bluuebunny/crossref_metadata_2025 huggingface dataset:
089 Inheritance of Powdery Mildew Resistance in Sweet Cherry (Prunus avium L.)
Authors: Olmstead James W. , Lang Gregory A. , Grove Gary G.
Published: February 2019

Most sweet cherry (Prunus avium L.) cultivars grown commercially in the Pacific Northwest U.S. are susceptible to powdery mildew caused by the fungus Podosphaera clandestina (Wall.:Fr.) Lev. The disease is prevalent in the irrigated arid region east of the Cascade Mountains in Washington State. Little is known about genetic resistance to powdery mildew in sweet cherry, although a selection (`PMR-1') was identified at the Washington State Unive. Irrigated Agriculture Research and Extension Center that exhibits apparent foliar immunity to the disease. The objective of this research was to characterize the inheritance of powdery mildew resistance from `PMR-1'. Reciprocal crosses between `PMR-1' and three high-quality, widely-grown susceptible cultivars (`Bing', `Rainier', and ëVaní) were made to generate segregating progenies for determining the mode of inheritance of `PMR-1' resistance. Progenies were screened for susceptibility to powdery mildew colonization using a laboratory leaf disk assay. Assay results were verified by natural spread of powdery mildew among the progeny seedlings in a greenhouse and later by placement among infected trees in a cherry orchard. Progenies from these crosses were not significantly different (P > 0.05) when tested for a 1:1 resistant to susceptible segregation ratio, indicating that `PMR-1' resistance is conferred by a single gene, which we propose to designate as PMR-1.
094 Efficacy of Water Source on Vase Life of Cut Anthurium cv. Large Pink
Authors: Ramcharan Chris
Published: February 2019

Three sources of water—WAPA, potable water produced by the Virgin Islands Water and Power Authority, cistern or rain water collected in below-house concrete tanks and bottled water were evaluated with and without addition of Flora Life (FL) preservative under greenhouse conditions for keeping cut Anthurium blooms. Significant differences in water source effects were recorded with untreated WAPA water having the longest vase life (VL) (29 days) followed by cistern and bottled water (23 days). Collectively, blooms in untreated water had a VL life of 24 days in contrast to 21 for FL-treated water. Untreated cistern and bottled water produced similar VL days, but the addition of FL significantly lowered the VL of cut flowers in bottled water. The apparent suitability of WAPA water for preserving cut Anthurium is significant since it is the least desirable for drinking and cooking in the VI and is less expensive than bottled water, but more so than cistern water.
095 Vase Life of Cut Roses Grown in Coal Bottom Ash-amended Media: A Correlation with Tissue Calcium
Authors: Cross Marlene , Bearce Bradford , Arora Rajeev
Published: February 2019

The vase life of roses grown in coal bottom ash (CBA)-amended media was evaluated. CBA is enriched in calcium, a nutrient implicated in delaying senescence. Two rose cultivars, Cara Mia and Dakota, were grown (from started eye plants) in four media: a 50% CBA medium and a peat:vermiculite medium amended with calcitic and dolomitic lime (1:1) were used as “high calcium” media, whereas a 25% CBA medium and a peat:vermiculite medium amended with dolomitic lime only were used as “low calcium” media. Vase life of the freshly harvested roses was evaluated. Elemental analysis of the leaves showed that roses grown in the “high calcium” media had greater calcium in the leaf tissue as well as longer vase lives (12.6 and 13.5 days) when compared to those grown in the “low calcium” media (12.1 and 10.9 days). However, petal tissue Ca was not affected by media and was not correlated with vase life. Petal tissue calcium was ≈15 times lower than leaf tissue calcium. Calcium and magnesium increased in the petal tissue over the vase life of the senescing petals. A comparison of `Cara Mia' roses (vase life of 14 days) and `Dakota' roses (vase life of 8.5 days) showed that the longer-lived `Cara Mia' had lower leaf and petal calcium levels. Both varieties followed a similar kinetics of electrolyte leakage (total E.C. and K) during their respective vase lives.
098 Effect of Storage Duration on Easter Lily Carbohydrate Concentration and Postharvest Flower Longevity
Authors: Pemberton H. Brent , Wang Yin-Tung , McDonald Garry V. , Ranwala Anil P. , Miller William B.
Published: February 2019

Case-cooled bulbs of Lilium longiflorum `Nellie White' were forced to flowering. When the tepals on the first primary flower bud split, plants were placed at 2 °C in the dark for 0, 4, or 21 days. After storage, plants were placed in a postharvest evaluation room with constant 21 °C and 18 μmol·m-2·-1 cool-white fluorescent light. Lower leaves, upper leaves, and tepals of the first primary flower from a concurrent set of plants were harvested for carbohydrate analysis using HPLC. Storage time did not affect carbohydrate levels in the lower leaf or tepal samples, but sucrose and starch levels decreased while glucose and fructose levels increased in the upper leaf tissue with increasing storage time. These changes were correlated with a decrease in postharvest longevity for the first four primary flowers. Longevity of the fifth primary flower and total postharvest life of the five primary flowers was unaffected by storage.
101 Postharvest and Flavor Quality of Fresh-cut `Gala' Apples after Harvest and CA Storage
Authors: Beaulieu J.C. , Miller J.A. , Ingram D.A. , Bett K.L.
Published: February 2019

Much fresh-cut apple research has focused on browning, yet little sensory and flavor analysis has been performed. We therefore evaluated postharvest and flavor changes in stored fresh-cut `Gala' apples prepared after harvest or after CA storage (3 months, 1.4% CO2 and 3% O2). Apples were washed, cored, sliced, dipped in browning inhibitors (BI; Na-erythorbate + CaCl2), packaged in LLDPE bags, and evaluated for descriptive flavor attributes, GC volatiles, firmness, CO2 and O2 and color after 0, 2, 7, and 14 days at 1 °C. Initial apple firmness pre-CA vs. post-CA was 38.3N and 32.7N. Bag O2 concentration dropped to 1% to 2% by day 14 and day 7 for pre- vs. post-CA, respectively. CO2 concentration in bags increased linearly through day 14 in both pre- and post-CA. All pre-CA Hunter L values were higher than post-CA for all treatments on all sampling days. Both BI treatments maintained color for 14 days, but freshly cut (FC) wedges were generally superior whereas stored untreated fresh-cut (SFC) wedges browned markedly by day 2. There was no apparent difference between BI levels in terms of browning or flavor. BI-treated wedges were rated more astringent than FC and SFC, especially after CA. With few exceptions, “fruity”, “raw/ripe apple,” and “sweet” attributes were higher in all pre- vs. post-CA treatments. This trend was conserved through 14 days of storage per treatment. “Sour” and “citrus” scores were higher after CA only in BI-treated wedges. Major compounds recovered were butanol, butyl acetate, hexanol, 2-methylbutyl acetate, amyl/isoamyl acetate, hexyl acetate, 2-hexenyl acetate, butyl 2-methylbutanoate, butyl hexanoate, hexyl butanoate, hexyl 2-methylbutanoate, hexyl hexanoate, isobutyl octanoate and α-farnesene. Flavor-related compounds varied markedly through storage and after CA. The GC volatile analysis will be presented along with any possible correlation to trained sensory evaluations.
102 Cultivar Evaluation of Sweetpotatoes for Minimal Processing
Authors: Moretti Celso Luiz
Published: February 2019

Sweetpotatoes (Ipomoea batatas L.) `Brazl,ndia Roxa', `Brazl,ncia Branca', and `Princesa' were minimally processed and evaluated for enzymatic browning during a 5-day storage period. Selected roots were washed and then sliced, sanitized (NaClO, 200 mg·kg–1), and centrifuged inside a cold-room (14 ± 1 °C). After centrifugation, roots were packed inside plastic films (multi-layer nylon), vacuum was added, and bags were stored inside cold-rooms at 3 °C. Daily, sweetpotato roots were evaluated to enzymatic browning according to the following scale of notes: 5 = no browning; 4 = slightly browned; 3 = few browning; 2 = browned; 1 = very browned; 0 - extremely browned. Roots showing notes below 3 were considered unsuitable for commercialization. `Brazl,ndia Roxa' and `Brazl,ndia Branca' were the cultivars that showed less browning, being significantly superior than `Princesa', which showed the highest index of enzymatic browning among the studied cultivars. At the 5th day of storage, `Princesa' showed a pronounced browning, being considered unsuitable for commercialization, according to standards employed in the present work. On the other hand, `Brazl,ndia Roxa' and `Brazl,ndia Branca' could still be commercialized after the 5-day storage period.
105 Mechanisms of Chestnut Rotting during Storage
Authors: Wang Xiaoming , Li Changzhu , Tang Shijun , Tang Wei
Published: February 2019

Chestnut (Castanea mollissima Bl.) is a popular nut in Chinese and International market. However, storage of chestnut is difficult. In this study, the relationships of respiration rate, metabolic pathway, key enzymatic activities, metabolites, and membrane peroxidation with chestnut rotting during storage at room temperature (25 °C) and low temperature (0–3 °C) were investigated. The results show that the respiration rate of chestnut gradually decreases during storage at room temperature. Under the lower temperature, the respiration rate reduced 67.53% within 1 day, then gradually increased. Compared with room temperature, the lower temperature also significantly inhibited glycolysis, maintained higher level of tricarboxylic acid cycling, and reduced the conversion of pyruvate to ethanol and lactate. In addition, chloramphenicol acetyltransferase activities were inhibited while superoxide dismutase activities were high under the lower temperature, which resulted in the reduction of membrane peroxidation. Subsequently, the chestnut rotting rate was significantly reduced. In conclusion, the primary reason for chestnut rotting is the reduction of proper physiologic function and then bacteria and pathogen infection. Chestnut rotting rate during storage can be significantly reduced through an appropriate environment and new techniques and chemicals.
106 Cellulose Coatings Reduce Rancidity of Pecans
Authors: Baldwin E.A. , Woods Bruce W.
Published: February 2019

Pecans (Carya illinoinensis) are full of unsaturated fatty acids, which are subject to oxidative cleavage. This results in the development of rancid off-flavors, which render the nuts unmarketable. For this reason, pecans must be stored under costly refrigerated conditions. Furthermore, pecans usually undergo retail distribution and marketing at ambient conditions, which promote development of off-flavors. Application of cellulose-based edible coatings reduced off-flavor, and improved overall flavor scores while adding shine to the nuts during 14 months of storage under ambient conditions. Development of rancidity involves hydrolysis of glycerides into free fatty acids, oxidation of double bonds of unsaturated fatty acids to form peroxides and then autooxidation of the free fatty acids once the peroxides reach a sufficient level to perpetuate this reaction. One of the products of autooxidation is hexanal which is, thus, a good indicator of rancidity. Analysis of pecans by gas chromatography revealed that hexanal levels were reduced in coated nuts by 5- to over 200-fold compared to uncoated controls, depending on the coating treatment. Some of the coating treatments affected nut color, but overall flavor and appearance were improved by certain formulations.
107 Postharvest Storage Profile of Spondias mombim Fruit
Authors: Martins L.P. , Silva S.M.
Published: February 2019

Spondias mombim L. fruit, commonly known in the Brazilian Northeast as “caj,” has increased its acceptance locally and abroad in recent years due to its exotic and delicious pulp. Spondias mombim fruit can be eaten raw or as juice, jellies, and sweet. Trade in S. mombim, however, has been limited by the highly perishable nature of the fruit. Comprehensive studies on proper postharvest technologies for its storage and enhanced shelflife are required to improve its commercial performance. The determination of proper storage temperature allows reducing the rate of metabolism without causing chilling injury. In addition, modified atmosphere packaging, by using low-density polyethylene (LDPE), may delay fruit ripening. Combination of proper temperature and film O2 and CO2 permeabilities, therefore, may enhance the postharvest shelflife of S. mombim fruits. Ripened fruits were stored with and without film, at temperatures varying from 16 °C to 5 °C, at 0.5 °C steps, in order to set proper storage temperature and shelflife. Changes in fruit weight loss, firmness, soluble solids, pH, titratable acidity, sugars, CO2 production, ascorbic acid, and carotenoids contents were measured during storage. Storage of S. mombim, wrapped with LDPE, at 8 °C allowed quality maintenance and increased the fruit postharvest shelflife by 12 days, without causing chilling injury.
109 Evaluation of Postharvest Quality Parameters in Lulo (Naranjilla) Stored at Different Temperatures
Authors: Diaz J.G. , Manzano-Méndez J.E.
Published: February 2019

Lulo (Solanum quitoense L.) fruits grown at the Andes farms, T·chira State in Venezuela, were harvested at the mature green stage, selected, washed, and transported to the postharvest Lab. Fruits were stored in small commercial carton boxes in storage rooms at 5, 10, and 15 °C during 3 weeks. Chemical parameters such as solid soluble concentration (SSC), pH, tritatable acidity (TA), ratio SSC/TA, and physical parameters such as Color: L*, Hue, Chroma, color index (a+b)/L × 100, texture and fresh fruit weight loss (FFWL), in pulp extract and from the whole fruit were analyzed at the initial and at the end of each storage week. These characteristics ranged in the fellowing way: SSC: 749% ± 8.09% and its media of 8.02%, TA: 1.05%–1.18% for temperature and 1.01–1.27 for storage time with an average of 1.16% (expressed as citric acid), color index: 4.54–5.22 for storage time and 4.30–5.13 for storage temperatures with an average of 4.86, chroma: 6.21–6.63 for storage time and 6.00–6.55 for storage temperatures with an average of 6.36, FFWL: 1.30%–1.44% for storage temperature and 0.67%–2.11% for storage time .The SSC decreased with increasing the storage temperature. The TA, color index, and chroma decreased with the storage time and increased with storage time, the FFWL values increased with storage temperatures and with storage time.
110 Postharvest Quality of Tamarillo Fruits under Different Storage Temperatures
Authors: Manzano-Méndez J.E. , Diaz J.G.
Published: February 2019

Tamarillo (Cyphomandra betacea L.) fruits, grown in the Venezuela Andes farms, were harvested at mature-green stage, graded, selected, washed, and transported to the posharvest lab. for analysis. Fruits were stored into plastic containers in storage rooms at (5, 10, and 15 °C for 3 weeks. The soluble solid concentration (SSC), pH, tritatable acidity (TA), ratio SSC/TA, color: L*, Hue, Chroma, color index (a+b)/L × 100, texture, and fresh fruit weight loss (FFWL) in pulp extract and in the whole fruit were determined on the first day of harvest and at the end of each storage week. These parameters ranged as follows: SSC: 7.92–8.84%, pH: 4.06–4.35, TA: 1.14%–1.21% (expressed as citric acid), SSC/TA: 1.58–1.75, Chroma 42.72—45.54, FFWL: 0.83% at the second storage day to 4.39% at the 3rd storage week. Also, FFWL was 1.03%–1.40% for 10 and 15 °C, respectively. Fruits stored at the highest temperature increased pH values, the TA decreased with stored time, the Chroma and FFWL values increased with the increasing temperature and storage time.
113 Ethylene Mediates Responses of `Gala' Apple Fruit to Ionizing Irradiation
Authors: Fan Xuetong , Buchanan David , Argenta Luiz , Mattheis James
Published: February 2019

Pre-climacteric `Gala' apple fruit treated with air (control) or 2 μmol·L–1 1-methylcyclopropene (MCP) were exposed to gamma irradiation at 0, 0.5, 1, or 1.5 kGy at 23 °C. Fruit were held at 20 °C for 3 weeks after treatment during which respiration rate, production of ethylene and other volatile compounds, fruit firmness, soluble solid content, titratable acidity, and irradiation injury were determined. MCP treatment reduced respiration and ethylene production and slowed loss of fruit firmness and titratable acidity. Irradiation induced increased respiration of MCP-treated fruit in a dosage-dependent fashion. Irradiation caused a decrease in ethylene production by control (non-MCP) fruit, and the magnitude of the decrease was dependent on irradiation dosage. Irradiation at 0.5, 1, and 1.5 kGy stimulated ethylene production of MCP-treated fruit for only 1 day after treatment. Irradiation induced internal browning and the injury severity increased with dosage. The severity and incidence of irradiation damage were higher in MCP-treated fruit than control fruit. The results indicate that ethylene is involved in mediating apple fruit responses to irradiation.
116 Preharvest Fruit Drop Studies, Harvest Quality, and Cold Storage of `Golden Delicious' and `Rome' Apples
Authors: Byers R.E. , Carbaugh D.H. , Combs L.D.
Published: February 2019

Combinations of aminoethoxyvinylglycine (AVG, ReTain) and NAA gave better control of fruit drop of `Golden Delicious' than either alone. When the full rate of ReTain (50 g/A) was compared to a reduced rate of ReTain (86 g/ha) plus NAA, equivalent control of fruit drop of `Golden Delicious' resulted. ReTain delayed softening and starch depletion of `Golden Delicious' fruit. NAA in some cases promoted earlier fruit maturity; but when used in combination with ReTain, maturity was similar to ReTain-treated fruit. Fruit with the highest firmness and starch came out of cold storage in the best condition. Neither 1-methylcyclopropene (MCP, EthylBloc) or NAA inhibited fruit drop of `Golden Delicious' fruit when applied at harvest; but previous ReTain and NAA data indicate that late applications are frequently much less effective than if applied 4 weeks before harvest. Ethephon spray treatments caused more rapid and extensive fruit drop than the control. Trees gassed or sprayed with EthylBloc before ethephon sprays also dropped rapidly. `Golden Delicious' fruit on the tree were dramatically maintained firmer by the EthylBloc gas, and to a lesser extent by EthylBloc sprays by 19.1 N and 10.2 N firmness, respectively, tested on 28 Oct. Starch was maintained by the EthylBloc gas, but not by the sprays. These data indicated that EthylBloc applied as a gas or spray did have a physiological affect but did not control fruit drop. Fruit diameter, soluble solids and color did not appear to be affected. Further study of earlier applications of EthylBloc or combinations with fruit drop control agents may be needed to get fruit drop control. NAA plus Silwet L-77 inhibited fruit drop of `Law Rome', but none of the EthylBloc sprays inhibited fruit drop when applied at harvest. Previous data with ReTain and NAA indicated that late applications are frequently much less effective than if applied 4 weeks before harvest. EthylBloc sprays applied 21 Oct. dramatically maintained fruit firmness tested on 3 Nov. Starch was not maintained by the EthylBloc gas, but starch had almost disappeared by the application time on 21 Oct. Fruit diameter, soluble solids, and color did not appear to be affected. Further study of earlier applications of EthylBloc may be needed to demonstrate fruit drop control. Shading trees with 92% polypropylene shade material for 3 or 7 days caused more rapid fruit abscission at 7 days than 3 days and both were greater than the control.
122 Processing Tomato Fruit Firmness, Color Uniformity, and Peeling Response to Ethephon Sprays
Authors: Bennett Mark A. , Francis David M. , Grassbaugh Elaine M.
Published: February 2019

Ethephon (2-chloroethyl phosphonic acid) has been widely used under field conditions as a growth regulator to trigger the ripening of processing tomatoes prior to mechanical harvesting. Recent interest in whole-peeled and diced tomato products has raised questions about ethephon rates, and possible split applications for top quality. This 3-year field study tested two commercial cultivars of processing tomatoes (`OH8245' and `P696') and the effect of various ethephon applications on fruit firmness, color uniformity, and peeling variables. Transplants were established in mid to late May of 1996–1998 on raised beds in single rows at the OSU/OARDC Veg. Crops Branch in Fremont, Ohio. Ethrel applications for each cultivar were: 0, 0.58, 0.58 × 2 applications, 1.17, 1.17 × 2 applications, 1.75, 2.34, 4.68, and 7.02 L·ha–1. Fruit were tested for firmness, color uniformity, pH, titratable acids, and soluble solids. Samples from ethephon treatments of 0, 1.17 × 2 applications, 2.34, 4.68, and 7.02 L·ha–1 were peeled and canned for color inspection and firmness after 18 months storage. Three-year data for red fruit yield showed a typical response to increasing amounts (0 to 7.0 L·ha–1) of applied ethephon. While high rates (4.7 or 7.0 L·ha–1) gave some of the highest red fruit yields, and the greatest percent red fruit values, high rates were also linked with among the lowest fruit solids values. Split application comparisons showed little influence on quality variables examined in this study. However, chroma values were improved (more vivid color) when 2.3 L·ha–1 was applied vs. 1.17 L·ha–1 applied twice. Split applications also tended to produce softer fruit. Our results suggest that single ethephon applications of 1.17 to 2.34 L·ha–1 provide optimal fruit ripening and quality under midwestern U.S. conditions.
124 Color Changes of Leaf Lettuce during Postharvest Storage
Authors: Nam Sang Yong
Published: February 2019

Leaf lettuce is a major and widely cultivated vegetable crop. Leaf lettuce is preferred for wrapping food, like rice or meat, and is much more popular than head lettuce in Korea. Color change and water loss condition are most important factor for buying decision as external quality. This paper studied color change during storage at 20 and 4 °C, 60% RH. The color analysis of adaxial surface of leaf lettuce during shelf-life storage condition showed that Hunter L and a value increased slightly after 5 days of harvest, while delta-Eab started increasing after 3 days of postharvest. Chlorophyll content decreased by half during the first 5 days after harvest. These color changes, however, could not explain the changes in leaf chlorophyll content while the color intensity of G (green) component in RGB analysis showed a close relationship with leaf chlorophyll content changes. Visual quality score showed that lettuce may kept its marketability up to 5 days after harvest. But, in refrigerator (4°C, 60% RH, cold chain system) storage condition. Leaf color is about three times longer than shelf-life. Theses results of each evaluation methods consistently demonstrated that leaf lettuce may keep its marketability up to 5 days in a distribution market without color quality damage.
125 Effect of Postharvest Curing on Respiration and Quality in Garlic Bulbs During Cold Storage
Authors: Yang Y.J. , Lee K.A.
Published: February 2019

Garlic (Allium stivum L. cv. `Seosan') grown in Kyungbuk, Korea were harvested on June 1999 and dried in the field for 2 to 3 days. Bulbs were selected for uniformity in size and maturity and divided into two groups. One group was further dried in the shade at 25 °C for curing before storage at 0 °C. The other group was stored at 0 °C immediately without additional drying. Respiration of garlic bulbs dried additionally for 3 months was low, ranging from 1.5 to 3.0 CO2 mL/kg per h for 95 days in storage; ethylene was not detected until 60 days in storage. Non-curing samples showed rapid increase of carbon dioxide production after 50 days of storage, this might be related to incidence of fungal decay. Ethylene showed maximum value at 45 days in storage, thereafter remained level of 5.6-6.3 μL/kg per h. All treatments did not show sprouting during storage period, but incidence of decay was significantly reduced by additional drying. The beneficial effect of curing for 3 months at 25 °C was maintenance of low water content in garlic bulbs, which resulted in reduction of decay.
129 Postharvest Life, Quality and Flavor Characterization of Three Strawberry Cultivars Kept in Air or CO2-enriched Atmospheres
Authors: Pelayo Clara , Hess-Pierce Betty , Ebeler Susan E. , Kader Adel A.
Published: February 2019

Elevated CO2 atmospheres reduce decay and extend postharvest life based on appearance of strawberries but flavor quality may be lost faster than appearance quality. California-grown `Aromas', `Diamante,' and `Selva' strawberries were stored at 5 °C in air or 20 kPa CO2 + air for 15 days and evaluated for quality attributes, chemical changes, and flavor. In a “Preference Test”, `Selva” and `Diamante' were more preferred than `Aromas'. This may be related to their higher titratable acidity (TA), total soluble solids (TSS), the concentration of total aroma compounds, a different methyl/ethyl esters ratio, and the presence of C6 aldehydes. The postharvest life in air was 7, 9, and 9 days for `Aromas', `Diamante' and `Selva', respectively and these periods were extended by 30%, 20%, and 45% in the CO2-enriched atmosphere. There were no significant differences in TA or TSS between fruits kept in air or in air + CO2 and panelists could not detect differences in sourness and sweetness after 9 days of storage. In contrast, there was a trend for CO2-stored fruits of the three cultivars to be categorized as more aromatic, and for `Aromas' and `Selva' fruits to be described as more “strawberry like” in flavor compared to the corresponding air-stored fruits. The total aroma concentration decreased to a lesser extent in `Aromas' and `Selva' strawberries kept in air + CO2 than in those stored in air. The CO2-enriched atmosphere stimulated fermentative metabolism only in `Aromas' and `Selva'; the higher concentration of ethanol in these two cultivars favored the synthesis of ethyl esters. The total content of aroma compounds and the methyl/ethyl esters ratio may be two of the multiple factors determining the overall fruit flavor.
135 Energy Balance and Water Loss of Two Shade Tree Species over Asphalt and Turf in Contrasting Climates
Authors: Kjelgren Roger , Cole Janet
Published: February 2019

We investigated water loss of shade trees over turf and asphalt in an arid and humid climate for Russian olive and silver maple. Total daily tree water loss, and dawn-to-dusk stomatal conductance (gs) and leaf temperature (Tl), as well as air temperature, surface temperature, and vapor pressure deficit, were measured in Logan, Utah, and Stillwater, Okla., in early and mid-summer. Midday air temperatures in mid-summer were similar at both locations, 30 to 35 °C. Comparable vapor pressure deficits (VPD, kPa) were much higher in Logan, 3.5–5.0, than Stillwater, 2–2.5. Differences in humidity and air temperature between asphalt and turf were negligible at both Stillwater and Logan. Midday surface temperatures for asphalt and turf averaged 34 and 50 °C, respectively, in Logan, but were 10 °C higher for both surfaces in Oklahoma. The effect of higher longwave radiation from hotter surfaces on stomatal conductance and water loss of trees over asphalt in Stillwater was not consistently different for either species from those over turf. However, at Logan, Tl of trees over asphalt were consistently 2 to 4 °C higher and gs was 10% to 20% lower than those over turf. Stomatal closure for trees over asphalt resulted in water loss that was the same or slightly lower as trees over turf. The effect of paved surfaces on tree water loss appears to be more pronounced in an arid than a humid climate. The combined effect of higher VPD in an arid region and greater longwave radiation from hotter paved surfaces induces stomatal closure that limits water loss, and likely photosynthesis. By contrast, in humid regions, increased tree radiation interception over asphalt does not appear to trigger stomatal closure due to lower VPD.
136 Landscape Carbon Acquisition Potential of Residential Landscapes in Phoenix, Arizona
Authors: Martin Chris A. , Stabler Linda B.
Published: February 2019

Urban sprawl of the greater Phoenix metropolitan area is rapidly replacing agricultural and non-irrigated desert vegetation with an irrigated urban forest comprised of a mixture of woody ornamental plant materials. Our objective was to estimate and compare the carbon acquisition potential (CAP) of residential landscape plants to the dominate plant species found in adjacent agricultural and desert sites. Maximum shoot and leaf gas exchange measurements were made at monthly intervals for one year (Aug. 1998 to July 1999) using a portable photo-synthesis system. Concurrent diel gas exchange measurements were made seasonally. Gas exchange measurements were made on alfalfa at agricultural sites, blue palo verde, creosote bush and bur sage at desert sites, and on a mixture of 19 different woody ornamental tree, shrub and ground cover species at residential sites. A trapezoidal integration model was used to estimate daily CAP at each site based on maximum assimilation flux values and seasonally adjusted diel assimilation patterns. Annual landscape CAP was then calculated as the summation of estimates of daily CAP. Calculated annual CAP was highest at agricultural sites (159.0 mol/m2 per year), lowest at desert sites (35.3 mol/m2 per year), and intermediate at residential landscape sites (99.3 mol/m2 per year).
137 Nitrate Assimilation and Carbon-14 Partitioning between Shoots and Roots of Tall Fescue
Authors: Sullivan W. Michael , Jiang Zhongchun , Hull Richard J.
Published: February 2019

Efficient use of nitrogen by turfgrasses depends on the ability of roots to absorb and assimilate nitrate. If a larger amount of nitrate is assimilated in the roots than in the shoots and organic N is transported to shoots as needed, nitrogen loss through clipping removal would be reduced. However, the ability of roots to assimilate nitrate depends on carbohydrate supply from the shoots. Our study examined the relationship between nitrate assimilation and photosynthate partitioning between shoots and roots of tall fescue grown in nutrient solution. To alter the pattern of nitrate reduction and photosynthate partitioning, we treated the plants as follows: 1) nutrient solution was aerated and nitrate was supplied to the roots, 2) nutrient solution was not aerated and nitrate was supplied to the roots, 3) nutrient solution was aerated and nitrogen was supplied to the leaves as nitrate, and 4) nutrient solution was aerated, and nitrogen was supplied to the leaves as urea. Photosynthate partitioning was assessed using carbon-14 as a tracer. Nitrate and nitrite reductase activities were determined by in vivo methods. Fortyeight hours after the grass leaves were exposed to carbon-14, >60% of the fixed carbon was translocated to stems and >15% to roots. Foliar application of urea resulted in less export of fixed carbon from leaves and lower leaf nitrite reductase activity than when nitrate was supplied to leaves. Less than 5% of the plant total nitrate reduction was attributed to root based activity. Root aeration decreased root nitrate reductase activity. Our results suggest that root-zone aeration and foliar N application could affect total nitrate assimilation and photosynthate partitioning to roots.
139 Flower Senescence in Hibiscus syriacus L.
Authors: Kwon Hye Jin , Kwon Song , Kim Ki Sun
Published: February 2019

This experiment was undertaken to characterize the physiological changes taking place during the petal senescence of Hibiscus syriacus. Five distinctive developmental stages were chronologically suggested. Flower bud dry weight increased almost linearly from Stage I to Stage IV at a rate of ≈15 mg/day. Fresh weight and fresh/dry weight ratio increased much more rapidly between Stage III and Stage IV than during the early stage of development. It showed that petal expansion was partially due to an increased water uptake. The highest osmolality (411 mmol) was found in the fully open flowers. During the subsequent senescence and collapse of the flower, from Stage IV to Stage V, there were a rapid loss of fresh and dry weight and the fall of fresh/dry weight ratio, corresponding to the wilting that characterizes early senescence. A rise in cell sap osmolality coincided with the increase in soluble sugar content and fresh/dry weight ratio, and with the expansion of Hibiscus syriacus petal. Therefore, buds at Stage III, where they are under physiological maturity, might be appropriate to harvest. Hibiscus syriacus flowers showed a small but respiratory peak at Stage IV. The maximum rate of respiration was obtained with fully open flowers (Stage IV), whereas ethylene production remained extremely low until the petals started to open. Ethylene production, ACC synthase, and ACC content increased as the fresh weight of the flowers started to decline. At Stage V, there were a loss of petal fresh weight and a considerable increase in ethylene production (9 nL/g per h). The results of the present study have shown that petal tissue at Stage IV, presenescent stage, was characterized by the increase of soluble sugar and fresh weight, which might be expected to lead to petal expansion and limit turgidity. ABA and the stomata on petal might promote the disorganization.
142 Root Mortality and Nutrient Uptake of Creeping Bentgrass in Response to Differential Root and Shoot Temperatures
Authors: Huang Bingru , Xu Qingzhang
Published: February 2019

This study was designed to compare and determine root growth and nutritional responses of creeping bentgrass cultivars that differ in heat tolerance to deferential, supraoptimal shoot and root temperatures. Shoots and roots of `Penncross' (heat sensitive) and `L-93' (heat tolerant) were exposed to four differential air/soil temperature regimes (20/20-control, 20/35, 35/20, and 35/35 °C) in water baths and growth chambers. Exposing roots to supraoptimal root temperature (35 °C) while maintaining shoots at normal temperature (20 °C), or at 35 °C in particular, reduced root fresh weight, root number, the content of N, P, and K in shoots and roots, and accelerated root death for both cultivars. High root temperature had a greater detrimental effects on root growth and nutrient accumulation than high shoot temperature for both cultivars. Reducing root temperature at supraoptimal shoot temperature improved root growth, reduced root mortality, and increased N, P, and K content in shoots and roots. Among the three nutrient elements, K was the most sensitive to changes in root temperature. L-93 generally maintained higher root fresh weight and number, and N, P, K content in shoots and roots, particularly K in roots, under high root (20/35 °C) or shoot/root (35/35 °C) temperatures. The results indicated that root growth and nutrient accumulation, particularly K, played an important role in creeping bentgrass tolerance to heat stress imposed to shoots by high air temperature or to roots by high soil temperatures. Reducing root temperature under supraoptimal ambient temperatures enhanced root growth and nutrient relations, and thus could lead to the improved shoot growth in cool-season grasses as reported previously.
144 The Effect of Water Stress on Growth of Several Warm-season Turfgrass Species
Authors: Bush Edward W. , McCrimmon James N. , Owings Allen D.
Published: February 2019

Four warm-season grass species [common carpetgrass (Axonopus affinis Chase), common bermudagrass (Cynodon dactylon [L.] Pers.), St. Augustinegrass (Stenophrum secondatum Walt. Kuntze.), and zoysiagrass (Zoysia japonica Steud.)] were established in containers filled with an Olivia silt loam soil for 12 weeks. Grasses were maintained weekly at 5 cm prior to the start of the experiment. Water stress treatments consisted of a control (field capacity), waterlogged, and flooded treatments. Waterlogging and flood treatments were imposed for a period of 90 days. The effects of water stress was dependent on grass species. Bermudagrass vegetative growth and turf quality were significantly reduced when flooded. Carpetgrass, St. Augustingrass, and zoysiagrass quality and vegetative growth were also reduced by flooding. St. Augustinegrass and zoysiagrass root dry weight was significantly decreased. Zoysiagrass plants did not survive 90 days of flooding. Leaf tissue analysis for common carpetgrass, common bermudagrass, St. Augustinegrass, and zoysiagrass indicated that plants subjected to waterlogging and flooding had significantly elevated Zn concentrations.
148 Seasonal Cold Hardiness Estimations of Male and Female Specimens of Two Holly Species
Authors: Lindstrom Orville M. , Florkowska Malgorzata A. , Ruter John , Lewis Pamela
Published: February 2019

Seasonal, stem and leaf cold hardiness levels of male and female plants of Ilex purpurea Hassk. and Ilex rotunda var. microcarpa (Lindl. ex Paxton) were determined over two winter seasons. The samples for the cold hardiness studies were taken from established plants growing at the Univ. of Georgia Bamboo Farm and Coastal Gardens in Savannah. Each month, 40 stem cuttings (4 to 5 inches long) were sent by overnight mail for evaluation. The plants were prepared for laboratory freezing exposure tests within 2 h of receiving. The samples were visually evaluated after freezing exposure to estimate their cold hardiness. In general, Ilex purpurea was more cold-hardy than I. rotunda var. microcarpa over both seasons tested, except in midwinter (Jan. 1998 and Feb. 1999) where I. rotunda var. microcarpa was more cold-hardy than I. purpurea. Ilex purpurea attained cold hardiness earlier in the fall and lost its hardiness later in the spring. In general, few consistent differences were observed between the cold hardiness of male and female plants within species.
152 Environmental Factors Affect the Growth and Transpiration Rate of Potted Oriental Cymbidium (Cymbidium goeringii)
Authors: Cho Keun Ho , Kwack Beyoung Hwa , Huh Moo Ryong , Lee Chiwon W.
Published: February 2019

The biomass yield, transpiration rate, and chlorophyll contents in Cymbidium goeringii plants grown under various light, temperature, and humidity conditions were investigated. Two-year-old plants potted in pine-bark medium were grown for 12 weeks during the summer months in polyethylene film-covered mini-greenhouses having four different environmental conditions: a) closed house (CH) with high humidity (95.1% RH), high light (800 μmol·m–2·s–1) and high temperature (37.5 °C), b) ventilated house (VH) with low humidity (41.4% RH), high light (800 μmol·m–2·s–1), and medium temperature (31.5 °C), c) shaded closed house (SCH) with high humidity (91.0% RH), low light (110 μmol·m–2·s–1) and medium temperature (33.3 °C), and d) shaded ventilated house (SVH) with medium humidity (61.5% RH), low light (110 μmol·m–2·s–1) and low temperature (30.5 °C). Plants grown in CH produced leaf chlorosis with 50% shorter leaves and 40% lower relative growth rate (7.9 mg/g fresh weight per day) compared to plants grown in SVH. Cymbidium plants grown in SCH or SVH showed higher leaf and root dry weights as compared to those grown in CH or VH. Leaf chlorophyll-a and -b contents as well as carbohydrate levels were the highest in plants grown in SVH, indicating the benefits of shading and ventilation. The rate of transpiration showed a quadratic response to increasing levels of leaf temperature (r2 = 0.81), wind velocity (r2 = 0.82), and vapor pressure deficit (VPD, r2 = 0.91). Regression analysis revealed that the maximum transpiration rate occurred at 25.4 °C leaf temperature, 2.1 m/s wind velocity, and 2.3 kPa VPD in this experiment.
154 Suppressing Purple Passion (Gynura aurantiaca) Flowering Using Selected Plant Growth Regulators
Authors: Chen Jianjun , Caldwell Russell D. , Robinson Cynthia A.
Published: February 2019

Gynura aurantiaca is a colorful foliage plant with creeping stems and velvety purple hairs that cover the green leaves. It grows rapidly, but is cultivated primarily for those attractive purple leaves. Annually during the spring, this plant produces prominent flowers both in appearance and smell, gaudy and malodorous. Flowering coupled with acquiring an over-grown leggy appearance have been key limitations in its production and use in interiorscaping. This study was undertaken to determine if an available commercial plant growth regulator could inhibit flowering. A-Rest (ancymidol), B-Nine (daminozide), Bonzi (paclobutrazol), cycocel (chlormequat chloride) and florel (ethephon) each diluted to three different concentrations were sprayed in two applications in early spring at 2-week intervals. Flowering and bud numbers and plant growth (number of lateral shoots, vine lengths and internode lengths) were recorded. Results indicated that applications of A-Rest, B-Nine, Bonzi and Cycocel, regardless of treatment concentrations, were ineffective in suppressing the flowering of this plant; whereas, florel completely suppressed flowering at the three concentrations used. The florel-treated plants also grew more lateral shoots, which produced a compact and dense bush-look, indicating that appropriate concentrations of florel application not only will stop flowering of purple passion but can also improve and prolong its aesthetic value as a potted or hanging-basket interior plant.
155 Fertilizer Concentration Affects Whole Plant CO2 Exchange and Growth of Subirrigated Pansies
Authors: van Iersel Marc , Kang Jong-Goo
Published: February 2019

Subirrigation is an economically attractive irrigation method for producing bedding plants. Because excess fertilizer salts are not leached from the growing medium, salts can accumulate in the growing medium. Fertilizer guidelines developed for overhead irrigation may not be appropriate for subirrigation systems. Our objective was to quantify the effect of the fertilizer concentration (N at 0, 135, 285, and 440 mg·L–1) on whole-plant CO2 exchange and growth of subirrigated pansies. Whole plant CO2 exchange rate (net photosynthesis and dark respiration) was measured once every 10 min for 31 days. Whole-plant photosynthesis, dark respiration, and carbon use efficiency increased during the experiment. Fertilizer concentration started to affect the growth rate of the plants after approximately 7 days. Maximum photosynthesis and growth were achieved with N at about 280 mg·L–1 in the fertilizer solution [electrical conductivity = 2 dS·m–1]. Growth was reduced by ≈10% when the plants were fertilized with N at 135 and 440 mg·L–1 compared to 280 mg·L–1. Growth of plants watered without any fertilizer was greatly reduced, and plants showed symptoms of N and K deficiency. The size of the root system decreased and the shoot: root ratio increased with increasing fertilizer concentration, but the size of the root system was adequate in all treatments. These results indicate that subirrigated pansies can tolerate a wide range of fertilizer concentrations with relatively little effect on plant growth.
156 Effects of the Inductive Period, Shoot Density, and Leaf Removal on the Flowering of Heliconia rostrata Ruiz & Pavon
Authors: Maciel Norberto , Criley Richard A.
Published: February 2019

Heliconia rostrata is a herbaceous-musoid sympodial rhizomatous plant that grows as clump. After three leaves are produced, each shoot of the clump may bear an inflorescence if it is induced by short days (SD). However, the relationship between shoot density and flowering has not been quantified. To evaluate the effects of the inductive period, number of shoots, and leaf removal on flowering, rhizomes were planted in 120 pots (8 L). One-third of the pots were planted with two rhizomes, while the remainder was planted with one. One-half of the pots with one rhizome were allowed to develop all their shoots for three generations, while in the remaining pots only one shoot per generation was allowed to grow. In addition, one-half of the plants in all the treatments were subjected to selective leaf removal. The plants were grown under long days (LD) >13 h in a glasshouse until four leaves were produced. Inductive SD was supplied to all the plants from 5:00 pm to 8:00 am. After 8 weeks of SD, one-half of the plants were given LD, while the other half continued under SD (conSD) until flowering. The highest percentage of flowering shoots (39% to 35%) was observed in plants under conSD; plants under SD-LD were 10% to 9%. The second generation of shoots showed the highest flowering (74% conSD and 21% SD-LD), followed by the first (62% conSD and 18% SD-LD), and third (31% conSD and 0% SD-LD) generations. Non-flowering shoots of the first generation were aborted or dead. Shoots of the third were still vegetative, since they had few leaves to be induced. Fewer flowers occurred in clumps allowed to develop all their shoots. Intact plants from rhizomes with one shoot per generation flowered more than the partially defoliated ones under conSD.
166 Influence of Crop Level on Growth and Quality of `Braeburn' Apple Fruit
Authors: Garriz P.I. , Colavita G.M. , Alvarez H.L.
Published: February 2019

Crop load and the genetic biological carrying capacity (source–sink relationships) determine the potential for fruit size development on apple; however, the environment within which the fruit grows attenuates this potential. The effects of different crop loads on the growth pattern and the progress of maturity in apples were evaluated at the Comahue National Univ., Argentina (lat. 38 56'S long 67 59'W), during the 1998–99 growing season. Our experiment was conducted on 6-year-old `Braeburn'/Malling Merton 111 apple (Malus domestica Borkh.) trees spaced 4.0 × 2.3 m and trained to palmette leader. Treatments were 1) light crop load (LC), 2.5 fruit/cm2 trunk cross-sectional area (TCSA), 2) moderate crop load (MC), 6.5 fruit/cm2 TCSA (standard commercial crop load) and 3) high crop load (HC), minimum 8 fruit/cm2 TCSA, no fruit removed from tree. Whole trees were hand-thinned 19 days after full bloom (DAFB). Fruit diameter (FD) was taken at two weekly intervals (n = 24 per date and treatment) and maturity indexes were determined at harvest. Analysis of variance was used and mean separations were computed with Student's t test. From 38 DAFB until harvest, fruit size was significantly reduced (P < 0.01) in the HC trees, indicating that they were source-limited during growth. At 166 DAFB, FD was 7.48, 7.14, and 6.89 cm for the LC, MC and HC treatments, respectively. Adequate carbon was apparently available to support a commercial crop load since no differences were found between LC and MC trees. Crop level influenced flesh firmness; at 173 DAFB, it was significantly lower in HC trees than MC and LC trees (84.33, 92.51, and 91.57 N, respectively). These results suggest some goals of thinning for ensuring sizable `Braeburn' fruit.
167 Nutrient Uptake and Growth Performance of OH87 and OH97 Pear Rootstocks
Authors: Dong Shufu , Cheng Lailiang , Ding Pinghai , Bi Guihong , Fuchigami Leslie H.
Published: February 2019

One-year-old (Old Home) OH87 and OH97 pear rootstocks were grown in 2-gallon containers under natural conditions at Corvallis, Ore., in in 1999. Uniform plants were harvested during August and September, and total leaf area, new shoot number and length, and root growth were measured. The kinetics of NH4+ and NO3- uptake by new roots of both rootstocks were determined with the ion-depletion technique. OH87 had larger total leaf area, and more and longer shoots than OH97. Total root biomass was similiar between the two rootstocks, but OH87 had a larger proportion of new roots and more extension roots than OH97. Both rootstocks had lower Km values for NH4+ absorption than for NO3- and therefore both had greater absorptive power for NH4+ than for NO3- at the low nutrient concentrations. The maximum uptake rates (Vmax) of OH97 were similiar for both NH4+ and NO3- absorption, but OH87 had a much higher maximum uptake rate for NO3- than for NH4+.