bluuebunny/crossref_metadata_2025 huggingface dataset:
BUMBLEBEES: AN ALTERNATIVE POLLINATOR FOR CUCUMBER
Authors: Stanghellini Michael S. , Ambrose John T. , Schultheis Jonathan R.
Published: February 2019

The effectiveness of bumblebees, Bombus impatiens, and honeybees, Apis mellifera, on the pollination of cucumber, Cucumis sativus, was compared at the individual bee level. A correlation between the number of bee visits a flower received and the resultant seed set was established. In both cucumber varieties, `Calypso' and `Dasher II', B. impatiens-visited flowers consistently had higher seed sets than A. mellifera when compared at equal visit numbers. This difference between bee types was found to be highly significant.
PERFORMANCE OF TROPICAL PUMPKIN (CUCURBITA MOSCHATA) INBREDS AND HYBRIDS
Authors: Maynard Donald N.
Published: February 2019

Traditional varieties and selections of tropical pumpkins have long trailing vines that produce two to five fruit weighing from 2 to 20 kg each. Bush inbreds have been developed from crosses between `La Primera', `La Segunda', and `Seminole' with `Bush Butternut'. These inbred plants produce four to 10 early-maturing fruit weighing 1 to 2 kg each at the crown of the plant. Hybrids made with the vining types produce plants that have short or intermediate-length vines. Fruit are produced at the crown and on short laterals on the short-vine hybrids and on laterals on the intermediate-vine hybrids. Some short-vined and intermediate-vined hybrids produce higher yields than the traditional type, but fruit size is smaller and the fruit wall is generally thinner. C42-1-9-1 x Linea C. Pinta, an intermediate-vine type, produced the highest yield in spring (66.5 t·ha–1) and fall (39.9 t·ha–1) at Bradenton, Fla. About three fruit weighing 4 to 5 kg each were produced per plant.
HARDINESS OF PRIMARY BUDS OF MUSCADINE GRAPE CULTIVARS
Authors: Clark John R. , Watson Paula
Published: February 2019

Eleven muscadine grape (Vitis rotundifolia Michx.) cultivars were evaluated in Nov. and Dec. 1994 and Jan. and Feb. 1995 for primary bud hardiness using differential thermal analysis. Vines sampled were located at the University of Arkansas Fruit Substation, Clarkeville. Data analysis indicated a significant date × cultivar interaction for mean low temperature exotherm (LTE). Mean LTE decreased for all cultivars during the sampling period. Hardier cultivars for November and December were `Sterling' and `Summit'; for January, `Nesbitt', `Summit', `Carlos', and `Sterling'; and for February, `Sugargate', `Carlos', and `Summit'. The minimum LTE for any cultivar was – 23.8C for `Sugargate' during February.
IRRIGATION NOZZLE HEIGHT INFLUENCES WATER CAPTURED BY CONTAINERS
Authors: Yeager Thomas H. , Beeson Richard C.
Published: February 2019

Rain drop momentum, based on the height from which it falls, is an important factor in drop penetration of plant canopy. This may explain why nursery operators report that substrates appear wetter from rain than from an equivalent amount of water applied with overhead irrigation. We investigated the influence of irrigation nozzle height on amount of water captured by Rhododendron sp. `Formosa' grown in 10-liter containers. A Wobbler® (#8, 7.6 liters·min–1) irrigation nozzle was positioned 1.2, 2.4, 3.6, 4.8, or 6.0 m above grade. Plants were placed in a circle 3.6 m from the riser base for the 1.2-m-high nozzle, 4.5 m from riser base for the 2.4-m-high nozzle, and 5.4 m from riser base for all other heights and irrigated for 3 hours. Preweighed disposable diapers were placed on substrate surface of each container with and without (control) plants. Diapers were weighed after irrigation and water captured was calculated and expressed as percentage of control containers. Capture increased from 144% at 1.2 m to 178% at 3.6 m then declined with increasing height. The decline was likely due to small drops with low momentum striking plants because plants remained 5.4 m from the riser base.
PARTIAL OIL EXTRACTION EXTENDS THE SHELF LIFE OF PECAN HALVES
Authors: Chrz Donna , Maness Niels , Brusewitz Gerald , Knight Sue
Published: February 2019

Pecans, because of their high oil and polyunsaturated fatty acid content, have a relatively short shelf life due to oxidation of the oil. Using a nondestructive supercritical CO2 extraction process, we evaluated oil reduction as a means for pecan shelf life extension. Pecan halves were extracted under sufficient conditions for 22% and 28% oil reduction, and then stored in modified-atmosphere packages with 21% O2 at 22C for up to 37 weeks. Kernel hexanal content and sensory rancid flavor were monitored at various times throughout the study. The resistance of oils to oxidation, indicated by the onset of sustained hexanal production, was increased from 6 weeks for full-oil halves, to 18 weeks for 22% reduced-oil halves, to 22 weeks for 28% reduced-oil halves. Objectionable rancid flavor was detected by the 22nd week of storage for full-oil pecans. Reduced-oil pecans never developed objectionable rancid flavor. Supported by USDA grant 93-341508409, OCAST grant AR4-044, and the Oklahoma Agricultural Experiment Station.
METHYL BROMIDE ALTERNATIVES IN FRESH MARKET TOMATO PRODUCTION
Authors: Ray Christopher L. , Wilson Sandra B. , Brock Kathy H. , Fortnum Bruce A. , Decoteau Dennis R.
Published: February 2019

Pest management is of primary importance to the vegetable industry in our nation. In recent years producers have undergone much scrutiny concerning their pest control strategies, which often include the use of chemical pesticides. Due to the detrimental effects of many fumigants, growers are being forced to incorporate more environmentally sound agricultural practices while still producing a healthy, marketable commodity. The effects of three different fumigants and reflective mulches on plant growth and development were studied in field-grown, staked tomatoes. Methyl bromide, Telone II, or Telone C-17 were used in fumigation of plots. The establishment of mulch color was done via applications of exterior enamel paint, white or red in color, to the surface of black polyethylene mulch. With the exception of total marketable yields, no interactions existed between mulch color and fumigant. Red mulch and Telone II treatments resulted in the highest total marketable yield. Telone II application increased early marketable yield. White mulch color increased preharvest yield and black mulch color decreased early marketable yield. Low initial populations of nematodes may be the cause for lack of response due to fumigation.
NITROGEN FERTILIZER EFFECT ON POSTHARVEST QUALITY OF `ARAPAHO' THORNLESS BLACKBERRY FRUIT
Authors: Alleyne Victorine , Clark John R.
Published: February 2019

An investigation was conducted in 1994 and 1995 to evaluate the effect of N rate and timing of application on postharvest performance of `Arapaho' thornless blackberry fruit. Treatments were 0 kg N/ha, 56 kg N/ha, 112 kg N/ha single application, and 112 kg N/ha split application. The N source was ammonium nitrate. Fruit samples were hand-harvested and stored for 0–8 days. In general, `Arapaho' fruit quality was not affected by N applications. Increasing N rates increased soluble solids content but had no effect on pH, titratable acidity, sugar: acid ratio, total solids, firmness, and weight loss. Nitrogen applications increased fruit N content.
RESPONSE OF CILANTRO (CORIANDRUM SATIVUM) TO COMBINATIONS OF GIBBERELLIC ACID, FOLCYSTEINE, AND NITROGEN
Authors: Morales-Payan Jose Pablo , Santos Bielinski M.
Published: February 2019

Field experiments were conducted in the Dominican Republic to determine the effect of combinations of N with folcysteine and gibberellic acid 3 on cilantro (Coriandrum sativum) yield. Nitrogen levels (0, 36, 55, 73, 91 kg·ha–1) in soil application at sowing were combined with foliar spray of the biostimulant folcysteine or gibberellic acid (0, 100, 200, 300, and 400 ppm) 15 days after emergence. Treatments were applied in a factorial arrangement on a randomized complete block design with three replications. Fresh weight of the aerial part of the plants was determined 40 days after emergence. No significant difference was found due to folcysteine treatment. Nitrogen had a significant effect, with optimal yield at 55 kg·ha–1. Significant interaction was detected for the combinations of gibberellic acid and N, with yield increasing as the rate of the two factors increased.
Orchard Cooling with Pulsed Overtree Irrigation to Prevent Solar Injury and Improve Fruit Quality of `Jonagold' Apples
Authors: Parchomchuk P. , Meheriuk M.
Published: February 2019

Pulsed application of overtree irrigation for evaporative cooling of `Jonagold' apples (Malus domestica Borkh.) reduced visible solar injury by 15.8% (1991) and 9.4% (1992). Maximum fruit surface temperature was reduced by 8.1 °C on a day when the average surface mean of nonsprayed fruit rose to 45.6 °C. Air heated more slowly than the exposed fruit surface and was cooled only 1 to 2 °C by overtree irrigation. Cooling did not affect fruit size, firmness, or redness but reduced soluble solids concentration and increased titratable acidity. Storage breakdown was unaffected in the first year but was reduced by 6.0% in the second year.
Organic Mulches Increase Growth of Young Pecan Trees
Authors: Foshee W.G. , Goff W.D. , Tilt K.M. , Williams J.D. , Bannon J.S. , Witt J.B.
Published: February 2019

Organic mulches (leaves, pine nuggets, pine straw, grass clippings, and chipped limbs) were applied at depths of 10, 20, or 30 cm in a 3 × 3-m area around young pecan [Carya illinoinensis (Wangenh.) K. Koch] trees. These treatments were compared to an unmulched herbicide treatment and a common bermudagrass [Cynodon dactylon (L.) Pers.] sod. Trunk cross-sectional areas (TCSAs) of the mulched trees were larger than those of trees in the sod or unmulched plots and increased linearly as mulch depth increased. All mulches influenced TCSA similarly. Mean TCSA for mulched trees increased 14-fold compared to an increase of 8-fold for the unmulched trees and the sod in this 3-year study. Thus, common yard-waste mulches can be used effectively to increase growth of young pecan trees.
UNIVERSITY OF CONNECTICUT DISEASE-RESISTANT PEPPER VARIETY TRIAL
Authors: Boucher Jude , Nixon Gianna , Ashley Richard
Published: February 2019

In 1995, we compared the horticultural characteristics of one Phytophthora blight, one cucumber mosaic virus, and 12 bacterial leaf spot–resistant varieties to two popular commercial peppers in a replicated trial at the University of Connecticut. Fruit were graded for size and shape and yields were separated into early and late-season harvests. Other parameters measured were plant height, canopy width, and fruit wall thickness, length to diameter ratio, number, weight, and the percent marketable. Unreplicated demonstration plantings with three or four resistant varieties each were conducted at 12 commercial farms in 1994–95 and at the university's research farm in 1994. Several resistant varieties were judged to be equal or superior to the two popular cultivars based on a combination of characteristics, including observations on disease susceptibility at local farms. Resistant varieties recommended for New England conditions include Boynton Bell (Harris Moran), King Arthur and PSX 271092 (Petoseed), Admiral and Reinger (Roger NK).
GENETIC RELATIONSHIPS AMONG RESISTANCE TO ZUCCHINI YELLOW MOSAIC VIRUS, WATERMELON MOSAIC VIRUS, PAPAYA RINGSPOT VIRUS, AND POWDERY MILDEW IN MELON (CUCUMIS MELO)
Authors: Anagnostou Konstantinos , Kyle Molly , Perl-Treves Rafael
Published: February 2019

We have studied the relationship of resistance to watermelon mosaic virus (WMV), zucchini yellow mosaic virus (ZYMV), papaya ringspot virus (PRSV), and powdery mildew (PM) in melon (Cucumis melo). We have confirmed monogenic dominant inheritance of these four resistances and report that PI414723-4S3, which was initially selected as a source of ZYMR, is also a source of dominant monogenic resistance to PRSV. Further, we observed departure from independent assortment for resistance to WMV and ZYMV in a study of 73 (UC Top Mark × PI414723-4S3) F3 families (χ2 = 39.87 significant at both 0.01 and 0.05 levels), indicating linkage between Wmv and Zym. The map distance between these resistance genes calculated from the number of recombinant families (RF% = 9.58) was 10.5 cM. Compari-sons among WMV, PM, ZYMV-PM, PRSV-PM, ZYMV-PRSV, and WMV-PRSV of 48 (TM × PI414723-4S3) F3 families, which were screened with all four pathogens, showed no consistent cosegregation.
MODELING WATER USE OF SHADE TREES IN FIELD PRODUCTION NURSERIES
Authors: Kjelgren Roger
Published: February 2019

Supplemental watering of shade trees in field production nurseries is needed, even in summer-rainfall climates, to achieve maximum growth. Scheduling the timing and amount of supplemental watering makes more efficient use of financial and water resources while maintaining maximum growth. Methods of scheduling supplemental watering based on uniform canopy and rooting in production agriculture must be modified, however, for shade trees in a production setting. Nursery trees are non-uniform in canopy and rooting compared to an agricultural crop. Applying the water budget method can be effective with sprinkler systems if tree water loss and rooting depth can be properly estimated. A measure of reference evapotranspiration and a species-specific multiplier are typically used to estimate water loss. Since species diversity in a field nursery is quite high, however, estimates of both tree transpiration and rooting depth must necessarily be simplified assumptions less accurate than for a uniform agricultural crop. If supplemental water is to be applied with drip irrigation, estimates of tree transpiration and soil water depletion need to be converted to volume units with information on total tree leaf area.
PERFORMANCE OF SIX GROUNDCOVER SPECIES UNDER MINIMUM IRRIGATION
Authors: Pittenger Dennis R.
Published: February 2019

The performance of six landscape groundcover species was evaluated in a field experiment with irrigation treatments of 50%, 40%, 30%, and 20% of real-time ET0. Analysis of seasonal plant performance ratings indicated that for Baccharis pilularis `Twin Peaks', Drosanthemum hispidum, and Hedera helix `Needle point' there were no season-long increases in plant appearance when irrigated more than 20% ET0. Vinca major, Gazania hybrid, and Potentilla tabernaemontanii exhibited no significant improvement in appearance when irrigated above 30% ET0. A marked decline in performance was apparent in Gazania and Potentilla at all treatments during the study period, however, suggesting that their long-term minimum irrigation needs exceed 50% ET0. In a follow-up study, five of the above species and Osteospermum fruticosum received 30% ET0 at irrigation schedules of three times/week, once/week, once/2 weeks, and once/4 weeks. Potentilla was not sustained in acceptable condition at any treatment, while there were no season-long differences in performance within the other species due to irrigation frequency.
Plant Growth and Yield of Red Raspberry following Primocane Defoliation
Authors: Raworth D.A. , Clements S.J.
Published: February 2019

Red raspberry (Rubus idaeus L. cv. Willamette) primocanes were artificially defoliated to various degrees and at two dates in each of 2 years to simulate defoliation caused by the twospotted spider mite (Tetranychus urticae Koch). The effect on primocane diameter, lateral length, yield and four yield components was determined. When defoliation occurred evenly along the length of the primocanes, and all floricanes and excess primocanes were removed in early Aug. 1989, yield was reduced 26% at 25%, 50%, and 75% defoliation and 55% at 100% defoliation compared with nondefoliated controls. The number of canes per stool, number of fruit per lateral, and weight per fruit were reduced when defoliation occurred earlier, in August rather than September, but the number of laterals per cane increased with early defoliation. The effect of increasing defoliation on plant growth and yield was generally nonlinear. When defoliation occurred in sections along the lower 2 m of all primocanes, and all floricanes and excess primocanes were removed in Nov. 1992, no significant differences in yield or three yield components were detected. The effects of primocane defoliation are not necessarily predictable, so T. urticae should be controlled before mite-induced defoliation occurs.
Wilt Avoidance in St. Augustinegrass Germplasm
Authors: Busey Philip
Published: February 2019

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is less drought-resistant than other C4 grasses and frequently requires irrigation in lawns. The objectives of this study were to search for St. Augustinegrass germplasm having little wilting and to determine if minimal wilting under drought is associated with reduced canopy loss. St. Augustinegrass cultivars and breeding lines, representing polyploids (2n = 27 to 32) and diploids (2n = 18), were grown in sand soil and exposed to irrigation suspensions during seasonal droughts in three experiments. In the first experiment, during brief (3 to 14 day) irrigation suspensions, wilted area over 3 years was significantly less for polyploids (6% of canopy) than for diploids (23%). In the second experiment, during a permanent irrigation suspension, frequency of wilt was highest for diploids (57%), least for African polyploids (27%), and intermediate (53%) for other polyploids. When rain resumed after 41 days of drought, allowing refoliation, canopy loss was 51%, 4%, and 47% for diploids, African polyploids, and other polyploids, respectively. In the third experiment, during a permanent irrigation suspension, wilted area was 33% for `Jade,' a diploid, which was more (P ≤ 0.05) than for the polyploid `FX-10,' with a wilted area of 20%. `Floratam' and `Bitterblue' were intermediate in wilted area, 28% and 25%, respectively. When rain resumed after 18 days of drought, canopy loss was 58% and 56% for `Jade' and `Bitterblue,' respectively, which was more than for `Floratam' and `FX-10,' 11% and 6%. Following permanent irrigation suspensions, canopy loss was closely associated with wilting, r2 = 0.88 and 0.94 by the Gompertz nonlinear model. Because the sand soil had low water-holding capacity, the wet subsoil and shallow (1.35 m deep) water table may have been a source of water. Wilt-avoidant St. Augustinegrass may help reduce turfgrass water use.
Testing Petiole Sap for Nitrate and Potassium: A Comparison of Several Analytical Procedures
Authors: Rosen Carl J. , Errebhi Mohamed , Wang Wenshan
Published: February 2019

An important aspect of establishing critical sap nutrient concentrations for diagnostic purposes is to determine the accuracy of the analytical method used. We compared a Cardy flat membrane NO3 electrode, a Hach portable NO3 electrode, and a Wescan N analyzer for their ability to determine NO3 concentrations in sap of potato (Solanum tuberosum L.) petioles. The Hach and Wescan instruments require diluted sap, while nondiluted sap can be used with the Cardy. Nitrate-N concentrations in nondiluted petiole sap measured with the Cardy electrode were 90 to 120 mg·L–1 higher than the other two methods. Using sap diluted with 0.075 m aluminum sulfate tended to lower Cardy NO3 readings to concentrations closer to the other methods, but made the procedure more complicated for practical use. We also compared a Cardy K electrode with flame emission spectroscopy for determining K concentrations in sap. Using nondiluted sap with the Cardy procedure resulted in K concentrations 200 to 2500 mg·L–1 lower than those determined by flame emission, depending on K concentration of the sap. Diluting sap with 0.075 m aluminum sulfate or deionized water for use with the Cardy electrode resulted in K concentrations similar to those determined by flame emission.
Physiological Changes Associated with Performance of Kentucky Bluegrass Cultivars during Summer Stress
Authors: Perdomo Pedro , Murphy James A. , Berkowitz Gerald A.
Published: February 2019

Understanding the factors influencing the performance of Kentucky bluegrass (Poa pratensis L.) cultivars under summer stress is necessary for developing criteria for identifying resistant germplasm. The objectives of this study were to evaluate two Kentucky bluegrass cultivars for leaf water (ψl) and osmotic potential (ψπ), stomatal resistance (Rs), leaf: air temperature differential (ΔT) and determine the relationship of these parameters to drought and heat tolerance. Stress-resistant (`Midnight') and susceptible (`Nugget') cultivars were evaluated in a field study during 1993 and 1994 under moisture-limiting conditions. Leaf water potential for `Nugget' was higher than for `Midnight' in 1993 and similar in 1994. `Midnight' had lower ψπ than `Nugget' during the evaluation period in 1994. `Midnight' maintained more open stomata (lower Rs) and lower ΔT than `Nugget' at the end of the dry down period when `Nugget' was showing visual signs of stress. `Midnight' and `Nugget' had similar root weight at the 0- to 45-cm depth zone in 1994. Lower basal osmotic potential (i.e., higher solute concentration) may be the physiological mechanism allowing larger stomatal aperture in `Midnight'. Greater transpirational cooling in `Midnight' relative to `Nugget' was correlated with higher turf quality for `Midnight'.
Composted Green Waste as a Container Medium Amendment for the Production of Ornamental Plants
Authors: Burger D.W. , Hartz T.K. , Forister G.W.
Published: February 2019

Seed germination and crop growth characteristics were determined for Tagetes spp. L. `Lemondrop', marigold; Catharanthus roseus Don. `Little Pinkie', vinca; Petunia hybrida Vilm. `Royalty Cherry', petunia; Dendranthema×grandiflorum (Ramat.) Kitamura `White Diamond', chrysanthemum; Pittosporum tobira Ait. `Wheeleri', sweet mock orange; Photinia ×fraseri Dress., photinia and Juniperus sabina L. `Moon Glow', juniper grown in various size containers containing blends of composted green waste (CGW) and UC Mix. Seed germination, plant height, and stem and root fresh and dry mass were lowest in unamended CGW. For most plants studied, a CGW: UC Mix blend containing at least 25% UC Mix was required for adequate growth and development. Germinating seeds and young seedlings were most adversely affected by unamended CGW. As plants grew and were transplanted into larger containers (10- and 15-cm pots, 530 and 1800 mL), they were better able to grow in media with higher CGW content.
Watermelon Weed Control: Current and Future Possibilities
Authors: Roberts Warren , Shrefler Jim , Duthie Jim , Edelson Jonathan , Watkins Wes
Published: February 2019

Watermelon is the major fresh-market vegetable grown in Oklahoma, but growers have few labeled herbicides from which to choose. Grower surveys in Oklahoma have identified weed control as the major production problem facing watermelon producers. In 1995 and 1996, various mechanical and chemical weed control strategies have been explored. `Allsweet' watermelons were grown with various combinations of labeled and unlabeled herbicides, as well as mechanical control treatments. Treatments included bensulide, clomazone, DCPA, ethalfluralin, glyphosate, halosulfuron, napropamide, naptalam, paraquat, pendimethalin sethoxydim, and trifluralin. Certain chemicals were used in combination. Paraquat and glyphosate were used as wipe-on materials. Glyphosate and paraquat could not be applied until weeds were taller than the watermelon foliage, causing serious weed competition. In general, superior results were obtained from hand-weeded plots, trifluralin, and DCPA. Halosulfuron gave superior control of broadleaf weeds, but had a negligible effect on grasses. Napropamide gave good control of grasses and broadleaf weeds other than solanaceous weeds. No chemical, when used alone, gave satisfactory control throughout the growing season. Early cultivation, followed by chemical application at layby, appears to be one of the better treatments.
Effect of Light during Cultivation on Weed Emergence
Authors: Maynard Elizabeth T.
Published: February 2019

This experiment was conducted to determine whether light conditions during cultivation affect the number or species composition of emerging weeds. Plots were cultivated on 31 May 1996 under the following light conditions: 1) Ambient nighttime light (full moon) plus tractor headlights, 2) ambient nighttime light plus tractor headlights covered by transparent green film (green tractor lights), 3) ambient nighttime light with no tractor headlights, 4) ambient mid-day light. A fifth treatment was not cultivated at all, but was treated with glyphosate on 31 May to kill emerged plants. Results discussed below are based on weed densities determined 3 weeks after cultivation. Cultivated plots had more broadleaf weeds than uncultivated plots (119/m2 vs. 40/m2). Annual grass populations were the same in cultivated and uncultivated plots (20/m2). Common lambsquarters (Chenopodium album) and carpetweed (Mollugo verticillata) were the most common annual broadleaf weeds, representing more than 80% of the annual broadleaf population in cultivated plots. Light conditions during cultivation did not influence the total number of broadleaves, number of annual grasses, or total number of weeds emerging. Lambsquarters emerged in greater numbers after daytime or night cultivation using green tractor lights (48/m2) than after night cultivation using standard tractor headlights (32/m2). These results suggest no practical benefit to night cultivation for reducing overall weed density. A similar study in 1995 led to a similar conclusion. Although measurable effects of light conditions on weed emergence were observed in both years, the magnitude and consistency of the effects were not enough to suggest changes in cultivation practices without further research.
Studies on the Allelopathic Effect of Corn Spurry (Spergula arvensis L.) on Cole Crops and English Pea
Authors: Harrison H.F. , Peterson J. K. , Snook M.
Published: February 2019

These studies were initiated to investigate severe growth inhibition observed when some vegetable crops were infested with corn spurry (Spergula arvensis L.). Interference by a natural population of the weed reduced the shoot weights of English pea (Pisum sativum L.) and collard (Brassica oleracea L.) by 93% and 72%, respectively. In a greenhouse experiment where light competition by corn spurry was prevented, broccoli (Brassica oleracea L.) shoot weights were reduced by corn spurry, but pea weights were not different from the controls. Homogenized corn spurry shoot tissue incorporated into a greenhouse potting medium inhibited the growth of both species, and a concentration effect was observed. Sequential hexane, dichloromethane, methanol, and 50% aqueous methanol extracts of corn spurry root and shoot tissue were tested for inhibitory activity using millet seed germination and broccoli seedling growth bioassays. Dichloromethane, methanol, and aqueous methanol shoot extracts were inhibitory to broccoli; whereas all shoot extracts inhibited millet germination. Shoot extracts were more inhibitory than root extracts. Further fractionation of the inhibitors using a combination of reversed-phase sephadex LH-20 and silicic acid column chromatographic procedures showed that a major portion of the millet germination inhibition was due to sucrose esters (SE). Preliminary characterization of the esters showed that there were four different SE groups. The major groups contained either octanoic or dodecanoic acid along with butanoic and petanoic acids. All groups inhibited seed germination at concentrations as low as 20 ppm. This is the first report of the SE class of defense chemicals in plant species outside of the solanaceae family.
Some Interesting Traits of European and Asian Fragaria Species
Authors: Bors Robert H. , Sullivan J. Alan
Published: February 2019

Several interesting attributes have been observed while working with European and Asian species of Fragaria. F. nilgerrensis has shown immunity to aphids and leaf diseases. F. iinumae produces runners that frequently have unusual tap roots. F. moschata demonstrated excellent winter hardiness in a water-logged field during an unusually long cold winter (1995–96) in southern Ontario, excellent leaf disease resistance, and high susceptibility to Botrytis. When grown in the greenhouse, F. moschata fruit taste like a concord grape. F. pentaphylla (Guelph P-1 and P-2) displayed unusually bright red-colored fruit that were uniformly wedged, firm, but lacking flavor. F. pentaphylla P-1 is extremely vigorous and immune to leaf diseases. F. nubicola and F. daltoniana are the smallest and least-vigorous plants in the Univ. of Guelph's collection, yet they appear to confer hybrid vigor to their progeny when crossed to other species. F. daltoniana's leaf has a waxy cuticle and dark green color similar to F. chiloensis. F. viridis has a spicy, cinnamon-like flavor. When F. viridis is crossed to most other diploids, powdery mildew and leaf diseases are prevalent. F. orientalis crosses easily to synthetic tetraploids, has a flavor similar to F. viridis and F. nubicola, but is extremely susceptible to viruses. Aroma is quite variable in F. vesca with the most desirable originating from Russian accessions.
Growth Dynamics of `Packham's Triumph' Pear Fruits
Authors: Garriz Patricia I. , Alvarez Hugo L. , Colavita Graciela M.
Published: February 2019

The objective of this work was to predict `Packham's Triumph' (Pyrus communis L.) fruit growth as a function of time using an empirical mathematical model. A mature crop was studied at the Experimental Farm of the Comahue National Univ., Rio Negro, Argentina, during the 1992–93, 1993–94, and 1994–95 growing seasons. Trees were selected at random and fruits were collected at weekly intervals. The range of sampling dates was 27 and 178 days after full bloom (DFB). Fresh fruit mass (FM) was measured using an electronic scale (n = 1169). Fruit number/trunk cross-sectional area was also determined; cultural practices were performed according to the local standard program. Equations were developed with SYSTAT procedure. Results showed that the following logistic model provided the most satifactory fit to the pooled data, as compared to the power and linear models: FM (g)= 316.081/(1+ e^5.030–0.039 DFB) R2=0.84 P < 0.001. The accuracy of predictions was tested on an independent crop in the 1995–96 growing season. According to the values of the statistical F test, no significant differences (Pr0.05) were detected between the mean squared deviations of the observed and the estimated values, suggesting that, overall, the model works well. It can provide growers with a means of determining adequate fruit mass at harvest, considering that unless a certain minimum size is obtained, the fruit will be given a lower grade and price.
Resistance in Cucurbita spp. to Silverleaf and Sweetpotato Whitefly
Authors: Wessel-Beaver Linda
Published: February 2019

Accessions of both domesticated and wild Cucurbita spp. were tested from Jan. to May 1996 in Isabela, Puerto Rico, for resistance to silverleaf and sweetpotato whitefly (Bemisia tabaci). None of the accessions tested were completely free of whiteflies, but some accessions were completely free of silverleaf. At 8 weeks, checks of `Soler' and `Butternut' had silverleaf ratings of 4.5 and 0.0, respectively (on a 0 to 5 scale, where 0 = no silverleaf). Both checks were highly infected with whiteflies. Wild Cucurbitas do not appear to be a good source of whitefly or silverleaf resistance. While no strong correlations were observed between number of whiteflies and degree of silvering, all plants that were highly silvered were also heavily infested with whiteflies. Some plants with little or no silverleaf had many fewer whiteflies. Plants from ≈40 accessions from a total of about 800 were selfed for further evaluation.
Predicting Dry Bean Yields in Phenological Time
Authors: Nuland David , Taylor R.G. , Hawley Robert
Published: February 2019

A multiple regression model was developed to predict dry bean yields for the dry bean-growing region of western Nebraska. Within the context of the dry bean phenological growth stages, the model assesses the significance and magnitude of weather, climatic and irrigation disasters, and technology. Yield data was taken from four western Nebraska counties (Box Butte, Morrill, Scotts Bluff, and Sheridan) for 1940 to the present. Weather data used to predict yield were daily maximum and minimum temperatures and precipitation from a single weather station in each respective county. Farmers and industry personnel in each county provided historical recollections of years when county-wide disaster events occurred, such as hail and early frost. Four 21-day growth stages were defined as: emergence and stand establishment, rapid vegetative growth, flowering and pod development, and pod fill and maturation. The model predicts current season yields at the end of each growth stage as the season progresses. In 1995, the model predicted a yield of 1731 lb/A—3% below the final USDA estimate for Scott Bluff county. The 1996 predicted value is for 2162 lbs/A—the fifth largest in history. Providing accurate real-time yield predictions assess which weather-related factors are significant, and ranks the relative impacts of weather effects on dry bean yields. Technological progress in yield can also be measured. This information aids farmers in the selection of varieties and management practices that reduce yield losses, predicts regional crop production for agribusiness planning, and provides plant breeders the guidelines for variety development.
Effect of Photoperiod on Stem Elongation and Flowering of 10 Hanging-basket Crops
Authors: Wang Shi-Ying , Carlson William H. , Heins Royal D.
Published: February 2019

Argeranthemum frutescens `Butterfly' and `Sugar Baby', Brachycome hybrid `Ultra', Helichrysum bracteatum `Golden Beauty', Scaevola aemula `New Wonder',Supertunia axillaris hybrids `Kilkenny Bells' and `Pink Victory', Sutera cordata `Mauve Mist' and `Snowflake', and Verbena hybrid `Blue' were grown in a glass greenhouse maintained at 20°C under seven different photoperiods (10-, 12-, 13-, 14-, 16-, 24-hr, and 4-hr night interruption). Black cloth was pulled at 1700 and opened at 0800 HR; incandescent lamps provided 2 μmol·m–2·s–1 to extend light hours to the designed photoperiods. Seedlings were pinched 3 days after transplant. Responses to photoperiod were clearly species-dependent. The tested species can be classified into three groups: 1) stem elongation and flowering were promoted in the long-day treatment (A. frutescens and S. axillaris hybrids), 2) only stem elongation was promoted in the long-day treatment (S. aemula, H. bracteatum, and B. hybrid), and 3) neither flowering nor stem elongation were affected by photoperiod (S. cordata and V. hybrid).
Microbial Populations and Potential Phytotoxicity of Rhizobacteria Isolated from Jamaican Anthurium
Authors: Bergfield W.A. , Sasseville D.N. , Kremer R.J. , Souissi T.
Published: February 2019

Pesticides are used extensively in ornamental production. Studies of repeated pesticide applications indicate that microbial changes occur in the rhizosphere of the plant. In addition to controlling the target pest, often a population shift of bacteria may occur. This has been previously shown in research associated with leatherleaf fern [Rumohra adiantiformis (Forst.) Ching] and the fungicide benomyl. Rhizobacteria (root-associated bacteria) of anthurium (Anthurium andraeanum) were investigated with respect to total populations and isolates that are potentially phytotoxic. The anthurium sample roots were taken from commercial Jamaican production sites. The sites had either a benomyl or non-benomyl history. Rhizobacterial populations were estimated by dilution plating and subcultures were taken for a phytotoxicity bioassay. Micrographs of samples were prepared to examine treatment effects on the morphology of roots. Rhizobacteria populations were frequently at 106 colony forming units per gram fresh weight. Consistently, greater than 50% of the isolates from each treatment were potentially phytotoxic. However, in the benomyl history samples, there was a greater diversity of phytotoxic isolates.
Methionine–Riboflavin Mixture Reduces Powdery Mildews in Strawberry
Authors: Wang Shiow Y. , Tzeng Dean Der-Syh , Galletta Gene J.
Published: February 2019

Foliar application of a mixture of methionine and riboflavin was effective in reducing the severity of powdery mildew [Sphaerotheca macularia (Wallr. ex Fr.) Jacz. F. sp. Fragariae] infection in 72 strawberry progenies and over 110 clonal genotypes. This biocidal activity was enhanced by supplement of copper, iron, and surfactants [such as sodium dodecyl sulfate (SDS), Triton X-100, or Tween-20]. Compounds free radical scavengers (n-propyl gallate, thiourea), or antioxidants (α-tocopherol, -carotene) reduced its biocidal activity. Plants treated with the MR formulation (26.6 μM riboflavin, 1 mM D,L-methionine, 1 mM copper sulfate pentahydrate and 1 mg·ml–1 SDS) or 29% SP formulation of MR (Technical Division of the American Cyanamid Corporation, Taiwan Subsidiary at Taipei) not only showed decreased powdery mildew infection but also showed increased chlorophyll content and leaf area and improved fruit quality. Results in this study suggest that treatment with mixture of methionine and riboflavin is beneficial to strawberry plants and may serve as an alternative to fungicides for controlling powdery mildew.
Screening Onion Lines for Resistance to Sclerotium cepivorumBerk. using Field and Onion Scale Assessments
Authors: McDonald M.R. , Hovius M.H.Y. , Sirjusingh C.
Published: February 2019

Resistance to Sclerotium cepivorum was investigated over 3 years at field sites with known histories of white rot in the Holland Marsh, Ontario, Canada. Onion lines from three sources (Petoseed, Asgrow Ltd., and Univ. of Wisconsin), including commercial cultivars, were direct-seeded (1995) or hand-transplanted (1994 and 1996) and the bulbs were assessed for white rot incidence at harvest. The incidence of white rot in 1994 was low (0% to 2.6%) and not significantly different among lines and cultivars. In 1995, white rot incidence was moderate at sites 1 and 2 (maximum 21.5% and 24%), but low at site 3 (0% to 6.3%). In 1996, white rot incidence ranged from 0.8% to 41.1% at site 1, but was not observed at sites 2 and 3. The results of the 1995 and 1996 assessment suggested that the breeding lines could be divided into two major groups with high (Univ. of Wisconsin) or low (Asgrow Ltd. and Petoseed) resistance to the fungus. Scale segments of harvested bulbs from the 1995 field trial and 35 commercial cultivars were inoculated with mycelial plugs of two isolates of Sclerotium cepivorum. The resulting lesions were measured. Significant differences in lesion diameters among onion lines (9.1–22.4 mm) and cultivars (10.5–26.75 mm) were found within isolates. There was a significant, high, and positive correlation between diameters of lesions formed by the two isolates on the 23 lines (r2 = 0.76, P = 0.05) and 35 cultivars (r2 = 0.62, P = 0.005). Both techniques demonstrated a wide range of resistance to white rot. This suggests a strong potential for increasing resistance through breeding.
Adventitious Shoot Formation and Plant Regeneration from Bell Pepper (Capsicum annuum L.) Cultivars and Dihaploid Lines
Authors: Huerta Agustin , Dolcet-Sanjuan Ramon
Published: February 2019

Adventitious shoots and viable plants were regenerated from bell pepper (Capsicum annuum L.) cultivars and dihaploid lines (DHLs) obtained from F1 hybrids via androgenesis (Dolcet-Sanjuan et al., in press). Hypocotil and cotyledon sections from in vitro-germinated seeds were used as explants. A modified MS medium (Murashige and Skoog, 1962) supplemented with IAA (0 to 3.2 μM) and BAP (0 to 100 μM) was used in a 3-week-long shoot primordia induction phase. Shoot elongation was best performed in the same basal medium, but supplemented with silver thiosulfate and GA3. Shoots were regenerated from eight selected DHLs (`C213', `C215', `C218', `C2123', `C2125', `C3111', `C3113', and `P493') and two cultivars (`Padrón' and `Yolo Wonder'). The percentage of cotyledon sections with shoot primordia after the induction phase was not genotype-dependent and always higher than with hypocotil sections (93.4% and 17.9%, respectively). The number of shoot primordia per responsive cotyledon section was also higher than with hypocotil sections (3.3 and 1.7, respectively). The genotype had a significant effect on the number of shoots regenerated per responsive cotyledon (1.1 to 5.5) or hypocotil (0.5 to 3.5) section. All adventitiously regenerated plants were fertile. This adventitious shoot regeneration protocol is being used to obtain transgenic plants from sweet bell pepper genotypes.
In Vitro Multiplication of Potato (Solanum tuberosum L.) cv. Cristal under Different MS Salt and Sucrose Concentrations
Authors: de L. Fortes Gerson R. , Andrade Luciana B. , de F. Oliveira Marisa , Müller Nilvane T.G. , Faria Janine T. C.
Published: February 2019

The potato cultivar Cristal has recently been released by the CPACT/EMBRAPA Breeding Program. Such cultivar was selected for having high dry matter and low sugar content, which makes it desirable for the chip industry. However, this is a recalcitrant cultivar as far as in vitro multiplication is concerned. The aim of this work was to improve the rate of multiplication for this cultivar when it was submitted to different MS salt and sucrose concentrations in the culture media. Two-bud microcuttings were inoculated in test tubes (20 × 150) mm with 10 ml MS media at 3/4-, 1/2-, and full-strength and MS vitamins added to: myo-inositol (100 mg·L–1), agar (7.0 g·L–1) and sucrose as follows: 10, 20 and 30 g·L-1. Each treatment was repeated eight times and each replicate had eight explants. After inoculation the whole material was kept in a growth room at 25 ± 2°C, 16-hr photoperiod and 2000 lux. The evaluation was done 35 days later. It was found and increase in the number of buds as the sucrose concentration in the media decreased. As far as MS salts are concerned no difference in bud number was observed. The rate of multiplication was slightly higher for MS media at full strength and sucrose at low concentration (10 g·L–1). This treatment could be recommended for this cultivar.
In Vitro Multiplication of Potato (Solanum tuberosum L.) cv. Cristal II—Microcutting Origin
Authors: de L. Fortes Gerson R. , Andrade Luciana B. , Faria Janine T.C. , de F. Oliveira Marisa , Müller Nilvane T.G.
Published: February 2019

The potato cultivar Cristal recently released by the CPACT/EMBRAPA Breeding Program has high dry matter and low reduce sugars. These are desirable characteristics as industry processing is concerned. Nevertheless, this is a recalcitrant cultivar. The meristem culture is difficult to establish along with a very low multiplication rate. The aim of this work was to improve the multiplication rate for this cultivar. Two-bud microcuttings derived from apical, mid, and basal regions were inoculated in test tubes with 10 ml MS culture media and vitamins as follows; myo-inositol (100 mg·L–1); sucrose (10 g·L–1). No growth regulator was added. All treatments were placed in a growth room in a 16-hour photoperiod; 25 ± 2°C and 2000 lux. One month later, although it was observed that the final growth was more pronounced for basal microcuttings, no difference could be detected for number of shoots and multiplication rate. It was concluded that it makes no difference whatsoever kind of microcutting is used to start the micropropagation process.
Effect on Yield and Incidence of Blossom-end Rot of Foliar Application of Calcium Products on Tomato Cultivated in Saline Conditions
Authors: Franco J.A. , Pérez-Saura P.J. , Durán A.
Published: February 2019

The appearance of blossom-end rot (BER) in tomato is related to a decrease in the absorption and translocation of Ca due to excessive salinity in the soil solution. An experiment was conducted to investigate the effects of calcium nitrate (NT), EDTA-Ca (ED) and Aminoquelant-Ca (AQ)—a product containing Ca, B and protein hydrolisate—on the yield and incidence of BER when applied to the leaves of tomato (Lycopersicon esculentum Mill. `Durinta') grown in the open with a drip irrigation using saline water from a well (mean ECw 5.2 dS·m–1). The three calcium treatments and control were replicated four times, with 12 plants per replication, in a completely randomized design. Although yield per plant was higher with AQ, the difference was not statistically significant. Fewer fruit were affected by BER after treatment with ED and AQ than with NT and in the control. Leaf Ca concentration did not differ significantly between treatments. However, leaf B concentration was higher after treatment with AQ. Fruit Ca and B concentrations did not differ significantly in any treatment. The total free amino acids content in leaves was higher after AQ treatment than in the other treatments and control, although no significant difference was observed between the treatments in the fruit.
Characterization of Alstroemeria Species using Random Amplified Polymorphic DNA (RAPD) Analysis
Authors: Picton Deric D. , Hughes Harrison G.
Published: February 2019

In this study, 11 species, hybrids, and color variants were characterized using randomly amplified polymorphic DNA (RAPD) analysis. Total genomic DNA was extracted using a 2% CTAB extraction buffer using fresh or frozen leaf material. The DNA was amplified using standard RAPD-PCR protocols utilizing 10-mer primers. All primers utilized exhibited a high degree of polymorphism in their banding patterns among the species and hybrids studied. The primers used produced ≈40 reproducible bands. It was possible to identify and uniquely distinguish all species and hybrids investigated using these bands.
The Response of Long-day Herbaceous Perennials to a Night-interruption at Low Night Temperatures
Authors: Frane Alison , Heins Royal , Cameron Art , Carlson William
Published: February 2019

A 4-hr night interruption (NI) is an effective way to promote flowering in many long-day herbaceous perennials. Some perennials are grown outdoors in the early spring and often are exposed to low night temperatures. Long days delivered by NI lighting ineffectively promote flowering under low-temperature conditions in some long-day species. The objective of this experiment was to determine the effectiveness of NI long-day lighting treatments delivered at different night temperatures in promoting flowering of several herbaceous perennials. Ten herbaceous perennial species were grown under natural short days augmented with a 4-hr NI. Night temperatures were 2.5, 5, 10, 15, 20, and 25°C with day temperature of 25°C for all treatments. Plants were transferred to 9-hr days at a constant 20°C after 7 weeks of treatment. Results on flowering percentage, date of visible bud and flowering, node count, flower bud count, and plant height at flowering will be presented.