bluuebunny/crossref_metadata_2025 huggingface dataset:
Calcium Sulfate Soil Amendment Reduces Incidence of Phytophthora Root Rot in Raspberry
Authors: Maloney K.E. , Pritts M.P. , Wilcox W.F.
Published: February 2019

Phytophthora is a debilitating root disease of many crops, and limits raspberry production in much of the world. Two fungicides are labeled for use against Phytophthora on raspberries in North America, but they are not effective when disease pressure is severe. We were interested in the effect of preplant soil amendments such as composts, fertilizers, gypsum and limestone on the incidence of Phytophthora in red raspberries. Various amendments were incorporated simultaneously at two sites prior to planting raspberries. Both sites had identical soil, but one had a known history of P. fragariae var. rubi and the other had no history of raspberry production. Differences in survival and plant growth of `Heritage' among fertilizer (ammonium nitrate, phosphorus acid), compost, gypsum and lime (calcitic or dolomitic) treatments were small in the uninfested site, whereas differences were large in the infested site. Gypsum (CaSO4) treated plots had higher yields and greater cane diameter, density, and height compared to control plots after 2 years. Plants in compost amended plots exhibited the most severe disease symptoms; liming had little effect. In a second field experiment, various sources of calcium and sulfate were compared in an infested site. As before, plants in calcium sulfate-amended plots performed better than plants in control plots or in plots amended with sulfur or potassium sulfate. In a greenhouse experiment using infested soil and artificial flooding, calcium sulfate also reduced disease incidence in `Titan' compared to unamended soil. Data from these three experiments suggest that gypsum could be used in an integrated approach to Phytophthora management in raspberries, and perhaps other crops as well.
Mapping Cold Tolerance QIL in Citrus grandis (L.) Osb. × Poncirustrifoliata (L.) Raf. Hybrids: A Three-pronged Approach
Authors: Weber Courtney , Sherman Wayne , Moore Gloria
Published: February 2019

A pseudo-testcross population of Citrus grandis selection DPI6-4 × Poncirus trifoliata cv. Rubideaux, cold-sensitive and cold-tolerant parents, respectively, is being used to map quantitative trait loci (QTL) for cold tolerance using bulked segregant analysis (BSA), selective genotyping, and interval mapping. A population of 500 young trees was frozen under controlled conditions to –9 and –15 °C to select contrasting bulk segregant populations from the distributional extremes of cold tolerance. A randomly selected subset of 61 individuals from this population was used to construct a linkage map for interval mapping. The pseudo-testcross population allows mapping of both the C. grandis and P. trifoliata genomes through the identification of parental origin of marker alleles. Screening of random 10-mer primers is ongoing and, to date, ≈100 primers have produced eight markers showing differences in mean stem dieback between the bulked populations. MAPMAKER-QTL was used to analyze all markers (122 presently) on the linkage maps for correlation to QTL for cold tolerance or susceptibility, and two regions of interest have been identified. Also, markers linked to those identified through BSA are being analyzed for association with QTL through selective genotyping. The goal of this research is to identify genomic regions and associated markers relating to QTL for cold tolerance for future use in Citrus cultivar improvement.
Disease Resistance and Yields of Transgenic and Traditional Summer Squash
Authors: Rowell Brent , Nesmith William , Snyder John C.
Published: February 2019

Kentucky vegetable growers exploiting a fall-harvested market window for summer squash (Cucurbita pepo L.) usually encounter severe virus and fungal disease pressure resulting in serious yield and quality reductions. Twenty-five summer squash varieties or advanced breeding lines (9 zucchini, 8 yellow straightneck, and 8 crookneck entries) were evaluated in a late summer planting for yield, quality, and disease resistance at the Univ. of Kentucky South Farm in Lexington. Both genetically engineered virus-resistant materials and new resistant/tolerant varieties from traditional breeding programs were compared with our recommended hybrids. Border rows of a virus-susceptible variety were planted alongside and between each of the four blocks to enhance virus spread throughout the trial. Virus incidence was determined visually before and after final harvest and leaf samples were collected for virus assays. Virus symptoms were absent or difficult to see on zucchini squash plants during most of the trial but became obvious near the final harvest date. Varieties from traditional breeding programs having virus tolerance were among the highest yielding zucchini types. Traditionally-bred cultivars with the precocious yellow gene and two transgenic lines were in the highest yielding group of yellow straightneck squash—in spite of high virus incidences in precocious yellow cultivars. Transgenic cultivars were clearly superior in terms of yields among yellow crooknecks with yields nearly double those of the lowest yielding traditional hybrids. Cultivars and breeding lines varied considerably in color, shape, overall appearance, and potential marketability.
Taste and Quality of Burpless and Bitterfree Cucumbers
Authors: Wehner Todd C.
Published: February 2019

Burpless cucumbers (Cucumis sativus L.) are listed in many seed catalogs as being milder for eating than the standard American slicing type. It has been suggested that burpless cucumbers 1) are genetically bitterfree, 2) cause less burping when eaten, or 3) are the marketing term for Oriental trellis cucumbers. The objective of this experiment was to determine whether burpless cucumbers are bitterfree, and whether they cause less burping when eaten. Bitterness of the plants was determined by tasting a cotyledon of six seedlings per cultivar. Burpiness of the fruits was determined in the field using two seasons (spring and summer) and two replications. Six judges evaluated three cultivars over two harvests by eating one half of a fruit of the three cultivars on three consecutive days (in random order). Burpiness was rated 0 to 9 (0 = none, 1–3 = slight, 4–6 = moderate, 7–9 = severe). `Marketmore 76' and `Tasty Bright' were normal-bitter, and `Marketmore 80' was bitterfree. Burpiness ratings were not significantly different for `Marketmore 76' (3.0), `Marketmore 80' (2.6), and `Tasty Bright' (2.5). Burpless cucumbers appear to be the American marketing term for Oriental trellis cucumbers.
Cauliflower Microshoots—A Potential Alternative to F1 Hybrid Seed?
Authors: Fuller M.P. , Kieffer M.L. , Jellings A.J.
Published: February 2019

Cauliflower is produced all year round in the United Kingdom, with winter production confined to relatively frost-free areas such as Cornwall in the southwest peninsula. Most production zones now take advantage of F1 hybrid varieties although winter production a complete suite of varieties is not yet available and growers must rely on open-pollinated varieties bred locally, which, although being variable, do have locally adapted resistance to prevalent wet weather diseases such as a Mycosphaerella brassicae (ringspot). Micropropagation of cauliflower is well-established and is used routinely by many breeding companies of both F1 and OP varieties for multiplying clones of parental lines. It is clear however, that the true micropropagation potential of cauliflower has never been realized since the curd has been estimated to bear up to 5 million meristems (Kieffer et al., 1997), yet yields of shoots per head are typically 10 to 100 plants. A new micropropagation schedule for cauliflower has recently been described (Kieffer et al, 1996; Kieffer et al., in press), and it is clear that this schedule does offer a new technology for production of many thousands of plants from a single curd. This paper will explore the potential of the technique as an alternative to F1 hybrid seed for growers particularly focusing on the limiting processes in the schedule and its cost-effectiveness.
Hormone Sprays and Supplemental Light Prevent Cold-storage-induced Postharvest Leaf Chlorosis and Abscission in `Stargazer' Hybrid Lilies
Authors: Ranwala Anil P. , Miller William B.
Published: February 2019

Rapid leaf chlorosis and abscission limits the use of cold storage for post-production short-term holding of potted lilies. We investigated the effects of storage temperature, storage irradiance and pre-storage foliar sprays of gibberellin and/or cytokinin on postharvest leaf and flower quality of Lilium sp. `Stargazer' hybrid lilies. Storage of “puffy bud” stage plants at 4, 7, or 10 °C in dark for 2 weeks induced leaf chlorosis within 4 days in a simulated consumer environment, and resulted in 60% leaf chlorosis and 40% leaf abscission by 20 days. Cold-storage also reduced the duration of flower bud opening, inflorescence and flower longevity, and increased flower bud abortion. Providing light up to 40 μmol·m–2·s–1 during cold-storage at 4 °C significantly delayed leaf chlorosis and abscission and increased the duration of flower bud opening, inflorescence and flower longevity. Foliar sprays of ProVide (100 mg·L–1 GA4+7) and Promalin [100 mg·L–1 GA4+7 and 100 mg·L–1 benzyladenine (BA)] effectively prevented leaf chlorosis and abscission at 4 °C, while ProGibb (100 mg·L–1 GA3) and ABG-3062 (100 mg·L–1BA) were not effective. Accel (10 mg·L–1 GA4+7 and 100 mg·L–1 BA) showed intermediate effects on leaf chlorosis. Flower longevity was increased and bud abortion was prevented by all hormone formulations except ProGibb. The combination of light (40 μmol·m–2·s–1) and Promalin (100 mg·L–1 GA4+7 and 100 mg·L–1 BA) completely prevented cold-storage induced leaf chlorosis and abscission and significantly improved flower opening and overall plant quality.
Control of Weeds, Insects, and Diseases on Cranberry with a Spring Flood
Authors: DeMoranville Carolyn , Averill Anne , Caruso Frank , Sandler Hilary , Else Mary Jane
Published: February 2019

An intensive study of the use of spring flooding to control pests and reduce chemical inputs in cranberry production began in 1995, following preliminary studies in 1993 and 1994. This 4-week flood, known as late water (LW), has been shown to suppress some insects, mites, and fungi, and to stimulate plant growth. We demonstrated that pesticide use could be reduced or eliminated in the year of the flood and to a lesser extent in the year following the flood. With the use of LW in from 1993 to 1996, cranberry grower participants in our study reduced insecticide sprays by 24% and reduced fungicide applications by 30% compared to standard practice bogs without effect on crop quality. LW increased mortality of Rubus sp. weeds so that their spread in a cranberry bed was checked. However, the weed population did not decrease over time. Effects of the flood on cranberry growth and productivity were examined. With changes in rate and timing of fertilizer inputs, growth was similar to that on control beds. However, following an abnormally mild winter and drought conditions in 1995, crops on LW bogs were reduced, sometimes severely, compared to the controls. Crop was not affected in 1993, 1994, or 1996. On a LW bog, it is possible to reduce insecticide use by up to 60%, fungicide use by up to 50%, and nitrogen use by 30%. Reductions and outcomes vary depending on seasonal conditions but, with careful management and weather monitoring, this practice remains a strong option for a sustainable cranberry production system.
Photosynthesis and Growth of Magnolia × soulangiana in Response to Consecutive Drought Stress
Authors: Fernandez R.T. , Schutzki R.E.
Published: February 2019

Responses of Magnolia × soulangiana `Jane' to consecutive short-term drought stresses were evaluated in this study. Plants were received from a commercial nursery in 19-L containers in a 4:1 pine bark:sand media. In Oct. 1997, plants were exposed to one, two or three consecutive 3-day drought stress periods, each separated by one rewatering period. There were 48 total plants with eight replicates per treatment for each stress period. Following each stress period, a group of eight control and eight stressed plants were planted in the field and well-watered to monitor recovery from each stress duration. Whole-plant photosynthesis, leaf photosynthesis, shoot growth, and soil moisture content were measured approximately every 2 days during the stress periods. Leaf photosynthesis, shoot growth, and leaf defoliation rate were monitored for recovering plants. Few differences in growth were noticed except more rapid defoliation with onset of autumn for the three 3-day stressed plants. Whole-plant and leaf photosynthesis were reduced by day 3 of the first 3-day stress for drought-stressed plants and remained lower while plants were under stress. After release from stress, photosynthesis returned to control levels for plants receiving one and two 3-day stress treatments in ≈1 week, while it was more than 3 weeks until recovery for plants receiving three 3-day stress treatments. Plants will be evaluated in Spring 1998 for bloom and growth characteristics.
Low-temperature Storage of Micropropagated Broccoli Plantlets under Varying Light Quality
Authors: Wilson Sandra B. , Rajapakse Nihal C. , Young Roy E.
Published: February 2019

Micropropagation is often associated with mass production at a competitive price. Since labor accounts for a large portion of micropropagation costs, alternative measures to distribute labor costs are necessary. One such method of distributing labor costs is the use of storage systems to hold micropropagated plantlets until market availability. Broccoli (Brassica oleracea L. `Green Duke') plantlets were cultured photoautotrophically (without sugar) or photomixotrophically (with sugar) on cellulose plugs in liquid media in vitro for 3 weeks at 23 °C and 150 μmol·m–2·s–1 photosynthetic photon flux (PPF). To determine the conditions that yield a zero carbon balance, plantlets were subsequently stored for 3 d under different temperatures (1, 5, 10, 15 °C), different light intensities (1.6, 4.1, 8.6 PPF), and different light spectra (provided by white or blue fluorescent bulbs or red Light Emitting Diodes). Plantlets under 3 PPF and 1 °C maintained a zero carbon balance. Subsequently, plantlets were stored for 4, 8, or 12 weeks at 1 °C under darkness or 3 PPF of white, red, or blue light. Prior to low temperature storage, photomixotrophic plantlets were characterized by increased chlorophyll, dry mass, total soluble sugars (TSS), leaf starch, and net photosynthetic rate (NPR). Illumination during storage was necessary to maintain dry mass, TSS, NPR, and regrowth potential of photoautotrophic plantlets. When sucrose was provided to the media, dark stored plantlets survived up to 12 weeks of storage. During storage, the quality of broccoli plantlets was best maintained under red light. Red light increased chlorophyll, TSS, and dry matter accumulation into leaves during storage. In addition, photoautotrophic plantlets stored for 8 or 12 weeks under red light had higher survival rates once acclimatized to the greenhouse when compared to photoautotrophic plantlets stored in darkness or under white or blue light.
Genetic Similarity Among Broccoli Inbreds “Essentially Derived” from Commercial Cultivars
Authors: Farnham Mark W. , Lu Jiang , Villand Julie M.
Published: February 2019

DNA markers can assess close genetic relationships between individuals of a crop as when one variety is developed (i.e., “essentially derived”) from another. An acceptable threshold, based on empirical results, should be established for a crop to indicate what constitutes an “essentially derived” variety in the absence of clear pedigree information. Empirical data could help settle infringements of intellectual property rights, but appropriate data are not being generated for most crops. Thus, our objectives were to characterize genetic relationships among broccoli varieties “essentially derived” from known parents using random amplified polymorphic DNA (RAPD) markers as a measure of genotype and to provide an empirical basis for threshold levels in this crop. Six F1 broccoli hybrids and three inbred lines (doubled-haploids) developed from each of the hybrids (24 entries) were evaluated by RAPD analysis. RAPD assays were conducted using 23 different oligonucleotide 10-mers. Of 179 RAPD bands scored, 94 were polymorphic among the entries. Similarity indices were computed from RAPD data, and a multi-dimensional scaling (MDS) plot was constructed. Similarity indices for all pairwise comparisons ranged from 0.40 to 0.90. `High Sierra' and it's derived lines were the most closely related group with indices from 0.81 to 0.90. With `High Sierra', `Sultan', and `Marathon', the three derived lines were more closely related to their respective parental hybrids than were any other entries. The hybrids `Futura', `Everest', and `Viking' were more genetically similar to other entries than to their derived lines. A threshold level based on data from `High Sierra', `Marathon', `Sultan', and their derived lines would not identify “essentially derived” lines developed from other hybrids.
Influence of Nitrogen Fertilization on Pecan Nut Quality and Yield
Authors: Sistrunk Laurence , Storey J. Benton
Published: February 2019

The influence of various nitrogen fertilization rates on the marketable yield and nut quality of 12-year-old grafted `Desirable', `Pawnee', and `Stuart' pecans in east Texas was investigated. Pecans are alternate-bearing, and this test was conducted during a high-yielding season. Terminal shoot growth and change in trunk diameter was measured to determine tree response to nitrogen rates. A standard rate of 44 kg N/ha was applied in March, April, and May to the control trees as NH4NO3. A second treatment used 112 kg N/ha in March and the standard rates the next two applications. A third treatment used 112 kg N/ha in March and April and the standard rate in May. The fourth treatment used 112 kg N/ha in all three applications. The treatments were arranged in a randomized block design. Nut yields were generally higher with the increase in nitrogen for all cultivars with the exception of `Stuart', which showed the least change. Highest yield, terminal and trunk diameter growth, and nut quality was obtained with the 336 kg N/ha rate. Some differences in percent kernel, marketable yield and nut size were measured with the three cultivars. Our data indicates that during a high-yielding crop load on young trees, nitrogen fertilization can make a significant difference in yield.
Effect of pH and NH4NO3 as a Spray Additive on Penetration of NAA Through Isolated Tomato Fruit Cuticle
Authors: Fader Royal G. , Bukovac Martin J.
Published: February 2019

We have reported that NH4NO3 (AN, 8 mM, pH 4.2), applied as simulated spray droplets, enhanced penetration of 14C-NAA through isolated leaf and fruit cuticles. One explanation for this response is that AN depresses NAA (pKa= 4.2) dissociation, increasing the nondissociated moiety, which penetrates more readily than the anion (NAA'). Direct measurement of AN (concn. 0-800 mM) effect on NAA (215 μM) dissociation as indexed by change in solution pH revealed no significant effect, with a pH change from 4.19 to 4.05. This change is not sufficient to account for the observed enhancement. When 14C-NAA, buffered (20 mM sodium citrate) at pH 3.2, 4.2, 5.2, 6.2, was partitioned against chloroform, there was a marked increase in NAA partitioning into chloroform as pH was decreased. AN (8 mM) did not alter this partition behavior, also indicating no effect on NAA dissociation. However, in cuticle penetration studies, using a finite dose system with 14C-NAA buffered at pH 3.2, 4.2, 5.2, 6.2, and in the presence and absence of 8 mM AN, there was no marked or consistent pH or AN (-70 to + 232 % of no AN control) effect on penetration as indexed by initial slope (4-12 h) or penetration after 120 h. The possible effects of AN and buffer on penetration of 14C-NAA from the droplet deposit will be discussed.
HACCP Principals and Product Operations: What is the Future?
Authors: Howard Luke
Published: February 2019

Food safety has become a major issue for producers and processors of fresh fruit and vegetable products. Although the safety of fresh and pre-cut fruit and vegetables is outstanding, several recent food-borne outbreaks have increased the public's awareness of microbiological hazards associated with these products. Hazard Analysis Critical Control Point (HACCP) programs are well-established for many food systems. HACCP is a systematic approach to the identification, assessment, and control of hazards associated with the environment in which foods are produced and handled. Fresh and pre-cut produce are ready-to-eat products that do not receive a preservation (heating) treatment like traditional canning or freezing methods. Since there is no microbiological kill step associated with these products, hazards cannot be eliminated. Therefore, it is critical that efforts be focused on minimizing the incidence of food-borne pathogens on fruits and vegetables through the use of good agricultural practices during growing, postharvest handling, storage, and minimal processing. Several sanitation hurdles can be combined in a synergistic effort to control food-borne pathogens. In addition to chlorination, researchers have investigated alternative treatments for sanitation such as ozone, hydrogen peroxide, trisodium phosphate, edible coatings containing antimicrobial agents, irradiation, pulsed light and bacteriocins. Selection of proper oxygen permeable packaging material is also important to prevent anaerobic conditions that may result in growth and toxin production by Clostridium botulinum. However, caution is advised when evaluating new sanitation and packaging materials for fresh produce, because the elimination of spoilage microorganisms may result in conditions that favor the growth of surviving pathogens.
A Mandatory Internship Program at a Land-grant University: The Case of Oklahoma State University
Authors: Kahn Brian A.
Published: February 2019

Internships provide well-documented advantages to students, colleges, and employers. The core requirements in Horticulture and in Turf Management at Oklahoma State Univ. were expanded to include 3 h of credit in an internship course, effective with the 1991–92 option sheets. All of our departmental teaching faculty advise undergraduate students, and each individual professor supervises the internship experiences of his/her advisees. Coordination is provided by a common syllabus booklet and by leadership from a faculty Undergraduate Horticulture Teaching Coordinator and the Department Head. Outcomes are assessed through student reports, cooperator evaluations, and a formal internship assessment seminar. The mandatory internship has added value to our degrees. Our students graduate with documented work experience in addition to their academic credentials. When our graduates are employed, they tend to more readily adapt to their jobs because they already have been exposed to some of the “real-world” aspects of their profession. This is especially true when an internship experience results in permanent employment with the same firm upon graduation.
The Regulation of N Uptake at the Whole-plant Level in Tree Crops
Authors: Youssefi Farbod , Brown Patrick H. , Weinbaum Steve A.
Published: February 2019

Coordinating fertilization practices with tree N uptake is important for reduction of groundwater contamination with nitrate. To reach this goal, the regulation of nitrogen uptake at the whole-plant level must be further understood. A theory that has been proposed on this subject is that a pool of amino-N, whose size is determined by above-ground N demand, cycles in the plant and regulates soil N uptake by exerting an inhibitory effect at the root level. Several experiments were carried out to study this hypothesis in fruit trees. First, foliar applications of N were made in almond trees, which led to the observation that soil N uptake was reduced in treated trees. In these trees, foliar-applied N was present in the roots when uptake was reduced; further, amino-N content of leaf and bark phloem sap was increased after several hours in the treated tree. In another experiment, amino-N content of phloem and xylem sap of almond trees of varying N status was determined. Several trees under each N status were given a pulse of abundant N fertilizer, so that their N uptake would be compared. Trees of higher N status, with greater amounts of amino-N cycling in their sap, did not take up more N than equivalent control plants, whereas lower N status trees did. To complete this series of experiments, it was observed that fruit-bearing shoots in walnut trees exported smaller proportions of foliar-applied N than non-bearing shoots, indicating that above-ground N demand may regulate the pool of N that moves down in the plant. These results and the principles that regulate N uptake will be discussed.
Relationships of Resveratrol, Anthocyanin, and Soluble Solids to Maturity in Vitis lambrusca
Authors: Jaubert Catherine
Published: February 2019

Resveratrol in Vitis vinifera cultivars has been shown to be important in resistance to infection of Botrytis cinerea (gray mold). Also, resveratrol is a constituent of wine that has been shown to confer protection against artherosclerosis, heart disease, and cancer. The relationship between grape maturity and resveratrol concentration levels, soluble solids, and anthocyanins were examined on V. lambrusca cultivars. `Concord' and `Catawba' grapes were harvested weekly from August to maturity from a production site in Lexington, Ky. Irradiation and non-irradiation of berries was performed in the laboratory and resveratrol concentration was analyzed. Berry skins were extracted with methanol/water (8:1 v/v) in 10 ml/g of fresh weight tissue. Resveratrol was quantified using reverse-phase HPLC. Soluble solids were measured weekly by refractometer, and anthocyanin content was determined by spectrophotometer. Results showed a marked increase in resveratrol concentration as grapes matured, and followed by a subsequent decrease at final harvest. Sugar content increased weekly in each cultivar, and was maximal at final harvest.
Differential Effects of Shade on Early-season Fruit and Shoot Growth Rates in `Empire' Apple
Authors: Bepete M. , Lakso A.N.
Published: February 2019

To determine relative dry-matter partitioning to early-season growth of extension shoots vs. fruits under competitive conditions in the shade, heavily cropping branch sections of `Empire' apple (Malus ×domestica Borkh.) were girdled and shaded to 15%, 40%, and 60% of available light for 9 days, while control branches were girdled and fully exposed. Treatments were applied at both 17 and 27 days after bloom, when fruit diameters averaged 13 and 23 mm, and the number of unfolded leaves on extension shoots averaged 13 and 19, respectively. Fruit diameters, extension shoot lengths, and numbers of unfolded leaves were monitored on the treated branches. Shoot growth was not affected by shading at either growth stage. Fruit growth rate was similar at 100% and 60% available light, but declined 25% at 40% available light and 50% at 15% available light. These results indicate that shoot growth has priority over fruit growth for partitioning in light-limiting conditions early in the season.
Changes in the Ultrastructure of the Epicuticular Wax and Postharvest Calcium Uptake in Apples
Authors: Roy Stephane , Conway William S. , Watada Alley E. , Sams Carl E. , Erbe Eric F. , Wergin William P.
Published: February 2019

Structural changes in the cuticle could be partially responsible for the differences in uptake of infiltrated Ca in apple fruit. We examined the relationship between the surface structure of epicuticular wax of `Golden Delicious' apple and Ca uptake by the fruit. Apples were nontreated or pressure infiltrated with distilled water, or with 0.14 or 0.27 mol·L-1 CaCl2 solutions 2 weeks before optimum harvest time, at optimum harvest, or after 2, 4, or 6 months of storage at 0 °C. Examination of the fruit surface with low-temperature scanning electron microscopy revealed that cracks in the epicuticular wax became wider and deeper as storage duration increased. After 6 months of storage, the cracks extended through the cuticle. Uptake of Ca by the infiltrated fruit was greater after 6 months of storage than after shorter storage intervals. These data indicate that as storage duration increased, epicuticular wax cracks became deeper and Ca uptake by the fruit increased.
Characterization of the Bentazon Herbicide Tolerance Factor in `Bohemian Chili' Pepper
Authors: Fery Richard L. , Harrison Howard F.
Published: February 2019

Greenhouse and field studies were conducted to determine the genetic relationship between bentazon tolerance exhibited by the pepper (Capsicum annuum L.) cultivars Bohemian Chili and Santaka, and to evaluate the importance of cytoplasmic factors in expression of the tolerance in `Bohemian Chili.' Greenhouse evaluation of parental and F2 populations of the cross `Santaka' × `Bohemian Chili' indicated that the major dominant gene conditioning bentazon tolerance in `Bohemian Chili' is probably the Bzt gene that conditions bentazon tolerance in `Santaka' or a gene closely linked to the Bzt locus. Field evaluation of F1 and F2 progeny populations of the cross `Bohemian Chili' × `Sweet Banana' in both `Bohemian Chili' and `Sweet Banana' cytoplasms demonstrated that cytoplasmic factors do not affect the expression of the bentazon tolerance gene in `Bohemian Chili.' We conclude that `Santaka' and `Bohemian Chili' are equally satisfactory sources of a bentazon tolerance gene for use in pepper breeding programs. Chemical name used: 3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (bentazon).
Distribution of Horseradish Peroxidase Activity in Horseradish Plants
Authors: Kushad Mosbah M. , Guidera Mohammed , Bratsch Anthony D.
Published: February 2019

Thirty horseradish (Armoracia rusticana Gaertn., Mey., & Scherb.) cultivars from eight countries in Europe and North America and from advanced lines developed at the Univ. of Illinois were evaluated for horseradish peroxidase (HRP; electrical conductivity 1.11.1.7, donor: hydrogen peroxide oxido-reductase) activity. Nearly 86% of the activity was present in the taproot and lateral roots and 14% in the leaf petiole, but there was no activity in the leaf blade. The 30 cultivars were divided into three groups with high (eight cultivars), medium (13 cultivars), and low (nine cultivars) activities [11.58 to 16.97, 7.19 to 9.79, and 2.88 to 6.91 μmol·min-1·g-1 fresh weight (FW), respectively]. The cultivars with the highest activity were 819-A from the Illinois and 810-A from Switzerland with 16.97 and 16.67 μmol·min-1·g-1 FW, respectively. The cultivar with the lowest HRP activity was 244-A from the United States with 2.88 μmol·min-1·g-1 FW. Cultivar 819-A also had the highest protein concentration (4.92 mg·g-1 FW). When HRP activity was expressed per milligrams of protein, cultivar 167-A, also known as `Bohemian', had the highest activity and cultivar 244-A had the lowest (5.35 and 0.83 μmol·min-1·mg-1 protein, respectively).
Flower Morphology in Blueberry Species and Hybrids
Authors: Ritzinger Rogério , Lyrene Paul M.
Published: February 2019

Several morphological features of Vaccinium ashei Reade, V. constablaei A. Gray, their F1 hybrids, V. simulatum Small, and southern highbush blueberry (V. corymbosum L. hybrids) flowers were compared in Gainesville, Fla. Desirable characteristics that could increase the extent of honeybee pollination, such as a large corolla aperture and a short anther-to-stigma distance, were common in V. constablaei but not in V. ashei. F1 (V. ashei × V. constablaei) hybrids were generally intermediate between the two parents. Thus, it appears that V. constablaei could be used to breed V. ashei cultivars with improved flower morphology. Vaccinium simulatum and V. constablaei flowers were similar in all features. The corollas of southern highbush blueberry flowers were wide and had wide apertures, but the distance between stigma and anther pore was also large.
Photoperiodic Control of Flowering in Seed-propagated Begonia ×tuberhybrida Voss.
Authors: Karlsson Meriam G. , Werner Jeffrey W.
Published: February 2019

Plants of Begonia ×tuberhybrida Voss. `Nonstop', `Clips', and `Musical' were exposed to 0, 1, 2, 3, or 4 weeks of short days (SD, 9-hour daylength) initiated at 0, 4, or 8 weeks following germination. Plants grown under long days (LD, 16-hour daylength) flowered 68 (`Musical'), 78 (`Clips'), or 83 days (`Nonstop') after germination. Exposure to SD delayed flowering in all three cultivars. The delay in `Nonstop' and `Clips' was independent of plant age at time of SD exposure. One to 4 weeks of SD delayed flowering 11 to 14 days in `Nonstop'. In `Clips', the delay in flowering increased linearly from 7 to 19 days with increasing duration of SD. Flowering was delayed up to 15 days in `Musical' when SD were begun 0 or 4 weeks after germination. Exposure to SD during the final 4 weeks of development did not affect flowering in `Musical'. Exposure to SD did not affect shoot, leaf, or flower number in any of the cultivars. The root/shoot dry-weight ratio within cultivars was independent of daylength.
Comparative Economic Efficiency of Four Peach Production Systems in California
Authors: DeJong T.M. , Tsuji W. , Doyle J.F. , Grossman Y.L.
Published: February 2019

A clingstone peach (Prunus persica L. Batsch `Ross' on `Nemaguard' rootstock) orchard was established at the Univ. of California Kearney Agricultural Center, Parlier, for evaluating the economic efficiency of three high-density planting systems in comparison with the conventional Open Vase system. The orchard contained four replicate plots (0.80 ha/plot), each containing four different planting systems. The four planting/training systems (in-row spacing given first) were: the “KAC-V” (a perpendicular V system spaced 2.0 × 5.5 m, 919 trees/ha); the “HiD KAC V” (spaced 1.8 × 4.6 m, 1196 trees/ha); the “Cordon” (spaced 2.4 × 4.0 m, with perpendicular harvest drives 4.8 m every 22 m and tree height limited to 2.5 m, 919 trees/ha); and the “Open Vase” (spaced 6.1 × 5.5 m, 299 trees/ha). All system-specific costs and crop yields were recorded annually on each subplot for the first 5 years. Although the Cordon system had the highest yields in the second year, the V systems had the highest returns after 5 years. Cumulative costs were: HiD KAC-V system > KAC-V ≥ Cordon > Open Vase. The system that was designed to maintain tree height <2.5 m (Cordon) tended to be less profitable than the V systems because of modest crop yields and high pruning costs that were not offset by increased harvest efficiency. In the last 3 years of the study, pruning, thinning, and harvesting accounted for the majority of the system-specific costs.
Sweetpotato Clone Tolerance to Weed Interference
Authors: La Bonte Don R. , Harrison Howard F. , Motsenbocker Carl E.
Published: February 2019

Field experiments were conducted to assess how sweetpotato [Ipomoea batatas (L.) Lam.] clones interfere with weeds and how clones tolerate weed interference. Eleven clones with architecturally different canopies were evaluated for yield, canopy surface area and dry mass, weed dry mass, and light interception at ground level. A 2-fold difference in ground area covered by canopy surface area was observed among the eleven clones 42 days after planting, and a 3-fold difference in canopy dry mass at harvest. Yields were reduced from 14% to 68% by weed interference. The yields of high-yielding clones, `Beauregard', `Excel', L87-125, `Regal', `Centennial', and W-274, were reduced to a significantly greater extent by weeds than were yields of the other five clones. No differences were observed between clones for weed suppression as measured by weed dry mass at harvest and ground light interception. Short-internode and long-internode clones had similar competitive abilities. Yield of high-yielding clones was impacted more by weed interference than was that of low-yielding clones.
Fertilizer Concentration and Moisture Tension Affect Growth and Foliar N, P, and K Contents of Two Woody Ornamentals
Authors: Rose Mary Ann , Rose Mark , Wang Hao
Published: February 2019

Crabapple [Malus ×zumi (Rehd.) `Calocarpa'] and maple (Acer ×freemanii E. Murray `Jeffersred') trees were grown in containers from 22 June to 3 Oct. with three fertilizer concentrations (50, 100, and 200 mg·L-1 N) and two levels of moisture tension in the medium [low setpoint (moist) = 5 kPa and high setpoint (dry) = 18 kPa]. Whole-plant growth was enhanced more by minimizing water stress than by increasing fertilizer concentration. Shoot length and whole-plant dry weight were greater (>29% for crabapple and >90% for maple) in low tension treatments (low water stress) but were unaffected by fertilizer concentration. Moisture tension also had a dominant effect on dry-weight allocation to leaves, stems, and roots. In contrast, foliar nutrient concentrations increased with fertilizer concentration but were affected to a lesser degree by moisture tension. Seasonal patterns in biomass allocation were little affected by treatments; the largest proportions of leaf and root biomass accumulated during summer and fall, respectively.
Growth Response of Snap Bean and Tomato as Affected by Salinity and Irrigation Method
Authors: Scholberg J.M.S. , Locascio S.J.
Published: February 2019

Although the effects of salinity on yield of tomato (Lycopersicon esculentum Mill.) grown under arid and semiarid conditions are well known, little information is available on the effects of salinity on crops grown in more humid conditions. In Florida, availability of high-quality water for irrigation may be reduced because of increased domestic consumption and sea water intrusion. Two greenhouse studies were conducted to determine the influence of irrigation system and water quantity and quality on the growth of tomato and snap bean (Phaseolus vulgaris L.). Bean plant heights and weights were greater with drip irrigation than with subirrigation. Bean seed germination percentage, plant height, and shoot weight decreased linearly with an increase in electrical conductivity of irrigation water (ECi) from 1 to 4 dS·m-1. Tomato leaf water potential and plant height decreased linearly with increasing salinity. Tomato stem and leaf weights were greatest at the intermediate salinity (2 dS·m-1) during initial growth, and stem weights decreased linearly with increased salinity during flowering. With drip irrigation, concentration of N for both crops decreased and concentration of P increased with an increase in water application from 0.75 to 1.5 times the estimated evapotranspiration rate (ETa). Tomato and bean tissue Na concentrations increased linearly with increased salinity. Total fruit yield and average fruit weight decreased linearly in tomato, and marketable fruit yield decreased quadratically with increased salinity.
Drought Stress Increases Densities but Not Populations of Two-spotted Spider Mite on Buddleia davidii `Pink Delight'
Authors: Gillman Jeffrey H. , Rieger Mark W. , Dirr Michael A. , Braman S. Kristine
Published: February 2019

Two experiments were conducted to determine the effect of drought stress on the susceptibility of Buddleia davidii Franch. `Pink Delight' to the two-spotted spider mite (Tetranychus urticae Koch). In the first experiment, drought stress was imposed by withholding water until predawn xylem pressure potential fell below -1 MPa. Shoot growth was 75% less in drought-stressed than in nonstressed plants. Mite population densities were not affected, but noninfested leaf area was 14% higher, and degree of mite damage was lower, in nonstressed plants. Evidently, the greater amount of new growth in nonstressed plants leads to lower spider mite densities by diluting populations. In a second experiment, nonstressed B. davidii `Pink Delight' plants were watered every 1 to 2 days and drought-stressed plants were watered every 3 days. Spider mite populations were monitored by sampling newly expanded and mature foliage. Mite populations on mature foliage were not affected by stress, but stressed plants grew less and had larger spider mite populations on their newly expanded foliage than did nonstressed plants.
Radopholus similis in Anthurium Shoot Tissue
Authors: Koon-Hui Wang , Sipes Brent S. , Kuehnle Adelheid R.
Published: February 2019

Radopholus similis distribution in Anthurium plant tissue was determined in a greenhouse experiment. Two thousand mixed life stages of R. similis per plant were inoculated onto Anthurium cultivars `Alii' and `Midori'. Nine months later, nematodes per gram of tissue were determined from stem sections (0-3, 3-6, and above 6 cm from the base), the lowest leaf petiole, and root tissue. R. similis occurred in all stem sections, leaf petioles, and roots in both `Alii' and `Midori'. Nematode distribution differed between the two cultivars. `Midori' had higher numbers of nematode in the roots whereas `Alii' had higher numbers of nematode in the stem sections and first leaf petiole. Anthurium apical stem cuttings could be contaminated with R. similis and may not be a nematode-free propagation material.
High Relative Humidity Reduces Anther Dehiscence in Apricot, Peach, and Almond
Authors: Gradziel Thomas M. , Weinbaum Steven A.
Published: February 2019

The regulation of anther dehiscence by relative humidity (RH) was assessed for detached anthers and detached whole flowers from a limited selection of apricot (Prunus armeniaca L.), peach [P. persica (L.) Batsch], and almond [P. dulcis (Mill.) D.A. Webb, syn. P. amygdalus Batsch; P. communis (L.) Arcangeli, non Huds.] genotypes, as well as an almond X peach F2 progeny. Dehiscence was evaluated at 33, 64, 87, 93 and 97% RH for detached anthers, and at 33, 64 and 97% RH for whole detached flowers. Anther dehiscence was suppressed with increasing RH for all genotypes. Apricot anthers showed the greatest dehiscence at low RH and measurable dehiscence at high RH even when detached. Anther dehiscence in almond appeared more suppressed than in apricot at all RH levels tested, being completely suppressed by high RH in detached anthers. Peach genotypes exhibited the full range of variability between apricot and almond patterns. Evidence for transgressive segregation of RH-controlled anther dehiscence was observed in the occurrence of cleistogamy in an almond × peach F2 progeny. Rates of anther dehiscence were approximately linear with change in RH in detached anthers but exhibited a more buffered, step-wise response when detached whole flowers were tested. Results are consistent with field observations, and highlight the low but measurable risk of cleistogamy in these species, as well as opportunities to modify the breeding systems and crossing environments to facilitate controlled hybridization, and to reduce pollination vulnerability to adverse environments.
Genetics of Floral Longevity in Petunia
Authors: Krahl Kimberly H. , Randle William M.
Published: February 2019

Petunia hybrida Vilm. is one of the major bedding plants grown worldwide, and, like most bedding plants, is grown primarily for its seasonal floral display. While increased floral and reflowering capacity have been the focus of breeding programs for many ornamental species, floral longevity has received little direct attention. Increased floral longevity would enhance the value of any crop grown for floral effect. In this study, four parental genotypes (two with short flower life, two with long flower life) were crossed in a partial diallel mating design to create six F1 families. The F1 individuals were then selfed and backcrossed to the appropriate parents to create F2 and backcross families. Data from parental and F1 genotypes were analyzed to determine general and specific combining ability for floral longevity in petunia. Results indicated the presence of significant additive gene effects and nonsignificant nonadditive gene effects for floral longevity in this germplasm. However, aberrant F2 and backcross family means were observed in all families. For each family, F2 and backcross means were lower than expected given normal Mendelian segregation. Further experiments will be necessary to elucidate the causes for the deviate F2 and backcross family means before specific recommendations for selecting for increased floral longevity in petunia can be made.
A cRNA Probe Detects Prunus Necrotic Ringspot Virus in Three Peach Cultivars after Micrografting and in Peach Shoots following Long-term Culture at 4 °C
Authors: Heuss K. , Liu Q. , Hammerschlag F.A. , Hammond R.W.
Published: February 2019

As part of a program to develop transgenic peach (Prunus persica L. Batsch) cultivars with resistance to Prunus necrotic ringspot virus (PNRSV), we are testing a system for measuring virus in peach shoot cultures. Micrografting in vitro is used for inoculation and slot-blot hybridization, with a digoxigenin (DIG)-labeled cRNA probe complementary to the 5′ open reading frame (ORF) of PNRSV RNA 3, for detection. In this study, we investigated whether infected shoots maintain virus infection over long periods of culture at 4 °C and if PNRSV-infected `Suncrest' shoot cultures can serve as graft bases to transmit virus equally well into cultivars Nemaguard, Springcrest, and Suncrest. The results of RNA hybridization analysis showed that virus was present in extracts of leaf samples from 2-year-old PNRSV-infected `Suncrest' shoots that had been subjected to varying lengths of incubation at 4 °C in the dark, suggesting that infected shoots can be maintained for repeated use. Rates of graft success were higher in heterografts between `Suncrest' bases and tips of `Springcrest' or `Nemaguard' than in autografts between `Suncrest' and `Suncrest', and there was equal efficacy of graft inoculation from `Suncrest' into these three cultivars.
Micropropagation of Baptisia `Purple Smoke'
Authors: Ault James R. , Havens Kayri
Published: February 2019

Shoot explants from actively growing, greenhouse-maintained plants of Baptisia `Purple Smoke' were cultured in vitro for shoot initiation on Murashige and Skoog (MS) basal medium containing vitamins and supplemented with 30 g·L–1 sucrose, 8.87 μm BA, and 4.14 μm K-IBA. All subsequent media were supplemented with 2.47 mm NaH2PO4 to enhance shoot growth. Single-node explants were subcultured for shoot multiplication on MS medium with either no plant growth regulator or with 2.22, 4.44, 8.87, 17.74, or 35.48 mm BA in combination with 0.0 or 4.14 μm K-IBA. Explants produced a maximum of 4.1 shoots on the medium with 2.22 μm BA. Shoots rooted on all concentrations of K-IBA (2.07, 4.14, 10.36, or 20.72 μm) and K-NAA (2.23, 4.46, 11.15, or 22.29 μm) tested. Maximum rooting was 100% on MS medium with 11.15 μm K-NAA; however, this treatment induced copious stem callusing. Rooted shoots were greenhouse-acclimatized for 2.5 weeks. Overall survival was 86%. For optimal rooting and subsequent acclimatization, treatment with 2.23 μm K-NAA is recommended; this resulted in 83% rooting and 87% acclimatization. Chemical names used: N6 benzyladenine (BA); potassium salt of indole-3-butyric acid (K-IBA); potassium salt of 1-naphthalene acetic acid (K-NAA).