bluuebunny/crossref_metadata_2025 huggingface dataset:
ABA, Hydraulics, and Gas Exchange of Split-rooted Apple Trees
Authors: Einhorn Todd C. , Caspari Horst W. , Green Steve
Published: February 2019

Approach-grafted 1-year-old `Gala'/M7 apple trees were grown with both tops for the remainder of the 2003 season in a greenhouse. Trees were supplied with >100% (control, PRD100) or 50% (PRD50, DI50) of daily ETc either applied to one root compartment only (PRD100, PRD50) or divided evenly across both root compartments (control and DI50). ETc was estimated from gravimetric measurements, and irrigation was switched between wet and dry root compartments several times throughout the experiment. Soil moisture was measured both gravimetrically (tripod) and volumetrically (time-domain reflectometry). Predawn leaf water potential (υpd) and single leaf gas exchange (photosynthesis, stomatal conductance, and transpiration) were recorded daily, and sap flow in stems and roots was monitored continuously using the heat-pulse technique. Leaves were collected for abscisic acid (ABA) determination following gas exchange measurements. Regardless of irrigation placement (i.e., PRD or DI), both 50% ETc treatments experienced similar declines in υpd and single leaf gas exchange relative to control levels. In addition, ABA concentrations were similar for PRD50 and DI50, and were significantly higher than the control and PRD100 treatments. PRD100 trees had similar υpd as control trees; however, gas exchange was reduced >25% compared to the control. Bulk leaf ABA concentration did not differ significantly from control levels and does not by itself explain the down regulation of stomata with PRD100.
Development of Lettuce Breeding Lines Resistant to Bacterial Leaf Spot
Authors: Hayes Ryan J. , Bull Carolee T. , Goldman Polly H. , Ryder Edward J.
Published: February 2019

Bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians (Xcv) is an important lettuce disease in California. No adequate control measures have been found, although resistance exists in several heirloom cultivars. Deployment of cultivars resistant to bacterial leaf spot will reduce these periodic and costly disease events. The objectives of this research were to 1) identify new sources of resistance within modern crisphead cultivars and 2) select for resistance in `Salad Crisp' × `Iceberg' progeny. Field plots were established and grown with overhead irrigation, and a three-strain mixture of Xcv was applied until runoff 1 week after thinning at 1 × 109 CFU/mL. Twenty-six crisphead cultivars were tested in unreplicated field trials and rated on a 1 (susceptible) to 4 (resistant) scale. Selection was carried out between and within families from the F2 to F4 generation. Sixteen F3 families were evaluated in unreplicated plots, and 12 F5 families were tested in replicated plots for disease incidence and severity. No usable levels of resistance were identified in the modern crisphead cultivars tested to date. All F3 families had resistance greater than `Iceberg', and 19 plants from eight families were selected for further breeding. Subsequently, 12 plants from two F4 families were selected. Replicated trials of 12 F5 families indicated that all lines have disease severity comparable to both parents. Breeding lines from crosses to `Salinas 88' are currently being developed.
Interpretation of Genotype-by-Environment Interaction for Carotenoid and Tocopherol Content in Broccoli
Authors: Ibrahim Khalid E. , Kobira Kanta , Juvik John A.
Published: February 2019

Genotype-by-environment interaction (G×E) is a fundamental concern in plant breeding since it hinders developing genotypes with wide geographical usefulness. Analysis of variance (ANOVA) has been widely used to interpret G×E, but it does not elucidate the nature and causes of the interaction. Stability analysis provides a summary of the response patterns of genotypes to different growing environments. Two classes of phytochemicals with putative health promoting activity are carotenoids and tocopherols that are relatively abundant in broccoli. Growing clinical and epidemiological evidence suggests that vegetables with enhanced levels of these phytochemicals can reduce the risk of cancer, cardiovascular, and eye diseases. The objective of this study is to have better understanding of the genetic, environmental and G×E interaction effects of these phytochemicals in broccoli to determine the feasibility of the genetic enhancement. The ANOVA and Shukla's stability test were applied to a set of data generated by the HPLC analysis of different carotenoid and tocopherol forms for six broccoli accessions grown over three environments. The ANOVA results show a significant G×E for both phytochemicals that ranged from 22.6% of the total phenotypic variation for beta-carotene to 54.0% for delta-tocopherol while the environmental effects were nonsignificant. The genotypic effects ranged from as low as 1% for alpha-tocopherol to 31.5% and 36.0% for beta-carotene and gamma-tocopherol, respectively. Stability analysis illustrated that the most stable genotype for all phytochemicals is Brigadier. The results suggest that feasibility of the genetic enhancement for major carotenoids and tocopherols. A second experiment that includes a larger set of genotypes and environments was conducted to confirm the results of this study.
Update on the Ornamental Breeding Program at the University of New Hampshire
Authors: Freyre Rosanna
Published: February 2019

The Ornamental Breeding Program at the University of New Hampshire (UNH) was initiated in 1998, aiming to develop new or improved vegetatively propagated cultivars. Initially, breeding focused on Anagallis monelli (Pimpernel). At the time, only one blue and one orange cultivar (`Skylover Blue' and `Sunrise') were grown commercially. Main breeding goals were to develop plants with more compact habit and earlier flowering in the spring. In 2002, the first two UNH cultivars were released as Proven Selections™: Anagallis`Wildcat Blue' and `Wildcat Orange'. We have also developed breeding lines with new pink, violet, lilac, and white flower colors that are currently in industry trials. Studies on genetics, biochemistry, and anatomy of flower color in A. monelli have been performed and molecular studies are in progress. Breeding of Nolana and Browallia started in 2000 and UNH lines are currently in industry trials. Nolana is comprised of over 80 species native to desert areas of Peru and Chile. Only two cultivars, N. paradoxa`Bluebird' and `Snowbird', and interspecific hybrid `Blue Eyes' are currently commercially available. We now have several Nolana species at UNH representing a wide germplasm base. Based on ornamental potential, some species have been selected for breeding, aiming to develop sterile interspecific hybrids. Studies to break seed dormancy to optimize germination rates are in progress, as well as research on floral development, which is being conducted in collaboration with Peruvian researchers. Interspecific hybridizations have been used in Browallia to develop breeding lines with new or improved traits than those available from seed cultivars.
Plant Regeneration from Protocorm-derived Callus of Five Paphiopedilum Hybrids
Authors: Compton Michael
Published: February 2019

Callus was induced from protocorms of five Paphiopedilum hybrids (Paph. 03-1, Paph. 03-4, Paph. 03-5, Paph. 03-6, and Paph. 03-7) on callus induction medium [MS inorganics (412.5 mg NH4NO3 instead of 1650 mg and 475 mg KNO3 instead of 1900 mg) and vitamins plus (per liter) 0.1 g myo-inositol, 30 g sucrose, and 2.5 g Gelrite; pH 5.5] containing various concentrations and combinations of thidiazuron (TDZ; 4.5 and 45 μm) and 2,4-D (4.5 and 45 μm). Callus formation was greatest for protocorms of Paph. 03-1, Paph. 03-4, Paph. 03-6, and Paph. 03-7. Among the most competent hybrids, callus formation was greatest among protocorms induced in medium containing 4.5 μm 2,4-D and 4.5 to 45 μm TDZ. Induced calli were transferred to 100 × 15 mm petri dishes containing 25 mL of PLB and plant regeneration medium (similar to callus induction medium) containing various concentrations of either benzyladenine (BA; 0.5, 5, or 10 μm), TDZ (0.25, 2.5, or 5 μm) or no growth regulator (control). PLB and plant formation was greatest on medium containing BA.
Reproductive Development in Pink Tickseed, Coreopsis rosea, Nutt.
Authors: Loehrlein Marietta , Siqueira Sandy
Published: February 2019

Landscape and garden use of Coreopsisrosea has been growing recently. With the introduction of the new varieties of Coreopsisrosea `Sweet Dreams' and `Limerock Ruby', there are increased opportunities for commercial sales. While plants can be propagated by vegetative means, seed production is generally less expensive, seed can be stored, and hybrid development depends on seed production. As a result, it is beneficial to understand the reproductive process of the plant. The purpose of this research was to investigate the reproductive development of Coreopsisrosea. This research also seeks to identify, describe and record inflorescence morphological characters, which could be useful in plant systematic and phylogeny studies. To this end, the anthesis process of pink tickseed, Coreopsisrosea Nutt., was studied in 100 inflorescences from 10 plants. Inflorescences were tagged when they were first visible and measured daily for a month. The following measurements were taken: number of ray flowers, inflorescence diameter, diameter of the disc floret cluster (head), timing of anthesis, presence of pollen, and the longevity of opened flowers. The inflorescence anthesis process was 19.8 (±1.6) days long and was subdivided into 13 stages of development. During the 20 days of inflorescence anthesis, the flower was open 27.5% of the time (5.4 days). When the disc florets started to open, they did so from the outer layer of the cluster to the center of the cluster; therefore, florets in the head did not mature at the same time. Micrographs were taken using a dissecting microscope (Cobra dynascope) to illustrate the entire process.
SSR Markers for Accelerated Hydrangea Breeding and Hybrid Verification
Authors: Rinehart Timothy , Reed Sandra , Scheffler Brian
Published: February 2019

Hydrangea popularity and use in the landscape has expanded rapidly in recent years with the addition of remontant varieties. Relatively little is known about the genetic background or combinability of these plants. We recently established microsatellite markers for hydrangea and evaluated their utility for estimating species diversity and identifying cultivars. We also verified an interspecific cross using these markers. Future research includes marker assisted breeding, particularly with respect to remontant flowering traits.
Cover Cropping and Cultivation Impacts on the Weed Seed Predator Harpalus rufipes
Authors: Shearin Amanda F. , Reberg-Horton S. Chris , Gallandt Eric R. , Drummond Francis A.
Published: February 2019

Seed predators may significantly reduce the weed seedbank. In Maine, one ground beetle species, Harpalus rufipes DeGeer, can consume 90% of the epigeous seeds of certain weeds. H. rufipes is the predominant carabid seed predator in Maine agricultural systems. The mechanisms by which H. rufipes can be promoted are not well understood. Two weed management techniques used by diversified vegetable growers in Maine (cover cropping and cultivation) were evaluated in 2004 for their impact on H. rufipes movement and abundance. H. rufipes individuals (n = 200 plot) were marked and released into 180-m2 plots that were either fallow or cover-cropped. Pitfall traps were installed in each plot to recapture marked beetles. The total recapture rate in fallow plots was 46% less than in cover crop plots. Movement of fallow-released beetles into cover crop plots was 48% higher than movement of cover crop-released beetles into fallow plots. A second study evaluated the impacts of tillage on H. rufipes. Marked beetles (n = 25 plot) were released into 9-m2 plots surrounded by raingutters. Plots were either tilled with a tractor-mounted rotovator to a depth of 15 cm or left undisturbed. There was no significant difference in beetle recapture rates in tilled (32%) vs. untilled (35%) plots, suggesting that beetles are capable of surviving even intensive tillage events. Variation in the number of H. rufipes across farming systems may not be due to tillage, as widely postulated in literature, but is instead a product of vegetative cover. Further research into the impacts of weed management on other life stages of H. rufipes is needed before firm conclusions can be reached.
A Comparison of Surface Mulch Type on Patterns of Above- and Below-ground Temperature and Surface Net Radiation in a Drip-irrigated Desert Landscape
Authors: Singer Catherine K. , Martin Chris A.
Published: February 2019

Mulches applied to landscape surfaces can moderate soil temperatures by changing the surface heat energy balance and conserve soil water by reducing evaporation rates. In the Southwest, decomposing granite is commonly used as landscape mulch. However, organic mulches, such as pine residue mulch and shredded tree trimmings, are becoming more available as industry by-products. Recent impetus toward water conservation and recycling forest and urban tree waste into urban landscapes has increased the need to better understand how such mulch types effect the temperature, moisture. and light quality of drip-irrigated landscapes typically found in the Southwest. We compared effects of three mulches, two organic (composted ponderosa pine residue and shredded urban tree trimmings) and one inorganic (Red Mountain Coral decomposing granite), turf grass, and bare soil applied to 14 drip-irrigated landscape research plots on below-ground soil temperatures at depths of 5 cm and 30 cm, temperatures at the mulch-soil interface, mulch surface temperatures, diel mulch surface net radiation, and albedo. Below-ground soil temperatures were more buffered by organic mulches, and mulch-soil interface temperatures were lower under organic mulch than inorganic mulches. Inorganic mulch daytime surface temperatures were lower than organic mulch surface temperatures. Nighttime net radiation values were less negative over organic mulches than inorganic mulches and albedo was significantly higher for the inorganic mulch and bare soil treatments. These results provide evidence to show that organic surface mulches have higher resistances to heat transfer than inorganic mulches, which could improve landscape plant water and nutrient use efficiencies by lowering high summer root zone temperatures.
Provenance Affects Growth of Taxodium distichum in Containers
Authors: Denny Geoffrey C. , Watson W. Todd , Lombardini Leonardo , Mackay Wayne A. , Solis-Perez Alma R. , Bryan Donita L. , Arnold Michael A.
Published: February 2019

Seedlings from 13 open-pollinated families of Taxodium distichum (L.) L.C. Richard from the gulf coast, central and south Texas, and Mexico were grown in a nursery in College Station, Texas. Forty seedlings per family were measured on three dates during the production cycle; 99, 109, and 133 days after sowing in Spring and Summer 2004. A two-step cluster analysis based on height and trunk diameter created 3 clusters of families. Cluster 1 had a mean height of 32 cm and a mean trunk diameter of 3.3 mm. Cluster 2 had a mean height of 33 cm and a mean trunk diameter of 3.4 mm. Cluster 3 had a mean height of 43 cm and a mean trunk diameter of 4.1 mm. Although clusters 1 and 2 are statistically significantly different, practically there is little difference between the two. The families from Mexico and central Texas were all in cluster 1 or 2 and the families collected from the gulf coast were all placed in cluster 3, with the exception of a single family from Biloxi, Miss., which was placed in cluster 1. Analysis of covariance revealed that family membership and days after sowing were both highly significant, as well as an interaction between family and days, for height. Families from Mexico and central and south Texas were 10 to 15 cm shorter than the families from the gulf coast, with the exception of the single family from Biloxi, Miss. Only days and the interaction between family and days were significant for trunk diameter. A pattern similar to the cluster analysis means was seen among the families for trunk diameter in the analysis of covariance.
The Involvement of Lipid Signaling in Citrus Fruit Abscission
Authors: Alferez Fernando , Singh Shila , Kostenyuk Igor , Burns Jacqueline
Published: February 2019

Abscission is a natural plant process that culminates in the removal of organs from the parent plant. Control of abscission remains an important goal of agriculture, but events that initiate and transduce abscission signals have not been well defined. An understanding of these events may reveal pathways that can be targeted to control abscission. The compound 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP) is a pyrazole-derivative that induces abscission selectively in mature citrus (Citrus sinensis) fruit when applied to the canopy. Peel contact is essential for efficacy. Previous work identified CMNP as an uncoupler. Timing of CMNP-induced events in citrus flavedo indicated that increased reactive oxygen species and electrolyte leakage occurred within 30 minutes and 2 hours after application, whereas reduced ATP content was measured 3 hours after application. Phospholipase A2 (PLA2) and lipoxygenase (LOX) activities, and lipid hydroperoxide (LPO) levels increased in flavedo of citrus fruit peel treated with CMNP, indicating that the lipid signaling pathway was activated. A specific inhibitor of PLA2 activity, aristolochic acid (AT), reduced CMNP-induced increases in PLA2 and LOX activities and LPO levels in citrus flavedo and greatly reduced abscission, suggesting that production of phospholipid-derived signals influence abscission process. However, AT treatment failed to halt the reduction in ATP content, indicating that reduction in ATP preceded the increase in PLA2 activity and the biological response. The results demonstrate a link between lipid signaling and abscission in citrus.
The Effects of Postharvest Storage Temperature on Vegetative Cutting Respiration
Authors: Enfield Amy L. , Faust James E.
Published: February 2019

Poinsettia `Prestige', New Guinea impatiens `Sonic White', and petunia `Improved Charlie' cuttings were harvested from stock plants, weighed, placed in glass jars, and placed at 10, 15, 20, or 25 °C. Carbon dioxide accumulation was measured and used to determine respiration rates at 2, 6, 10, 24, and 48 hours. Vegetative cuttings have very high initial respiration rates that quickly decline over time. At 2 hours, respiration rates at 25 °C were 5.4-, 2.4-, and 4.3-fold higher vs. 10 °C in poinsettia, New Guinea impatiens, and petunia, respectively. By 48 hours, there was little difference in respiration rates. In a second experiment, poinsettia `Prestige' cuttings were pre-cooled at 10 °C for 0, 3, 6, 12, or 24 hours before being transferred to 20 °C. Respiration rates were measured at 0, 2, 6, 10, 24, 48, and 72 hours in the 20 °C environment. Regardless of pre-cooling duration, respiration rates increased when cuttings were transferred from 10 to 20 °C. Respiration rates of cuttings pre-cooled for 3, 6, or 12 hours were not significantly different from cuttings maintained at constant 20 °C. However, after transfer, cuttings pre-cooled for 24 hours had a respiration rate significantly lower than cuttings maintained at constant 20 °C, but by 72 hours, there were no significant differences.
Variation in Media pH and Electrical Conductivity in Geraniums
Authors: Peters Carinne , McIntosh Marla S.
Published: February 2019

Pour-through extraction can provide data indicating geranium container nutrient status for growers to diagnose nutritional problems and prevent plant loss. The objective of this study was to examine changes in growing media pH and electrical conductivity during the production cycle of 10 cultivars from each of the three geranium classes (zonal, ivy, and regal). Thirty cultivars of geraniums were grown in pots using standard commercial greenhouse production guidelines for 12 weeks. Pour-through extractions were performed every 5 d and media pH and electrical conductivity were determined on the collected leachate. While there was a significant reduction in media pH for zonal and ivy geraniums 36 d after transplanting plugs, only one regal cultivar exhibited a decrease in pH during the production cycle. Statistically significant differences for mean media pH and electrical conductivity were also observed among cultivars within each class at several sampling dates. The results of this study indicate that zonal, ivy, and one regal cultivar's media pH decreases rapidly from day 21 to day 36, and then returns to initial levels by day 46. Because of the importance of media pH to nutrient uptake, this study allows for a better understanding of nutritional problems that are linked to pH that frequently occur at the stage of growth. It also suggests that fertigation rates should be adjusted by cultivar and growth stage to address this pH variation.
Phytotoxicity of TriStar Formulations on Fully Colored Poinsettia Cultivars
Authors: Warnock Daniel F.
Published: February 2019

Late season control of whitefly is problematic in many production ranges as systemic insecticides may not provide full season control. Most commercially available contact insecticides are not labeled for use on fully colored poinsettia, Euphorbia pulcherrima, plants due to potential phytotoxicity or residue on colored bracts. Recent formulation changes in TriStar make late season applications possible. This study assessed phytotoxicity and residue impacts of two formulations of TriStar on potted poinsettias. On 4 Aug. 2004, rooted cuttings of 47 poinsettia cultivars obtained from four commercial suppliers were transplanted into pots containing a soilless medium. A total of 235 cuttings were used to arrive at five pots per cultivar. Plants were grown using standard production techniques. On 11 Nov. 2004, all plants were fully colored and treated with TriStar 70 WSP or TriStar 30SG at maximum label rates. Phytotoxicity and residue levels were assessed 7 days later using a 1 to 9 visual scale. Overall the formulations had few negative impacts on poinsettias. Phytotociticy ratings were minimal for most cultivars; however, some cultivars, such as `Silverstar Red' expressed an elevated level of phytotoxicity. Dark colored cultivars showed more residue than light colored cultivars. The TirStar 30SG formulation had the least amount of residue. TriStar 30SG may be an acceptable insecticide for late season control of whitefly on poinsettia crops. Producers are cautioned to test cultivars for phytotoxicity before applying to an entire crop as some cultivars are sensitive to TriStar 30SG.
Antioxidant Activity of `Rio Red', `Marsh White', and Commercial Juice In Vitro Model Systems
Authors: Girennavar Basavaraj , Patil Bhimanagouda , Jayaprakasha Guddadarangavvanahally
Published: February 2019

Antioxidant activity is widely used as a parameter to characterize different plant materials for potential health benefits. This activity is related with compounds capable of protecting a biological system against the harmful effect of reactions that can cause excessive oxidation, involving reactive oxygen and nitrogen species (RONS). There has been growing interest in the beneficial health effects of consuming fruits and vegetables. Mainly, the presence of lycopene, ascorbic acid, and phenolic antioxidants is believed to have the protective mechanism. The free radical-scavenging activities of grapefruit extract of `Rio Red', `Marsh White', and commercial juice were extracted with different solvents, such as hexane, ethyl acetate, and chloroform. The dried extracts were screened for their radical scavenging activity using the α,α -diphenyl-β-picrylhydrazyl (DPPH) method. The ethyl acetate extracts of commercial juice and `Marsh White' were found to possess more radical scavenging activity compared with the other two extracts. However, chloroform extracts of `Rio Red' grapefruit were the most active, which may be ascribed to the presence of more lycopene. Furthermore, the antioxidant capacity of `Rio Red' and `Marsh White' extracts was assayed through the phosphomolybdenum method and expressed as equivalent to ascorbic acid (μmol·g-1 of the extract). The order of antioxidant capacity for `Rio Red' extracts was found to be hexane > chloroform > ethyl acetate, while the order for `Marsh White' was chloroform > hexane > ethyl acetate. The results indicate that the extent of antioxidant activity of the extract is in accordance with the amount of lycopene/phenolics present in that extract; commercial juice and `Rio Red' may provide a good source of antioxidants.
Integrating the Local School System in Food Safety Training
Authors: Blackwelder Darrell E. , Sanders Douglas C. , Osborne Dennis , Ward Donn
Published: February 2019

Food safety, including fresh produce food safety programming and GAPs (Good Agricultural Practices) third-party audit considerations are impacting the ability of producers marketing their crops. These relatively new federal programs are voluntary, but major buyers and chain stores are beginning to require that growers and sellers demonstrate participation in the programs. Recently, there were no training programs or materials readily available to meet educational needs of Cooperative Extension clients. Local producers began to request information on participation, compliance, and the end results. In Rowan County, N.C., two different programs addressed information and training material limitations for local producers. In one training session, local farmer's market participants were introduced to risk management concepts that helped them meet the GAPs training requirements. In another program, local school personnel were introduced to new food safety concepts in a local training for Hispanic workers. Since translation capability is limited, we have partnered with Spanish speakers from a local bank and from a migrant worker education group. This networking was valuable to our cooperators, since they reached new clients, and to us in getting workers trained in food safety.
Seed Dormancy in Three Wild Rye (Elymus) Species
Authors: Duncil Barry , Geneve Robert
Published: February 2019

Wild rye (Elymus) contains several species of cool season grasses that are important components of forest and woodland ecosystems. Little specific information is known about seed dormancy in wild rye species, but cool season grasses generally display endogenous, non-deep physiological dormancy that would normally be satisfied by moist chilling during winter to permit early spring germination. However, few studies have documented the effect of extended chilling stratification on dormancy release in cool season grasses. Therefore, the objective of this study was to document the dormancy condition of representative wild rye species and to observe the impact of chilling stratification on dormancy release. Three species of wild rye (E. virginicus, E. macgregorii, and E. villosus) were selected based on their taxonomic and ecological relationships. All species showed conditional dormancy with respect to germination temperature. At 15 °C, E. virginicus, E. macgregorii, and E. villosus germinated at 75%, 81%, and 40%, respectively, compared to 5%, 3%, and 12% for each species at 20 and 25 °C. Chilling stratification at 10 °C improved germination compared to non-stratified seeds to 95% and 94% for E. m acgregorii and E. villosus, but had no effect or reduced germination in E. virginicus. Stratification at 5 °C was not as effective as 10 °C for dormancy release and appeared to cause chilling injury in E. virginicus and E. macgregorii. The data suggest that these wild rye species express a form of conditional endogenous, non-deep physiological dormancy that is most pronounced when seeds are germinated at non-optimal temperatures.
Effect of Multiple Plants per Plug on Processing Tomato Yield in California
Authors: Le Strange Michelle
Published: February 2019

In recent years, an estimated 65% of processing tomato acreage has converted from direct seeding to transplanting the crop. Growers have been switching to transplants for a number of reasons, including land use efficiency, water conservation, and weed management. Field studies investigating plant spacing and multiple plants per transplant plug (cell) were initiated when observations by growers indicated that there were seemingly decreased fruit yields from transplanted crops. A transplant density experiment was established in 2004 in a commercial field of processing tomatoes grown on the west side of Fresno County in the San Joaquin Valley, the major tomato production area in California. The field trial investigated in-row spacing (37.5 cm and 75 cm), the number of plants per transplant plug (1, 2, or 3), on a medium vine size variety (Halley 3155) and a large vine size variety (AB2). Individual plots were large enough for mechanical harvest. Yield results indicate that these two varieties responded similarly to increasing plant density. In general, a spacing of 37.5 cm with 2 or 3 plants per plug yielded significantly more than 1 plant per plug, regardless of variety. There was no yield advantage in seeding 3 plants per plug when compared to yields with 2 plants per plug, regardless of variety or in-row plant spacing. A plant spacing of 75 cm with only 1 plant per plug yielded the least.
Postharvest Peel Pitting in Citrus Fruit at Nonchilling Temperatures Is Affected by Climatic Factors and Advanced by Changes in Peel Water Status
Authors: Alferez Fernando , Zacarias Lorenzo , Burns Jacqueline
Published: February 2019

Several citrus varieties, including `Navel' oranges, `Marsh' grapefruit and `Fallglo' tangerines are prone to develop postharvest peel pitting at nonchilling temperatures. The disorder is characterized by depressions in flavedo that ultimately affect oil glands. Increasing evidence indicates that changes in peel water status during postharvest handling of fruit plays a major role in the appearance of the disorder. Peel pitting was triggered when fruit were transferred from low to high relative humidity (RH) consistently in several citrus growing areas. A transient increase in fruit ethylene production and ABA content was observed within the first 24 hours after transfer from low to high RH. Water potential decreased with storage at low RH in flavedo and albedo, and recovered faster in flavedo than in albedo cells upon transfer to high RH. The differential recovery in water potential between flavedo and albedo is postulated to cause collapse of external albedo layers and pitting. The effect of climatic conditions in the field at harvest was also examined. Harvesting fruit at low RH induced more severe pitting after storage than harvesting at high RH. In addition, increasing hours of low RH storage prior to storage at high RH resulted in increased pitting. The results demonstrate that change in peel water status is a major factor leading to the development of postharvest peel pitting in citrus.
(136) Survey of Landscape Influence on Spider Migration into Homes
Authors: O'Meara Carol
Published: February 2019

Claims of disproportionate numbers of spiders in certain homes and public demand for non-pesticide means of pest control fostered a closer look at whether landscaping and the manipulation of yards can have an influence on spider migration into homes. Typically, spiders are unwanted houseguests, and homeowner concern over potential contacts with spiders poses challenges to acceptance of these beneficial animals. A 2-year survey was conducted to determine if the complexity of landscaping surrounding a home influences the diversity and abundance of spiders entering houses. The survey consisted of simple and complex landscapes in a regional area. Complexly planted yards had significantly higher numbers of spiders and greater diversity of spider taxa in houses, suggesting a correlation between landscape density and spider invaders. Species data include those that are synanthropic throughout the United States as well as species that are seasonal home invaders. In all, 804 spiders were collected, with 26 species and 31 genera. Results of this 2-year survey will be presented.
(179) An Overview of the Sonoran Vegetable Industry
Authors: Zamora Everardo , Guerrero Jose Cosme , Ayala Santiago
Published: February 2019

Sonora, Mexico, is an outstanding area for growing good quality and high-yield vegetables, fruits, and nuts for year-round exportation. Each year, Sonora produces important, large quantities of fruits and nuts for exportation, including table grape, citrus, pecan, and olive fruit. Also, fresh vegetable production in Sonora is very important. Annually, large volumes of melon, pumpkin, summer squash, chili, husk tomato, tomato, and asparagus are produced for exportation to the United States, Europe, and Japan. Throughout the year, two important growing seasons for vegetable production have been established in Sonora. The most important growing season for vegetable exportation in Sonora is the autumn-winter season, when higher prices are reached for summer vegetables in the U.S. markets. The autumn–winter season begins in August and finishes in December. In Sonora, during the 2002–03 agricultural cycle, 39,666 ha (89,000 acres) of vegetables were established in the field. Many growers in Sonora are investing in imported high technologies for protected cropping from several developed countries, such as the United States, Canada, Israel, and some European countries. Currently in Sonora, high technology is applied by growers for vegetable production, i.e., plastic mulching, low and high tunnels, greenhouses, and shadow frames, which have been frequently used on fresh vegetable commercial production to improve both quality and yield. Because of a large labor force and the attractive income from fresh vegetable exportations to the United States, fresh vegetable production is a very important industry in Sonora. In fact, growing summer vegetables for exportation during the wintertime in Sonora, Mexico, is a good business.
(181) Effect of Mulch, Mycorrhizal Inoculation, and Surround on Late Fall Pepper Production
Authors: Makus Donald J.
Published: February 2019

Four week-old pepper (Capsicum annuum) cultivars Sonora Anaheim and Capistrano were transplanted on 7 Oct. 2004 into a sandy loam soil near Weslaco, Texas (lat. 26°08'N). Plants were subject to eight treatments consisting of sweet sorghum mulch, mycorrhizal (Bio Organics) inoculation, kaolin (Surround) application and their factorial combinations. Mulch was applied at 2.4 kg·m-2 and kaolin weekly at 25 kg·ha-1. Mulch applications reduced soil temperatures at 5 cm typically 8 °C during the 1200–1800 HR period of the day during the first 14 days after planting, but decreased soil temperatures to less than 2 °C by 22 Dec. Volumetric soil moisture content at 0–20 cm was initially 4% (absolute) higher in the mulch treatments during the first week after planting but deceased with time as the mulch deteriorated. Mulching increased root dry weight 70 days after transplanting. Mycorrhizal association was evaluated in four treatments, where incidence of mycorrhizal infection was “mulch + mycorrhizae” > “mycorrhizae only” = `“mulch only” » “control.” Kaolin reduced plant height, plant top fresh weight, and improved yield in both cultivars by increasing earlier flowering and, in the case of `Sonora Anaheim', reducing fruit drop caused by pepper weevil (Anthonomus eugenii). In both cultivars, mulch reduced yields and mycorrhizal inoculation gave no agronomic benefit.
(182) Delayed Planting and Plug Cell Volume Effects on Growth, Development, and Yield of Transplanted Sweet Corn
Authors: Menasha Sandra , Tignor Milton , Heleba David
Published: February 2019

Transplanting sweet corn is commonly practiced in the northeast U.S. to improve stand establishment and promote early harvest. However, early spring storms and labor constraints can delay transplanting when establishment is most desirable. `Temptation' sugary enhanced (se) sweet corn transplants 0-, 2-, 4-, 6-, and 8-days-old beyond the “grower” 2-week growth period were field planted to explore the effects delayed planting combined with plug cell volume differences would have on transplant ear quality and early yields. The transplant treatments were evaluated in a two-way factorial (five delayed planting dates × three plug volumes) arranged in a split-plot design with five replications. Field sites were the whole plot treatment and the factorial treatments were the split-plots. All transplants were planted on 24 May 2004 at the two field sites. The final density was ≈22,000 plants/acre. Transplant cell volume (15, 19, and 29 mL) had no significant effect on ear quality and total marketable yield. Ear length was significantly affected by field site (P≤ 0.0001) and ear diameter was significantly affected by planting delay (P= 0.0145). Field site (P≤ 0.0001) and planting delay (P= 0.0090) both significantly affected the number of early marketable ears/acre. The results indicate that transplants can remain in the plug cells up to 20 days (2 weeks + 6 day delay) before the delay negatively impacts ear diameter, tip fill, and early marketable yield.
Mentha longifolia (L.) L.: A Model Species for Mint Genetic Research
Authors: Vining K.J. , Zhang Q. , Tucker A.O. , Smith C. , Davis T.M.
Published: February 2019

Mentha longifolia, a wild relative of the polyploid, cultivated Mentha (mint) species, was evaluated as a potential model system for genetic research relevant to the cultivated mints. Fourteen Mentha longifolia accessions maintained by the US Department of Agriculture (USDA), Agricultural Research Service, National Clonal Germplasm Repository (NCGR), were highly diverse with respect to geographic origin, oil composition, verticillium wilt resistance, aspects of morphology, and molecular marker polymorphism. Accession CMEN 584 was the only carvone chemotype, while CMEN 682 was the only accession with high menthol content. Trans-piperitone oxide was the primary oil component of accessions CMEN 17 and CMEN 18, while pulegone was most abundant in CMEN 20, CMEN 500, CMEN 501, and CMEN 585. Four accessions—CMEN 585, CMEN 17, CMEN 501, and CMEN 81—were consistently resistant to verticillium wilt, while CMEN 584 and CMEN 516 were highly susceptible. Pairwise similarity coefficients were calculated and a UPGMA (unweighted pair-group analysis) tree was constructed on the basis of 63 informative randomly amplified polymorphic DNA (RAPD) marker bands. CMEN 585 and CMEN 584 shared the greatest number of bands (16), and formed a distinct cluster in the UPGMA tree. Seven pairs of accessions had no bands in common, emphasizing the high degree of molecular diversity represented by these accessions. The favorable features of diploid (2n = 2x = 24) genome constitution, comparatively small genome size (400 to 500 Mb), self-fertility, fecundity, and diversity with respect to economically relevant traits, contribute to M. longifolia's potential usefulness as a model system for the cultivated mints. As a perennial species amenable to vegetative propagation, M. longifolia's spectrum of susceptibility/resistance to an important vascular wilt disease encourages its further evaluation as a system for broader studies of plant–microbe interactions and disease resistance mechanisms.
Randomly Amplified Polymorphic DNA Analysis in the Genus Hosta
Authors: Sauve Roger J. , Zhou Suping , Yu Yingchun , Schmid Wolfram George
Published: February 2019

A randomly amplified polymorphic DNA (RAPD) technique was used to identify and determine the phylogenetic relationships of 37 hosta accessions representing the major subgenera, sections and groups in the genus Hosta. Results of this study show that RAPD markers were able to differentiate not only the main groups, whose plants shared many genetic traits, but also cultivars within a species. Some accessions were identified by a single primer while others had high intercross linkage and required many markers for their separation. The phylogenetic clustering showed that H. plantaginea, the only night-blooming species, and H. ventricosa, the only known natural tetraploid, are unique and should be classified separately. The four species in the subgenus Bryocles, section Lamellatae H. venusta, H. minor, H. capitata, and H. nakaiana have very low genetic similarity since they do not share many amplified fragments. The other accessions were classified into four main clusters; cluster 1: H. venusta, H. tardiva, H. pycnophylla, H. tsushimensis `Ogon', H. montana, H. tibae, H. montana f. macrophylla, H. kikutii `Kikutii', H. longissima `Longifolia', H. rectifolia `Rectifolia', H. takahashii and H.`Undulata'; cluster 2: H. laevigata, H. sieboldiana, H. pycnophylla × H. longipes f. latifolia, H. longipes `Urajiro' and H. ibukiensis; cluster 3: H. capitata, H. kikutii `Polyneuron', H. nigrescens, H. kikutii `Yakusimensis', H. pachyscapa, H. kikutii `Caput-Avis', H. longipes f. latifolia, H. hypoleuca, H. okamotoi, H. densa and H. takiensis; and cluster 4: H. aequinoctiiantha, H. rupifraga, H. `Amanuma', H. minor and H. kikutii `Densa'.
Stomatal Density in Antirrhinum majus L.: Inheritance and Trends with Development
Authors: Martin William J. , Stimart Dennis P.
Published: February 2019

Stomatal density during plant development and inheritance of the trait were investigated with the goal of utilizing stomatal density as a correlated trait to cutflower postharvest longevity in Antirrhinum majus L. Inbred P1 (stomatal index = 0.2) was hybridized to inbred P2 (stomatal index = 0.3) to produce F1 (P1 × P2), which was backcrossed to each parent producing BCP1 (F1 × P1) and BCP2 (F1 × P2). P1, P2, F1, BCP1, and BCP2 were used to examine changes in stomatal density with plant development and early generation inheritance. An F2 (F1 self-pollinated), and F3, F4, and F5 families, derived by self-pollination and single seed descent, were used to obtain information on advanced generation inheritance. Stomatal density was stable over time and with development of leaves at individual nodes after seedlings reached two weeks of age. Therefore, stomatal density can be evaluated after two weeks of plant development from a leaf at any node. Stomatal density is quantitatively inherited with narrow sense heritabilities of h2F2:F3 = 0.47 to 0.49, h2F3:F4 = 0.37 ± 0.06 to 0.60 ± 0.07, and h2F4:F5 = 0.47 ± 0.07 to 0.50 ± 0.07.
Size of Vegetation Free Area Affects Nonbearing Pecan Tree Growth
Authors: Smith Michael W. , Cheary Becky S. , Carroll Becky L.
Published: February 2019

Newly planted pecan (Carya illinoinensis Wangenh. C. Koch cv. Kanza) trees were grown for 5 years in a bermudagrass [Cynodon dactylon (L.) Pers.] sod with vegetation-free circles 0, 0.91, 1.83, 3.66, or 7.32 m in diameter. Trees were irrigated and fertilized to minimize growth differences associated with competition from the bermudagrass. There were no differences in trunk diameter among treatments the first 2 years of the study. During the next 3 years, trunk diameter increased curvilinearly as the vegetation-free circle increased. A vegetation-free circle diameter of 1.83 m produced near maximum tree growth. Although trunk diameter improved slightly as the vegetation-free diameter was increased up to 7.32 m, it was not sufficient to justify the additional expense for herbicides nor exposure of unprotected soil to erosion.
Cover Crop Residues Enhance Growth, Improve Yield, and Delay Leaf Senescence in Greenhouse-grown Tomatoes
Authors: Kumar Vinod , Abdul-Baki Aref , Anderson James D. , Mattoo Autar K.
Published: February 2019

Cover crop management in growing horticultural produce has attracted attention for reducing soil erosion and limiting the input of synthetic fertilizers and pesticides. Hairy vetch (Vicia villosa Roth.), one of the cover crops, exhibits desirable attributes such as high N fixing ability, biomass quality, adaptability to low temperatures, resistance to pests, and fitness in vegetable production, particularly in rotation with tomatoes. The interactions between the cover crop mulch and the tomato plant in the field plots result in delayed leaf senescence and increased disease tolerance. The mechanisms underlying these interactions are largely unknown. Limits in pursuing these studies year-round in the field—growing season and complexity and variability of the field environment—could be circumvented if the observed responses of tomato plants to hairy vetch mulch in the field could be reproduced under greenhouse conditions. We have tested tomato plants for two years in the greenhouse using soil residues brought from field plots where respective cover crops had been previously grown. Treatments were a) bare soil from a fallow, weed-free field plot, b) soil from a field plot that had been planted into a rye cover crop, and c) soil from a field plot that had been planted into a hairy vetch cover crop. Pots with soil from the rye or vetch field plots were further topped with rye or vetch residues, respectively, after transplanting the tomato plants. Additional N was applied to 50% of the plants in each treatment. In the greenhouse, cover crop residue-supplemented tomatoes exhibited high vigor, higher marketable yield and delayed senescence compared to those grown in bare soil. All treatments responded favorably to additional N from commercial fertilizers. Delayed leaf senescence correlated with the accumulation of rubisco large subunit and chitinase, two proteins central to photosynthesis and pathogenesis, respectively. This study shows that the responses of tomato plants to cover crops seen in the field can be mimicked under greenhouse conditions.
Prevalence and Potential Impact of Soil-dwelling Pests and Insect Pathogenic Nematodes in Strawberry Fields
Authors: LaMondia James A. , Cowles Richard S. , Los Lorraine
Published: February 2019

Surveys mailed to strawberry growers in 1999 determined the state of nematode and root weevil awareness and practices for their management. Based on the survey response, 41 fields representative of various practices were selected for sampling throughout Connecticut. Adult black vine weevils (Otiorhynchus sulcatus) were found in only 3 fields, but notched leaves characteristic of their feeding were found in 40 fields, indicating a greater prevalence than perceived by growers. The percentage of notched leaves was positively correlated with years in production, suggesting that it took some time for the flightless weevils to migrate into and to increase to damaging numbers in fields. In fields older than 2 years, bifenthrin insecticide reduced leaf feeding compared to untreated fields or to fields treated with endosulfan or azinphos-methyl. Lesion nematodes (Pratylenchus penetrans) were detected in 31 fields and were present in about 58% of plants. When present, nematode numbers were greater in the margins of poor areas than in adjacent healthy plants (735 vs. 428 per g root, respectively). Lesion nematode numbers were also greater in replanted strawberries than rotated fields (760 vs. 304, respectively). Soil fumigation with methyl bromide, but not methyl dithiocarbamate or the combination of 1,3-dichloropropene and chloropicrin, reduced nematode densities in the following strawberry crop. Based on an economic model, nematodes reduced accumulated profit over 4 fruiting years by more than the percent loss of fruit yield. Beneficial insect pathogenic nematodes, predominantly Heterorhabditis bacteriophora and Steinernema feltiae, were found in 75% of fields to which commercially obtained nematodes had been applied, and to 14% of the remaining fields. Presence of naturally occurring insect pathogenic nematodes in strawberry fields may control root weevil populations and lead to more years of productivity.