bluuebunny/crossref_metadata_2025 huggingface dataset:
Germination and Growth of Four Species of Ericaceous Plants
Authors: Englert John M. , Barrack Carroll , Woolston Dan
Published: February 2019

The germination of ericaceous plant species is often variable and not well-defined. We have had some difficulty in obtaining good germination and significant establishment and growth after transplanting. Four different moisture regimes and two different media were used for the germination of Kalmia latifolia, Oxydendrum arboreum, Rhododendron maximum, and Vaccinium corymbosum seeds. Seeds were surface-sown on peat or peat + bark (1:4) media. Pots were then placed under either one of two different misting regimes, set in a tray of water, or set in a tray of water under a humidity tent. Germination was higher and more consistent for all species sown on peat and occurred sooner for seeds under the humidity tent. Rhododendron and Kalmia under the humidity tent grew more rapid than with other treatments. Increases in germination under the humidity tent were due more in part to higher temperatures than to the minimal increase of humidity inside the tent. Germination was poor for seeds under the high-mist treatment, presumably because there was too much moisture. Germination of Vaccinium and Oxydendrum was low for all treatments.
Study of the Effect of Different Media Beds, Time, and Wounding Factors on the Rooting of Semi-hard Cuttings of Olive [Olea europaea (Roghani & Zard Zeitoun C.V.)] under Mist Conditions
Authors: Talaie A. , Ghassemi M.
Published: February 2019

To determine the most proper bed, time, and wounding factors on the rooting of semi-hard cuttings of olive (Olea europaea), cuttings were selected and research was conducted at the Faculty of Agriculture of the Tehran Univ. in Karaj. The required cuttings were taken from healthy and similar mother trees at the Roodbar Research Station. Then, semi-hard cuttings of 15 cm in length and 3 to 5 mm in diameter with four terminal leaves were prepared. Then those prepared cuttings were treated with IBA at 4000 ppm and Captan fungicide at 3000 ppm before planting. This experiment was designed in a factorial with a randomized complete block, with four media bed factors for rooting in seven levels (peatmoss + perlite, sawdust + sand, peatmoss + sand, and perlite, sand, and perlite + sand), the time factor for cutting preparation in four levels (May, August, September, and March), cultivars at two levels (Roghani and Zard Zeitoun), and wounding treatment at two levels (unwounded and wounded); there were three replications (20 cuttings per replicate per each unit). The results indicate that, among the selected beds, perlite with 53% of rooting average yield has the highest and peatmoss + perlite with a rooting average of 43.8% has the lowest. As far as time is concerned, those cuttings prepared in March show the highest rooting average of 69.3%, while those prepared in August show the lowest average of 12.7%. The comparison between the two cultivars shows that Roghani, with 60.4% rooting yield, is preferred to Zard Zeitoun, with 48.2% rooting average. There were no significant differences between wounded and unwounded cuttings with regard to rooting.
Stress-induced Ethanol Production in Fresh Fruit and Vegetables
Authors: Forney Charles F. , Jordan Michael A.
Published: February 2019

Fresh fruits and vegetables produce ethanol when they are held in atmospheres containing low concentrations of oxygen. Ethanol concentrations in the headspace of fresh Brassica vegetables held 24 hours in nitrogen at 20°C ranged from 5 to 110 mmol·m–3. The absence of oxygen induced anaerobic respiration and the production of ethanol in these vegetables. However, other stresses, including heat and high concentrations of carbon dioxide, can also stimulate the production of ethanol in fresh fruits and vegetables held in aerobic atmospheres. Fresh heads of broccoli dipped in 52°C water had increased concentrations of headspace ethanol 2 hours after treatment when held at 20°C in air. Concentrations were 6, 160, and 490 times greater in broccoli treated for 1, 2, or 3 minutes than in nontreated controls, respectively. Fruit of three highbush blueberry cultivars held in 25% carbon dioxide for 6 weeks at 0°C had 80 to 190 times more ethanol than fruit held in air. The 25% carbon dioxide atmosphere also induced blueberries to soften and develop off-flavors. Ethanol may be a fast and easy-to-measure indicator of physiological stress in stored fresh fruits and vegetables. Monitoring induced ethanol production could identify injurious storage environments or postharvest treatments. Possible mechanisms of stress-induced ethanol production will be discussed.
Effects of Anaerobic Atmosphere on the Metabolism of Sulfur Volatile Compounds Produced by Broccoli
Authors: Derbali Ezzedine , Vezina Louis-Philippe , Makhlouf Joseph
Published: February 2019

Objectionable off-odors are produced by broccoli (Brassica oleracea, L.) when it is held under anaerobic conditions. These off-odors were attributed to sulfur volatile compounds mainly methanethiol (MT) and hydrogen sulfide. The present study was undertaken to investigate the effects of anaerobic conditions on the metabolism and emission of sulfur volatiles by broccoli. Inhibition assays using aminooxyacetic acid (AOA)—a potential inhibitor of pyridoxal-phosphate-dependent enzymes-confirmed the enzymatic origin of these volatiles. However, anaerobic atmosphere had no inducible effect on the enzymes cystine lyase, cysteine desulfhydrases and S-alkylcysteine lyase. These pyridoxal-phosphate-dependent enzymes thought to catalyze the respective degradation of cystine, cysteine and S-methyl-L-cysteine to sulfur volatiles showed no significant activity increase. Storage of sterile broccoli seedlings under anaerobic atmosphere resulted in an important increase of the content of sulfur amino acids that corresponded to an increased emission of sulfur volatiles. Cysteine and methionine content increased particularly at 24 hours and decreased later. Whereas, S-methyl-L-cysteine content increase was more obvious after 48 hours. The results suggest a possible involvement of the pathways for synthesis and breakdown of sulfur amino acids via methionine.
Rapid Analysis of Volatile Flavor Compounds in Horticultural Produce Using Solid-phase Microextraction and Gas Chromatography–Time-of-flight Mass Spectrometry
Authors: Song J. , Beaudry R.M.
Published: February 2019

Aroma analysis of horticultural produce is an emerging field in which both flavor producing and malodorous compounds are detected from within a complex sample matrix. Qualitative and quantitative information is desired to monitor produce ripeness and provide quality control over processed products such as juices, preserves and canned products. Conventional analysis methods such as purge and trap and gas chromatography–mass spectrometry provide much of this information but are laborious and time consuming. Faster techniques are required when large numbers of samples are being analyzed and when rapid feedback to the produce harvester is required. Solid-phase microextraction (SPME) has recently been shown to significantly reduce the sampling times required by more conventional methods. The use of fast gas chromatographic techniques along with the recently commercialized time-of-flight mass spectrometer has also significantly reduced the separation and analysis times. We have combined SPME with gas chromatography–time-of-flight mass spectrometry as a rapid and quantitative tool for the analysis of flavor volatiles in apples and tomatoes. The sampling and analysis processes provide significant improvements to sample throughput, with analysis times taking only 2–6 minutes. The linear response of this system to butylacetate, ethyl-2-methylbutanoate and hexylacetate ranges from ppb to ppm levels, and the identification of unknown flavor compounds is possible even in the presence of other co-eluting compounds. The SPME technique is able to investigate volatiles changes in apple cuticle and tissues, which open the new possibility for flavor biochemistry research.
Photocatalysis of Ethylene in Air: Reactor Design and Performance Evaluations
Authors: Cushman K.C. , Tibbitts T.W. , Anderson M. , Fu X. , Zeltner W.
Published: February 2019

The performance of a reactor designed to convert volatile hydrocarbons to carbon dioxide and water by a combination of surface chemistry and UV radiation was tested under conditions relevant to horticulture. Air containing 65 to 1100 nL·L–1 ethylene gas passed through a bed of catalyst crystals at a rate of 0.1 to 2.0 L·min–1. The catalyst bed consisted of 14 g of zirconia-titania particles, 0.50 to 0.75 mm in size, that occupied the space between a 4-W UV lamp and a stainless-steel housing. Dew-point temperatures of the air passing through the reactor ranged from 5 to 22°C and internal reactor temperatures ranged from 20 to 80°C. Increasing internal reactor temperature, ethylene concentration, or air flow resulted in increasing ethylene photocatalysis by the reactor. Increasing dewpoint temperature of the air stream resulted in decreasing ethylene photocatalysis by the reactor. Operation of the reactor over a 120-day period showed that reactor design and catalyst performance were stable and robust during continuous duty. Our results demonstrate that the reactor performed well over a wide range of conditions and may be useful for applications in horticulture. This research was, in part, NASA sponsored, and a reactor similar in design to that used in our studies has been used for plant growth in space.
Analysis of MADS Box Gene Expression during Ethylene-insensitive Flower Senescence using Quatitative RT-PCR
Authors: Lange Nathan E. , Valpuesta Victoriano , Napoli Carolyn A. , Reid Michael S.
Published: February 2019

The metabolic pathway and function of ethylene during the senescence of many fruits and flowers have been extensively studied, the molecular basis of ethylene-insensitive flower senescence remains unknown. The ephemeral flowers of daylily (Hemerocallis) were used as a model system for the examination of ethylene-insensitive senescence. Senescence-associated cDNA clones were isolated from a cDNA library constructed from mRNA expressed in senescing tepals of daylily flowers. Up-regulated cDNA clones were identified by differentially screening the cDNA library. Sequence analysis of one of the clones, designated as SEN12, indicates that it contains a MADS box domain and an associated leucine-zipper K-box region and may be a transcription factor similar to floral homeotic genes. Northern analysis indicates that SEN12 encodes for a rare message. Therefore, reverse transcriptase polymerase chain reaction (RT-PCR) assays were used to quantitate the abundance of SEN12 transcripts during floral senescence. RT-PCR assays demonstrated that SEN12 transcripts significantly increase in abundance during the earliest stages of flower senescence and continue to increase until the end of senescence. We propose that SEN12 may be involved in controlling senescence in ethylene-insensitive flowers and we are continuing to investigate this hypothesis.
Prolonging the Vase Life of Snapdragons and Carnations with a Natural Lipid, Lysophosphatidylethanolamine (LPE)
Authors: Kaur Navjot , Palta Jiwan P.
Published: February 2019

Freshly cut snapdragon (Antirrhinum majus L) spikes or carnation (Dianthus caryophyllus L cv. White Sim) stems were put in LPE (10 ppm for carnation, 25 ppm for snapdragon) solution for 24 hours and then transferred to deionized water. Parallel controls were kept continuously in deionized water. Snapdragon spikes were harvested when they had one-third of the florets opened which is a standard commercial practice. The carnations used in the experiment were harvested at three different stages of flower development starting from open brush bud stage (Stage IV) to fully opened (Stage VII, petals 45(to the stem) flower. LPE treatment delayed senescence in snapdragon by four days. Furthermore, it enhanced the opening of floral buds and opened all the florets on every spike. LPE treatment also significantly delayed loss in fresh weight of spikes associated with senescence, lowered the endogenous ethylene production and reduced ion leakage from florets. LPE had a similar effect on fresh weight and ion leakage from carnations if it was applied at an early stage of flower opening. Older carnations (Stage VII) were found unresponsive to LPE. In conclusion, LPE has the potential in enhancing the vase life of snapdragons and carnations. Carnations must be harvested at the open brush bud stage for effective LPE application. Our results suggest that LPE is prolonging vase life of cut flowers by reducing ethylene production and maintaining membrane integrity.
Physiological, Biochemical, and Molecular Changes in Pelargonium Cuttings Subjected to Short-term Storage Conditions
Authors: Arteca Richard N. , Arteca Jeannette M. , Wang Tzann-Wei , Schlagnhaufer Carl D.
Published: February 2019

The purpose of this study was to evaluate physiological, biochemical and molecular changes which occur in unrooted Pelargonium ×hortorum cuttings during storage. Pelargonium cuttings of `Sincerity' (good shipper), `Wendy Ann' (moderate shipper), and `Snowmass' (poor shipper) were stored at 25°C and evaluated over a 5-day period. Following removal from storage, cuttings exhibited progressive declines in photosynthesis, respiration, carbohydrate, starch and protein over time which was significant in all three cultivars, however there was little difference among the cultivars. Ethylene levels produced by `Sincerity' and `Wendy Ann' began to increase 3 days following the initiation of storage, whereas `Snowmass' showed an increase after one day reaching a peak at 3 days and was followed by a sharp decline. When unrooted cuttings of `Snowmass' were stored for a 5-day period at temperatures from 4 to 25°C, it was observed that those stored at 4°C had a significantly higher visual rating, chlorophyll content, root and shoot weight than at higher temperatures tested. The decline in quality progressively became greater from 10 to 25°C. Changes in gene expression of two ACC synthases and an ACC oxidase were evaluated in `Snowmass' cuttings which were stored at 4 and 25°C. Correlations between ethylene and ACC levels with gene expression were observed.
Effectiveness of Methyl Jasmonate on Reducing Chilling Injury in Grapefruit
Authors: Wang Chien Yi , Buta J. George
Published: February 2019

Freshly harvested unwaxed `Marsh Ruby' grapefruit (Citrus paradisi Macfad.) were obtained from Wabasso, Fla. The fruit were treated with methyl jasmonate by dipping, pressure infiltration (82.7 kPa for 3 minutes), or vapor fumigation. Control fruit were similarly treated with distilled water. All fruit were then stored at 1°C. Samples from all treatments were transferred to 20°C for 3 days after 4 and 10 weeks of storage at 1°C for evaluation of chilling injury. Symptoms of chilling injury were negligible in all treatments after 4 weeks of storage. However, after 10 weeks of storage, moderate to severe pitting occurred in the control fruit but the severity of chilling injury was significantly reduced by methyl jasmonate treatments. The most effective treatments were either pressure infiltration using a 0.1 mm emulsion or fumigation with vapor at saturation.
The Effect of Ethylene during Controlled-atmosphere Storage of Bananas
Authors: Blankenship Sylvia M.
Published: February 2019

Banana fruit respiration rates and quality parameters such as peel color, pulp pH and soluble solids content were examined at 14°C under a number of controlled atmosphere (CA) environments. CA conditions were 1%, 2%, 4%, or 8% oxygen with or without 5% carbon dioxide. Each treatment combination was also done with or without 50 μL·L–1 ethylene added to the atmospheres. Green banana fruit were either gassed with ethylene (triggered) or ungassed. One percent oxygen was too low to consistently give undamaged bananas. The addition of 5% carbon dioxide to the controlled atmosphere increased fruit respiration rate whereas air plus 5% carbon dioxide showed decreased respiration when compared to air control fruits. Green, triggered fruit partially ripened under the CA conditions. Pulp pH and soluble solids content changed in a normal ripening pattern, however peel color was poor. Addition of ethylene to the atmospheres advanced fruit ripening somewhat in all fruit. When green, ungassed bananas were placed under CA, the presence of ethylene in the atmosphere did not cause the bananas to turn yellow, although some changes in pH and soluble solids were detectable. In triggered fruit the presence of ethylene in the storage advanced ripening with higher oxygen concentrations promoting faster ripening. Bananas that have ripened under CA conditions are not as high quality as those ripened in air in terms of visual appearance.
Interactions between the Timing of the Application of Hypoxia and Rate of Sugar Accumulation and Activities of Invertase, Sucrose Synthase, and Sucrose Phosphate Synthase
Authors: Gong Yanwen , Solomos Theophanes
Published: February 2019

Previous research has shown that subjecting bananas to low O2 treatment during the climacteric rise decreases the rate of sugar accumulation but the fruits eventually ripen. In the present study we applied low O2 in fruits whose ripening had been initiated by exogenous C2H4 and in preclimacteric ones. In preclimacteric fruits low O2 suppressed the climacteric rise during the duration of the experiment (20 days). It completely inhibited the increase in sugars, invertase and sucrose phosphate synthase (SPS) activities while there was a sharp increase in sucrose synthase (SS). In control fruits the increase in sugar content coincides with a sharp increase in invertase, and SPS and a decline in SS. Hypoxia inhibited the increase in invertase and SPS while it induced an increase in SS. Nevertheless, the activities of invertase and SPS in the climacteric hypoxic fruits was higher than in hypoxic preclimacteric ones. The results, thus, indicate that the imposition of low O2 at the preclimacteric stage is much more efficient in delaying banana ripening than when it is applied after the initiation of ripening.
Mango Tolerance to Reduced Oxygen Levels in Controlled-atmosphere Storage
Authors: Bender R.J. , Brecht J.K. , Sargent S.A. , Huber D.J.
Published: February 2019

Exposure to hypoxic O2 levels has been reported to result in better epidermal color, higher titratable acidity and soluble solids levels, delayed softening and reduced ethylene production and respiratory activity in many fruit species. Mangoes have been shown to tolerate short term (4 days) exposures to O2 concentrations below 0.5% with beneficial effects on firmness retention and maintenance of ground color. In the present work, `Haden' mangoes were stored for 14 days at 15°C with O2 levels ranging from 2% to 5% and compared to an air control and an atmosphere of 25% CO2 in air. `Tommy Atkins' mangoes were stored under the same treatments at 12°C for 21 days. After storage at 12 or 15°C the mangoes were transferred to air at 20°C for 5 days. Ethanol production rates during controlled atmosphere (CA) storage were significantly higher at O2 levels of 4% and below. Respiration (CO2 production) rates were reduced during CA storage but did not differ from the control after transfer to air. There were no differences in ethylene production as well as in flesh firmness, titratable acidity and total sugars. The ground color of mangoes kept under the lowest O2 concentration and under 25% CO2 was greener, as indicated by higher hue angles, than in the other treatments upon transfer to air at 20°C. However, only the mangoes stored under high CO2 maintained higher hue angles during the subsequent 5 days at 20°C.
Study on Canning Methods of Date (Mozafati and Karout Varieties)
Authors: Talaie A. , Seddigh J.
Published: February 2019

Research was conducted in the laboratory of Horticulture Dept. of Seeds and Plants Improvement Research Inst. in Karaj to review the possibility of canning soft and nectariferous `Mozafati' and `Karout' dates from Bam and Zahedan cities. According to the existing information, there are large amounts of postharvest spoilages on this fruit because of their storage in carton boxes or other packing materials and due to a large amount of nectar. Thus, there are physical and chemical changes particularly during ripening (date), and, as a result, there is always a severe effect on the quality of the product. It seems that canning of date under proper conditions could maintain the characteristics of the proposed variety and also the physical and chemical properties of the fruit for a longer time and it could be easily transported to all parts of the world. The samples for this experiment were collected in tamer stage because there are a lot of changes in the ripening stage of these varieties, which lead to severe fruit drop. The proposed samples were randomly collected from 10 date palms. The specifications and characteristics of the collected samples were recorded after the preliminary test procedures, washing, and disinfection. In this experiment a complete randomized design with four treatments were used. The experimented factors were variety and treatment. The experimented varieties were Mozafati and Karout and the proposed treatments were control tree–date syrup, sugar syrup, sugar beet molasses, and vacuum conditions. This experiment was repeated for four times for all treatments, and the best canning method was determined. The results indicate that vacuum conditions are the best canning method for Mozafati, while canning with sugar beet molasses is the best method for Karout.
Volatile Emissions and Quality of Bagged `Fuji' Apples
Authors: Mattheis J.P. , Buchanan D.A. , Fellman J.K.
Published: February 2019

Enclosing apple fruit in bags during development is widely practiced in Japan. Bags create a barrier that reduces damage from insects and fungal pathogens as well as treatments to control these problems. Bags also reduce the incidence of sunburn and change fruit appearance by altering peel pigmentation composition, two features that have prompted northwestern United States producers to bag `Fuji' apples. Fruit maturity and quality of bagged and nonbagged Fuji apples grown in Washington state were evaluated at harvest and after refrigerated storage in air or controlled atmosphere. Bagged fruit had less watercore and lower ethylene production at harvest compared to non-bagged fruit with similar starch ratings. Bagged fruit had lower soluble solids content, titratable acidity and firmness at harvest and during storage. Emission of ester and alcohol volatiles was consistently lower for bagged fruit. Postharvest volatile emissions were negatively correlated with bagging duration during development. Bagged fruit had no incidence of a peel disorder with similarity to delayed sunscald.
Aroma Volatiles of `GoldRush' and `Golden Delicious' Apples
Authors: Yu Liangli , Charles Denys J. , Janick Jules , Simon James E.
Published: February 2019

The aroma volatiles of ripe fresh `GoldRush' and `Golden Delicious' apples (Malus ×domestica Borkh) were examined using dynamic headspace to capture the volatiles and gas chromatography (GC)–GC–mass spectroscopy (MS) analysis for compound identification. A total of 21 aroma volatiles were identified, with 16 being common to both cultivars: toluene, butyl acetate, hexyl formate, 2-methylbutyl acetate, xylene, butyl propionate, pentyl acetate, s-butyl butanoate, hexyl acetate, iso-butyl 2-methylbutanoate, hexyl propionate, hexyl butanoate, hexyl 2-methylbutanoate, hexyl hexanoate, a-farnesene, and ethyl phthalate. Three volatiles [dipropyl disulfide, pentyl 2-methylpropionate, and 2,6-bis(1,1-dimethylethyl)-2,5-cyclohexadiene-1,4-dione] were unique to `Golden Delicious'; two compounds (nonanal and nerolidol) were unique to `GoldRush'. Most identified compounds were esters. Hexyl acetate (18.39%) was the major volatile in `Golden Delicious', while butyl acetate (13.40%) was the highest in `GoldRush'.
Storage Potential for `Ginger Gold' and `Nittany' Apples
Authors: Barden Cynthia L.
Published: February 2019

High-quality processing and fresh market cultivars are critical to the Mid-Atlantic apple industry. Dual purpose cultivars such as `Ginger Gold' and `Nittany' are of particular interest. `Ginger Gold' is an early cultivar harvested in mid to late August and is of interest to processors in the area. Early cultivars typically do not store well. The at-harvest quality is high and we have initiated studies to determine if quality of `Ginger Gold' can be maintained in storage for an acceptable length of time. Apples harvested 25 Aug. were placed in three storage atmospheres: air, 3% O2 + <2% CO2, or 0.7% O2 + 1% CO2, all at 0°C. At harvest the firmness was 85 N with soluble solids concentration (SSC) of 12.6. After 4 months of storage both CA treatments maintained firmness better than the air control treatment. SSC and decay were not different among storage treatments (SS = 13.5 and % decay = 5%–8%). Data indicate that `Ginger Gold' can be stored for some time in CA and that low-oxygen storage may be beneficial. `Nittany' apples harvested 6 Oct. were placed in 2 storage atmospheres - 3% O2 + <2% CO2 or 0.7% O2 + 1% CO2. At harvest the firmness was 85 N and the SSC was 12.7. After 6 months in storage the fruit in low O2 were firmer than in standard CA. The SSC was 14.5 and decay 6% for all samples.
Ethanol Vapor Controls Superficial Scald of Apples during Storage: A New Alternative Approach
Authors: Wang Zhenyong , Dilley David R.
Published: February 2019

We are investigating alternative strategies to control scald on apples. Ethanol vapors were applied to `Law Rome' and `Red Delicious' apples in the storage chambers by ventilating air through aqueous solutions of ethanol at different concentrations, and in modified atmosphere packages by adding various initial concentrations of ethanol vapor. Fruits in storage chambers treated with ethanol vapor at 1600 ppm for about 2 months showed no scald when stored for an additional period in air storage whereas the scald index in control was up to 2.33 (the highest is 3). The similar results in the modified atmosphere experiments confirmed that ethanol vapor could prevent apple scald. Ethanol vapor treatment was also correlated with a reduction of α-farnesene production by the fruits. α-farnesene is an isoprenoid metabolite in the pathway to carotenoid synthesis that has been implicated indirectly as a factor in scald development. Evidence for this based on diphenylamine (DPA) reducing the level of a conjugated terpene product of α-farnesene oxidation. Our results suggested that the control of scald by ethanol vapor treatment may be related to the reduction of α-farnesene production and its subsequent oxidation. Ethanol vapor treatment resulted in accumulation of ethanol in the fruits in direct proportion to the ethanol concentration administered and reduced the rate of ethylene production, and the internal ethanol levels dropped rapidly when fruits were returned to air without ethanol vapor.
Polygalacturonase Levels Influence Electrolyte Efflux in Tomato Fruit
Authors: Huber D.J.
Published: February 2019

Tomato fruit transformed with the PG-antisense gene have been shown to exhibit persistent structural competence and extended shelf-life compared with normal, PG-containing lines. In this study, PG-antisense and nontransformed, wild-type fruit were examined for electrolyte efflux trends during ripening and following extended storage at the full-ripe stage. Pericarp disks from PG-antisense fruit showed minimal differences in net electrolyte efflux compared with the normal, wild-type fruit at the mature-green through ripe stages of development. Following extended storage (14 days) of ripe fruit, or in response to storage at chilling (1°C) temperatures, significantly higher (25%–33%) values for proportional electrolyte efflux were observed for wild-type fruit. Additionally, ripe wild-type fruit following extended storage or in response to chilling injury exhibited increased (15%–20%) total soluble electrolytes, particularly in tissues subjected to freeze-thaw versus thermal-disruption. Although PG-antisense fruit do exhibit increases in net electrolyte efflux during ripening, the enhanced efflux and electrolyte generation from wild-type ripe fruit during extended storage was due, in part, to the release of polyelectrolytes originating from pectin hydrolysis. These data may explain the divergence in postharvest performance and structural integrity of PG-antisense and normal, wild-type fruit during post-ripe storage and also suggest that modification of the apoplastic environment resulting from developmental increases in electrolyte efflux can enhance the catalytic activity of PG in vivo.
Quality of Tomatoes Stored at Chilling Temperatures following Prestorage Heat Treatments and Partial Ripening
Authors: McDonald R.E. , McCollum T.G. , Baldwin E.A.
Published: February 2019

Mature green `Sunbeam' tomato fruit (Lycopersicon esculentum Mill.), were treated in varying order with C2H4, 42°C water for 60 minutes, 38°C air for 48 hours, partial ripening for 48 hours at 20°C, or not treated, and then stored at 2°C for 14 days before ripening at 20°C. Heat treated fruit stored at 2°C and transferred to 20°C ripened normally while 63% of nonheated fruit decayed before reaching red ripe. More chilling injury (CI) developed when C2H4 was applied following heat treatment rather than before. There was more CI in fruit that were 42°C water treated compared with the 38°C air treatment. Less CI developed on fruit that were partially ripened for 2 days at 20°C before a 42°C water treatment rather than following it. At red ripe, nonchilled fruit were firmer than chilled heat treated fruit. Fruit treated in 42°C water were firmer when the heat treatment was applied before the C2H4 treatment rather than following it. Chlorophyll and lycopene content and internal quality characteristics of fruit were similar at the red ripe stage irrespective of C2H4 or heat treatment. Chilling and heat treatments reduced some of the 15 flavor volatiles analyzed. Volatile levels were lower in fruit treated with C2H4 before heat treatment compared with fruit treated with C2H4 following heat treatment. Prestorage heat treatments could allow for storage of mature green tomatoes at low temperatures with little loss in their ability to ripen normally.
Ethanolic Fermentation of Carrot Root Shreds under Low Oxygen
Authors: Kato-Noguchi Hisashi , Watada Alley E.
Published: February 2019

Although a number of studies have been conducted to evaluate the effect of control and modified atmosphere on the quality and storability of carrot roots (Daucus carota L.) under low O2 atmosphere, little is known about the underling biochemical changes in particular changes in anaerobic respiration. Carrot root shreds were stored under a continuous flow of 0.5% and 2% O2 (balance N2), or air for 7 days at 5 and 15°C to study the regulation of glycolysis and the accumulation of glycolytic end products, such as ethanol and/or lactic acid. Low O2 atmosphere caused increases in the concentrations of ethanol and acetaldehyde and the activities of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC). By day 3, ethanol increased 38-, 25-, 13-, and 9.5-fold, acetaldehyde increased 20-, 13-, 7.7-, and 5.6-fold, ADH increased 7.6-, 6.3-, 3.8-, and 2.7-fold, and PDC increased 4.2-, 3.9-, 2.3-, and 2.2-fold for 0.5% O2 at 15 and 5°C, 2% O2 at 15 and 5°C, respectively, compared with corresponding air control. These results shows that the production of ethanol was higher in 0.5% O2 than in 2% O2 at both temperatures. The enhancement of the glycolytic flux under 0.5% O2 indicates that under these conditions the mitochondrial terminal oxydases were restricted, hence, the enhancement of ethanol synthesis, to compensate partly for the decrease in ATP production.
Potassium Nutrition and Shelf Life of Carrots (Daucus carota L.)
Authors: Shibairo S.I. , Upadhyaya M.K. , Toivonen P.M.A.
Published: February 2019

The effect of potassium (K) nutrition on the shelf life of carrots was studied using a hydroponics system involving rockwool slabs as support. Carrots were grown for 192 days under greenhouse conditions and supplied with 0, 0.1, 1.0, 10, and 15 mm of K. Increase in K concentration in the nutrient medium decreased postharvest weight loss. Carrot weight and tissue K content increased and water potential, osmotic potential, and relative solute leakage decreased with increasing K concentration in the nutrient feed. Differences in postharvest weight loss were mainly associated to root weight and relative solute leakage. Root weight correlated negatively and relative solute leakage correlated positively to water loss. Water and osmotic potential also correlated to water loss, but not as strongly as root weight and relative solute leakage. These results suggest that K nutrition influences postharvest weight loss by influencing carrot size and membrane integrity. Effects on cell water and osmotic potential are also important in this regard but to a lesser extent.
Influence of Preharvest Water Stress on Postharvest Weight Loss of Carrots (Daucus carota L.)
Authors: Upadhyaya M.K , Shibairo S.I. , Toivonen P.M.A.
Published: February 2019

To understand the relationship between preharvest water stress and postharvest weight loss, carrot cultivars Eagle and Paramount were grown in muck soil in 6-L pots (eight carrots per pot) in a greenhouse at the Univ. of British Columbia. The plants were watered to field capacity every second day for 4 months before receiving 100, 75, 50, and 25% field capacity water stress treatments, henceforth referred to as low, medium, high, and severe water stress, respectively. Postharvest weight loss of carrots was monitored at 13°C and 32% relative humidity. Carrot weight loss increased with duration of storage in all treatments. It was low in the low-water-stressed and high in severely water-stressed carrots for both cultivars. Root crown diameter, weight, water, and osmotic potential decreased, and specific surface area and relative solute leakage increased with increasing preharvest water stress. Water potential followed by relative solute leakage were the variables that affected weight loss the most. The results show that carrots adjust to water stress by lowering water and osmotic potential. Preharvest water stress lowers membrane integrity of carrot roots making them lose more moisture during storage.
Volatile Constituents of Muskmelon (Cucumis melo cv. Mission)
Authors: Yu Liangli , Charles Denys J. , Hetzroni Amots , Simon James E.
Published: February 2019

The volatiles of muskmelon (Cucumis melo L. reticulatis cv. Mission) were sampled by dichloromethane extraction and dynamic headspace methods and analyzed by gas chromatography (GC) and GC–mass spectroscopy (MS). A total of 34 constituents were identified, with esters contributing 8%–92% of the total volatiles. Butyl propionate, ethyl 3-methylpentanoate, hexadecanoic acid, methyl (methylthio)acetate, propyl butyrate, phenylpropyl alcohol, and vanillin, were recovered only by solvent extraction, while hexanal was only detected using dynamic headspace sampling. Methyl butyrate 35.2%, ethyl acetate 17.1%, butyl acetate 11.6%, ethyl propionate 8.3%, and 3-methylbutyl acetate 6.3% were the major constituents by solvent extraction sampling method. Butyl acetate 35.5%, 3-methylbutyl acetate 20.9%, ethyl acetate 7.3%, 2-butyl acetate 5.6%, and hexyl acetate 3.8% were the major constituents recovered by headspace sampling. Fruit tissue was also separated into five layers (exocarp, outer mesocarp, middle mesocarp, inner mesocarp, and seed cavity) and the volatile constituents differed significantly in content and composition by tissue.
Overcoming Gas Sampling Problems: Analysis of Volatiles Using Capillary Column Needles
Authors: Deng Weimin , Beaudry Randolph M.
Published: February 2019

Sampling factors that could affect gas chromatograph (GC) response for volatile analysis such as syringe pumping time, injection volume, needle length, temperature, and the type of volatile were investigated. Capillary GC column segments (steel and glass) were installed in gas-tight syringes and used as needles for volatile analysis. Standard stainless-steel needles were also used. Hexylacetate, ethyl-2-methylbutyrate, 6-methyl-5-hepten-2-one, and butanol standard were measured. The number of pumps required to maximize GC response for each needle–volatile combination was determined. Maximal GC response for hexylacetate using standard stainless steel, capillary glass, and capillary steel needles required 10, 20 and 30 pumps, respectively. However, for butanol measurement, the optimal syringe pump number was 5 to 10 for all needle types. The use of a capillary needle resulted in an increase in GC response in the range of 3- to 15-fold relative to a standard stainless steel needle. Injection volume affected GC response in a needle-and volatile-dependent manner. In no case did injection volume vs. GC response extrapolate through origin. The GC response for capillary column needles increased as temperature decreased. Capillary column needles may be useful tools for analysis of volatiles that readily partition into the column coating.
Development of a Sensory Descriptive Profile for `Gala' Apple
Authors: Plotto A. , McDaniel M.R. , Mattheis J.P.
Published: February 2019

`Gala' is an early maturing apple variety that has a distinctive aroma and flavor. Its storage season is short and flavor volatile production is reduced following controlled atmosphere (CA) storage. The aroma and flavor characters of `Gala' apples were identified by 10 trained panelists. A vocabulary of 13 descriptors for the aroma of whole and cut fruit and 16 descriptors for flavor were used to characterize the changes of apples stored in CA and/or regular atmosphere (RA) during five months. When compared to RA storage, intensity of fruity (pear, banana and strawberry) and floral characters decreased after 2.5 months in CA for whole and cut fruit aroma and flavor. During the entire storage period under CA, aroma of cut apples retained high vegetative and citrus characters but had a less intense anise aroma. Sourness, starchiness and astringency were significantly higher, however, sweetness was significantly lower. A musty note was perceived in whole apples stored in CA for 5 months. Differences in fruitiness of whole fruit and sourness only were found between fruit stored for 4 months in CA followed by 1 month in RA and fruit stored 5 months in CA. Relationships between panel ratings of specific characters and corresponding quantitative analysis will be discussed.
Bioavailability of Calcium from Common Vegetables Assessed in Teenagers
Authors: Grusak Michael A. , Abrams Steven A.
Published: February 2019

Calcium is an essential human nutrient that is important in bone growth and metabolism. While dairy products in reasonable quantity can supply minimum daily requirements of calcium, the current decline in the consumption of dairy products, especially among teenagers, implies that dietary requirements must be met from other sources. Green beans, spinach and broccoli contain high concentrations of calcium, but the bioavailability of calcium from these food sources has not been determined in children. To provide accurate dietary recommendations for these foods, we have developed a recirculating hydroponic system for the growth and intrinsic labeling of plants with stable isotopes. Plants were maintained on a non-labeled nutrient solution until an appropriate developmental age and were then presented with nutrient solution containing 42-Ca. Labeled green bean pods and spinach were harvested at the proper commercial age, and were cooked, pureed and frozen until use. Thirteen teenage subjects seven girls, six boys) were recruited for a 2-week stay in the Metabolic Research Unit, and were fed 42-Ca-labeled vegetables along with 48-Ca-enriched milk; an intravenous dose of 46-Ca was also administered. Blood, urine and fecal samples were collected during the 2-week study. Calcium bioavailability and kinetics were determined using a multi-compartment model. The bioavailability of calcium averaged 28% from green beans, which was comparable to that of milk calcium. Calcium bioavailability from spinach averaged only 3%, due probably to the high oxalate content of spinach. Our results suggest that low-oxalate containing vegetables such as green beans can serve as good dietary sources of calcium. This research was funded in part by USDA-ARS Coop. Agr. No. 58-6250-1-003 and USDA-CRS Grant No. 94-347200-0605.
Oxidative Stress and Chilling Tolerance in Tomato Seedlings
Authors: Kerdnaimongkol Kanogwan , Bhatia Anju , Joly Robert J. , Woodson William R.
Published: February 2019

Diurnal variation in the chilling sensitivity of tomato seedlings was examined. Sensitivity to chilling in tomato seedlings is a response to light and not under the control of a circadian rhythm. Chilling sensitivity is highest in seedlings chilled at the end of the dark period, and these seedlings become more resistant to chilling injury upon exposure to the light. Diurnal variation in chilling sensitivity was associated with changes in catalase and superoxide dismutase activities. The results show an increase in catalase and superoxide dismutase activities at the end of the light period. The recovery of the net photosynthesis rate following chilling was faster in seedlings chilled at the end of the light period. It is suggested that an increase in catalase and superoxide dismutase activities at the end of light period before the chilling plays a role in the resistance to chilling stress in tomato seedlings. Forty-eight hours of 14°C acclimation or hydrogen peroxide pretreatment conferred chilling tolerance to tomato seedlings and were correlated with elevated catalase activity. Acclimated seedlings still exhibited diurnal variation in chilling sensitivity while hydrogen peroxide treated seedlings showed little evidence of a diurnal variation in chilling sensitivity. Transgenic tomato plants expressing an antisense catalase gene were generated. A several-fold decrease in total catalase has been detected in the leaf extracts of transformants. Preliminary analysis of these plants indicated that modification of reactive oxygen species scavenging in plant system can lead to change in oxidative stress tolerance.
Indexing Cold Tolerance/Resistance of Hazelnut
Authors: Peng Lixin , Wang Mingqi , Liang Weijian
Published: February 2019

Cold tolerance/resistance of 41 hazelnut hybrid strains was investigated by evaluating electrolyte seepage velocity, recovering growth, and tissue browning for the tested cold temperatures. Results demonstrated that electrolyte seepage velocity of all tested strains was faster as temperatures dropped down. The S curve relationship was found between seepage velocity and temperature. Turning point temperature used as the half deadly injured index (LT50) was developed using a logistic equation. The mean LT50 and temperature causing tissue browning were excellent indexes to predict cold tolerance/resistance. After treated at –30 or –35 °C and then evaluated for their recovering growth, 10 cold-resistant hybrid hazelnut strains were developed. These hybrids are being tested for regional adoption and will be released as commercial cultivars.
Hardiness and Aesthetic Quality of Boxwood Cultivars as Affected by Landscape Exposure
Authors: Le Duc Alice , Pair John C.
Published: February 2019

Five cultivars of boxwood (Buxus microphylla)—'Winter Gem', B. microphylla var. japonica `Green Beauty', `Green Velvet', `Green Mountain' and `Glencoe'—were planted in twelve different exposures at Manhattan and Wichita, Kan., representing USDA hardiness zones 5 and 6 respectively. The 1995–96 winter was one of great extremes. Lows of –25°C for Manhattan and -23°C for Wichita were recorded, along with sharp 24-hour temperature drops of 31–32°C in January and March. Differences in cultivar performance were noted between the sites. At the Wichita site best winter color was exhibited by `Green Velvet' and `Glencoe', whereas `Green Mountain' sustained some bronzing of foliage due to winter sun. At Manhattan only `Glencoe' in protected locations exhibited good winter color. All other surviving cultivars showed considerable bronzing. In addition, `Green Beauty' was severely damaged at Manhattan, sustaining bark splitting due to low temperatures, although most plants survived at Wichita. Shaded locations on north, northeast and northwest produced best plant quality of all cultivars; whereas, the poorest plant performance occurred on south and southeast exposures.
Influence of Fluctuating Temperatures on the Cold Hardiness of Container-grown Nursery Stock
Authors: Kelley Kathleen M. , Peterson N. Curtis , Howell G Stanley
Published: February 2019

The loss of container-grown nursery stock during winter months may be due to lack of root hardiness when exposed to cold temperatures. After Euonymus alatus `Compactus', Weigela florida `Java Red', and Hibiscus syriacus `Paeonyflora' reached midwinter hardiness, replicates of each cultivar were subjected to 12 hours of 21°C followed by 12 hours of 0°C each 24-hour period for up to 16 days. Controlled temperature freezing was conducted after each 48-hour period, with temperatures ranging from –6 to –27°C to determine the level of root hardiness. Plants were placed in a greenhouse environment to observe post-stress performance. Weigela was the most cold hardy, followed by Euonymus and Hibiscus. In general, the early accumulation of warming temperatures decreased root hardiness and delayed budbreak, with a noticeable loss of vigor. Results of this research will be presented.
Drought Responses of Mycorrhizal and Nonmycorrhizal Neem Plants of Comparable Size and Tissue Nutrition
Authors: Phavaphutanon L. , Davies F.T. , Boutton T.W. , Duray S.A.
Published: February 2019

Mycorrhizal (VAM) and phosphorus (P)-supplemented nonmycorrhizal neem plants (non-VAM) of comparable size and tissue nutrition were subjected to a slowly developing drought. VAM and non-VAM plants responded to drought similarly. However, mycorrhiza compensated for low P supply, allowing VAM plants to have comparable growth, tissue P, and other physiological parameters as non-VAM plants, which received higher P supply. Drought decreased growth, transpiration (E), photosynthetic rate (A), stomatal conductance (gs), and plant water status. Osmotic adjustment did not occur, but the relatively low osmotic potential of this species helped maintain turgor during drought. Plant water relations and A of stressed plants fully recovered in 24 hours after rehydration, while gs and E partially recovered. Instantaneous water use efficiency (A/E) increased during drought and recovery, except for a decrease at peak stress due to very low A. Carbon isotope discrimination (D) values of mature leaves remained constant regardless of mycorrhiza or drought. However, D decreased in expanding leaves that developed during a drought period, indicating an increased long-term water use efficiency of these leaves.
Effect of Mycorrhiza on Growth Recovery of Neem Plants after Drought Exposure
Authors: Phavaphutanon L. , Davies F.T. , Duray S.A.
Published: February 2019

Growth recovery of mycorrhizal (VAM) and nonmycorrhizal (non-VAM) neem plants after drought exposure were followed under low phosphorus conditions. Drought significantly decreased plant growth regardless of mycorrhiza. Relative growth rate of droughted plants was greater than nondroughted plants during the growth recovery period, and compensated the loss of growth during the previous drought. VAM increased plant growth and improved regeneration of new roots outside the original root balls, particularly in plants previously exposed to drought. New roots of VAM plants were readily colonized by the VAM fungi, while those of non-VAM plants remained uncolonized. VAM growth enhancement after drought exposure was associated with greater uptake of phosphorus and other nutrients, and improved root regeneration.