bluuebunny/crossref_metadata_2025 huggingface dataset:
470 Ethylene Inhibits the Development of Chilling Injury in Fresh-cut Tomato Slices during Storage at Low Temperature
Authors: Hong Ji Heun , Gross Ken
Published: February 2019

Experiments were conducted to determine if ethylene influences chilling injury, as measured by percent of slices showing some water-soaked areas and associated fungal growth in fresh-cut tomato slices (Lycopersicon esculentum Mill.; cvs. Mountain Pride and Sunbeam). Ethylene concentration in containers without a perforation (perforations were made by piercing the lid of the container forming a 0.7-mm hole) significantly increased during storage at 5 °C, while little or no accumulation of ethylene occurred in containers with from one to six perforations. Chilling injury was greatest in slices in containers with six perforations, compared to slices in containers with one perforation an,d was over 12-fold greater than that of slices in control containers with no perforations. The percent ofage visible fungal growth of slices was roughly correlated with the degree of chilling injury. An experiment was also performed to investigate the effectiveness of including an ethylene absorbent pad in containers on subsequent ethylene accumulation and chilling injury. While ethylene in the no-pad control increased continually during storage at 5 °C under modified-atmosphere conditions, no increase in accumulation of ethylene was observed in containers containing ethylene absorbent pads throughout storage with `Sunbeam' and `Mountain Pride' tomatoes. The ethylene absorbent pad treatment resulted in a significantly higher percent of chilling injury and visible fungal growth compared with the no-pad control. In studies aimed at inhibiting ethylene production using 1-aminoethoxyvinylglycine (AVG) during storage of slices, the concentration of ethylene in control containers (no AVG) remained at elevated levels throughout storage compared to containers with slices treated with AVG. Chilling injury in controls was 5-fold greater than that in slices treated with AVG. All slices treated with AVG had visible fungal growth, while the percent of slices showing visible fungal growth in no-AVG controls was 54%. Furthermore, we tested the effect of ethylene pretreatment of slices on subsequent slice shelf-life and quality. In slices treated with ethylene (0, 0.1, 1, and 10 μL·L-1) immediately after slicing, ethylene production in untreated controls was greater than that of all other ethylene pretreatments. However, pretreatment of slices at 3 days after slicing resulted in a different pattern of subsequent ethylene production during storage. The rate of ethylene production by slices treated with 1 μL·L-1 ethylene at 3 days after slicing was greater during storage than any of the other ethylene treatments. With slices pretreated with ethylene both immediately and 3 days after slicing, the rate of ethylene production tended to show an negative correlation with chilling injury.
473 Beneficial Effect of Heat-shock Treatments on Lettuce Applied before and after Wounding
Authors: Loaiza-Velarde Julio G. , Saltveit Mikal E.
Published: February 2019

Changes in phenolic metabolism are induced by minimally processing, which ultimately leads to the browning of lettuce tissue. Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5.) is greatly influenced by storage temperature. Evaluation of PAL activity at temperatures going from 0 to 25 °C showed that peaks occurred sooner at higher temperatures but at lower levels. Heat-shock treatments (50 °C, 90 s) have a protective effect against browning, help to retain greenness of tissue, and decrease the production of phenolics when applied either after or before wounding. To achieve a considerable, beneficial effect from hot water treatments applied after wounding these should not be delayed more than 36 h. The best results for heat-shock treatments before wounding occurred when applied at ≈12 h before cutting the tissue. Although cycloheximide did reduce PAL activity in a similar pattern as heat-shock treatments, it did not prevent browning itself. Cycloheximide seems to cause some sort of chemical damage that promotes the browning of lettuce tissue. When cycloheximide was applied in combination with heat-shock treatments browning did not occur.
476 In Vitro Mortality of Eggs and Third Instar Larvas of Anastrepha ludens and A. obliqua with Insecticidal Controlled Atmospheres at High Temperature
Authors: Yahia Elhadi M. , Ortega Dora , Martinez Alejandro , Moreno Pamela
Published: February 2019

In this study, we report on the effect of insecticidal controlled atmospheres at high temperatures on the in vitro mortality of eggs and third instars larvas of A. ludens and A. obliqua. Atmosphere evaluated were air, 0% O2, 13% O2 + 20% CO2, and 0% O2 + 50% CO2 at 44°C for 160 min. Other treatments evaluated included 0% O2 + 50% CO2 at 48°C for 160 and 220 min and the same atmosphere at 40, 50, 51, 52, 54, and 55°C for 240 min and at 48°C and 55°C for 80, 160, and 240 min. Both species responded similarly to the treatments applied. Larvas were more sensitive than eggs in both species. A 100% mortality of larvas of the two species was obtained in 0% O2 + 50% CO2 at 48°C, but there were survivals in eggs of both species. Treatment with 0% O2 + 50% CO2 at 55°C for 240 min resulted in 100% mortality in eggs and larvas of both species. Less extreme conditions (temperature and duration of treatment) caused high but inconsistent mortality, probably due to variability in insect population. Statistical analysis for the calculation of probit 9 will be discussed.
480 Evaluation of Potted Anthurium Cultivar Performances under Interior Environments
Authors: Chen Jianjun , Henny R.J. , Mellich T. , Caldwell R.D. , Robinson C.A.
Published: February 2019

Anthurium cultivars are being produced primarily as cut-flower plants. Whether Anthurium can be used as a flowering interiorscape plant is not well documented. Therefore, five finished Anthurium cultivars were evaluated in interior acclimatization rooms under two light intensities provided by cool-white fluorescent lamps for 12 hours daily: 16 mmol·m–2·s–1 (low light) and 48 16 mmol·m–2·s–1 (high light). Temperature of the rooms was maintained at 24 °C with a relative humidity of 60%. Total number of open flowers and number of senesced flowers were recorded weekly over 5 months. In addition, plant canopy height and width and total number of leaves were measured monthly. Number of open flowers per week ranged from 1.4 to 4.7 under low light and 2.4 to 6.3 under high light. The cultivar Red Hot showed the best performance with a weekly average flower count of 4.7 under low light and 6.3 under high light. All cultivars continued to produce new leaves, ranging from one to five per month under low light and two to five leaves under high light. Leaves were dark green and shiny under the interior conditions. Growth index of `Red Hot' increased 31% under low light and 20% under high light. Results from this study demonstrate that Anthurium can continue to grow and produce flowers under interior environmental conditions. Variation among cultivars indicates that genetic potential exists for selecting improved cultivars based on interior performance.
481 Early Applications of Growth Regulators to Bedding Plants
Authors: Barrett J.E. , Wieland C.E. , Nell T.A. , Clark D.G.
Published: February 2019

In some species of bedding plants, rapid hypocotyl elongation during germination makes size control in plug production difficult. Commercial growers often start applying growth regulators as cotyledons are expanding or after the first true-leaves are expanding. Using `Bonanza Spry' marigolds, we evaluated applying paclobutrazol at sowing and after 3 and 6 days. Sprays at 30 mg·L–1 in a volume of 0.2 L·m–2 or 3 mg·L–1 in 0.6 mg·L–1 applied at sowing reduced hypocotyl elongation by 25% and produced more compact plugs. In a second study, plugs of `Double Madness Rose' petunia, `Showstopper Orange' impatiens, `Wizard Rose' coleus, and `Cooler Rose' vinca were grown in 10-cm pots with a growing medium that did not contain pine bark. Uniconazole was sprayed in a volume of 0.2 L·m–2 onto the surface of the medium before planting at concentrations of 25%, 50%, and 100% of the label's recommended concentration for each crop. An additional treatment was uniconazol applied 2 weeks after planting at the label concentration. All early applications reduced final plant size compared to the nonsprayed plants. For impatiens, the early application at 25% of the label concentration produced plants similar to the spray at 2 weeks after planting. For the other crops, the 50% treatment prodcued plants similar to the spray after planting. The early applicaiton of growth regulators offers the industry an additional stradagy to use for controlling the growth of vigorous bedding plant crops.
486 Growth Responses of Tomato, Pepper, Broccoli, and Corn Grown in Soils Amended with Ammonium Lignosulfonate
Authors: Soltani Nader , Lazarovits George
Published: February 2019

Ammonium lignosulfonate (ALS) is a liquid waste by-product of pulp and paper industry that may be a source of organic fertilizer. Four plots each of tomato, pepper, broccoli, and corn were set up in a randomized block design on the AAFC-SCPFRC farm in the Spring 1998. Treatments were untreated control, 0.5% (v/w) ALS, and 1% (v/w) ALS. Soil samples were taken at 0, 2, 4, 8, and 22 weeks after amendment incorporation and analyzed for pH, microbial population, and water soluble ions. Soil temperature was measured at 8-cm depth. Leaf chlorophyll content was measured at four sampling dates. Tomato and pepper fruit were evaluated for symptoms of diseases. Soil temperature in 0.5% and 1.% ALS treatments were 2 and 7 °C warmer, respectively, than the control. Soil pH was lower in ALS-treated plots. 1% ALS caused more than 10-fold increase in bacterial population. Fungal populations in both 0.5% and 1% ALS treatments were 10- to 100-fold higher than control soil and continued to be higher to the last sampling date. Weeds were reduced by more than 50% by 0.5% or 1% ALS treatments. Both ALS rates caused an initial increase in NH4, NO3, NO2, K, Na, Cl, PO4, Ca, and SO4. NH4 and SO4 remained elevated for 22 weeks in both ALS treatments. ALS slightly increased chlorophyll content in tomato, pepper, and corn, but not in broccoli plants. The number of diseased tomato fruit in ALS plots were reduced by 50% to 70%. Bacterial spot decreased by more than 50% in both ALS-treated plots, while anthracnose declined by 50% to 75%. There were no significant differences in early and total yield of tomato, peppers, and corn. Early broccoli yield decreased in ALS treatments, while total yield increased over that of control in both ALS treatments.
487 Assessment of Chemical Induction of Acquired Resistance to Phytophthora Fruit Rot in Field-grown Pickling Cucumber
Authors: Hockin Priscilla M. , Widders Irvin E.
Published: February 2019

Systemic acquired resistance (SAR) is a physiological defense response in plants conferring broad spectrum resistance to pathogens. SAR is inducible through infection by necrotizing pathogens or chemical inducers and involves the systemic activation of defense related genes. Our objectives were to evaluate resistance expression to phytophthora soft rot fruit in cucumber in response to increasing concentrations of 2,6 dichloroisonicotinic acid (INA) and benzo (1,2,3)thiadiazole-7-carbothioc acid S-methyl ester (BTH) by foliar applications. Excised leaves exhibited a resistance response to foliar applications of all concentrations of INA and BTH tested when challenge inoculated with Colletotrichum lagenarium. There was increasing benefit with increasing concentration of each chemical applied. Harvested cucumber fruit, 3.4 to 4.5 cm in diameter, were challenge inoculated with Phytophthora capsici; there were no significant chemical and rate interactions in terms of internal lesion measurements. Overall, INA consistently reduced lesion size in cucumber fruit. A bioassay conducted on fruit of different maturity levels, as defined by fruit diameter, revealed that larger sized fruit (4 to 5 cm) were more resistant to fruit rot. Fruit with diameters of 3 to 4 cm from plots treated with BTH showed little resistance as compared to the control and fruit from the same treatment with diameters of 2 to 3 cm. Fruit from plots treated with INA had at least 50% reduction in lesion size than the control. It is unclear if these differences were attributable to changes in physiological or anatomical factors. The true importance of these results should be interpreted with caution. Yield studies have not been conducted, and thus, with the experienced stunting, treatment with 100 ppm INA would be expected to lower yield and perhaps fruit quality. Determination of the optimal application regime and other cultural factors will provide broad control of plant diseases.
489 Detection of Hidden Sectorial Chimeras in Almond Shoots through Distortions in Flower Symmetry
Authors: Gradziel Thomas M. , Thorpe Mary Ann
Published: February 2019

Somatic mutations in shoot growing points, while considered relatively common in many horticultural clones, cannot be detected unless the mutation results in a distinguishable change and comes to occupy sufficient shoot area to be observable. Noninfectious bud-failure (BF) in almond, a genetic mutation which results in failure during early development of vegetative but not flower buds, behaves as a chimera in its incidence within an affected tree and in vegetative progeny from bud-failure prone clonal sources (i.e., vegetative lineage). Early stages of BF development are thought to occur as very limited and so undetected sectorial or mericlinal chimeras. Detection of BF during these early stages would be very valuable for the selection of low-BF source clones for nursery increase. Flower symmetry, as measured by differences in the size of each of the five petals of an almond flower, was evaluated as an indicator of the relative fitness of the individual cell lineages from which different petals were derived. Several hundred flowers from individual clonal sources of the almond variety `Nonpareil', known to produce either very low, medium, or very high levels of BF in their vegetative progeny, were tested over 3 separate years. Significant reductions in flower symmetry were consistently observed for medium BF potential clonal sources relative to either low- or high-BF sources despite the lack of any observable BF symptoms in the medium-BF trees tested. Associated with asymmetric-flower-prone sources was a greater number of an easily distinguishable distorted petal morphology. Medium BF-potential sources consistently produced 2- to 3-fold greater numbers of this petal morphology relative to low BF-sources, although the occurrence of distorted petals in both low and medium BF sources limits its use as an efficient field selection tool. Research findings, however, are allowing a more detailed understanding of the developmental ontogeny of “bud-sport” mutations and may have application in the analysis of otherwise hidden chimeras resulting from either somatic mutations or genetic transformation/regeneration schemes.
491 An Evaluation of Dry Particulates as Pollen Diluents for Supplemental Mass Pollination
Authors: Wetzstein Hazel Y. , Law S. Edward
Published: February 2019

Pollination is essential in the production of many agricultural crops. Insufficient pollination can lead to reduced yield and lower harvest quality in many fruit and vegetables. Recent declines in insect pollinators and the use of cultural systems where compatible pollen is limiting have caused pollen-related production problems in many crops. Supplemental mass pollination (SMP) may be beneficial in such cases. However, the high cost of pollen may prohibit its use unless pollen is efficiently and uniformly applied. Our objective was to evaluate the feasibility of using selected dry particulate materials as pollen diluents for SMP. Viability was assessed in apple pollen mixed and held with selected powders (i.e., two formulations of Rilsan® nylon, polyester resin, diatomaceous earth, wheat flour, and CaCO3). Also, an assessment of inhibitory substances was made using in vitro germination tests with extracts obtained from liquid suspensions of the different particulates. Several powders, viz., Rilsan® nylon formulations, polyester resin, and wheat flour were identified as nontoxic to pollen held for 1 h as dry pollen: particle mixtures. Likewise, leachates from these diluents had no significant effect on pollen germination. Diatomaceous earth exhibited slight, but statistically significant, inhibitory effects on germination, while CaCO3 completely inhibited germination. The morphology and size of particulates were evaluated using scanning electron microscopy and will be discussed vis-a-vis pollen dispersion and metering requirements.
493 Inducing Polyploidy Pollen in Apple Cultivars
Authors: Shi Yinping , Wang Qiangsheng , Yang Jianming , Sui Congyi , Sun Qingrong
Published: February 2019

To perform apple polyploid breeding the ways of inducing polyploidy pollen with temperature and chemicals were studied. Materials include 13 diploid cultivars: Red Chief, Dai Hong, Rose Red, Golden Delicious, Mollie's Delicious, Gala, Bella, Jonathan, Fuji, Qiu Kou Hong, and Yan Qing, OBIR-2T-47. Chemicals: Chloroform, N-nitroso-ethylurea. At the beginning of PMC meiosis, fruiting branching groups were covered with plastic bags to raise temperature or were treated with chemical. After covering, temperature during the day increased 2 °C, generally not lower than 0 °C. Whether branches received high temperature or chemicals treatment, polyploidy pollen was induced to produce. The pollen grain of CK is tricolporat, its polar view is triangular, and its diameter almost 40 μm, showing no difference in size. Rate of empty pollen grain is low. Pollen grains that were treated were different in size, and rate of empty pollen is high, part of pollen grains germinating colporat change into tetracolporat with a few polycolporat, its polar view is square, round, and oval. The diameter of large pollen grains was 45-48 μm, increased by 11-12%. Giant pollen grain are 50-68 μm, increased by 25%-70%. Rate of induction is different in different cultivars. For most cultivars, giant pollen grain is 0.3%-0.5%. Gala and OBIR-2T-47 were higher, reaching 2.5%-7%. Chemicals caused damage on cultivars. Delicious strains were easily damaged.
495 Prison Master Gardener Program Contributes to Improved Social and Vocational Skills
Authors: Traunfeld Jon H. , Kafami D.M.
Published: February 2019

Patuxent Institution, a maximum security prison in central Maryland, enlisted Maryland Cooperative Extension (MCE) in 1996 to develop a master gardener (MG) program for inmates as part of its horticultural therapy program. The twin goals are to improve inmate social and coping skills and provide vocational training in horticulture. The program has graduated 30 certified master gardeners over three training cycles. Selected trainees are carefully screened and must complete a preliminary horticulture course before entering the MG program. To earn the MG certificate, inmates receive 65 hours of training, pass a 100-question closed-book exam, and contribute 40 hours of service to the program. The inmates apply their knowledge to a 2-acre garden site that includes a production greenhouse. Placing released inmates in green industry jobs is an important program goal. The program has two unique features: 1) inmates are taught by MG from surrounding counties and MCE faculty. MG volunteers who present subject matter, earn volunteer credit for their participation, gain experience in a horticultural therapy setting, and express a high degree of satisfaction teaching and interacting with inmates. 2) All horticultural crops are produced organically by the inmates (all of whom have a substance abuse history) to demonstrate that life can be nurtured without chemical substances. One self-report research instrument showed that participants had a decreased vulnerability to addiction.
497 Customers in Seven U.S. Markets Assess Service Quality In Traditional and Non-traditional Retail Garden Center Outlets
Authors: Behe Bridget , Barton Susan
Published: February 2019

SERVQUAL has been demonstrated to be a reliable and valid tool to measure customer perceptions and expectations of service quality. Two previous uses of the survey in the horticulture industry were identified. In Spring 1997, we adapted the SERVQUAL instrument to survey 701 customers of 10 retail garden centers (TR) and four nontraditional retail or mass-merchandise outlets (MM) in seven U.S. markets. Among the seven markets, customers differed on only two of six demographic characteristics: income and number of people residing in the household. Demographic characteristics of TR and MM customers were similar in terms of age (47 and 45 years), people residing in the household (2), percent female respondents (77% and 73%), and family status. Customers differed demographically on 1996 household income ($50,722 and $44,753). Customers of TR and MM had similarly high expectations for three of five service quality and one product quality dimensions. However, TR customer perceptions were consistently higher on all service and product quality dimensions than MM customers. This yielded consistently higher service quality gaps for MM customers when compared to TR customers. We concluded that TR hold an advantage in these seven markets with higher customer perceptions of product and service quality.
501 Viewing Red-flowering Geraniums Altered Fast-beta Brain Wave Activity and Improved Positive Attention of Low-attentive Female College Students
Authors: Kim Eunhee , Mattson Richard H.
Published: February 2019

Psychophysiological responses to geranium visual stimuli were analyzed on female college students with low attentiveness. Alpha and fast-beta brain wave activities, electrodermal activities, and skin temperature were measured continuously during a 5-min baseline, a 10-min induced stressor, and a 5-min treatment. Each of 75 female college students viewed a film of a stressful human situation—an induced stressor, then was exposed to a randomly assigned treatment: red-flowering geraniums, nonflowering geraniums, or no plants. Based on responses to the induced stressor, students were placed into non-, mild-, and high-induced stress groups. Regression models of psychophysiological responses to each treatment were developed for over-all stress levels. Non-induced stress female students exposed to red-flowering geraniums in contrast to nonflowering geraniums and no-plants showed greater fast-beta brain wave activity. Greater fast-beta of non-induced stress female students exposed red-flowering geraniums was associated with increased positive attention and not because of increased stressful tension. This conclusion was supported by more positive emotional states self-reported using the Zuckerman Inventory of Personal Reactions. Conclusive findings from over-all stress levels suggest that benefits of viewing red-flowering geraniums occur to both nonstress and high stress female college students; red-flowering geraniums improve positive attention of female students with no stress (low attentiveness) and enhance stress recovery of female students with high stress (tension).
504 Detection of Water Stress Using Infrared Imaging
Authors: Lin W.C. , Block G.S. , Chen S. , Ehret D.L.
Published: February 2019

In commercial production of greenhouse cucumber, moderate water stress is often undetectable until plants show severe wilting. The purpose of this study was to establish a noncontact, early detection method for such moderate stress before visual wilting takes place. An infrared imaging system including an infrared camera, a personal computer, and necessary image processing software was placed in a greenhouse with the camera elevated and viewing the plant canopy. Selected plants, each in a bag of sawdust growing medium, were subjected to water stress by removing irrigation tubes from the growing medium. The infrared images obtained from a crop canopy displayed an increase in foliar temperature of stressed plants, which were located among normally watered (control) plants in the same greenhouse. Increased foliar temperatures of stressed plants occurred 1 to 3 days before wilting was observed. When visual wilting occurred, the stress treatment was stopped and irrigation was resumed within the same day. Cucumber plants showed no crop loss after one cycle of moderate stress. Repeated moderate stress caused yield loss. The potential applications of this nondestructive, noncontact detection method in plant science research and in commercial greenhouse production will be discussed.
507 Production of Compact Cucumber, Tomato, and Bell Pepper Transplants by Use of Photoselective Plastic Films
Authors: Li Shumin , Rajapakse Nihal C. , Oi Ryu
Published: February 2019

Growth chamber experiments were conducted to investigate the effectiveness of several photoselective plastic films in controlling height of `Sweet Success' cucumber, `Mt. Pride' tomato, and `Capistrano' bell pepper transplants. Four types of treatment films; a control, two far-red light intercepting films (YXE-1 and YXE-10), and a red light intercepting film (SXE-1), with R: FR ratios of 1.0, 2.0, 1.6, and 0.8, respectively, were used as the covering materials of experimental chambers. Photosynthetic photon flux (PPF) was adjusted to be the same in all chambers with cheese cloth. Treatment period for cucumber and tomato was 15 days and that for bell pepper was 20 days. At the end of the treatment, significantly shorter plants were found in both YXE-1 and YXE-10 chambers for all the three tested crops. However, YXE-10 was more effective than YXE-1 in producing compact cucumber, tomato and bell pepper transplants. SXE-4 film produced taller plants than control film. Magnitude of response to filtered light varied with the crop species. Number of leaves was not significantly affected by the light transmitted through photoselective filters, indicating that the height reduction was mainly caused by the reduction in internode length. With the commercial development of photoselective greenhouse covers or shade material in the near future, nursery and greenhouse industry could potentially reduce the cost for growth regulating chemicals, reduce the health risks to their workers and consumers, and reduce environmental pollution.
510 Alteration of Fruit Characteristics in Transgenic Tomatoes with Modified Gene Expression of Endo-xyloglucan Transferase
Authors: Asada Kiyozo , Ohba Toshiharu , Takahashi Shuichi , Kato Ikunoshin
Published: February 2019

Endo-xyloglucan transferase (EXGT, also called xyloglucan endotransglycosylase, or XET) is a cell wall enzyme catalyzing molecular grafting between xyloglucan molecules, which is essential for expansion and morphological change of plant cells. EXGT gene was first isolated by us from Azuki bean hypocotyl and sequenced and later isolated by several other groups from variety of plants including monocots. In tomato, three genes have been identified, i.e., LeEXGT, tXET-B1, and tXET-B2. LeEXGT mRNA accumulated transiently in early stage of development (immature green and mature green stage). It accumulated slightly also in breaker stage in which fruit color turns to pink. The peak of LeEXGT mRNA accumulation was ≈12 days after pollination. To elucidate a physiological role of EXGT, especially in fruit development, tomato plants were transformed to produce LeEXGT sense or antisense RNA constitutively using Ti plasmid-based transformation system, and we obtained several lines of plants with different levels of LeEXGT transcripts. In these transgenic tomatoes, fruit size was positively correlated with the level of LeEXGT transcripts monitored at its peak stage of expression. However, the refractive index of tomato fruit sap, which is closely correlated with the total solids contents and reflects the sugar status of the fruit, was negatively correlated with the level of LeEXGT transcripts. These results first represent the evidence that EXGT can control in vivo morphological and biochemical properties of plants by changing the level of its expression. This finding opens the possibility of improvement by transgenic approach of fruit plants, such as melon, watermelon, kiwifruit, and apple, in which sugar contents are important economic characters for evaluation.
511 Toward Mapping and Cloning Late Blight Resistance Derived from the Wild Solanum bulbocastanum using Potato + S. bulbocastanum Somatic Hybrids
Authors: Bradeen James M. , Ness S. Kristine , Haberlach Geraldine T. , Wielgus Susan M. , Helgeson John P.
Published: February 2019

Late blight of potato, caused by the fungal pathogen Phytophthora infestans, is of great economic significance and no important U.S. potato cultivars are reliably resistant. The diploid species Solanum bulbocastanum is highly resistant to late blight, even under extreme conditions, but is sexually incompatible with potato. We have generated potato + S. bulbocastanum somatic hybrids. These hexaploid hybrids are highly resistant to late blight and progeny from two successive backcrosses to cultivated potato are either fully resistant or susceptible. The advanced generations are morphologically similar to potato. We have initiated mapping efforts to identify bulbocastanum chromosomal regions responsible for late blight resistance. Using RFLPs, RAPDs, and AFLPs, we identified a single chromosomal region (i.e., single gene or group of linked genes) on chromosome 8 that accounts for 62.2% of the observed resistance. The tomato cDNA clone CT88 cosegregates with late blight resistance in our material and was used to isolate a homeologous BAC clone from a S. bulbocastanum library. Our current efforts include mapping resistance in both fusion-derived and diploid S. bulbocastanum materials via map merging. As markers linked to late blight resistance are identified, we will attempt to convert them to marker forms useful for large-scale breeding efforts. To date, we have successfully converted RAPD and RFLP markers to SCAR and CAPS marker forms. Finally, continued fine mapping and BAC clone characterization will enable future map-based cloning efforts.
513 Use of Reverse Transcription PCR (RT-PCR) to Study the Potato Stearoyl-ACP Desaturase (Delta9) Gene Expression at the Transcript Level during Cold Acclimation
Authors: Vega Sandra E. , Palta Jiwan P.
Published: February 2019

Previous studies in our laboratory both in pine needles and potato leaves have shown evidence of an increase in 18: 2 (linoleate) in the purified plasma membrane fraction during cold acclimation. This increase was reversible on deacclimation, thereby suggesting a link between the accumulation of 18: 2 and acquisition of freezing tolerance. These studies suggest that the activity of specific desaturases may be modulated during cold acclimation. This study was aimed at studying the possible involvement of stearoyl-ACP desaturase (delta9) in potato cold acclimation response. Our approach was to study the induction of delta9 desaturase at the transcript level by using potato delta9 desaturase gene specific primers and reverse transcriptase. For this purpose, mRNA from S. tuberosum (cold sensitive, unable to acclimate) and S. commersonii (cold tolerant, able to cold acclimate) was extracted before and after acclimation. Sequence analysis confirmed that the amplified band was delta9 desaturase. Our results show that there is an increase in delta9 desaturase gene transcripts during cold acclimation and that this increase is associated with the cold acclimation response in potato. These results together with previous reports on the increase in 18: 2 in the plasma membrane during cold acclimation give more evidence toward the involvement of stearoyl-ACP desaturase (delta9) in the potato cold response.
514 Consistency of Detected QTL for Bacterial Brown Spot Resistance Using RAPD Markers over Environments in Common Bean
Authors: Jung G. , Nienhuis J. , Hirano S. , Upper C. , Ariyarathne H. , Coyne D.P.
Published: February 2019

Bacterial brown spot (BBS), incited by the bacterial pathogen Pseodomonas syringae pv. syringae is important disease of common bean. Phenotypic visual readings of infected areas and a leaf freezing assay estimating the population size of Pss on leaf surface were used for disease assessment for 2 years using 78 RI lines derived from Belneb RR-1 x A55 population grown in Wisconsin. The objectives of this research were to determine the genomic regions of QTL affecting the genetic variation of bacterial brown spot resistance in both assays over 2 years (1996 and 1998) and to determine the size of their genetic effects. In addition, we examined the consistency of detected QTL over environments. Three chromosomal regions associated with QTL for BBS resistance were identified in both assays in 1996 and one chromosomal region was consistently detected over 2 years.
516 Predicting Fruit Set and Evaluating the Effects of Chemical Thinners on Apples
Authors: Greene Duane W.
Published: February 2019

The lack of pollination and the effects of blossom thinners were simulated by enclosing selected `McIntosh' apple spurs in super-light insect barrier netting at the pink stage of flower development. Fruit set was recorded and fruit size measured at 2- to 3-day intervals from petal fall until initial set. The effects of lack of pollination or the use of blossom thinners on initial set could not be determined with any degree of accuracy until at least 8 days after petal fall. NAA was applied at 8 ppm when fruit were 8.5 mm in diameter. Fruit set and fruit size were taken at 2- to 3-day intervals until the end of June drop. Fruit set on NAA-treated trees was greater than that on check trees for 2 weeks following application. Although NAA ultimately did cause significant thinning, it was not until 3 to 3.5 weeks after application that it was possible to determine with accuracy the thinning response to NAA. However, the thinning response to NAA could be predicted within a week after application, since growth of fruitlets that ultimately abscised slowed 4 to 7 days after the application of NAA. A working model to predict effective pollination and the response to chemical thinners in apples will be discussed.
523 Prohexadione-Ca: Induction of Resistance against Bacterial and Fungal Pathogens in Apple
Authors: Rademacher W. , Speakman J.B. , Krack G. , Scholtissek M. , Wolf R. , Evans J.R. , Roemmelt S. , Treutter D.
Published: February 2019

Prohexadione-Ca (BAS 125 W) is currently developed as an inhibitor of excessive vegetative growth in apple. In addition to the control of shoot growth, pronounced effects on the incidence of scab (Venturia inaequalis) and fire blight (Erwinia amylovora) are observed that are not due to any fungicidal or bactericidal effect of the compound. Prohexadione-Ca induces marked changes in the metabolism of phenylpropanoids most likely by inhibiting distinct dioxygenases, such as flavanone 3-hydroxylase, which require 2-oxoglutarate as a co-substrate. The content of flavonoids such as luteoliflavan (which does not normally occur in apple tissue) and eriodyctiol is drastically increased reaching levels in the range of 50 mg per gram of dried young shoot tissue. Simple phenols, the identity of which is still unknown, also undergo intense changes. Since phenylpropanoids have often been found to be involved in defense mechanisms of higher plants, further studies on their role in pathogen resistance in apple are justified from these results.
524 Primocane Tipping to Delay `Heritage' Red Raspberries Harvest Date in Chile
Authors: Bañados M. Pilar , Alvarez Carolina , Soto Alejandra
Published: February 2019

To evaluate the effect of the time of primocane tipping on harvest date of `Heritage' red raspberry in the central valley of Chile (southern hemisphere), we tipped primocanes at three dates during the 1996–97 growing seasons: in Nov. 1996 (PN), Dec. 1996 (PD), and Jan. 1997 (PJ). Tipping was done manually at a 1.10-m height. Harvest date, fruit quality, and yield component was evaluated in the control and three tipping dates. A difference of 75 days on the initiation of harvest date was detected among treatments. Harvest date initiation was on 20 Jan. for the control with no tipping and for PN, 3 Mar. for PD, and 4 Apr. for PJ. Fruit of the PN treatment was smaller and lighter than the rest of the treatments; however, little differences in soluble solids, acidity, and pH were detected among treatments. Primocane lateral number was 14 for the control treatment and decreased to seven in tipped primocanes. Lateral length increased largely with tipping treatments: 7.8 cm in the control, 30 cm in PN, 29 cm in PD, and 42 cm in PJ. Fruit per lateral ranged between 6.2 in control and 12.2 in PD. Yields estimation for the fall production were 8.5 t/ha in the control, and increased to 12 t/ha estimated for the PJ treatment. The time of primocane tipping had an important effect on `Heritage' red raspberry harvest date, lateral length, and estimated yield.
526 Hydrogen Cyanamide Hastens Fruit Development and Increases Fruit Yield and Berry Size of Blueberry
Authors: Williamson J.G. , Miller E.P.
Published: February 2019

Field-grown `Misty', `Star', and `Southmoon' southern highbush, and `Climax' rabbiteye blueberry plants were sprayed to drip with 0, 7.7 and 15.4 g·L–1 concentrations of hydrogen cyanamide in north central Florida on 17 Dec. 1997 and 6 Jan. 1998. Plants were dormant with slightly swollen flower buds (stage 2) at the times of applications. The extent and earliness of vegetative budbreak were increased by both hydrogen cyanamide sprays. Hydrogen cyanamide also increased mean fruit fresh weights and reduced fruit development periods for `Misty', `Southmoon' and `Climax' but not for `Star'. Yield response to hydrogen cyanamide was variable among cultivars. Fruit yields of `Misty' and `Climax' increased slightly by 7.7 g·L–1 sprays and decreased significantly by 15.4 g·L–1 sprays. In that case, increased fruit yields appeared to be the result of greater mean fruit fresh weights while reduced yields resulted from significant flower bud thinning that occurred at the highest spray concentration. Both hydrogen cyanamide spray concentrations increased fruit yield for `Southmoon' and decreased fruit yield for `Star' when compared to controls. Spray date had no effect on fruit yield and little effect on fruit development period. Hydrogen cyanamide has potential for increasing fruit quality and earliness of some blueberry cultivars that are grown in the lower southeastern United States.
528 Use of Cultivar and Plant Characteristics as the Basis for Fertilizer Nitrogen Applications in Cranberry (Vaccinium macrocarpon Ait.)
Authors: DeMoranville Carolyn , Davenport Joan
Published: February 2019

The relationship between yield and applied N in cranberry has been investigated. Cultivar was important in determining optimum seasonal N rate. Sustained production for the hybrid `Stevens' required an annual seasonal total of N at up to 67 kg·ha–1, higher than was optimal for native selections `Early Black' and `Howes'. High N rates were associated with increased fruit rot and vine overgrowth. Optimum N rate varied within cultivar, likely due to variation in soil conditions, but soil N test results have not correlated well with subsequent yield in cranberry. Soil organic matter content can predict potential N release, but plant response must also be taken into account. To refine N rate recommendations, plant characteristics that might predict N requirements/status of cranberry were investigated. A standard of 0.9% to 1.1% N in August tissue has been established for cranberry. To find characteristics that could be used earlier, we surveyed 30 sites for percentage of N in tissue, length of new growth, SPAD chlorophyll meter ratings, fertilizer N use, and yield. Length of new growth could be used as an indicator of cranberry N status from June until bloom, being positively correlated with subsequent yield. The SPAD meter proved to be a viable alternative to in-season monitoring of tissue N during June and July. Readings below proposed standard values indicated the need for N fertilizer if vegetative growth was in the standard range. Thus, the easily determined factors of upright length and SPAD rating could be used to refine fertilizer rates during the active growing season, while tissue testing for percentage of N could be used as a “report card” on the fertilizer program at the end of the season.
534 1-Methylcyclopropene Extends Shelf Life of Tomato at All Stages of Maturity
Authors: Mir Nazir A. , Khan Najma , Beaudry Randolf M.
Published: February 2019

The effects of 1-MCP on ripening and shelf life in fruit of five classes of maturity (1, mature green; 2, turning; 3, half-ripe; 4, ripe; and 5, over-ripe) of `Plum' tomato (Lycopersicon × esculentum, Mill) at 22 °C were evaluated. 1-Methylcylopropene (1-MCP) reduced the rate of red color development in fruit of all maturity classes. However, the effect was more discernable in fruit with higher hue angle value. Single application of 1-MCP delayed the color development by 10 days. While a second application of 1-MCP at day 10 delayed color development by another 10 days for mature green tomatoes, it did not influence the color change in all other classes of maturity. The effects of 1-MCP on firmness loss were similar to color development. Compared to the control, 1-MCP reduced the ripening-related rate of respiration by approximately 40%. Contrary to this, ethylene production was not affected by 1-MCP application. Potential exists to use 1-MCP in tomato to reduce ethylene-associated changes in texture and color.
536 Role of Phospholipase A2-derived Lysophospholipids as Senescence Retardants of Plant Tissues: From Basic Science to Commercial Applications
Authors: Ryu Stephen B. , Palta Jiwan P.
Published: February 2019

Lipids have been thought to be important largely in membrane structure and energy reserve. It is now evident that lipids and lipid-derived metabolites play a role in many critical cellular processes. Recent studies have shown that membrane lipid-based signaling mediated by phospholipases such as phospholipase A2 (PLA2), phospholipase C (PLC), and phospholipase D (PLD) constitutes a crucial step in plant responses to abiotic and biotic stresses. Phospholipases and their products also play a role during plant growth and development. For example, PLA2-derived lysophospholipids acted as growth regulators that retard senescence of plant tissues. Interestingly, the PLA2 products inhibited the activity of PLD, which has been suggested to be a key enzyme responsible for membrane lipid breakdown leading to plant senescence. Endogenous levels of lysophospholipids, such as lysophosphatidylethanolamine (LPE), could be increased in castor bean leaf discs by the treatment of auxin (50 μM), which is known to be a activator of PLA2. Pretreatment of leaf discs with a PLA2 inhibitor before auxin treatment nullified the auxin effect and rather resulted in accelerated senescence even compared to the nontreated control. Our recent results suggest a potential role of PLA2 products as biologically active molecules mediating hormonal regulation of growth and senescence. One such product LPE is being commercially exploited for retarding senescence and improving shelf life of fruits, vegetables, and cut flowers.
537 Use of Lysophoshatidylethanolamine (LPE), a Natural Lipid, to Prevent Damaging Effects of Ethephon on Tomato Plants
Authors: Ozgen Mustafa , Palta Jiwan P.
Published: February 2019

Ethephon [2-(chloroethyl) phoshonic acid] is used widely to maximize the yield of ripe tomato fruit. However, ethephon causes rapid and extensive defoliation, overripening, and promotes sunscald damage to the fruit. Recent studies from our laboratory have provided evidence that lysophoshatidylethanolamine (LPE) can reduce leaf senescence. We investigated the potential use of LPE to reduce damaging effect of ethephon on tomato foliage. Three-month-old tomato plants (variety Mountain Spring) grown in greenhouse conditions were sprayed with 200 ppm LPE (with 3% ethanol) at 6 and 24 h before ethephon treatment. After 8 days, plants treated with ethephon alone showed about 80% foliar damage while plant treated with LPE before ethephon treatment showed about 25% foliar damage. In a parallel study, LPE together with ethephon was found to maintain three to four times greater chlorophyll content in the leaves compared to ethephon alone. Treatments of LPE did not reduce the fruit ripening response by ethephon. Both sources of LPE were effective in preventing damaging effects of ethephon on the foliage. These results suggest that LPE treatments 6 and 24 h before ethephon application can prevent damaging effects of ethephon on foliage while allowing the acceleration of fruit ripening.
538 Use of Lysophoshatidylethanolamine (LPE), a Natural Lipid, to Accelerate Ripening and Enhance Shelf Life of Cranberry Fruit
Authors: Ozgen Mustafa , Ozgen Senay , Palta Jiwan P.
Published: February 2019

Recent studies from our laboratory have demonstrated that lysophoshatidylethanolamine (LPE) is able to accelerate fruit ripening while at the same time promoting shelf life. LPE is a natural lipid and is commercially extracted from egg yolks and soybeans. We studied the influence of LPE on the pattern of anthocyanin accumulation and storage quality of cranberry fruit (Vaccinium macrocarpon Ait. cultivar Stevens). For this purpose 2 x 2-m plots were established in cranberry beds at two separate locations near Wisconsin Rapids. Experiments were conducted in 1997 and 1998 seasons. Plots were sprayed with LPE (extracted from egg yolk and soybean) 3 to 4 weeks before harvest. Spray solution included 200 ppm LPE, 3% ethanol, and 0.1% detergents (either Tergitol or Sylguard). Fruit samples were taken from a part in the plot periodically to determine the changes in the fruit. The rest of the plots were commercially wet harvested with a machine and stored in cold storage. Marketable fruit were counted at various times of cold storage to determine effect of LPE on shelf life of cranberries. In general, application of LPE from both sources resulted in 20% to 35 % increase in fruit anthocyanin contents. Also LPE treatment resulted in 10% to 20% increase in marketable fruit in cold storage. A postharvest dip of cranberry fruit with 50 ppm LPE solution for 15 min also resulted in about a 20% to 30% increase in marketable berries during cold storage. The results of this study shows that pre- and postharvest applications of LPE can add value to cranberry crop including better and more uniform colored fruit, enhance self life, and earlier harvest.
540 Field-grown Garden Chrysanthemum Responses to Pinching and Plant Date
Authors: Starman Terri W. , Faust James E.
Published: February 2019

Our objective was to determine the effect of planting date and pinching on flowering dates and plant size of field-grown garden mums. Experiments were conducted in the field during two consecutive growing seasons in 1997 and 1998. In one experiment, 15 to 20 cultivars were planted on five dates (14 May, 4 June, 25 June, 16 July, and 4 Aug.) and received no pinching, one manual pinch 2 weeks after potting, or two manual pinches 2 and 4 weeks after potting. In another experiment, four cultivars were planted at the five dates. Pinch treatments were control, one manual pinch, two manual pinches, one Florel spray at 500 mg·L–1, or two Florel sprays at the same time as the manual pinches but on separate plants. Data were collected for days to first color, first open flower, 10 open flowers, and full bloom. Height and width were measured at 10 open blooms. Although the 1998 season was warmer and caused heat delay, the flowering data followed the same trends as the 1997 experiments. Pinching delayed flowering for the early plant dates. Pinching did not affect plant height or plant width. Planting date affected days to 10 blooms for most early season varieties but not late-season varieties. Planting early produced larger plants and more uneven flowering and resulted in greater heat delay of heat-sensitive varieties. Florel delayed flowering and increased plant size. We concluded that pinching was not required to produce high-quality garden mums of many new cultivars.