bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Treatments Control Extension Growth and Enhance Microbial Disinfection of Minimally Processed Green Onions
Authors: Cantwell M.I. , Hong G. , Suslow T.V.
Published: February 2019

Extension growth of minimally processed (removal of roots and compressed stem) green onions (Allium cepa L. × A. fistulosum L.) was greatly reduced by storage in air at 0 °C, while growth of 10-20 mm occurred at 5 °C over 10 days. Heat treatments of 52.5 and 55 -°C water for 4 and 2 min, respectively, were especially effective in reducing growth to less than 5 mm during 12-14 days at 5 °C. Growth was inhibited irrespective of whether the heat treatments were applied before or after cutting. Heat treatments resulted in higher average respiration rates during 12 days at 5 °C, but did not affect the overall visual quality or shelf life. Treatments with 52.5 °C water alone or in combination with different chlorine concentrations (50 to 400 mg·L-1 NaOCl, pH 7.0) were more effective than use of water or chlorine solutions at 20 °C for initial microbial disinfection.
Resistance to Gray Leaf Spot in Capsicum Peppers
Authors: Cho H.J. , Kim B.S. , Hwang H.S.
Published: February 2019

Of 467 accessions of Capsicum pepper (Capsicum annuum L.) tested for resistance to gray leaf spot, KC321, KC220, KC208, KC47 (PI244670), KC43 (PI244670), KC380, and KC319 were highly resistant to both Stemphylium solani and S. lycopersici, the causal agents of gray leaf spot.
Plant Preservative Mixture™ Can Affect Shoot Regeneration from Leaf Explants of Chrysanthemum, European Birch, and Rhododendron
Authors: George Mary W. , Tripepi Robert R.
Published: February 2019

Plant Preservative Mixture™ (PPM), a relatively new, broad-spectrum preservative and biocide for use in plant tissue culture, was evaluated as an alternative to the use of conventional antibiotics and fungicides in plant tissue culture. Concentrations of 0.5 to 4.0 mL·L-1 were tested with leaf explants of chrysanthemum (Dendranthem×grandiflora Kitam), European birch (Betula pendula Roth), and rhododendron (Rhododendron catawbiense Michx.). PPM had little effect on the percentage of explants forming shoots and the number of shoots formed per explant in birch and rhododendron, but dramatically reduced both responses in chrysanthemum. Therefore, the effects of PPM must be evaluated for each species of interest prior to use.
Zinc Requirements of Annual Bluegrass and Creeping Bentgrass
Authors: Xu Xia , Mancino Charles F.
Published: February 2019

Annual bluegrass (Poa annua L.) is becoming an important component of golf course putting greens. A greenhouse sand culture experiment was conducted to study the zinc (Zn) requirements of three genotypes of flowering annual bluegrass (FAB) and three genotypes of vegetative annual bluegrass (VAB), which were compared with the three parents of `Penncross' creeping bentgrass [Agrostis stolonifera L. (CB)]. Clonally propagated plants were grown in sand culture without Zn for 6 weeks prior to the initiation of the Zn treatments. The plants were then irrigated for 3 weeks with half-strength Hoagland's nutrient solution containing 0, 2.5, 5.0, or 40 mg·L-1 Zn from ZnSO4. Color was the only parameter affected by genotype; each genotype showed a significant quadratic response to increasing levels of Zn, with highest color ratings occurring at 2.5 mg·L-1. No genotypic differences were observed among CB, VAB, and FAB for shoot fresh and dry weight, root dry weight, or shoot tissue Zn concentrations. Shoot dry weight of all genotypes increased quadratically with Zn levels. Root dry weights of both VAB and FAB increased, while that of CB remained unchanged, as Zn level increased. Zinc concentrations in shoot tissue increased linearly as Zn level increased. Shoot Zn concentrations were higher in both VAB and FAB than in CB at each Zn level, but differences between VAB and FAB were insignificant. Maintaining shoot Zn concentrations below 109 mg·kg-1 in CB and 200 mg·kg-1 in VAB or FAB prevented Zn phytotoxicity from occurring.
Consumer Preferences for Color, Price, and Vitamin C Content of Bell Peppers
Authors: Frank Christopher A. , Nelson Robert G. , Simonne Eric H. , Behe Bridget K. , Simonne Amarat H.
Published: February 2019

Most bell peppers (Capsicum annuum L.) produced and consumed are green. However, yellow, red, orange, white, black, and purple bell peppers are also available. While bell pepper consumption in the United States has been increasing in the past 10 years, limited information is available on how their color, retail price, and vitamin C content influence consumer preferences. A conjoint analysis of 435 consumer responses showed that, for the total sample, color was about three times more important than retail price in shaping consumers' purchase decisions, while vitamin C content was nearly irrelevant. Six distinct consumer segments were identified through cluster analysis. Four segments favored green peppers, while one segment favored yellow and one favored brown. Demographic variables generally were not good predictors of segment membership, but several behavioral variables, such as past bell pepper purchases, were significantly related to segment membership. While green is generally the preferred color, market segments exist for orange, red, yellow, and even brown peppers. Applications to marketing strategies suggested that price sensitivity could explain why green peppers were priced individually, but those of other colors were priced by weight, and that promotion of increased vitamin C content would be most effective if associated specifically with yellow and orange peppers.
Transplant Timing Affects First-season Root Growth of Turkish Hazelnut (Corylus colurna L.)
Authors: Harris J. Roger , Smith Richard , Fanelli Jody
Published: February 2019

Rapid posttransplant root growth is often a determining component of successful establishment. This study tested the effect of transplant timing on first-season root growth dynamics of bare-root Turkish hazelnut trees. Trees were either harvested and planted in the fall (F-F), harvested in the fall and planted in the spring after holding in refrigerated storage (F-S), or harvested and planted in the spring (S-S). All trees were transplanted into 51-L containers, adapted with root observation windows. Root growth began in F-F and F-S trees 1-2 weeks before spring budbreak, but was delayed in S-S trees until ≈3 weeks after budbreak. Budbreak was 6 days earlier for fall-harvested than for spring-harvested trees. No new roots were observed before spring. Root length accumulation against observation windows (RL) was delayed for S-S trees, but rate of increase was similar to F-F and F-S trees soon after growth began. Seasonal height, trunk diameter growth, and RL were similar among treatments. Surface area of two-dimensional pictures of entire rootballs was not correlated with seasonal RL.
Floral Development and Bolting of Spinach as Affected by Photoperiod and Integrated Photosynthetic Photon Flux During Transplant Production
Authors: Chun Changhoo , Tominaga Machiko , Kozai Toyoki
Published: February 2019

We recently showed that spinach (Spinacia oleracea L.) transplants produced under a short photoperiod and low air temperature were characterized by a delay of bolting and short flower-stalk length at harvest (Chun et al., 2000a). The present study was conducted to determine whether these changes are caused by the short photoperiod itself or by the lower integrated photosynthetic photon flux (IPPF). Shoot and root dry weights of transplants increased significantly with increasing IPPF, but were not affected by a change in the photoperiod. However, the floral development indices of transplants were significantly greater under a 16-than under a 10- or 13-hours/day photoperiod, but were not affected by a change in IPPF. The percentage of bolted plants 3 days after transplanting (DAT) increased significantly with increasing photoperiod (from 0% at 10 hours/day to more than 85% at 16 hours/day). Flower-stalk length increased with increasing photoperiod (e.g., at 14 DAT, from 15 mm at the shorter photoperiods to 80 mm at 16 hours/day), but was not affected by a change in IPPF. These results show that the delay of bolting that occurs when the photoperiod is reduced during transplant production is due to the delay of floral development and not to retarded vegetative growth as a result of reduced IPPF.
Manipulation of Flowering Time by Pruning of Protea cv. Sylvia (P. eximia × P. susannae)
Authors: Gerber Audrey I. , Theron Karen I. , Jacobs Gerard
Published: February 2019

The date of pruning affected flowering time of Protea cv. Sylvia (P. eximia × P. susannae) by influencing the flush on which inflorescence initiation occurred, and the harvest could be manipulated to fall within the optimum marketing period for export to Europe. Flowers initiated on the spring flush reached anthesis in January-February, those on the first and second summer flushes in April-May and July-August, respectively, and those on the autumn flush in November-December. Thus, flowering shoots harvested within the optimum marketing period (September to February) initiated inflorescences on the autumn and spring flushes. Because shoots on the spring flush initiated inflorescences readily, many flowering shoots harvested in January and February (following initiation the previous spring) were short and therefore unmarketable. For commercial production, pruning in July is recommended to allow harvest in October-December of the following year. Since the vegetative and reproductive cycles necessary to produce inflorescences on long stems span more than a year, a biennial cropping system is recommended.
Timing and Concentration of Hydrogen Cyanamide Affect Blueberry Bud Development and Flower Mortality
Authors: Williamson J.G. , Maust B.E. , NeSmith D.S.
Published: February 2019

The effects of hydrogen cyanamide (H2CN2) sprays on vegetative and reproductive bud growth and development were evaluated for `Climax' rabbiteye (Vaccinium ashei Reade) and `Misty' southern highbush blueberry (V. corymbosum L. hybrid). `Climax' plants were sprayed with 0% or 1% H2CN2 (v/v) at each of several time intervals or flower bud growth stages following either 270 or 600 hours of artificial chilling. `Misty' plants were sprayed with 0%, 1%, or 2% H2CN2 (v/v) immediately after exposure to 0, 150, or 300 hours of artificial chilling. H2CN2 application to `Climax' plants at 3 days after forcing (DAF) and at 10% to 30% stage 3 flower bud development dramatically accelerated leafing, and only minimal flower bud damage was observed at these application times. For `Misty', vegetative budbreak was increased and advanced by both H2CN2 spray concentrations, regardless of pretreatment chilling levels; the number of vegetative budbreaks per plant increased with increased concentration. Timing of anthesis did not appear to be affected by H2CN2, but fruit maturity was hastened. Increased pretreatment chilling also hastened fruit development. This effect on maturity appears to be due primarily to increased and accelerated vegetative budbreak, which probably increased leaf: fruit ratios. Greater flower bud mortality from H2CN2 occurred in nonchilled plants than in those chilled for 150 or 300 hours, especially at 2% H2CN2. These results indicate that H2CN2 has potential value in stimulating vegetative bud development, which potentially hastens maturity in blueberries grown under the mild winter conditions of the Southeast. However, spray concentration and timing of application will be critical to successful use of this compound.
Technique for Collecting Thrips for Use in Insecticide Efficacy Trials
Authors: Cloyd Raymond A. , Warnock Daniel F. , Holmes Keith
Published: February 2019

An affordable device comprised of off-the-shelf parts, initially called the “Small Insect Aspirator” was developed to gently collect western flower thrips, Frankliniella occidentalis (Pergande), from a rearing colony for use in insecticide efficacy trials. This device allows for a designated number of thrips to be placed onto any experimental test plant. The device is a battery-motorized driven aspirator comprised of two pieces of copper tubing (6.0 mm in diameter) attached to a copper housing, which contains a threaded plastic lid and glass vial (20-mL). The aspirator is fully portable when attached to a battery-driven vacuum device, which allows researchers to efficiently collect thrips in outdoor field situations. When turned on, the vacuum gently pulls western flower thrips (adult and larval stages) through the copper tubing and deposits them into the collection vial. The vial is then detached and sealed with a threaded lid until the collected thrips are deposited onto experimental test plants.
Foliar Sprays of Clay Reduce the Severity of Powdery Mildew on Long English Cucumber and Wine Grapes
Authors: Ehret David L. , Koch Carol , Menzies Jim , Sholberg Peter , Garland Tim
Published: February 2019

Foliar sprays of a nonswelling chlorite mica clay were applied to leaves of greenhouse-grown long English cucumber (Cucumis sativus L.) plants, either before or after an artificial inoculation with powdery mildew [Sphaerotheca fuliginea (Schlech.:Fr.) Poll.] and to field-grown wine grapes (Vitis vinifera L.) before natural inoculation with powdery mildew [Uncinula necator (Schwein.) Burrill]. In all cases, the clay sprays did not eradicate the pathogen, but resulted in significant reductions in disease severity. In cucumber, a single spray of 0.5% clay reduced colony numbers on leaves by up to 60%. Spraying after inoculation was generally more effective than spraying before inoculation. In grapes, repeated sprays of either 2% or 4% clay were applied through the season to `Reisling' and `Chancellor' vines. Four percent clay reduced the amount of leaf surface covered by mildew by 22% in `Reisling' and 51% in `Chancellor'. Both concentrations reduced the incidence of mildew on clusters and canes. No treatment effects were observed on fruit quality. Our results demonstrate that foliar sprays of clay can reduce the severity of Sphaerotheca fuliginea and Uncinula necator on cucumbers and grapes, respectively.
Combining Controlled Atmosphere Storage and Ethanol Vapors to Control Superficial Scald of Apple
Authors: Chervin C. , Raynal J. , André N. , Bonneau A. , Westercamp P.
Published: February 2019

The effects of ethanol vapors, controlled atmosphere (CA) storage, and a combination of both on superficial scald development on `Granny Smith' apples (Malus ×domestica Borkh.) are reported. The major result was that ethanol vapors, applied in cold storage, prevented scald development over a week at 20 °C in apples that had been CA-stored for 4 months, then left for 1 month in cold air storage. Interrupting CA storage aimed to reproduce industry practices when fruit in part of storage rooms has to be sold and the remaining fruit is held in air for later sale. The estimated cost and further development of this method are discussed.
High Production Temperature Increases Postproduction Flower Longevity and Reduces Bud Drop of Potted, Miniature Roses 'Meirutral' and 'Meidanclar'
Authors: Monteiro José A. , Nell Terril A. , Barrett James E.
Published: February 2019

The effect of two temperature regimes (29 °C day/24 °C night and 24 °C day/18 °C night) and of a 4-hour night interruption, during production, was studied on postproduction flower longevity and bud drop of 'Meirutral' and 'Meidanclar' potted, miniature roses (Rosa L. sp.). High production temperatures increased postproduction flower longevity and decreased postproduction bud drop. In 'Meidanclar', the high production temperature increased incidence of malformed flowers. No effects of night interruption could be shown on either postproduction flower longevity or bud drop.
Seed Enhancements to Improve Spinach Germination
Authors: Katzman Leslie S. , Taylor Alan G. , Langhans Robert W.
Published: February 2019

Rapid, synchronized, and high percentage of germination is required for commercial spinach (Spinacia oleracea L.) production using hydroponic techniques. Seed treatments examined to improve seed germination were: 1) decoating; 2) leaching in water; and 3) soaking seeds for 4 hours in 0.5% NaOCl, leaching for 15 hours in water, and sowing in 0.3% H2O2 (this treatment will be referred to as NaOCl/H2O2). Germination studies were conducted on four cultivars at a constant 18 °C (optimal) or 30 °C (inhibitory). At 18 °C, germination rate (T50) was maximized by both hydration treatments, but uniformity of germination (Tsd) was greatest for decoated seeds; final germination was ≥89% for all treatments. At 30 °C, decoating resulted in greatest uniformity of germination. The NaOCl/H2O2 treatment resulted in highest germination (94%) at the high temperature, whereas decoating was least effective (69%). Reduced germination of decoated seeds was attributed to atypical germinants. Cultivars differed in response to the treatments at both temperatures. Component analysis of the NaOCl/H2O2 treatment was studied with two slow-to-germinate cultivars. Treatment with H2O2, with or without NaOCl, improved the rate, uniformity, and percentage of germination of seeds of both cultivars, but NaOCl alone did not. Pericarp removal or pericarp removal plus NaOCl/H2O2 treatments reduced variability in germination time and enhanced speed of germination at 30 °C, but decoating produced a higher percentage of atypical seedlings than did other treatments. Therefore, the NaOCl/H2O2 treatment is recommended for growers who are unable to maintain cool germination temperatures and/or cannot afford the costs associated with cooling. If growers can maintain a germination temperature of ≈18 °C, decoated seeds are preferable, based on the high uniformity of germination.
Fertilizer Source and Irrigation System Affect Geranium Growth and Nitrogen Retention
Authors: Morvant Jaime K. , Dole John M. , Cole Janet C.
Published: February 2019

Pelargonium ×hortorum Bailey `Pinto Red' plants were fertilized with equal amounts of N, P, and K derived from: 1) 100% constant liquid fertilization (CLF); 2) 50% CLF plus 50% controlled-release fertilizer (CRF); or 3) 100% CRF per pot and irrigated using hand (HD), microtube (MT), ebb-and-flow (EF), or capillary mat (CM) irrigation systems. The treatment receiving 100% CRF produced greater total dry weights, and released lower concentrations of NO3-N, NH4-N, and PO4-P in the run-off than the 100% CLF treatment. The percentage of N lost as run-off was greatly reduced with the use of CRF. MT irrigation produced the greatest plant growth and HD irrigation produced the least. The EF system was the most water efficient, with only 4.7% of water lost as run-off. Combining the water-efficient EF system with the nutrient-efficient CRF produced the greatest percentage of N retained by plants and medium (90.7) and the lowest percentage of N lost in the run-off (1.7).
Factors Affecting Pollen Dispersal in High-density Apple Orchards
Authors: Kron Paul , Husband Brian C. , Kevan Peter G. , Belaoussoff Svenja
Published: February 2019

Knowledge of pollen dispersal is essential for maximizing cross-fertilization in apples (Malus ×domestica Borkh.) and achieving optimal orchard design. Using allozyme markers, we examined dispersal of pollen from trees of a single cultivar (`Idared') throughout two apple orchards. In each orchard, the percentage of seeds sired by `Idared' was estimated for trees sampled at regular intervals along three transects, extending up to 18 rows (86 m) from the closest donor trees. The percentage of seed sired by `Idared' pollen ranged from 76% to 1% of seed sampled for a row. No differences in pollen dispersal were found among transects, despite differences in proximity to the bee colonies. Variation in `Idared' siring success was attributable to the cultivar of the fruit-bearing trees as well as their distance to the nearest `Idared' tree. Cultivar effects were associated with differences in flowering overlap, but not cross-compatibility with the pollenizer. Furthermore, flowering overlap was a good predictor of siring success only when the flowering times of competing pollenizer cultivars were also considered. The implications for orchard design are discussed.
Influence of Frozen Storage Duration and Forcing Temperature on Flowering of Oriental Hybrid Lilies
Authors: Lee Jong Suk , Roh Mark S.
Published: February 2019

The effect of long-term storage of lily bulbs at -2 °C (frozen storage) and of high forcing temperatures on plant height and floral abnormalities was investigated with Oriental hybrid lilies from 1998 to 2000. `Acapulco' and `Simplon' bulbs were stored frozen at -2 °C for various lengths of time and were forced in fan- and pad-cooled greenhouses with temperatures ranging from 11 to 31 °C, depending on the season. The same cultivars were also forced in greenhouses and maintained year-round under refrigerated air conditioning with day/night temperatures of 16/15.5 °C or 18.5/18 °C. Floral development immediately after storage and at different intervals thereafter was observed by scanning electron microscopy (SEM). The prolonged frozen storage reduced the number of flowers. High greenhouse forcing temperatures during summer significantly accelerated flowering, resulted in short plants, and increased the number of abnormal flowers. Forcing at a low temperature (15.5 °C) after planting the frozen stored bulbs resulted in longer cut stems than those forced at 25 °C for 30 days after potting. Bulbs can be stored up to 9 months and still produce high-quality Oriental hybrid lilies.
Urea Nitrogen Uptake by Citrus Leaves
Authors: Bondada B.R. , Syvertsen J.P. , Albrigo L.G.
Published: February 2019

Foliar-applied urea nitrogen (N) has potential to become an important component in fertilizer programs for citrus in Florida and other citrus growing areas as it can reduce nitrate leaching into ground water. We evaluated seasonal absorption characteristics of three urea formulations, Triazone-urea, liquid urea, and spray grade urea by citrus leaves that were from 2 weeks to 6 months old. The effect of leaf age on 15N absorption by N-deficient and N-sufficient leaves, together with urea absorption over an eight-week period were studied using greenhouse-grown and field-grown plants. All foliar N applications were based on a recommended rate of 34 kg N/ha in 469 L of water. In the field studies, leaf N was increased similarly by the three urea formulations one week after three weekly applications. Young leaves (0.25 month and 1 month old) absorbed a greater percentage of N than the older leaves (3 month and 6 month old). Epicuticular wax concentration increased and 15N absorption declined with leaf age. Nitrogen deficient leaves (1.80% N) had greater wax concentration and lower N absorption than N sufficient leaves (2.60% N). Four to 8 weeks after urea applications, Triazone-urea sprayed leaves had significantly greater leaf N concentration than leaves sprayed with liquid urea or nonsprayed control leaves. The greenhouse studies revealed that the 15N absorption was greater through abaxial leaf surfaces than through adaxial surfaces regardless of leaf N level and application time. Applying foliar 15N-urea during night (2000 hr to 2200 hr) resulted in greater absorption of 15N than in the morning (0800 hr to 1000 hr) or afternoon (1200 hr to 1400 hr). It is clear that maximum N absorption from foliar urea sprays occurred at night through the abaxial surfaces of young leaves with sufficient N. Triazone-urea acted as a slow-release N source that could be exploited in supplying N over an extended period of time.
Nutrient Requirements for Lettuce Transplants Using a Floatation Irrigation System. I. Phosphorus
Authors: Soundy Puffy , Cantliffe Daniel J. , Hochmuth George J. , Stoffella Peter J.
Published: February 2019

Several levels of P were supplied via floatation irrigation to `South Bay' lettuce (Lactuca sativa L.) transplants to determine the optimum P concentration necessary. Plants were propagated by floating flats (ebb and flow system) in a nutrient solution containing P at either 0, 15, 30, 45, or 60 mg·L-1 in summer and fall experiments, and either 0, 15, 30, 60, or 90 mg·L-1 P in a factorial combination with 60 or 100 mg·L-1 N in a winter experiment. Adding more than 15 mg·L-1 P had minimal effect on growth. Transplants produced with 0 P grew poorly, regardless of the level of N applied. Nitrogen at 100 mg·L-1 improved the response of shoot growth to any level of P, but adversely affected root growth compared with N applied at 60 mg·L-1. In general, relative growth rate was improved, while net assimilation rate was reduced at all levels of P. High-quality transplants had a root to shoot ratio of about 0.25, total root lengths between 276 and 306 cm, and total root area between 26 and 30 cm3 in a 10.9-cm3 cell volume. Only 30% of the plants produced without P could be pulled from the transplant flats, whereas 90% could be pulled when P was added. Pretransplant P hastened maturity and increased lettuce head weight at harvest in the field. This work suggested that at least 15 mg·L-1 P, supplied via floatation irrigation to a peat + vermiculite mix, was required to produce a transplant with sufficient roots for ease of pulling, rapid field establishment, and earlier harvest.
Fruit Weight, Cropload, and Return Bloom of 'Empire' Apple Following Thinning with 6-Benzyladenine and NAA at Several Phenological Stages
Authors: Stover Ed , Fargione Mike , Risio Richard , Yang Xiaoe , Robinson Terence
Published: February 2019

Thinning with BA reportedly increases size of 'Empire' fruit more than does thinning with NAA because of enhancement of cell division by BA. This study was conducted to determine the phenological stage at which BA application provides maximum fruit weight relative to degree of cropload reduction. In all years, treatments were applied at a range of timings: petal fall (PF), 5-, 10-, or 15-mm king fruitlet diameter (KFD). For each thinner, the same concentration was used throughout the study. In 1994, only Accel® at 75 mg·L-1 was evaluated. In 1995, NAA (7.5 mg·L-1) + carbaryl (600 mg·L-1), Accel®, and a BA-only formulation were compared, but BA alone was applied only at PF, 10- and 15-mm KFD. In 1996, Accel® and NAA were compared with and without carbaryl at all timings. Most treatments reduced cropload and enhanced fruit weight. When data for all 3 years were combined, Accel® or BA increased cropload-adjusted fruit weight (CAFW) in 8 of 10 treatments made at 10- or 15-mm KFD, PF treatments never increased CAFW, and only one of four applications at 5-mm KFD increased CAFW. In contrast, NAA + carbaryl increased CAFW in four of four treatments applied at PF or 5-mm KFD, but in only one of four treatments at 10- or 15-mm KFD. Accel® was less effective than NAA in reducing fruit clusters to a single fruit per spur in most comparisons, either with or without carbaryl. Return bloom varied greatly across years, but was always influenced by application time and types of thinners. In 1994 and 1996, return bloom was closely related to cropload the previous year. Although return bloom was very low for most treatments in 1995, 10- and 15-mm KFD applications of NAA + carbaryl increased it three-fold in comparison with other treatments (NAA + carbaryl at PF or 5 mm or BA at 10-mm KFD) that had similar effects on cropload. Chemical names used: 6-benzyladenine (BA); naphthaleneacetic acid (NAA).
Increased Persistence of Beauveria bassiana Spore Viability Under High Ultraviolet-blocking Greenhouse Plastic
Authors: Costa H.S. , Robb K.L. , Wilen C.A.
Published: February 2019

A field study was conducted to assess the effect of various commercially available polyethylene plastic greenhouse coverings on the persistence of viable spores of the microbial insecticide Beauveria bassiana. Selected coverings blocked the transmission of UV light with wavelengths of 360 nm and below or 380 nm and below. Two coverings also contained an infrared blocking component. A commercial formulation of B. bassiana was applied for 3 consecutive weeks to plants growing in the plastic covered hoop houses. The percentage of viable spores was calculated up to 13 days after the final application. The persistence of viable B. bassiana spores was significantly longer under the plastic that blocked a greater portion of the UV spectrum (<380 nm) than the plastics that only blocked UV wavelengths below 360 nm. One week after application, percentage of spore germination was at least twice as high under the <380 nm blocking plastic compared to <360 nm blocking plastics.
Quality and Microbial Changes of Fresh-cut Mango Cubes Held in Controlled Atmosphere
Authors: Rattanapanone Nithiya , Lee Yuen , Wu Tianxia , Watada Alley E.
Published: February 2019

The marketable period of fresh-cut `Tommy Atkins' and `Kent' mango cubes was 3 to 5 days at 10 °C and 5 to 8 days at 5 °C. The marketable period was extended by 1 to 2 days when cubes were held in a 4 kPa O2 + 10 kPa CO2 or 2 kPa O2 + 10 kPa CO2 (balance N2) atmospheres, depending on cultivar and temperature. Variations in texture (shear force), pH, and soluble solids were greater among cubes from different mango lots than among cubes held at different temperatures or atmospheres. Yeast count increased more with time than did the total mesophilic aerobic count, and the increase was less under controlled atmosphere (CA) than in air at 10 °C. The CA was beneficial in maintaining quality of the cubes; however, low temperature was more effective than CA.
A New Method for Rapid In Vitro Propagation of Apple and Pear
Authors: Bommineni V.R. , Mathews H. , Samuel S.B. , Kramer M. , Wagner D.R.
Published: February 2019

Improved in vitro clonal propagation methods are valuable tools for nurseries and growers, and are essential for manipulation and improvement of tree fruit germplasm using the tools and techniques of biotechnology. We have developed a rapid shoot multiplication procedure for clonal propagation of apple, Malus ×domestica cv. Gale Gala and pear, Pyrus communis L. cv. Bartlett. Rapid clonal multiplication was achieved after the following series of steps: pre-conditioning of micropropagated shoots, sectioning pre-treated stems into thin slices, placing slices onto shoot induction medium and incubating directly under cool-white fluorescent lights or after a brief dark incubation. Multiple induction of shoots recovered from stem slice explants within three weeks of culture. A maximum of 37% of cultured apple stem slices, and 97% of pear stem slices, showed induction of shoots. More shoots were recovered on phytagel solidified shoot induction medium than on agar. Cultured stem slices of both apple and pear showed maximum recovery of shoots from shoot induction medium supplemented with thidiazuron (TDZ) compared to medium supplemented with BAP and kinetin. Under ideal conditions, pear stems generated four times the shoots as the same quantity or length of apple shoots. Micropropagated shoots were rooted and transferred to the greenhouse and field nursery for further evaluation. Chemical names used: N-phenyl-N′-1,2,3-thidiazol-5-ylurea (thidiazuron or TDZ); 6-benzylaminopurine (BAP).
Loss of Putting Greens-grade Fertilizer Granules Due to Mowing
Authors: Mancino Charles F. , Petrunak Dianne , Wilkinson Douglas
Published: February 2019

The loss of fertilizer granules collected in turf clippings during routine putting green mowing has not been determined. The objective of this study was to quantify the amounts of greens-grade granular potassium (K) and nitrogen (N) fertilizers collected during the routine mowing of a `Pennlinks' creeping bentgrass (Agrostis palustris Huds.) putting green. In the first study, five K-containing granular fertilizers were applied at K rates of 2.43 and 4.86 g·m-2. A second study was also performed with six granular Ncontaining fertilizers and one liquid N fertilizer applied at an N rate of 4.86 g·m-2. Both studies were performed twice. Irrigation (6.4 mm) was applied immediately after each fertilizer application and again on the following day. These two irrigations, plus additional irrigation and rain, resulted in each study receiving about 2.54 cm of water over each nineday study period. Mowing and clipping collection using a walk-behind greens mower set to cut at 3.96 mm began two days after treatment (2 DAT) and continued until 9 DAT. The clippings were oven-dried and separated from the fertilizer using a small pneumatic seed cleaner. Collected fertilizer was weighed and expressed as a percentage of the fertilizer applied. Liquid N fertilizer loss was estimated to be the difference between clipping N content of treated plots and untreated controls. Total K fertilizer loss was: UHS Signature 15-0-30 (15.3% to 22.9%) > Lebanon Isotek 11-3-22 (8.7% to 10.7%) > Scott's Contec 13-2-26 (4.9% to 7.4%) > Lesco Matrix 12-0-22 (0.1% to 0.4%) = Lesco Matrix 5-0-28 (0.1% to 0.5%). Signature was the only fertilizer significantly affected by rate and a greater percentage of loss occurred at the lower K application rate. Most loss occurred during the first and second mowing events with small amounts of fertilizer found in clippings from later mowings. The two Lesco materials were not found in clippings after the first mowing. Nitrogen fertilizer granule loss was also greatest with the first and second mowings. Total percentage of losses were IBDU 31-0-0 (75.4%) > Polyon 41-0-0 (70.8%)> Milorganite 6-2-0 (55.7%) > Nutralene 40-0-0 (47.0%) > UHS Signature (19.3%) > Isotek 11-3-22 (9.5%) > N-Sure Pro 30-0-0 (1.9%). In both studies, fertilizer loss appeared to be most related to water-solubility of the fertilizer, but size and density might also be factors.
Storage and Handling Characteristics of Trinexapac-ethyl Treated Kentucky Bluegrass Sod
Authors: Heckman Neil L. , Horst Garald L. , Gaussoin Roch E. , Frank Kevin W.
Published: February 2019

Internal heating during sod storage can lead to plant deterioration and is a limiting factor in sod transportation. Storage practices such as the use of refrigeration and vacuum packaging have increased storage time; however, these are usually not practical or economical. Experiments were conducted to develop a feasible growth regulator management technique, using trinexapac-ethyl, to increase the storage life of Kentucky bluegrass (Poa pratensis L.) sod. Experimental setup for all experiments was a completely randomized design with a 2 (trinexapac-ethyl vs. control) × 3 (storage times) factorial treatment arrangement with 3 replications. Trinexapac-ethyl was applied at 0.23 kg·ha-1 to Kentucky bluegrass 2 weeks prior to harvesting. Results showed that sod treated with trinexapac-ethyl was as much as 10 °C cooler than the controls in the center of the sod stacks after 48 hours of storage. The reduced sod temperatures led to a 30% greater tensile strength and 17% better quality ratings in treated sod after 24 hours of storage. A preharvest application of trinexapac-ethyl appears to increase storage times of Kentucky bluegrass sod, which may improve sod market quality. Chemical name used: [4(cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester] (trinexapac-ethyl).
Seasonal Changes and Cultivar Difference in Turf Quality, Photosynthesis, and Respiration of Creeping Bentgrass
Authors: Liu Xiaozhong , Huang Bingru
Published: February 2019

Summer decline in turf quality of creeping bentgrass (Agrostis palustris Hud.) is a major problem in golf course green management. The objective of this study was to examine whether seasonal changes and cultivar variations in turf performance are associated with changes in photosynthesis and respiration rates for creeping bentgrass. The study was conducted on a USGA-specification putting green in Manhattan, Kans., during 1997 and 1998. Four creeping bentgrass cultivars, `L-93', `Crenshaw', `Penncross', and `Providence', were examined. Grasses were mowed daily at 4 mm and irrigated on alternate days to replace 100% of daily water loss. In both years, turf quality, canopy net photosynthetic rate (Pn), and leaf photochemical efficiency (Fv/Fm) were high in May and June and decreased to the lowest levels in July through September. Whole-plant respiration rate (R) and canopy minus air temperature (▵T) increased during summer months. In October, turf quality and Pn increased, whereas R and T decreased. During summer months, turf quality was highest for `L-93', lowest for `Penncross', and intermediate for `Providence' and `Crenshaw'. Seasonal changes and cultivar variations in turf quality were associated with the decreasing photosynthetic rate and increasing respiration rate.
Apple Tree and Fruit Responses to Early Termination of Irrigation in a Semi-arid Environment
Authors: Ebel Robert C. , Proebsting Edward L. , Evans Robert G.
Published: February 2019

Drought stress was imposed in two `Delicious' apple (Malu×domestica Borkh.) orchards on a sandy loam soil of different soil depths (0.8 and 1.2 m) in the semi-arid environment of central Washington by withholding irrigation all season or from 3, 5, 7, 9, 11, 13, 15, or 17 weeks before harvest. Total pan evaporation was 1005 mm and precipitation was negligible from May through Sept. Soil of the control trees was near field capacity all season, and stem water potential (Ψstem) averaged -1.29 MPa. Total available soil water (TAW) declined after irrigation was terminated for each treatment. As TAW declined to 35%, the TAW that commercial growers are recommended to allow soil to dry to before irrigating, Ψstem was 93% of the controls, fruit growth rate was 97% of the controls, and leaf senescence did not exceed the control trees. As TAW decreased below 30%, leaves senesced acropetally starting with transition leaves near the bud-scale scar. Soil moisture of nonirrigated trees was depleted in July in the orchard on shallow soil and in late August in the orchard on deep soil. Normal June drop was reduced in the driest treatments, but crop load was not affected in the other treatments. There was no difference in drought response between the two rootstocks studied (M.7 and MM.111), but nonspur-type trees exhibited slightly greater symptoms of drought stress than the smaller spur-type trees. A Crop Water Deficit Index (CWDI) based on Ψstem measurements was linearly related to fruit weight at harvest (r2 = 0.87). All trees were well-watered the following year and yield was reduced only for trees that were severely stressed the previous year.
Apple Tree Rootstock and Fertilizer Application Timing Affect Nitrogen Uptake
Authors: Aguirre Paula B. , Al-Hinai Yahya K. , Roper Teryl R. , Krueger Armand R.
Published: February 2019

Nitrogen (N) uptake was compared on 10 dwarf apple rootstocks (M.9 EMLA, M.26 EMLA, M.27 EMLA, M.9 RN29, Pajam 1, Pajam 2, B.9, Mark, B.469, and M.9 T337) grafted with the same scion (`Gala') in a four year-old orchard. Trees were treated in either Spring or Fall 1998 with 40 g of soil applied actual N per tree using ammonium nitrate enriched to 1% 15N. Both percentage of N (%N) and N from fertilizer (NFF) in leaf tissue were highly affected by the rootstock and the season of N application. Generally, higher %N and NFF were observed for spring than fall applications, except for leaves collected during early June 1998. Generally, M.26 EMLA, M.27 EMLA, and M.9 RN29 were the most efficient rootstocks in N uptake for spring applied nitrogen. M.9 EMLA was most efficient late in the season following fall application. Mark was more efficient early in the season for fall applied N than spring application. However, trees on Mark rootstock had the lowest %N throughout the season regardless of the time of N application. Pajam 1 and Pajam 2 were the least efficient rootstocks in N uptake following fall N application. Rootstock also significantly affected %N and NFF of wood tissue. Generally, trees on B.469 had the highest %N in their wood regardless of the season of application. No single rootstock had consistently higher N from fertilizer in their wood tissue after spring application. At the May 1999 sampling date, M.26 EMLA had higher NFF than M.27 EMLA, Pajam 1, Pajam 2, and B.9 with a fall application. Other rootstocks were intermediate. Samples collected in August showed that Pajam 1 was the least efficient rootstock in N uptake for fall applied N compared to other rootstocks, except for Pajam 2 and B.9 that were intermediate. Leaf and wood tissue analysis showed that different rootstocks had different N uptake efficiencies throughout the season. Generally, M.26 EMLA, M.27 EMLA, M.9 RN29 and M.9 EMLA were more efficient at N uptake regardless the season of N application. Pajam 1 and Pajam 2 were the least efficient.
Yield, Shoot and Root Growth, and Physiological Responses of Mature Peach Trees to Grass Competition
Authors: Tworkoski Thomas J. , Glenn D. Michael
Published: February 2019

Competitive effects of different grass species were evaluated on growth, yield, leaf N, and leaf water potential of 8-year-old peach [Prunus persica (L.) Batsch.] trees and on weed abundance. Two cultivars (`Loring' on Lovell rootstock and `Redhaven' on Halford rootstock) of peach trees were planted in separate orchards in 1987. Nine orchard floor treatments were installed beneath the peach trees in 1995: Festuca arundinacea Schreber (tall fescue); Lolium perenne L., var. Manhattan II (perennial ryegrass); Lolium perenne L., var. Linn; Agrostis gigantea Roth (red top); Dactylis glomerata L. (orchardgrass); Phleum pratense L. (timothy); Bromus carinatus Hook. and Arn. (brome); weedy control; and herbicide weed control (simazine, glyphosate). In general, grasses reduced vegetative growth and yield in both cultivars. Orchardgrass was one of the most competitive species and reduced vertical water sprout length by 15% to 27% and lateral shoot length on fruit-bearing branches by 19% to 30% compared with herbicide treatments. Orchardgrass reduced yield by 37% and 24% in `Loring' and `Redhaven', respectively. All grasses were not equally competitive; `Linn' perennial ryegrass did not significantly reduce growth or yield in `Redhaven'. Control treatments with weeds also did not differ from herbicide treatments in peach tree growth and yield. Grass and weed ground covers consistently reduced peach tree leaf N by at least 10%, compared to herbicide treatment, possibly due to reduced root growth. `Redhaven' root density in the top 10 cm of soil was ≈12 cm·cm-3 in herbicide strips vs. 1 cm·cm-3 in weedy or ground-covered strips. Peach leaf water potential was not affected by grass and weeds. Weed weights were significantly reduced by all grasses compared with weedy control. The results indicate that peach cultivars respond differently to grass competition, but the relative competitiveness of each grass species was similar for both cultivars. Grass competition reduced growth, yield, and pruning weights of mature peach trees, but the reduction in vegetative growth did not significantly reduce pruning time per tree. Grasses that are less inhibitory to peach yield may be useful for weed management in orchards.
Strawberry Growth and Development in an Annual Plasticulture System
Authors: Fernandez Gina E. , Butler Laura M. , Louws Frank J.
Published: February 2019

The growth and development of three strawberry cultivars commonly grown in a plasticulture system were documented. Strawberry plants were harvested monthly and divided by roots, crown, leaves, flowers, and fruit and then dried in an oven. The dry matter production and resource allocation proceeded along a predictable pattern of development. The establishment phase was characterized by an active period of growth of root, crown and leaves in the fall. Through the winter, the plants underwent slow growth, ending in a transition period in the late winter/early spring when resources were allocated to both vegetative and reproductive growth. In the spring, all plant parts received significantly increased allocation of, or redistribution of, resources. Cultivars of California origin, `Chandler' and `Camarosa', displayed similar trends in yield, dry matter production, seasonal resource allocation, and growth analysis variables throughout the season. `Sweet Charlie', a cultivar from Florida, showed lower dry matter accumulation and relative growth rate in the spring, higher harvest index and lower yield than the California cultivars.
Salt Tolerance of Tomato Plants as Affected by Stage of Plant Development
Authors: del Amor F.M. , Martinez V. , Cerdá A.
Published: February 2019

In order to simulate the usage of brackish irrigation water in greenhouse tomato (Lycopersicum esculentum Mill. cv. Daniela) culture in perlite, plants were supplied with nutrient solutions containing 0, 20, 40, and 60 mm NaCl. The three highest salinity treatments were applied at three different plant growth stages, during early vegetative growth [16 days after transplanting, (DAT)], beginning of flowering (36 DAT), and starting fruit development (66 DAT). Salt tolerance of tomato plants increased when the application of salinity was delayed. Salinity significantly decreased size and number of marketable fruits, but increased fruit quality by increasing total soluble solids and sugar content. Leaf and fruit calcium and potassium concentrations were decreased significantly by increasing salinity levels. This was compensated for the accumulation of sodium. Anion accumulation was increased by increasing chloride concentration. These results indicate that it is feasible to use brackish water for growing tomato with minimum yield losses if salt concentration and duration of exposure are carefully monitored.
Role of Ethylene and 1-MCP in Flower Development and Petal Abscission in Zonal Geraniums
Authors: Jones Michelle L. , Kim Eun-Sun , Newman Steven E.
Published: February 2019

Geraniums are sensitive to ethylene during shipping and respond by abscising their petals. Treatment of stock plants with ethylene (ethephon) in order to increase cutting yield resulted in earlier flowering in Pelargonium × hortorum `Kim' and `Veronica', but did not result in increased susceptibility to petal abscission following exposure to 1.0 μL·L-1 ethylene. Treatment of `Kim', `Veronica', `Fox', and `Cotton Candy' with 1.0 μL·L-1 ethylene resulted in increased petal abscission within one hour, with `Fox' being the most sensitive and `Kim' the least. Pretreatment of florets with 1-MCP for 3, 6, 12, or 24 hours at concentrations of 0.1 or 1.0 μL·L-1 decreased petal abscission in all cultivars following exposure to 1.0 μL·L-1 ethylene. Treatment with 0.1 μL·L-1 1-MCP for 1 hour reduced petal abscission rates in ethylene treated florets to that of non-ethylene treated controls in all cultivars except Fox. `Fox' florets, which are more sensitive to ethylene, required 12 to 24 hours of exposure to 1-MCP to reduce petal abscission rates to that of control flowers. Pretreatment of geranium plants with 1-MCP can be used to reduce petal shattering during shipping. Chemical names used: 2-chloroethanephosphonic acid (ethephon); 1-methylcyclopropene (1-MCP).
Combining Ability and Heterosis for Capsaicinoids in Capsicum pubescens
Authors: Zewdie Yayeh , Bosland Paul W. , Steiner Robert
Published: February 2019

The inheritance of capsaicinoid content was studied in five Capsicum pubescens Ruiz & Pav. genotypes using diallel analysis. General combining ability and specific combining ability effects were significant for all capsaicinoids studied, indicating additive and nonadditive gene actions are present. The association of high capsaicinoid contents with high positive general combining ability of the parents also indicates the predominance of additive gene action in capsaicinoid inheritance. Because of the predominant additive gene effect, recurrent selection would be a good breeding method to increase capsaicinoid level in the population studied. Heterosis was observed in hybrids for some of the capsaicinoids, suggesting that F1 hybrids could also be used to increase capsaicinoid content.