bluuebunny/crossref_metadata_2025 huggingface dataset:
220 Gibberellic Acid Tank Mix and Adjuvant Effects on Peel and Juice Quality of `Hamlin' Oranges
Authors: Davies F.S. , Fidelibus M.W. , Campbell C.A.
Published: February 2019

An experiment was conducted to determine if gibberellic acid (GA; ProGibb, Abbott Labs) can be mixed with Aliette or Agri-Mek and oil to reduce application costs, without reducing GA efficacy, and if Silwet and Kinetic adjuvants enhance GA efficacy. Five tank mixes were tested along with a nonsprayed control. The tank mixes included: 1) GA, 2) GA + Silwet, 3) GA + Kinetic, 4) GA + Silwet + Aliette, and 5) GA + Silwet + Agri-Mek + oil. All compounds were applied at recommended concentrations. In September, ≈24 L of each tank mix was applied with a hand sprayer to mature `Hamlin' orange trees [Citrus sinensis (L.) Osb.] on sour orange (Citrus aurantium L.) rootstock. Peel puncture resistance (PPR), peel color, and juice yield (percent juice weight) were evaluated monthly between Dec. 1997 and Mar. 1998. On most sampling dates the fruit of treated trees had higher PPR and were less yellow in color than fruit from control trees. However, in Jan., fruit treated with GA + Silwet and GA + Kinetic had greater PPR than other treatments. In Feb., fruit treated with GA + Silwet + Agri-Mek + oil had the lowest PPR. The effect of the different tank mixes on juice yield was usually similar to the effect of the tank mixes on PPR and peel color. On 8 Jan. 1998, fruit from trees treated with GA alone yielded significantly more juice than fruit from control trees. On 24 Feb. 1998, fruit from trees treated with GA alone yielded more juice than fruit from the other treatments. Thus, GA efficacy is generally not reduced by these tank mixes, nor improved by adjuvants.
222 The Use of Polyacrylamide Polymer to Improve the Growth of Young Apple Trees
Authors: Smith D.E. , Crassweller R.M.
Published: February 2019

Water-sorbing polymers have been used in greenhouses and in arid and semiarid regions to improve soil water properties. Laboratory and field studies were conducted to investigate the effects of a cross-linked polyacrylamide polymer when incorporated into a silt loam. The soil treatments consisted of 0%, 0.06%, 0.12%, and 0.25% polymer by weight. The laboratory study consisted of four soil columns each containing a treatment. Water was added at a rate of 6.1 mm to the columns every 2 days. Soil moisture and volume was measured daily. The field experiment contained apple trees planted into soil amended with the different rates of polymer and covered with a polypropylene weed barrier. Tree growth and fruit yield were recorded from 1996-1998. The volume and bulk density of the soil-polymer matrix were dependent on the moisture content due to the swelling properties of the polymer. Bulk density was highest when no polymer was added and lowest for soil containing 0.25% polymer. Soil moisture measured by time delay reflectometry showed multiple wetting fronts in the soil columns after water was added. During the 1996 growing season, soil moisture was higher for field plots containing the weed barrier and amended with polymer; however, this trend was reversed in 1997. Tree growth was not effected in any of the years data was taken. Fruit yields did not differ between treatments in 1997. Fruit set and yield in 1998 was greater for trees planted without the weed barrier and polymer. The addition of polymer was not found to benefit apple tree growth or yields.
223 Prohexadione-Ca: Effects against Apple Scab (Venturia inaequalis)
Authors: Rademacher W. , Stammler G. , Creemers P.
Published: February 2019

Many trials have demonstrated that apple and pear trees treated with the plant growth regulator prohexadione-Ca (BAS 125 W) are less susceptible to infestation by the bacterial disease fire blight. In further investigations we have studied the effect of this compound against fungal diseases, concentrating on scab (Venturia inaequalis) in apple. Working with apple seedlings and artificial inoculation under greenhouse and field-like conditions, scab infestation could be reduced by applications of prohexadione-Ca. Whereas this effect was rather marginal if inoculations were made shortly after treatment, highly significant effects were found in the time span of ≈1 to 4 weeks after application. Preliminary results from trials conducted under orchard conditions support these findings. We assume that, similar to the situation with fire blight, changes in phenylpropanoid metabolism are mainly responsible for the reduced scab incidence. It should not be ruled out, however, that anatomical and morphological changes caused by prohexadione-Ca may also contribute to this effect.
225 Prohexadione-Ca: Reduction in Vegetative Growth and Pruning of Apple Trees
Authors: Evans J.R. , Balles J.A. , Brinkman B.A. , Harris V.E. , Helm J.D. , Kirksey K.B. , McKemie T.E. , Thomas G.G. , Rademacher W.
Published: February 2019

Prohexadione-Ca (BAS 12511W or Apogee™ Plant Growth Regulator) acts within a plant by blocking the biosynthesis of growth-active gibberellin. The result is decreased cell and shoot elongation; thus, vegetative growth in apple trees can be reduced. Air blast applications of prohexadione calcium were made in the Spring 1998 in commercial orchards. Application rate was 125 ppm a.i. applied twice beginning at 5 to 12 cm of new shoot growth. Reduction of shoot growth averaged 45% across locations. As a result of reduced vegetative growth, dormant pruning was reduced. In total, significant benefits to the grower included reduced pruning costs in addition to other positive effects such as improved light penetration and enhanced resistance to some pathogens. Research will continue with the effect of prohexadione-Ca on pruning in multiple year studies.
229 Solid Matrix Priming of Gourd Seeds for Fast and Uniform Germination
Authors: Bang Hae-Jeen , Hwang Soo-Jung , Ham Hyun-Sook , Lee Jung-Myung
Published: February 2019

Grafting is common in all cucurbits in Asia, and gourd (Lagenaria siceraria) is the most popular rootstock for watermelons. Since the grafting is practiced at very early stage (right after the cotyledon expansion), uniform germination of rootstocks as well as the scions is crucial for grafting efficiency. Seeds were divided into three groups; intact, dry-heat treated (75 °C for 72 h), and brushed (575 rpm for 5 min). In each group, various solid matrix priming (SMP) treatments were imposed. Microcel E was used for SMP treatment with water or chemical solutions (10 seed: 1 Microcel E: 3 water, by weight). SMP treatment promoted earlier seed germination in all tested cultivars, thus resulting in higher rate of graftable seedlings. Brushing before SMP further enhanced earlier and uniform seed germination. Dry heat treatment, which can eliminated the seed-borne Fusarium spp. and virus, significantly delayed the early germination although the final germination percentage was not influenced. The characteristics of seedlings will also be presented.
230 Seed Priming of Triploid Watermelon Seed
Authors: Loehrlein Marietta , Ray Dennis T.
Published: February 2019

Triploid watermelon seed does not germinate in cold, wet soils as well as diploids; germination is slower due to reduced embryo size and thicker seed coat; fissures on the seed coat provide safe harbour for fungal spores; and triploid fruit set is later than most diploid cultivars. Because of these problems producers often transplant rather than direct-seed seedless watermelons. Seed priming has been shown to improve germination in other crops and would be an attractive method allowing for direct seeding of seedless watermelons. Seed from open-pollinated 4n × 2n crosses were primed in solutions of H2O, polyethylene glycol 8000, KNO3, or left untreated. Treatment times were 1, 3, or 6 days, and treated seed were subsequently dried for either 1 or 7 d. Seed were scored for germination in the laboratory and emergence under field conditions. Germination was better using H2O than KNO3 and PEG but not always better than the untreated control. Treatment time of 1 day was superior to 3 or 6 days, but length of drying time was insignificant. In the field trial, treatments did not differ in emergence.
237 Rootstock and Scion Trials for Lemon in Arizona
Authors: Wright Glenn C.
Published: February 2019

Five rootstocks, `Carrizo' citrange, Citrus macrophylla, Rough lemon, `Swingle' citrumelo, and Citrus volkameriana, were selected for evaluation using `Limoneira 8A Lisbon' as the scion. Four years of yield and fruit packout data indicate that trees on C. volkameriana and C. macrophylla are superior to those on other rootstocks in growth and yield. `Swingle' and `Carrizo' are performing poorly, and Rough lemon is intermediate. In a similar trial, four `Lisbon' lemon selections, `Frost Nucellar', `Corona Foothills', `Limoneira 8A', and `Prior' selections of Lisbon lemon were selected for evaluation on Citrus volkameriana rootstock. Four years of yield and packout data indicate that the `Limoneira 8A Lisbon' selection has generally outperformed the other selections in both growth and yield, although `Corona Foothills' has been superior in the 1998-99 harvest season.
246 Arbuscular Mycorrhizal Fungal (AMF) Colonization of Carica papaya `Waimanalo' Grown in Composted Landscape Yard Trimmings
Authors: Martin Chris A. , McDowell L. Brooke , Marler Thomas E. , Stutz Jean C.
Published: February 2019

Seedlings of Carica papaya L. `Waimanalo' (papaya) were transplanted into 27-L containers filled with nonsterile composted landscape yard trimmings passed through a 1.3-cm screen. At transplanting, papaya plants were inoculated with either one of three different AMF communities or were not inoculated as control plants. Two of the AMF communities were from Arizona citrus orchards, and one AMF community was from an undisturbed western Chihuahuan Desert soil. After transplanting, papaya plants were grown for 4 months under well-watered conditions in a temperature-controlled (32 °C day/24 °C night) glasshouse (45% light exclusion). Control plants remained non-mycorrhizal. Total colonization of papaya roots by AMF communities ranged from 56% to 94%. Depending on mycorrhizal treatment, AMF arbuscules and internal hyphae were present in 30% to 60% and 20% to 24% of roots, respectively. Noticeably absent in papaya roots were AMF vesicles. Papaya height, trunk diameter, and leaf phosphorus concentration were similar for inoculated and control plants. Compared with control plants, papayas inoculated with AMF communities had about 20% less shoot dry weight and about 50% less root dry weight. Under nonlimiting conditions in an organic substrate, AMF communities did not stimulate papaya growth but rather appeared to function as a carbon sink.
252 Oil Emulsions Enhance Transcuticular Movement of Captan into Apple Leaves
Authors: Bondada B.R. , Sams C.E. , Deyton D.E
Published: February 2019

Oil sprays increase the phytotoxicity of captan to apple foliage. The purpose of this study was to determine if oils increase the penetration of captan through leaf cuticles. Enzymatically isolated apple leaf cuticles were used as a model system to study captan penetration. A bioassay was developed using the inhibition of growth of Penicillium cyclopium on potato-dextrose agar as a measure of captan penetration through the cuticle. Captan penetrated through both surfaces, but significantly more penetrated through the abaxial cuticles than the adaxial cuticles. Increasing the captan concentration increased the captan penetration through the abaxial cuticle in a linear relationship. Captan penetration through the cuticle was increased by 63% when cuticles were treated with captan plus 1% emulsified soybean oil. Abaxial cuticles treated with captan plus emulsified soybean oil or with captan plus SunSpray Ultra-Fine oil had >125% greater captan penetration than cuticles treated with only captan. Cuticles treated with captan plus dormant oil (petroleum oil) had 220% more captan penetration than the captan only treatment.
253 The Use of Particle Film Technology in Tree Fruit Production
Authors: Glenn D.M. , Puterka G. , Drake S.
Published: February 2019

Particle film technology uses inert mineral particles to envelope a plant in a protective and porous “particle film.” The film appears to protect against insect damage by creating a hostile and unfamiliar environment, causing nonrecognition of the host, acting as an irritant, and giving poor adhesion or gripping of eggs and insects to the plant surface. Being porous, the particle film allows free exchange of water and carbon dioxide from the leaf during photosynthesis. The mineral particles are reflective of infrared radiation and reduce the heat load on the plant. Laboratory, greenhouse, and field trials demonstrate that particle film technology is a viable pest control practice for a wide range of insect and disease problems with additional horticultural benefits due to reduced heat stress. In field studies, reducing heat stress improved red apple color development, increased leaf photosynthetic rates, and increased yield. Particle film technology appears to be a viable alternative to conventional pesticide use in apple and pear production. Particle films have the added benefits of reducing plant heat stress and improving safety to farm workers, consumers, and the environment.
258 Pampas Grass (Cortaderia argentea) Response to Ancymidol, Paclobutrazol, and Uniconazole Substrate Drenches
Authors: Sellmer James , Adkins Craig R. , McCall Ingram , Whipker Brian
Published: February 2019

Plant growth retardant (PGR) substrate drenches (in milligrams active ingredient) of ancymidol at 0.25, 0.5, 1, 2, or 4; paclobutrazol at 1, 2, 4, 8, or 16; and uniconazole at 0.25, 0.5, 1, 2, or 4 were applied to pampas grass (Cortaderia argentea Nees) to compare their effectiveness at chemical height control during greenhouse forcing and evaluate the residual effect on plant growth in the landscape. Cortaderia argentea plant height exhibited a quadratic dose response to paclobutrazol and uniconazole, while ancymidol-treated plants showed a linear dose effect. During greenhouse production, all rates of uniconazole reduced plant height by 56% to 71% compared to the untreated control, whereas paclobutrazol and ancymidol treatments reduced plant height by 14% to 61% and 0% to 34%, respectively. Severe height retardation was evident at 2 mg of uniconazole. By week 5 in the field all plants treated with uniconazole, paclobutrazol doses of 4, 8, or 16 mg, and with 4 mg of ancymidol were shorter than the untreated control. By week 24 in the field, all plants exhibited similar heights except plants treated with uniconazole at 1, 2, or 4 mg remained shorter than the untreated control. In conclusion, each PGR was effective in controlling plant height of Cortaderia argentea during greenhouse forcing. Furthermore, plants treated with low to moderate rates of ancymidol or paclobutrazol grew out of the regulating effect by week 5 in the landscape. These results demonstrate that PGR can be effectively and economically employed in the production of Cortaderia argentea.
259 Comparison of On-site and Electronic Meteorological Service Weather Data for Use with a Disease Forecast System
Authors: Maletta M.H. , Cowgill W.P. , Manning T. , Tietjen W. , Johnston S.A. , Nitzsche P.
Published: February 2019

Weather information has many applications in crop production practices, including disease forecasting. A variety of weather instruments are available for on-farm use, but associated costs and need for regular calibration and maintenance can limit actual use, especially by smaller growers. Subscription to an electronic meteorological service may be a viable alternative to on-site weather stations. In 1997 and 1998, hourly temperature, relative humidity and leaf wetness were monitored at six sites in a 400-m2 area of New Jersey with Field Monitor™ data loggers (Sensor Instruments, Inc.) and by subscription to SkyBit, Inc., an electronic meteorological service. There was close correspondence in temperature data from the two sources at all sites, the average seasonal difference ranging from 0 to 2 °F. Relative humidity data was variable between the two sources, the greatest variation occurring at low and high humidity, the ranges at which relative humidity sensors had been shown to be least accurate. Leaf wetness estimates from the two sources agreed at least two-thirds of the time. Data differences related to source were attributed to both systematic and random error. The usefulness of electronic weather data in crop production depends on how sensitive the particular weather-dependent applications (e.g., predictive disease and insect models) are to variation in the input data. The TOM-CAST early blight forecaster for tomatoes was not particularly sensitive to differences between SkyBit and Field Monitor leaf wetness estimates.
263 Selected Seed Treatments to Enhance Germination of Oil-bearing Oenothera Species
Authors: Murphy C.L. , Hopper N.W. , McKenney C.B. , Auld D.L.
Published: February 2019

The oil extracted from seed of selected accessions of Oenothera, also known as the wildflower evening primrose, has documented medical applications. Evening primrose oil contains from 0.0 to 12.0% gamma-linolenic acid (GLA) (C 18:3, delta 6, 9, 12). This unique fatty acid, which occurs in only a few plant species, can correct deficiencies in the delta 6 desaturase enzyme. Low levels of this enzyme prevent formation of the long chain fatty acids responsible for the production of prostaglandins and thromboxanes. Supplementation of the diet with evening primrose oil rich in GLA ensures adequate levels of these essential products. Inconsistent seed germination, poor emergence, and small seed size of accessions containing higher levels of GLA have limited commercial production of this crop. Currently, most producers establish their field through transplants. In this project, methods of improving seed germination have been explored. Seed coatings using diatomaceous earth were shown to facilitate handling and improve germination in the laboratory. Osmotic priming and red light exposure were also evaluated as means of improving germination.
265 Root Architecture in Quercus falcata after Physical Removal of the Radicle Tip or Copper Treatment
Authors: Martins Gisele G. , Geneve Robert , Kester Sharon
Published: February 2019

Quercus falcata acorns were cold-stratified for 120 days and then sown in vermiculite under greenhouse conditions. When radicles were 7 cm long, the root tip was either removed (physically pruned) or dipped in a copper hydroxide solution (copper-treated). Intact root systems were used as control. Seedlings were then moved to a root box to observe root system architectures. The box was built of clear plexiglass 2.5 mm thick, and each face was 25.7 × 35.7 cm. Styrofoam spacers were used to separate faces, and nuts and bolts were placed along edges to hold the root box together. To permit observation of the entire root system, plants were grown in a plane between the plexiglass surface and a nylon sheet that separated roots from the medium (MetroMix 510). At 7, 9, and 11 days after treatment, the entire root system was traced on an acetate sheet, and number of internal and external links and number of secondary and tertiary roots were recorded. Total length, internal and external root links length, were obtained using digital analysis (MacRhizo). Dry weight of roots and shoots was collected at the end of this experiment (day 11). Treatment effects were evident 11 days after treatment. Copper-treated plants had statistically more secondary roots and larger internal link length than control or physically pruned plants. Also, copper-treated plants had smaller mean external link length, showing a more branched root system. Root biomass was similar for all treatments; however, copper-treated plants had smaller root: shoot ratio. This suggests that copper was acting as more than a pruning agent because copper-treated plants showed a different root system architecture compared to physically pruned plants.
269 Effect of ReTain on Peach Harvest Delay and Fruit Quality
Authors: Ebel Bob , Boozer Bobby , Pitts Jim
Published: February 2019

This experiment was conducted to determine peach harvest delay, quality, and storage life by ReTain. ReTain was applied to `Loring' at 50 ppm at 17, 14, 12, 10, or 7 days before harvest (n = 4). Fruit were harvested based on conversion of ground color to yellow over five dates at 3- to 4-day intervals in July. Fruit were segregated into five size classes, counted, and weighed. Ten fruit were randomly selected from the 2.5-in. size class, and fruit quality was measured at harvest and after 5 days at 20 °C. Some fruit were stored for 5 days at 4 °C, removed from storage, and fruit quality measured 4 h after removal. Harvest date was not affected by ReTain. Firmness was higher for fruit held at 5 days in cold storage with earlier treatment application but not at harvest or after 5 days at room temperature, although the trend at harvest was similar to the 5-day storage data. Soluble solids were not affected at harvest, after storage or after 5 days at room temperature. Red blush was slightly less at harvest and after 5 days in cold storage with earlier application rates, but differences disappeared after 5 days at room temperature. Yellow color was higher with earlier application date after 5 days of cold storage but not at harvest or after 5 days at room temperature. These results indicate that ReTain may have some utility for improving peach firmness at harvest, but there was no benefit of harvest delay at the rates applied in this study.
272 Development of Apple Cuticular Matrix Sub-structure
Authors: Curry Eric , Bair Donald , Young Jim
Published: February 2019

The cuticle is a complex organ. As the first line of defense for apple fruit, its main function is to protect cells from desiccation. It begins developing within several weeks of anthesis and continues responding to environmental conditions until the underlying tissue becomes necrotic. The physicochemical properties of the cuticle differ with cultivar and stage of development but are thought to be composed of carbohydrate fibers extending from the cell wall or the aqueous apoplast. If the latter is true, these fibers could allow contact or exchange with the environment through the lipoidal cuticle matrix. This visual report is the result of an examination of the substructure of the apple cuticle using scanning electron microscopy. These high-resolution micrographs suggest a transcuticular continuum exist in the form of tubular fibers.
275 Water Relations of Fruit Cracking in Single-truss Tomato Plants
Authors: Ikeda Takashi , Okano Kunio , Sakamoto Yuka , Watanabe Shin-ichi
Published: February 2019

This study was undertaken to investigate the water relations of tomato (Lycopersicon esculentum Mill.) fruit cracking for single-truss tomato plants. The tomato plants were cultured on a closed hydroponic system in greenhouse. Water status of culture solution and plant tissues was measured with psychrometers. Water potential of the culture solution for the stressed plant was changed from -0.06 MPa (control plants) to -0.36 MPa at 24 days after anthesis. Hardness of the fruit skin was not different significantly between the stressed plants and the control plants. Fruit cracking occurred frequently in the control plants, but not in the stressed plants. Water potential gradient between the tissue of fruit flesh and water source for the control plants was bigger than that of the stressed plants. Turgors were increased at the tissues of fruit flesh and fruit skin at the control plants between predawn and morning but not at the stressed plants. These results indicated that the water potential gradient and the increased turgor in these tissues might be a trigger for the occurrence of fruit cracking on single-truss tomato plants.
281 Water Use in Herbaceous Landscape Plants
Authors: Paul Catherine A. , Davis Greg L. , Horst Garald L. , Rodie Steven N.
Published: February 2019

Water conservation in a landscape is an important issue because periodic water shortages are common in many regions of the world. This increases the importance of specifying landscape plants that require less water and matching the plant to site microclimates. Our objectives were to establish water-use rates for three herbaceous landscape plants and to determine the level of water reduction these plants can tolerate while maintaining both visual and landscape quality. Water use rates were determined for Schizachyrium scoparium (Little bluestem), Hosta spp. (Hosta) and Festuca cinerea `Dwarf' (Dwarf blue fescue) in studies using pot lysimeters at the Univ. of Nebraska Horticulture Research Greenhouse facility. Each lysimeter was watered to saturation, allowed to drain to field capacity, and weighed. The lysimeters were weighed again 24 h later, and the process was repeated to determine daily evapotranspiration. Results indicated that hosta used less water than dwarf blue fescue and little bluestem. In a subsequent study to compare the relative effects of withholding irrigation among these species, seven groups of five replicates of each species were grown in 1 peat: 0.33 vermiculite: 0.66 soil: 1 sand (by volume) in 7.6-L containers. Each container was watered to saturation, allowed to drain for 24 h to reach field capacity, and allowed to dry down in 10-day increments. Results of the dry-down study indicated that little bluestem maintained the best visual quality for the longest duration of drought, followed by dwarf blue fescue and hosta in decreasing order of visual quality.
285 Interaction between Cold Duration, GA3, and Photoperiod on Raphanus sativus L. Flowering
Authors: Warner R.M. , Erwin J.E. , Smith A.G.
Published: February 2019

Previous research indicated that Raphanus sativus L. `Chinese Radish Jumbo Scarlet' (CJRS) has an obligate vernalization requirement for flowering and can be vernalized as an imbibed seed in less than 10 days at 6 °C. For these reasons, it serves as an excellent model system for vernalization studies. This study was initiated to gain an understanding of the interaction between cold duration, exogenously applied GA3, and photoperiod on R. sativus CJRS flowering. R. sativus CJRS seeds were sown in 90-mm petri plates on Whatman no. 1 filter paper saturated with plain water or a solution containing 10-5 M or 10-3 M GA3. After germination (i.e., when the radicle was visible), seedlings were either directly transplanted into 10-cm pots and placed in a greenhouse, or transferred to another petri plate onto filter paper saturated with water only and placed in a growth chamber at 6 °C (75 μmol•m-2•s-1 for 8 h) for 2, 4, 6, 8, or 10 days. Greenhouse conditions were: 20 °C, ambient light (December to January, St. Paul, Minn.) plus 70 μmol•m-2•s-1 supplemental light (high-pressure sodium lamps, 0830-1630 hr), under either an 8-h photoperiod (covered with opaque cloth from 1630-0830 hr), or ambient photoperiod plus night-interruption lighting (2 μmol•m-2•s-1, using incandescent lamps, 2200-0200 HR). Results will be presented.
290 Nutrient Uptake by New Roots of Six Clonal Apple Rootstocks
Authors: Dong Shufu , Cheng Lailiang , Fuchigami L.H.
Published: February 2019

The nutrient uptake kinetics by new roots of 1-year-old potted clonal apple rootstocks (M7, M9, M26, M27, MM106, and MM111) were determined by the ion depletion technique at the stable development stage of trees in August. The total roots of five of the rootstocks (except MM111) consisted of more than 60% feeder roots and less than 12% extension roots. MM111, the most vigorous rootstocks tested, had 60.7% feeder roots and 24.5% extension roots. Root: top ratio was negatively related to the growth inhibiting character of the rootstock. Nutrient uptake by excised new roots was found to fit into Michaelis-Menton kinetic model for all rootstocks tested. The kinetic characteristics (maximum uptake rate, Imax, apparent Michaelis-Menton constant, Km, and root absorption power, (α = Imax•1/Km) between rootstocks differed significantly. MM111 had the highest Imax for NH4+ absorption and M9 for NO3-. Root affinity to ions was highest with MM106 for NH4+ and with M26 for NO3-. Root absorption power (α = Imax•1/Km) was greatest in MM106 for NH4+ and M9 for NO3-. At this developmental stage the data suggest no relationship between nutrient uptake and dwarfing character of the rootstocks.
291 Effect of Nitrogen Fertilization Time on Nitrogen Storage and Return Bloom of Pecan
Authors: Acuña-Maldonado Laura E. , Smith Michael W.
Published: February 2019

A study was conducted to compare a single nitrogen application in March (125 kg N/ha) vs. a split application in March (75 kg N/ha) and October (50 kg N/ha) on 15-year-old `Maramec'. After one season, N application time did not affect return bloom. A split N application increased trunk wood Kjeldahl-N but decreased Kjeldahl-N in the current season's reproductive shoots and 1-year-old branches compared to a single application in March. Kjeldahl-N concentration was not affected by treatment in current season's vegetative shoots, trunk bark or roots. Nitrate-N concentration was not affected by treatment in any tissue sampled. Between the first week of October and the first killing frost in November, Kjeldahl-N increased 29% in current season's shoots, 21% in trunk bark, 32% in roots >1 cm in diameter, and 15% in roots <1 cm in diameter but decreased 42% in trunk wood and 5% in 1-year-old branches. Roots <1 cm in diameter accumulated more nitrate-N than other tissues during November.
300 Bioregulators Can Affect Apple Mineral Nutrition
Authors: Ouma George , Matta Frank
Published: February 2019

Experiments were performed in 1995 and 1996 at the Mississippi State Univ. Agricultural Experiment Station, Pototoc Ridge, to investigate the effect of Accel and carbaryl sprayed 2 weeks postbloom on fruit set, yield, and plant nutrition of three apple cultivars (Empire, Jon-A-Red, and Braeburn). The treatments consisted of Accel 25 ppm, Accel 50 ppm, Accel 75 ppm, Carbaryl 0.05%, Carbaryl 0.1%, Carbaryl 0.2%, and an unsprayed control. Thinning trials using the two bioregulators conducted over 2 years indicated that Accel and Carbaryl consistently thinned the apple cultivars and increased the yields. Leaf mineral concentrations were affect by the treatments. In 1995, the treatments affected leaf concentrations of N, Ca, and Mg, while in 1996 the treatments affected the leaf contents of N, P, K, Ca, Mg, Fe, Mn, and Zn, but no copper. The treatments also affected the fruit flesh mineral concentration by increasing the contents of K, P, and Mg in 1996. It can therefore be concluded that, depending on apple cultivar, N content was reduced by the treatments while Ca and Mg were generally increased. Similarly, the fruit flesh contents of Fe, K, P, and Mg were also increased. The two bioregulators therefore thin apples, increase yields, and affect the fruit quality.
303 Effect of Growth Regulators on the Growth and Performance of Celosia plumosus
Authors: Shaw Sabrina L. , Williams Eddie B. , Hayslett William F.
Published: February 2019

Seedlings of Celosia plumosus `New Look', a new variety, were evaluated for their response to the recommended rates of three different plant growth regulators commonly used by growers. The plant growth regulators were B-nine, paclobutrazol, and uniconizole. These plant growth regulators were applied at the rate recommended by the manufacturer for this species. Group I, the control, was not treated with a plant growth regulator, but was sprayed with water at the same time the other treatments were applied. Plants were grown in 5-inch plastic pots in the greenhouse. Plant height was recorded before treatment and once weekly thereafter for the duration of the experiment. Upon termination of the experiment, plant top fresh weight and top dry weight were measured. Results showed that at the recommended rate for all three plant growth regulators, there were no significant difference in height or weight between the plant growth regulator-treated groups of plants or the control group. The only observable difference noted was in leaf coloration of the plants treated with plant growth regulators.
305 Omega-3 Fatty Acid Concentration of Purslane (Portulaca oleraceae L.) Is Influenced by the Stage of Harvest and the Variety
Authors: Palaniswamy U. , McAvoy R. , Bible B.
Published: February 2019

Omega-3 fatty acids (O3FA) are essential for normal human growth, development, and disease prevention. Purslane (Portulaca oleraceae L.) is an excellent source of alpha-linolenic acid (LNA, an O3FA) and the anti-oxidant alpha-tochopherol. Twenty-one-day-old seedlings of cultivated purslane seedlings were transplanted into greenhouse (≈18-20 °C) and arranged in a randomized complete-blocks design with six replications. Plants were fertilized with nitrogen at 25 mg·mL-1 for the first week, 50 mg·mL-1 for the next week, and 100 mg·mL-1 until harvest using a 20N-4.4P-16.6K water-soluble fertilizer in the irrigation water. The terminal three nodes of shoots were harvested at 6, 10, and 14 trueleaf stage. At each harvest the dry mass (DM), fresh mass (FM), and leaf area were determined. The leaf and stem LNA concentration were determined using gas chromatography. The leaf fatty acid concentrations were 30% to 52% higher at the 6- and 14-leaf stages than at 10-leaf stage. The fatty acid concentrations at the 6- and 14-leaf stages did not differ significantly from each other. FM, DM, and leaf area were the highest at the 14-leaf stage. These data indicate that fatty acid levels do vary with the stage of development in purslane. A more detailed study is necessary to follow the change in LNA concentration in purslane throughout its ontogeny beyond 14 leaves. In another study to determine if the LNA concentration of the upright cultivated type of purslane differed from that of the prostrate wild type, we observed that at 14 to 16 true-leaf stage. the leaves from the cultivated type had 52.5% and 35.2% greater linoleic acid and LNA, respectively, than the wild purslane. In both varieties, leaves were richer in LNA than were the stems. Though the varieties did not differ significantly in the DM yield, the FM and leaf area were higher in the cultivated type than the wild type.
307 Characterization of Amylolytic Activities of Tulip Bulb Scales
Authors: Ranwala Anil P. , Miller William B.
Published: February 2019

Amylolytic activities extracted from scales of tulip (Tulipa gesneriana L. cv. Apeldoorn) bulbs stored at 4 °C for 6 weeks under moist conditions were characterized. Anion exchange chromatography of enzyme extract on DEAE-Sephacel revealed three peaks of amylolytic activity. Three enzymes showed different electrophoretic mobilties on nondenaturing polyacrylamide gels. The most abundant amylase activity was purified extensively with phenyl-agarose chromatography, gel filtration on Sephacryl S-200, and chromatofocusing on polybuffer exchanger PBE 94. The purified amylase was determined to be an endoamylase based on substrate specificity and end product analysis. The enzyme had a pH optimum of 6.0 and a temperature optimum of 55 °C when soluble starch was used as the substrate. The apparent Km value for soluble starch was 1.28 mg/ml. The inclusion of 2 mM CaCl2 in the reaction mixture resulted in a 1.4-fold increase in the enzyme activity. The presence of calcium ions also enhanced the thermo-stability of the enzyme at higher temperatures. The enzyme was able to hydrolyze soluble starch, amylose, amylopectin, and beta-limit dextrin, but it had no activity against pullulan, inulin, maltose, or p-nitrophenyl alpha-glucopyranoside. Only maltooligosaccharides, having a degree of polymerization of 7 or more, were hydrolyzed to a significant extent by the enzyme. Exhaustive hydrolysis of soluble starch with the enzyme yielded a mixture of maltose and matlooligosaccharides. This amylase activity was not inhibited by alpha- or beta-cyclodextrin upto a concentration of 10 mM. Maltose at a 50 mM concentration partially inhibited the enzyme activity, whereas glucose had no effect at that concentration.
308 Antioxidant Activity in Leaves and Fruit of Blackberry, Raspberry, and Strawberry
Authors: Wang Shiow Y. , Lin Hsin-Shan
Published: February 2019

Fruit and leaves from different cultivars of thornless blackberry (Rubus sp.), red raspberry (Rubus idaeus L.), black raspberry (Rubus occidentalis L.), and strawberry (Fragaria × ananassa D.) plants were analyzed for total antioxidant capacity (oxygen radical absorbance capacity, ORAC) and total phenolic content. In addition, fruit were analyzed for total anthocyanin content. Compared to fruit, leaves were found to have higher ORAC values. In fruit, ORAC values ranged from 7.8 to 33.7 μmol Trolox equivalents (TE)/g of fresh berries, while in leaves, ORAC values ranged from 20.8 to 45.6 μmol TE/g of fresh leaves. Fruit harvested at different stages of maturity were analyzed in blackberries, raspberries, and strawberries. Blackberries and strawberries had their highest ORAC values during the green stages, while raspberries generally had the highest ORAC activity at the ripe stage (with exception of cv. Jewel, a black raspberry). Total anthocyanin content increased with maturity for all three fruit. There was a linear correlation existed between total phenolic content and ORAC activity for fruit and leaves. For ripe berries, there was also a linear relationship between ORAC values and anthocyanin content. Of the ripe fruit and leaves tested, raspberry plants appeared to be the richest source for antioxidants.
309 Fertilizer Applications on the Growth of Three Groundcover Species in Sun and Shade
Authors: Sink R.A. , Einert A.E. , Klingaman G.L. , McNew R.W.
Published: February 2019

Use of groundcovers in the landscape is often limited due to their slow establishment rate compared to that of turf. Hedera helix L., (English ivy), Euonymus fortunei `Coloratus' (Turcz.) Hand.-Mazz. (purpleleaf wintercreeper euonymus), and Liriope spicata Lour. (creeping lily-turf) were evaluated in a full sun and 50% shade environment to determine the effects of fertilizer applications on their establishment and growth. Fertilizer treatments, of 13N-13P-13K at a rate of.45 kg/93 m2, used were: 1) at planting only; 2) at planting and once during the summer; 3) at planting, in summer, and once in the fall; or 4) at planting, in summer, in fall, and once the following spring. Data collected included fresh and dry weight comparisons of pruned material, percentage canopy cover, plant quality and vigor by visual assessment and photographs, and time required for maintenance of each plot. Results show limited fertilizer effects and interaction according to species during the first several months of growth. Establishment and survivability of Hedera was influenced mainly by light exposure rather than fertilizer applications. There was no difference in establishment rates between Liriope and Euonymus, however, under shade, Euonymus did not develop its characteristic fall color. Hedera was established in one season under 50% shade and can be considered very competitive with turf under the same conditions.
310 Lowbush Blueberry Response to Soil- or Foliar-applied Zinc Fertilizers
Authors: Smagula J.M. , Litten W. , Dunham S.
Published: February 2019

Lowbush blueberries (Vaccinium angustifolium Ait.) in two commercial fields were treated with a preemergent soil application of ZnSO4 at 0.34 g Zn/m2 or a prune-year or crop-year foliar application of Zintrac (1.76 g Zn/L) in a RCB design with five treatments and nine blocks, using 1.5 x 15-m treatment plots. Prune-year foliar Zintrac treatments were applied 20 June and 30 June at 53.8 mL·m-2 or 20 June at 107.6 mL·m-2. A crop-year application of Zintrac at 53.8 mL·m-2 was made on 26 June at only one location. Composite leaf tissue samples taken 14 July of the prune year indicated that two applications of Zintrac at 53.8 mL·m-2 raised Zn concentrations at both locations more than a single application at twice the rate. Soil application of ZnSO4 did not raise leaf Zn concentrations compared to the control at either location. Crop-year leaf samples taken 6 July at the site that received the crop-year foliar treatment indicated no carryover effect of prune-year Zn treatments on leaf Zn concentration, but crop-year foliar application of Zn from Zintrac did raise leaf Zn concentrations compared to the controls. The characteristics of stems sampled in the fall of the prune year at each location (stem density, stem length, flower bud formation) were not meaningfully affected by any of the prune-year treatments. Blueberry yield was not affected by any of the treatments at either location. These data suggest that control plot leaf Zn concentrations of about 15 ppm in both fields were adequate. Raising the leaf Zn concentrations to about 80 ppm with two applications of Zintrac at 53.8 mL·m -2 had no effect on growth or yield.
318 Interrelationships among Cumulative Yield, Scion Weight, and Trunk Cross-sectional Area of Apple Trees
Authors: Barden John A. , Marini Richard P.
Published: February 2019

Productivity of perennial fruit plants depends to a sizeable degree on partitioning of assimilates between vegetative and reproductive structures. Cultivars and rootstocks modify the partitioning pattern, but there are very few data published on these relationships. The termination of a long-term evaluation of standard-growing and spur-type strains of `Delicious' and `Golden Delicious' on several dwarf and semi-dwarf rootstocks and interstocks provided an excellent opportunity to assess the relationships among cumulative yield, scion weight, and trunk cross-sectional area (TCA). Cultivars were `Goldspur' and `Smoothee' strains of `Golden Delicious' and `Redchief' and `Red Prince' strains of `Delicious'. Rootstocks and interstocks included Malling 9 (M.9), M.26, M.9/Malling Merton 106 (MM.106), M.9/MM.111, M.7, MM.106, and MM.111. Row spacing was standard at 6.1 m. Tree spacing varied with anticipated vigor and ranged from 1.8 to 5.5 m. Pruning times and weight of prunings were recorded in two years. After 18 years, trees were cut off just above the soil line and weighed. TCA and scion weight were highly correlated despite of considerable differences in degree of containment pruning required, and cumulative yields were well correlated with both TCA and scion weight. The ratio of cumulative crop weight to final scion weight decreased quadratically with increasing TCA. Pruning times and weight of prunings were somewhat better correlated with TCA in `Delicious' than in `Golden Delicious'.
320 Does Water Availability Influence Photosynthesis and Yield Components of the Lowbush Blueberry (Vaccinium angustifolium Ait.)?
Authors: Glass V.M. , Percival D.C. , Proctor J.T.A.
Published: February 2019

Drought is the most limiting factor of crops worldwide. Sound management of any crop is based on a knowledge of its physiology as well as response to drought. Therefore, water use management has become an agricultural priority, with increased research focusing on plant growth and yield under limited water conditions. The lowbush blueberry (Vaccinium angustifolium Ait.) is the most important horticultural crop in Nova Scotia in acreage, export sales, and value to the economy. A study initiated at the Nova Scotia Wild Blueberry Inst., Debert (45°26′N, 63°27′W), N.S., during the 1998 growing season investigated the effects of water availability on the growth and development of the lowbush blueberry. Treatments consisting of supplemental irrigation (i), drought stress (d), and a control (c) were applied to plants in their cropping phase of production. Net photosynthetic rates (Pn) were highest during bloom (i: 11.9, d: 9.7, c: 9.8 μmol·m-2·s-1) and then declined throughout the season. No significant (P = 0.05) treatment effect on Pn was observed. Stem sample analysis before harvest showed no significant differences (P = 0.05) between stem length, node number, flowering node number, flowering zone length, or number of fruit per stem. Samples from 1-m2 quadrats indicated the drought-stressed plots produced the lowest yield (378 g·m-2) compared with the supplemental irrigation (449 g·m-2) or control (512 g·m-2) plots. Results from this study suggest drought stress on the lowbush blueberry does not produce significant differences in the number of fruit set; it does result in smaller fruit.
323 Identification of Aglaonema Cultivars for Resistance to Chilling Temperatures
Authors: Chen Jianjun , Henley R.W. , Henny R.J. , Robinson C.A. , Caldwell R.D.
Published: February 2019

Aglaonema is among the most popular tropical ornamental foliage plants used indoors because of its bright foliar variegation, low light and humidity tolerance, and few pests. Aglaonema, however, has been labeled as one of the most chilling-sensitive foliage plants. The dark, greasy-appearing patches on leaves injured by chilling can result in completely unsalable plants. With recent breeding activity, more and more Aglaonema cultivars have been developed and released. How new cultivars respond to chilling temperatures is, however, mostly unclear. This study was undertaken to evaluate cultivar chilling responses to identify chilling-resistant cultivars. Twenty cultivars were chilled at 1.7, 4.4, 7.2, 10, and 12.7 °C for 24 h using a detached single-leaf method and also whole-plant assay. Results indicate that great genetic variation exists among the cultivars, ranging from no injury at 1.7 °C to severe injury at 12.7 °C. A popular cultivar, Silver Queen, is the most sensitive, while the cultivar Stars is the most resistant. There was also a chilling response difference based on leaf maturity. Young leaves showed less injury than did either mature or old leaves. In addition, there was a significant correlation between the single-leaf and whole-plant assay for chilling resistance in Aglaonema'; the single leaf assay could be particularly useful for a quick test.
324 Heat Tolerance Varies with Species, Provenance, and Accession in Fragaria
Authors: Archbold Douglas D. , Clements Ann M.
Published: February 2019

Several components of whole-plant growth were compared among accessions of Fragaria chiloensis (FC) and F. virginiana (FV) grown at 23 and 31 °C daytime temperatures. The accessions loosely represented North American (NA) and South American (SA) provenances of FC and Kentucky (KY) and eastern Canadian (CN) provenances of FV. Differences in component values between species and by provenance and accession within species were observed at each temperature. Using the ratio of the component value at 31 °C to that at 23 °C as a basis for comparisons, whole-plant relative growth rate (RGR), leaf net assimilation rate (NAR), root RGR, and root: shoot ratio were reduced relatively more by high temperature in FC than FV, while crown RGR, leaf RGR, and leaves produced per day were not consistently affected by temperature or and did not differed significantly between species. While the SA FC exhibited higher values for nearly all components than the NA FC at both temperatures, both were affected similarly by high temperature. The CN FV exhibited somewhat greater sensitivity to high temperature than the KY FV, with significantly lower leaf NAR, crown RGR, and leaves produced per day in the former group.