout production not only produced the highest grain yield at harvest but had the highest shoot harvest index, which is important for resource-recovery strategies in advanced life-support systems proposed for space.
Taxane and ABA Production in Yew under Different Soil Water Regimes
Authors: Hoffman Angela , Shock Clinton , Feibert Erik
Published: February 2019

Taxol® (paclitaxel), an important anticancer agent, is found in many species of yew. As the need for Taxol increases, sustainable sources must be found for this drug. Plants often respond to stress with increased production of terpenoid compounds such as Taxol and related taxanes or hormones such as abscisic acid (ABA). To determine whether water stress would enhance the production and recovery of Taxol from stem clippings, 100 young Taxu×media `Hicksii' shrubs were grown for sustainable production of Taxol from stem clippings for two seasons in the dry climate of the Malheur Experiment Station in Ontario, Ore. Shrubs were grown under minimal, moderate, or severe water stress, and the relationships between taxane content and 1) soil and plant water potentials, 2) percentage of stomatal closure, and 3) ABA content were examined. Severely water-stressed shrubs produced significantly more taxanes and ABA than did the less stressed shrubs. Chemical names used: Taxol; 10-deacetyl baccatin III; baccatin III; 10-deacetyl taxol, cephalomannine; 7-epi; 10-deacetyl taxol; abscisic acid. Taxol is a registered trademark of Bristol-Myers Squibb.
Take-all Patch Suppression in Creeping Bentgrass with Manganese and Copper
Authors: Hill W.J. , Heckman J.R. , Clarke B.B. , Murphy J.A.
Published: February 2019

Take-all patch, caused by Gaeumannomyces graminis (Sacc.) Arx. & D. Olivier var. avenae (E.M. Turner) Dennis (Gga), is a disease of creeping bentgrass (Agrostis stolonifera Huds.), which most often is associated with golf courses. Synthesis of ligneous and phenolic compounds by plants requires adequate Mn+2 and Cu+2 nutrition and may be a factor in disease resistance. An experiment was conducted on a creeping bentgrass fairway naturally infested with Gga to determine if foliar applications of Mn+2 (1.02 and 2.04 kg·ha–1 per application) and Cu+2 (0.68 kg·ha–1 per application) would reduce take-all severity. Prior to initiating treatments, soil pH was 6.4 and Mehlich-3 extractable Mn+2 and Cu+2 were 5 mg·kg–1 and 1.7 mg·kg–1, respectively. Manganese and copper sulfate treatments were initiated in July 1995 and foliarly applied every 4 weeks through 1997 with the exception of December, January, and February. Disease incidence was decreased from 20% on untreated turf to 5% with the high rate of MnSO4. For both years, turf treated with the high rate of Mn+2 had less disease than turf receiving the low rate of Mn+2. The application of CuSO4, however, did not influence disease development.
Ethephon Increases Carotene Content and Intensifies Root Color of Carrots
Authors: McGiffen Milton E. , Ogbuchiekwe Edmund J.
Published: February 2019

Poor root color is a recurring problem in carrot (Daucus carota L.) production. Consumers prefer dark orange carrots that are high in carotene. However, unfavorable environmental conditions and certain production practices can lead to light orange roots with low carotene content. Growers sometimes refer to this as “white root.” No one has clearly established the causes or cures for this disorder. Several environmental factors are known to affect the color of carrots, but to date there is no practical treatment. High-density planting often reduces carotene content. Field studies were conducted in the 1995-96 and 1996-97 winter growing seasons to determine if foliar applications of ethephon would improve carrot color, carotene content, and yield. Carotene content and root color increased as the number of applications or the amount of ethephon applied with each application increased. Root weight was not significantly affected.
Effect of Bee Pollination and GA3 on Fruit Size and Maturity of Three Rabbiteye Blueberry Cultivars with Similar Fruit Densities
Authors: NeSmith D. Scott , Krewer Gerard
Published: February 2019

Plants of the rabbiteye blueberry (Vaccinium ashei Reade) cultivars Brightwell, Climax, and Tifblue were subjected to pollination with bees or to applications of 250 mg·L-1 of gibberellic acid (GA3) to examine the influence on fruit size and maturation period. Plants were thinned to a similar fruit density (FD) 4 weeks after anthesis. `Tifblue' and `Climax' fruit were smaller on GA3-treated than on bee-pollinated plants, but no difference was observed for `Brightwell'. The fruit maturation period for `Climax' was not affected by treatments, but `Brightwell' and `Tifblue' fruit on pollinated plants ripened 2 weeks earlier than fruit on GA3-treated plants. These data suggest that excess fruit load is not the primary factor responsible for the smaller fruit size and lengthened fruit development period resulting from GA3 applications to rabbiteye blueberries.
Irradiation, Stage of Maturity at Harvest, and Storage Temperature during Ripening Affect Papaya Fruit Quality
Authors: Miller W.R. , McDonald R.E.
Published: February 2019

Solo-type papaya (Carica papaya L.) fruit at the mature green (MG) or one-quarter yellow (QY) stage of maturity were imported through the Port of Miami, Fla., and either irradiated (0.675 kGy) or not irradiated. Fruit condition and quality attributes were determined after ripening to the edible ripe stage at 25 °C before and after storage for 7 days at 10, 12, or 15 °C. The incidence and severity of peel scald was increased by irradiation regardless of storage and ripening regime; however, the degree of severity was dependent on fruit maturity at irradiation. Irradiated QY fruit tended to have the most serious incidence and severity of scald. Mature green fruit ripened at 25 °C without storage had the lowest incidence of fruit with hard areas in the pulp (“lumpy” fruit). The QY fruit generally were second only to irradiated MG fruit stored at 10 °C in incidence of lumpiness. Anthracnose sp. decay and stem-end-rots affected 53% of all fruit. The least decay occurred on fruit ripened at 25 °C without storage, regardless of fruit maturity, and the most decay occurred on QY fruit with or without irradiation. Fruit ripened at 25 °C without storage had more palatable pulp (5.5 N) at the edible ripe stage than did fruit held in storage and then ripened. The effect of fruit maturity or irradiation dose on fruit firmness, however, was dependent on the storage temperature. Mature green fruit ripened at 25 °C lost less weight than did those stored at cold temperatures prior to ripening. We recommend that importers obtain fruit with only a slight break in ground color, and distribute them as rapidly as possible, while maintaining transit/storage temperatures at or above 15 °C with or without exposure to irradiation.
Susceptibility to Chilling Injury of Peach, Nectarine, and Plum Cultivars Grown in California
Authors: Crisosto Carlos H. , Mitchell F. Gordon , Ju Zhiguo
Published: February 2019

The susceptibility to chilling injury (CI) or internal breakdown (IB) was evaluated in the most currently planted yellow- and white-flesh peach [Prunus persica (L.) Batsch] and nectarine [Prunus persica var. nectarine (L.) Batsch] and plum [Prunus salicina Lindel] cultivars from different breeding sources and fruit types. Cultivars were segregated into three categories (Cat. A, B, and C) according to their susceptibility to CI or IB symptoms (mealiness and flesh browning) when exposed to 0 °C or 5 °C storage temperatures. Cultivars in Cat. A did not develop any symptoms of CI after 5 weeks of storage at either temperature. Cultivars in Cat. B developed symptoms only when stored at 5 °C within 5 weeks of storage. Cultivars were classified in Cat. C when fruit developed CI symptoms at both storage temperatures within 5 weeks of storage. Most of the yellow- and white-flesh peach cultivars developed IB symptoms when stored at both storage temperatures (Cat. C). Most of the new nectarine cultivar introductions did not develop CI symptoms when stored at 0 °C or 5 °C after 5 weeks (Cat. A). Three out of six plum cultivars tested had CI symptoms within 5 weeks storage at 0 °C. However, all of the plum cultivars tested developed CI symptoms when stored at 5 °C (Cat. B). The importance of proper temperature management during postharvest handling was demonstrated.
Small Divisions of Ornamental Grasses Produce the Best Growth Following Direct Potting
Authors: Brand Mark H.
Published: February 2019

Potting of bare-root spring divisions is a simplified approach to ornamental grass production. Large and small divisions of eight common ornamental grasses were directly potted into 7-L nursery containers and grown outdoors for 20 weeks to determine an appropriate division size for each grass. Response to division size was dependent on the grass species. Large divisions of Calamagrostis ×cutiflora `Karl Foerster' (Schräd.) produced twice as many inflorescences as small divisions. At harvest, large divisions of Miscanthus oligostachyus `Purpurascens' (Stapf.) had twice as many inflorescences and 1.5 times as many tillers as small divisions. However, new tiller production in large divisions was only 50% of that in small division plants. Large divisions of Miscanthus sinensis (Anderss.) cultivars produced more tillers and greater fresh and dry weights than did small divisions, but again, the differences were not proportional to the size difference between the initial divisions. Large divisions of Panicum virgatum (L.) produced 50 more tillers per plant than did small divisions, but plant weight, size, and number of inflorescences were not affected by division size. Plants from large divisions of Pennisetum alopecuroides (L.) Spreng. were 7 cm shorter than small divisions and produced 24% more inflorescences and 27% more tillers, but appeared nutrient and/or water stressed. For most grasses, smaller division size is recommended for direct spring potting.
Fruit Temperature and Maturity Affect Development of Blossom End Clearing in Grapefruit
Authors: Echeverria E. , Burns J.K. , Miller W.M.
Published: February 2019

The effect of fruit temperature and fruit maturity on the development of blossom end clearing (BEC) in Florida grapefruit (Citrus paradisi Macf. vars. Ruby Red and Marsh) was investigated. Field and storage temperature studies indicated that development of BEC was directly associated with temperature; BEC increased when fruit temperature rose above 21 °C. Cooling fruit prior to packingline operations reduced BEC significantly. Older fruit were more susceptible to BEC than were younger fruit.
Application of Random Amplified Polymorphic DNA Markers for Identification of Marula Genotypes
Authors: Gutman Feiga , Nerd Avinoam , Mizrahi Yosef , Bar-Zvi Dudy , Raveh Dina
Published: February 2019

Twenty-four genotypes of marula (Sclerocarya birrea subsp. caffra) were characterized using randomly amplified polymorphic DNA (RAPD) analysis. A distinct band pattern was obtained for each of the trees, using as few as four arbitrary 10-mer primers. Trees propagated vegetatively by grafting showed identical fingerprints. These results suggest that RAPD markers provide a useful system for documenting the identity of marula genotypes.
Resistance to Cucurbit Yellowing Stunting Disorder Virus (CYSDV) in Cucumis melo L.
Authors: López-Sesé A.I. , Gómez-Guillamón M.L.
Published: February 2019

Forty-four accessions of Cucumis melo L. and related wild species were tested for reaction to a yellowing disease, incited by the recently identified cucurbit yellowing stunting disorder virus (CYSDV), under natural and controlled-inoculation conditions. The C. melo TGR-1551 accession and one Cucumis metuliferus Naud. accession were asymptomatic. The segregation ratios obtained following controlled inoculations of the family produced by crossing TGR-1551 with the susceptible Spanish cv. Piel de Sapo revealed that the resistance to CYSDV in TGR-1551 is conditioned by a dominant allele at one locus. The name Cucurbit yellow stunting and symbol Cys is proposed for this locus.
Self-incompatibility Alleles of Apple Cultivars and Advanced Selections
Authors: Sakurai Kenji , Brown Susan K. , Weeden Norman
Published: February 2019

The S-alleles of 55 apple (Malus ×domestica Borkh.) cultivars and selections were determined using an allele-specific polymerase chain reaction (PCR) amplification system for 11 different S-alleles (S2, S3, S4, S5, S7, S9, S24, S26, S27, Sd, Sf). Four cultivars had S-alleles different than those predicted by their parentage. Three commercial cultivars of unknown pedigrees had S-genotypes that suggested `Delicious' and `Golden Delicious' were the parents. S-genotyping results supported controlled pollination test results. The genotypes of the five triploid cultivars examined were consistent with the unreduced gamete being contributed by the female parent. Although a large number of S-genotypes is available in apple, artificial selection or repeated use of the same cultivars as parents appears to have significantly restricted the number of compatibility groups associated with commercial clones. In controlled reciprocal crosses between two cultivars of known S-genotypes, the segregation of S-genotypes and S-alleles was 1:1:1:1, the ratio expected for random pairing of alleles.
Seed Germination of Selected Provenances of Atlantic White-Cedar as Influenced by Stratification, Temperature, and Light
Authors: Jull Laura G. , Blazich Frank A.
Published: February 2019

Seeds of six provenances (Escambia Co., Ala.; Santa Rosa Co., Fla.; Wayne Co., N.C.; Burlington Co., N.J.; New London Co., Conn.; and Barnstable Co., Mass.) of Atlantic white-cedar [Chamaecyparis thyoides (L.) B.S.P.] were stratified (moist-prechilled) for 0, 30, 60, or 90 days at 4 °C. Following stratification, seeds were germinated at 25 °C or an 8/16-hour thermoperiod of 30/20 °C with daily photoperiods at each temperature of 0 (total darkness), 1, or 24 hours. The germination of nonstratified seed did not exceed 18%. Seeds germinated at 25 °C required 60 to 90 days stratification to maximize germination. In contrast, 30 days stratification maximized germination at 30/20 °C. Regardless of stratification duration, germination was generally lower at 25 °C than at 30/20 °C for each provenance. Averaged over all treatments, seeds of the Alabama provenance exhibited the greatest germination (61%), followed by those from Florida (45%), with the remaining provenances ranging from 20% to 38%. However, specific treatments for each provenance induced germination >50%. Germination of seeds not exposed to light was <8%, in contrast with 48% and 55% germination for daily photoperiods of 1 and 24 hours, respectively. Seeds from each of the provenances, except for Alabama, exhibited an obligate light requirement when germinated at 25 °C. At 30/20 °C, the North Carolina, New Jersey, Connecticut, and Massachusetts provenances required light for germination, whereas the Alabama and Florida provenances did not.
The Potential Use of Photoperiod during Transplant Production under Artificial Lighting Conditions on Floral Development and Bolting, Using Spinach as a Model
Authors: Kim Hyeon-Hye , Chun Changhoo , Kozai Toyoki , Fuse Junya
Published: February 2019

Spinach (Spinacia oleracea L.) was chosen to demonstrate that the respective vegetative or reproductive conditions of transplants can be controlled in their early stages of development under artificial light in a closed system. Transplant production under artificial light was divided into three growth phases and the photoperiod during each of these phases was varied. The rate of floral development was controlled by photoperiod, but floral initiation itself was not affected. Short photoperiod treatments (8 or 12 hours/day) retarded floral development and stem elongation (bolting). This delay continued even after the transplants were transferred to natural long-day (15.5 hours/day on average) conditions with high temperatures (17 and 37 °C minimum and maximum). We concluded that by using short photoperiods during transplant production, marketable plants with reduced bolting could be produced under natural long-day conditions. In Japan, spinach with this rosetting capacity would be of greater value. Further, this concept opens the possibility of producing better quality transplants of several species under artificial lighting conditions of appropriate length, and thereby controlling their floral development and/or bolting.