bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethylene Inhibitors Delay Fruit Drop, Maturity, and Increase Fruit Size of 'Arlet' Apples
Authors: Byers Ross E. , Carbaugh D.H. , Combs L.D.
Published: February 2019

Aminoethoxyvinylglycine (AVG) applied as a spray to 'Arlet' apple trees inhibited fruit drop and increased the pull force necessary to detach the fruit. AVG delayed the loss of fruit firmness, starch degradation, fruit shriveling, and red color development. 1-Methylcyclopropene (1-MCP), applied as a gas or spray to trees in the field, did not affect fruit drop or pull force. The combination of AVG + 1-MCP (spray or gas) provided better control of fruit drop, slowed the loss of fruit firmness, starch degradation, and decrease in pull force than AVG alone. Thirty five days after the optimum harvest date, fruit firmness from trees sprayed with AVG + 1-MCP was maintained at 74.3 N. Fruit of the control was significantly lower at 61.4 N firmness. The delay in harvest caused untreated control fruit stems to turn brown and die, but stems on AVG treated trees remained green and fruit continued to grow. In the 35 days after the optimum harvest date, treated fruit increased 2.5 cm in fruit diameter. Chemicals used: Aminoethoxyvinylglycine (AVG), 1-Methylcyclopropene (1-MCP), and trisiloxane ethoxylate methyl ether (an organosilicone surfactant, Silwet L-77).
Relative Susceptibility of New Apple Cultivars to Arthropod Pests
Authors: Hogmire Henry W. , Miller Stephen S.
Published: February 2019

As part of a regional NE-183 project (Multidisciplinary Evaluation of New Apple Cultivars), 23 apple (Malus ×domestica Borkh.) cultivars were evaluated for arthropod pest susceptibility. Incidence or injury data were collected from six foliage and eight fruit pests under field conditions over a four year period (2000–03). Cultivars were ranked based on susceptibility (least to most) to each pest, and rankings were summed for members of the foliage and fruit pest group to develop a susceptibility rating for foliage, fruit and all pests combined. Cultivars with lowest susceptibility to foliage pests included `GoldRush' and `Pioneer Mac', whereas `Yataka' and `Cameo' were most susceptible. For fruit pests, susceptibility was lowest for `Pristine' and `Sunrise', and highest for `Cameo', `Fuji Red Sport #2', and `Gala Supreme'. When both foliage and fruit pests were combined, susceptibility was lowest for `Sunrise' and `Pioneer Mac', and highest for `Cameo'. Some increasingly popular cultivars had high levels of injury from a few pests, including plum curculio and apple maggot on `Ginger Gold', codling moth and oriental fruit moth on `Cameo', and japanese beetle, plum curculio and apple maggot on `Honeycrisp'. A positive and significant correlation was found between day of harvest and percent fruit injury from codling moth/oriental fruit moth and tufted apple bud moth/redbanded leafroller, with later maturing cultivars experiencing higher injury levels presumably due to more exposure to later generations of these pests. Differences among cultivars in pest incidence and injury can be used by growers to improve pest management through cultivar selection, or by making modifications in control programs based on cultivar susceptibility.
Rimsulfuron Controls Hairy Nightshade, but not Eastern Black Nightshade, in Tomato
Authors: Greenland Richard G. , Howatt Kirk A.
Published: February 2019

Nightshade species are difficult to control in tomato production and their interference reduces both tomato yield and quality. Rimsulfuron can be used to control nightshades, but species and biotypes vary in their response to rimsulfuron. The objectives of this study were to evaluate control of hairy nightshade (Solanum sarrachoides Sendt.) and eastern black nightshade (Solanum ptycanthum Dun.) by rimsulfuron and compare North Dakota eastern black nightshade accession response to three acetolactate synthase (ALS)-inhibitor herbicides. In field studies conducted at Oakes, N. Dak., rimsulfuron at rates of 26 or 53 g·ha–1 a.i. was applied within 1 week after transplanting tomato (EPOST) or 2 to 4 weeks after transplanting (POST). Rimsulfuron gave excellent control of hairy nightshade when applied POST, and poor to excellent control when applied EPOST, with control being much better when hairy nightshade had emerged before the EPOST application. Rimsulfuron at 53 g·ha–1 provided greater control than at 26 g·ha–1 only for the EPOST applications. Rimsulfuron controlled hairy nightshade which allowed eastern black nightshade (which was not controlled by rimsulfuron) to dominate tomato. Tomato yield was lower when dominated by hairy nightshade than by eastern black nightshade. This was due to the earlier emergence and faster growth of hairy nightshade compared to eastern black nightshade. Tomato yield was higher in the hand-weeded check than for all other treatments in 1999, the only year the hand-weeded check was included in the study. Greenhouse studies on plants grown from seed collected at the experimental site verified that eastern black nightshade was tolerant to rimsulfuron but was controlled by tribenuron and imazethapyr. Rimsulfuron can be used in tomato production to control hairy nightshade, but not the accession of eastern black nightshade found in this study. Chemical names used: N-((4,6-dimethoxypyrimidin-2-yl)aminocarbonyl)-3-(ethylsulfonyl)-2-pyridinesulfonamide (rimsulfuron); (α,α,α-trifluoro-2,6-dinitro-N,N dipropyl-p-toluidine) (trifluralin); methyl 2-[[[[(4-methoxy-6-methyl–1,3,5-triazin-2-yl)methylamino]carbonyl]amino]sulfonyl]benzoate (tribenuron methyl); (±)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo–1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid (imazethapyr).
Effect of Postharvest Soil and Foliar Application of Boron Fertilizer on the Partitioning of Boron in Apple Trees
Authors: Sánchez Enrique E. , Righetti Timothy L.
Published: February 2019

This study was carried out on mature `Delicious' apple trees (Malus domestica Borkh.) on EM 9 rootstock. Labeled B (99.63 Atom % 10B) was applied as boric acid. Treatments were postharvest foliar B at 375 mg·L–1, postharvest foliar B (375 mg·L–1) plus urea (2.5% wt/vol), and a soil application at the same per-tree rate as the foliar treatments (16 g boric acid/tree). Postharvest foliar B applied with or without urea was efficiently transported from the leaves into storage tissues for the next year's growth. However, soil-applied B remained mostly in the roots while very little was translocated to the above-ground portions of the tree at full bloom. When urea was added to a foliar B spray, the amount of B in the roots and flower clusters increased at full bloom. Although increasing the efficiency of foliar B applications may not be necessary, combining urea and B into a single application is recommended when growers want to apply both N and B. Shoot leaves from all treatments collected late in the season (midsummer) had similar B concentrations, even though treatments altered the amount of added B that was present in different tree tissues early in the season.
Effects of NAA, AVG, and 1-MCP on Ethylene Biosynthesis, Preharvest Fruit Drop, Fruit Maturity, and Quality of ‘Golden Supreme’ and ‘Golden Delicious’ Apples
Authors: Yuan Rongcai , Carbaugh David H.
Published: February 2019

Effects of naphthaleneacetic acid (NAA), aminoethoxyvinylglycine (AVG), and 1-methylcyclopropene (1-MCP) alone or in combination on fruit ethylene production, preharvest fruit drop, fruit quality, and fruit maturation were examined in ‘Golden Supreme’ and ‘Golden Delicious’ apples (Malus ×domestica Borkh.). In ‘Golden Supreme’ apples, the combination of two applications of AVG and one application of NAA 3 and 1 week, respectively, before the anticipated optimum harvest date synergistically inhibited fruit ethylene production and delayed fruit drop and ripening. Compared with one or two applications of AVG, the combination of one application of AVG and two applications of NAA had much lower preharvest fruit drop, although there was no significant difference in fruit ethylene production among these treatments. In ‘Golden Delicious’ apples, 1-MCP at 396 mg·L−1 had a better effect in delaying fruit drop than did AVG at 125 mg·L−1 or NAA at 20 mg·L−1 when they were applied a week before the optimum harvest date. The combination of NAA and 1-MCP or AVG was more effective in delaying fruit drop than were NAA, 1-MCP, or AVG alone. Fruit ethylene production was inhibited by 1-MCP and AVG but not by NAA. 1-MCP and AVG delayed fruit ripening, whereas NAA increased fruit ripening as determined by fruit firmness and starch.
1-Methylcyclopropene Inhibits Degreening But Stimulates Respiration and Ethylene Biosynthesis in Grapefruit
Authors: McCollum Greg , Maul Pilar
Published: February 2019

We determined the effects of 1-methylcyclopropene (1-MCP) and ethylene on color change and CO2 and ethylene production in grapefruit. Treatment with 1-MCP at concentrations equal to or greater than 75 nL·L−1 inhibited ethylene-induced degreening, but increasing 1-MCP concentrations greater than 150 nL·L−1 did not cause additional inhibition of degreening. Although ethylene-induced degreening was inhibited by 1-MCP, the effect was transient. Treating grapefruit with 15 to 75 nL·L−1 1-MCP resulted in a slight suppression of CO2 production, whereas treatment with 150 or 300 nL·L−1 1-MCP resulted in rates of CO2 production significantly higher than nontreated fruit. 1-MCP treatment also caused a very pronounced increase in the rate of C2H4 production that was both dose- and time-dependent. The effects of 1-MCP on respiration and ethylene evolution were reduced if fruit was subsequently exposed to ethylene. Fruit treated with 1-MCP alone had the highest rates of CO2 production, fruit treated with ethylene after 1-MCP or ethylene alone had intermediate rates of CO2 production, and control fruit had the lowest rate of CO2 production. Rates of C2H4 evolution were ≈200 nL·kg−1·h−1 from control and C2H4-treated fruit compared with ≈10,000 nL·kg−1·h−1 from 1-MCP-treated fruit; fruit treated with ethylene after 1-MCP had ethylene production rates of ≈400 nL·kg−1·h−1. Our results lend further support for a regulatory role for ethylene in degreening of citrus and suggest that endogenous levels of ethylene regulate ethylene production.
Effect of Radiofrequency Heating on the Quality of ‘Fuyu’ Persimmon Fruit as a Treatment for Control of the Mexican Fruit Fly
Authors: Monzon Maria E. , Biasi Bill , Mitcham Elizabeth J. , Wang Shaojin , Tang Juming , Hallman Guy J.
Published: February 2019

The external and internal quality of ‘Fuyu’ persimmon fruit (Diospyros kaki L.) was evaluated after heating with radiofrequency (RF) energy to 48, 50, or 52 °C, holding at the target temperatures for durations ranging from 0.5 to 18 minutes, hydrocooling, and ripening at 20 °C for 12 days. These treatment conditions were identified for control of third instar Mexican fruit fly larvae (Anastrepha ludens). The treatments had no commercially significant effect on firmness, soluble solids content, titratable acidity, or weight loss of the fruit. RF-treated persimmon fruit attained a deeper orange–red skin color than control fruit. There was a greater incidence of slight to moderate flesh browning in fruit heated to 50 and 52 °C as compared with 48 °C. Calyx browning increased slightly in all RF-treated fruit and was the highest in the longer treatments at each temperature. Heating persimmon fruit with RF to 48 °C and then holding for 6 or 12 minutes showed the least damage, and the latter treatment was longer than should be required for a quarantine treatment against the third instar Mexican fruit fly. Holding persimmons for 6.6 minutes at 48 °C should provide control of the Mexican fruit fly and maintain fruit quality. Confirmation tests with infested fruit should be conducted.
Freezing Tolerance of 27 Saltgrass Ecotypes from Three Cold Hardiness Zones
Authors: Rukavina Hrvoje , Hughes Harrison G. , Qian Yaling
Published: February 2019

Freezing is the major abiotic stress that limits geographic distribution of warm season turfgrasses. Prior studies have indicated variation in freezing tolerance in saltgrass clones. Therefore, this study examined freezing tolerance of 27 saltgrass clones as related to collection sites in three zones of cold hardiness. Furthermore, these clones were evaluated for time of leaf browning in the fall with the intent to determine if there was a correlation between this trait and freezing tolerance. Rhizomes were sampled during 2004 and 2005 midwinters from clones established in Fort Collins, Colo., and then subjected to a freezing test in a programmable freezer. Saltgrass freezing tolerance was highly influenced by the climatic zone of clone origin in both years of the experiment. Clones with greater freezing tolerance turned brown earlier in fall in both seasons. Ranking of zones for the average LT50 (lethal temperature at which 50% of rhizomes died) was: zone 4, most northern (−17.2 °C) < zone 5 (−14.4 °C), < zone 6, most southern (−11.1 °C) in 2004, and zone 4 (−18.3 °C), < zone 5 (−15.7 °C) < zone 6 (−13.1 °C) in 2005. Clones from northern areas tolerated lower freezing temperatures overall. This likely indicates that freezing tolerance is inherited. Large intraspecific variation in freezing tolerance may be effectively used in developing cold hardy cultivars.
Diversity of Fruit Quality Characteristics in Capsicum frutescens
Authors: Jarret Robert L. , Baldwin Elizabeth , Perkins Brian , Bushway Rod , Guthrie Kelly
Published: February 2019

Fruit of 40 genotypes of Capsicum frutescens L. from the US Department of Agriculture/Agricultural Research Service Capsicum germplasm collection were analyzed for a variety of fruit quality parameters, including fruit size, weight, and concentrations of capsaicinoids, sucrose, glucose, fructose, malic acid, and total acid equivalents. Fruit weight ranged from 0.23 g fresh weight to 4.04 g fresh weight (average 1.05g). Fruit length/width ranged from 1 to 8.0 (average, 3.61). Capsaicin concentrations ranged from 34 to 350 mg·100 g−1 fresh weight (average, 135 mg·100 g−1 fresh weight). Sucrose concentrations ranged from 0.28 to 1.0 g·100 g−1 (average, 0.6 g·100 g−1 fresh weight). Total sugar extracts ranged from 0.73% to 2.6% (average, 1.55%). Malic acid concentrations and total acid equivalents ranged from 0.62 to 2.29 g·100 g−1 fresh weight (average, 2.07 g·100 g−1 fresh weight) and 0.97 to 3.31 g·100 g−1 (average, 1.87 g·100 g−1) respectively. These data demonstrate an approximate 4 to 14-fold range in values for the characteristics examined, suggesting the presence of sufficient variability for these traits within this species to support the development of germplasm enhanced for specific or multiple fruit quality attributes.
Effect of Spent Mushroom Substrate on Seed Germination of Cool-season Turfgrasses
Authors: Aamlid Trygve S. , Landschoot Peter J.
Published: February 2019

Spent mushroom substrate (SMS) is used by the turf industry in the northeastern United States for soil improvement. When tilled into soil at high rates, some turfgrass managers claim that SMS inhibits turf seed germination. The authors’ objectives were 1) to determine whether fresh SMS inhibits turf seed germination and, if so, which species are most adversely affected; 2) to evaluate whether any inhibition incited by SMS is the result of osmotic effects or toxicity of compounds in SMS extracts; 3) to determine whether any negative effect of SMS on germination can be eliminated by leaching the SMS-amended soil before seeding; and 4) to assess the performance of SMS on seedling emergence in the field. Germination of nine turfgrass species was evaluated in mixtures made from fresh SMS (electrical conductivity of saturated paste extract = 11.9 dS·m−1) and a loamy sand soil. Germination inhibition resulting from SMS was most pronounced in the following order: Colonial bentgrass (Agrostis capillaris L.) > sheep fescue [Festuca ovina L. ssp. hirtula (Hackel ex Travis) Wilkinson] > Kentucky bluegrass (Poa pratensis L.) > hard fescue [Festuca trachyphylla (Hackel) Krajina] > creeping bentgrass (Agrostis stolonifera L.) > chewings fescue [Festuca rubra L. sp. commutata (Thuill.) Nyman] = strong creeping red fescue (Festuca rubra L. ssp. rubra Gaud.) > slender creeping red fescue [Festuca rubra L. sp. litoralis (Meyer) Auquier] > perennial ryegrass (Lolium perenne L.). SMS had a stronger negative effect on germination rates than on final germination percentages. Germination of perennial ryegrass and Kentucky bluegrass on blotter paper moistened with SMS extracts or polyethylene glycol of equivalent osmotic potentials showed that the inhibition was primarily the result of osmotic effects. In an experiment with a 50% soil/50% SMS (v/v) mixture, Kentucky bluegrass germinated better in pots that had been watered with 133% or 167% of the evaporation rate for 10 days prior to seeding than in unleached pots. Although the negative effect of SMS on seed germination was not confirmed in a field study in which ECe values never exceeded 4.1 dS·m−1, the authors conclude that incorporation of high rates of SMS represents a potential problem for turfgrass establishment.
Evidence for Colinearity among Genetic Linkage Maps in Cucumber
Authors: Staub Jack E. , Sun Zhanyong , Chung Sang-Min , Lower Richard L.
Published: February 2019

Cucumber (Cucumis sativus L. var. sativus; 2n = 2x = 14), has a narrow genetic base (3% to 8% polymorphism). Nevertheless, several genetic maps exist for this species. It is important to know the degree of colinearity among these maps. Thus, the positions of random amplified polymorphic DNAs, sequenced characterized amplified regions, simple sequence repeat, restriction fragment length polymorphisms, and fluorescent amplified fragment length polymorphism markers were compared in four maps. A previously unreported map was constructed in a narrow cross (processing line 2A × Gy8; C. s. var. sativus; ≈7% polymorphism) and compared with the three published maps [two narrow-based (processing type; C. s. var. sativus; 8% to 12% polymorphism) and a broad-based (C. s. var. sativus × C. s. var. hardwickii (R.) Alef. ≈12%)]. Common makers were identified in seven linkage groups, providing evidence for microsynteny. These common markers were used as anchor markers for map position comparisons of yield component quantitative trait loci. The relative order of anchor markers in each of six linkage groups (linkage groups 1, 2, and 4–7) that had two or more anchor markers within each group was colinear, and instances of microsynteny were detected. Commonalities in the position of some yield component quantitative trait loci exist in linkage groups 1 and 4 of the maps examined, and the general synteny among these maps indicates that identification and mapping of additional anchor markers would lead to successful map merging to increase cucumber map saturation for use in cucumber breeding.
Refraction as a Measure of Soluble Carbohydrates in Storage Roots of Asparagus
Authors: Feller Carmen , Fink Matthias
Published: February 2019

The objective of our study was to determine how accurately refractometry can quantify soluble carbohydrates in the storage roots of asparagus (Asparagus officinalis L.). Fructose, glucose, sucrose, and fructans as well as refraction were measured in 51 root samples that were taken from commercial fields. There was substantial variation in refraction both within roots of the same plant (cv, 6%) and within plants in the same field (cv, 20%). Samples of asparagus root sap contained fructose, glucose, sucrose, and fructans in varying fractions and, in addition, significant amounts of other solubles, which contributed considerably to refraction. Therefore, refraction readings are no direct measure of fructose, glucose, sucrose, and fructans in asparagus root sap. However, the concentration of these carbohydrates can be well estimated by a regression function, which uses refraction readings as input (r = 0.89).
Influences of Organic Fertilization, High Tunnel Environment, and Postharvest Storage on Phenolic Compounds in Lettuce
Authors: Zhao Xin , Carey Edward E. , Young Janice E. , Wang Weiqun , Iwamoto Takeo
Published: February 2019

As the largest group of phytochemicals, dietary phenolics play an important role in human health and disease prevention. Cultural practices have been shown to have the potential for affecting phenolic compounds in food crops. Spring and summer trials were conducted in 2003 to examine the effects of organic fertilization and high tunnel environments on phenolic constituents of lettuce (Lactuca sativa L.) cultivars Red Sails and Kalura. Effects of postharvest storage at 4 °C for 16 days on total phenolics of lettuce harvested from the summer trial were also evaluated. Total phenolics, excluding anthocyanins, were measured spectrophotometrically, and major phenolic constituents were identified and quantified by high-performance liquid chromatography. Chlorogenic acid and quercetin glycosides were found to be predominant in lettuce. ‘Red Sails’ consistently exhibited significantly higher phenolic concentrations than ‘Kalura’. Organic (compost + fish emulsion) and conventional (N–P–K + CaNO3) fertilization did not consistently differentially affect lettuce phenolics in our recently established organic and conventional plots. The high tunnel environment generally reduced phenolic levels in lettuce relative to the open field. However, differences between high tunnel and open field varied with cultivar and season. Effects of production factors on lettuce phenolics were maintained during cold storage. There was a substantial increase in total phenolics during storage, likely correlated with declining lettuce quality. Further studies are warranted to more fully assess the impact of cultivar and production management, including organic fertilization, on lettuce phenolics.
Effect of Cooling of Medium on Fruit Set in High-bench Strawberry Culture
Authors: Ikeda Takashi , Yamazaki Keisuke , Kumakura Hiroshi , Hamamoto Hiroshi
Published: February 2019

We demonstrated the effect of cooling of the medium on the fruit set of strawberries (Fragaria × ananassa Duch.) grown on high benches for forcing culture. The cooling by water evaporation promoted by a fan enabled to cool the medium by an average of several degrees compared with no cooling. When runner plants were transplanted in late summer, cooling accelerated flower bud emergence almost 10 days on the primary axillary branch compared with plants grown in uncooled medium. Also, with cooling, fruit was harvested from the inflorescence of the primary axillary branch almost 10 days earlier. We expect that this technique will allow early transplanting around the end of summer and will shorten the time between fruit set on the terminal inflorescence and that on the inflorescence of the primary axillary branch.
Fruit Exploration Supported by the National Plant Germplasm System, 1980 to 2004
Authors: Forsline Philip L. , Hummer Kim E.
Published: February 2019

The National Plant Germplasm System (NPGS) of the U.S. Department of Agriculture (UDSA), Agricultural Research Service (ARS), has greatly expanded since 1980. Foremost in this expansion was the addition of seven repositories for clonally propagated fruit and specialty crops. Many collections at state agricultural experiment station sites were in jeopardy as breeders retired. These collections can now be preserved by the NPGS. The NPGS has provided funding for plant exploration and exchange. From 1980 to 2004, 37 exploration/exchange proposals for fruit crops were funded, and over 3000 accessions introduced as a result. Crop Germplasm Committees (CGCs), established for each commodity have prepared genetic vulnerability statements and prioritized collection activities. The USDA ARS, National Germplasm Resources Laboratory (NGRL), facilitates international relationships, and the USDA Animal and Plant Health Inspection Service (APHIS), National Plant Germplasm Quarantine Center (NPGQC), tests and makes pathogen-tested germplasm available. As a result of the Convention on Biological Diversity (1993) and the International Treaty on Plant Genetic Resource for Food and Agriculture (2004), the USDA now pursues germplasm collection through the establishment of bilateral agreements of mutual benefit.
Relative Salinity Tolerance of Turf-type Saltgrass Selections
Authors: Qian Y.L. , Fu J.M. , Wilhelm S.J. , Christensen D. , Koski A.J.
Published: February 2019

Salt-tolerant turfgrass is highly desirable in areas associated with saline soils or saline irrigation waters. To determine the salt tolerance of 14 saltgrass [Distichlis spicata var. stricta (Greene)] selections, two greenhouse studies were conducted by means of a hydroponic culture system. Five salinity levels (from 2 to 48 dS·m−1) were created with ocean salts. In general, turf quality decreased and leaf firing increased as salinity increased. However, varying levels of salt tolerance were observed among selections based on leaf firing, turf quality, root growth, and clipping yield. Selections COAZ-01, COAZ-18, CO-01, and COAZ-19 exhibited the best turf quality and the least leaf firing at 36 and 48 dS·m−1 salinity levels in both Experiments 1 and 2. At the highest salinity level (48 dS·m−1), COAZ-18 and COAZ-19 exhibited the highest root activity among all accessions. Salinity levels that caused 25% clipping reduction ranged from 21.2 to 29.9 dS·m−1 and were not significantly different among entries. The data on 25% clipping reduction salinity of saltgrass generated in this study rank saltgrass as one of the most salt-tolerant species that can be used as turf.
Resistance to Gummy Stem Blight in Melon (Cucumis melo L.) Germplasm and Inheritance of Resistance from Plant Introductions 157076, 420145, and 323498
Authors: Wolukau Joseph N. , Zhou Xiao-Hui , Li Ying , Zhang Yong-Bin , Chen Jin-Feng
Published: February 2019

Gummy stem blight incited by the fungus Didymella bryoniae is a major disease of melons worldwide. The objectives of the present study were to critically evaluate melon (Cucumis melo L.) germplasm for resistance to D. bryoniae and to characterize the genetics of resistance in the resistant accessions. Two hundred sources of germplasm (plant introduction accessions, cultivars, breeding lines, landraces, and wild relatives) were screened against a single highly virulent isolate (IS25) of D. bryoniae in a plastic tunnel. The genetics of resistance to D. bryoniae was studied in three crosses between plant introductions 157076, 420145, and 323498, resistant parents that were fairly adapted (flowering, fruiting, powdery mildew tolerance) to Nanjing conditions, and plant introductions 268227, 136170, and NSL 30032 susceptible parents, respectively. Six populations of each cross (susceptible parent, resistant parent, F1, F2, the two reciprocal backcrosses) were analyzed for their responses to D. bryoniae. Seedlings in both studies were inoculated with a spore suspension (5 × 105 spores/mL−1) of D. bryoniae at the four to six true-leaf stages and assessed for leaf and stem damage at 7, 14, and 21 d postinoculation. Results of germplasm screening indicated most germplasms reported as resistant elsewhere were confirmed resistant under our conditions. However, some plant introductions identified as highly resistant elsewhere were susceptible under our conditions, the most interesting being plant introduction 482399. This plant introduction that was considered resistant was highly susceptible in our study. We also identified other sources of resistance not reported previously, for example, JF1; a wild Cucumis from the highlands of Kenya was rated highly resistant. Analysis of segregation of F1, F2, and backcross generations of the three crosses indicated that each of the three plant introductions carry a single dominant gene for resistance to the D. bryoniae.
Anthocyanin Levels in Nine Lettuce (Lactuca sativa) Cultivars: Influence of Planting Date and Relations among Analytic, Instrumented, and Visual Assessments of Color
Authors: Gazula Aparna , Kleinhenz Matthew D. , Scheerens Joseph C. , Ling Peter P.
Published: February 2019

Leaf samples collected from field plots of nine lettuce cultivars established in the early (ES) and late (LS) summer of 2002 and 2003 in Celeryville, Ohio, were subjected to spectrophotometric measurement of anthocyanin concentrations or color analysis based on colorimeter and spectroradiometer readings and human panelist ratings. Interactions among year (Y), transplanting date (TD), and cultivar (C) main effects for anthocyanin concentration were significant as a result of shifts in response magnitude but not direction. Anthocyanin levels were higher after LS than ES transplanting regardless of Y and C. The effects of TD were pronounced in 2002, when differences in average daily temperature between ES and LS transplantings tended to be larger. Also, regardless of Y and TD, anthocyanin levels followed the pattern ‘Impuls’ > ‘OOC 1441’ > ‘Valeria’ > ‘OOC1426’ > ‘Lotto’ > ‘SVR 9634’ > ‘OOC 1434’ = ‘OOC 1310’ > ‘Cireo’. Treatment-based color differences were also evident in colorimeter and spectroradiometer readings. Also, panelists differentiated samples grown in 2003 based on red color intensity. Correlations between analytic and instrumented and human panelist-based measures suggest instrumented assessments of red coloration may serve as proxies for direct measures of anthocyanin levels or human panelist ratings, particularly if the aim is to establish color differences between major experimental groups and assign quantitative, repeatable values to red color intensity.
Spatial Variability of Kiwifruit Quality in Orchards and Its Implications for Sampling and Mapping
Authors: Taylor James A. , Praat John-Paul , Bollen A. Frank
Published: February 2019

Published statistics on the spatial variation of fruit quality observed in orchards has been rudimentary to date. Dry matter and fruit weight data were collected spatially within 11 kiwifruit (Actinidia deliciosa var. deliciosa ‘Hayward’) orchards in the Bay of Plenty, New Zealand, to characterize the variability in fruit quality in terms of nonspatial and spatial statistics. Fruit weight was statistically more variable and exhibited a stronger spatial structure than the dry matter data. Individual variograms were derived for each orchard and then all the data were collated into average variograms for both quality attributes. The average variogram parameters were used to determine the optimum spacing for grid sampling to achieve a desired level of confidence when interpolating the data. A grid spacing of 28 m appears suitable for mapping fruit quality, provided sufficient area exists to collect enough points to perform block kriging. Plots of individual orchard and average variograms, and a table of nonspatial and variogram statistics are presented as a reference for future work in this area.
Microclimate Prediction for Dynamic Greenhouse Climate Control
Authors: Körner Oliver , Aaslyng Jesper Mazanti , Andreassen Andrea Utoft , Holst Niels
Published: February 2019

Greenhouse energy-saving and biocide reduction can be achieved through dynamic greenhouse climate control with computerized model-based regimes. This can be optimized when next to greenhouse macroclimate (i.e., the aerial environment) also, the crop microclimate is predicted. The aim of this article was to design and apply a simple deterministic microclimate model for dynamic greenhouse climate control concepts. The model calculates crop temperature and latent heat of evaporation in different vertical levels of a dense canopy of potted plants. The model was validated with data attained from experiments on dynamic or nondynamic (regular) controlled greenhouse cultivation. Crop temperature was with a 95% confidence interval of 2 °C or 2.4 °C for sunlit or shaded leaves, respectively, accurately predicted in a simple greenhouse with predefined climate set points. With a more dynamic greenhouse control also including assimilation lighting and screens, the prediction quality decreased but still had a 95% confidence interval of crop temperature prediction of 3.8 °C for sunlit leaves. Simulations showed that controlling greenhouse temperature according to the predicted crop temperature rather than according to the air temperature can save energy. Energy-saving is highest during winter and 12% energy saving was attained during January under Danish climate conditions.
Efficacy of Spiromesifen Against Greenhouse Whitefly (Homoptera: Aleyrodidae) on Strawberry
Authors: Bi J.L. , Toscano N.C.
Published: February 2019

Spiromesifen is a novel insecticide (belonging to the new chemical class of spirocyclic phenyl-substituted tetronic acids) with a unique mode of action. Laboratory and field experiments were conducted to test the efficacy of this insecticide against the greenhouse whitefly, Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae) on strawberry, Fragaria ananassa (L.). Laboratory experiments showed that spiromesifen at 0.5 and 1.0 μg·mL−1 a.i. inhibited egg hatching by 80% and 100%, respectively, whereas at concentrations of 3.1, 3.0, and 10.0 μg·mL−1 a.i., this insecticide, respectively, killed 100% of the first, second, and third instar nymphs. Much lower toxicity to adults was observed. Field trials revealed that application of spiromesifen reduced the whitefly egg numbers by 61% to 80% from 2 to 3 weeks posttreatment in comparison with the pyriproxyfen treatment, whereas the application lowered the egg numbers by 34% to 73% from 2 to 5 weeks posttreatment compared with the buprofezin treatment. In comparison with pyriproxyfen treatment, spiromesifen application decreased the numbers of immature whiteflies by 29% to 92% from 1 to 6 weeks posttreatment. The effect of spiromesifen on reduction of immatures was similar to that of buprofezin. Also, the efficacy of spiromesifen on suppression of adult numbers was comparable to that of pyriproxyfen or buprofezin. Spiromesifen shows promise for inclusion in integrated greenhouse whitefly management programs and insecticide resistance management programs on strawberry.
Response of Olive Cultivars to Stem Puncture Inoculation with a Defoliating Pathotype of Verticillium dahliae
Authors: López-Escudero Francisco Javier , Blanco-López Miguel Ángel , Del Río Rincón Carmen , Caballero Reig Juan Manuel
Published: February 2019

The resistance of 26 olive (Olea europaea L.) cultivars to the defoliating pathotype of Verticillium dahliae Kleb. was evaluated in experiments under controlled conditions by stem puncture inoculation. The area under disease progress curve with reference to the maximum value potentially reached over the assessment period (AUDPCP), calculated from the symptom severity values (0–4 rating scale), was the main parameter for assessing resistance, and the percentage of dead plants (PDP), the final mean symptom severity (FMS), and the disease recovery were used as additional parameters. Five cultivars were catalogued as extremely susceptible showing values of AUDPCP, PDP, and FMS higher than 70%, 50%, and 3.0, respectively. Six other cultivars exhibited AUDPCP values ranging from 50% to 70% and FMS higher than 3.0 and were classified as susceptible. A group of 11 cultivars, including ‘Koroneiki’, was moderately susceptible with AUDPCP ranging from 31% to 50%. Finally, ‘Frantoio’, ‘Grosal de Albocafer’, ‘Kato Drys’, and ‘Manzanilla Picúa’ showed maximum AUDPCP values of 22%, no dead plants, and slight symptom severity, being classified as resistant. Stem puncture inoculation was an effective tool for identifying resistance in olive cultivars, but a reduction or a delay in the disease symptom expression of plants was observed regarding the symptom progress observed in plants root dip-inoculated in previous works of resistance assessment. These differences were more pronounced in susceptible than in resistant cultivars.
Quality and Chemical Changes Associated with Flavor of ‘Camarosa’ Strawberries in Response to a CO2-enriched Atmosphere
Authors: Pelayo-Zaldívar Clara , Ben Abda Jameleddine , Ebeler Susan E. , Kader Adel A.
Published: February 2019

Quality and chemical changes associated with flavor were evaluated in ‘Camarosa’ strawberries (Fragaria ×ananassa) that had been kept at 5 °C in air or in air + 20 kPa CO2 for 3 and 6 days to elucidate possible factors contributing to the loss of flavor during storage. The elevated CO2 treatment did not affect flesh firmness, total soluble solids, pH, or titratable acidity. In contrast, decreases in color (as indicated by a higher hue angle value) and in concentrations of sucrose, reducing sugars, and citric acid were detected in fruits exposed to elevated CO2. Fermentative metabolites were present in strawberries stored in air and in higher concentration in those kept in air + 20 kPa CO2. Also, strawberries kept in air + 20 kPa CO2 had higher levels of ethyl esters and a major reduction in the level of methyl esters. Thus, clear differences in the aroma profile of strawberries at harvest and after 3 and 6 days of storage at 5 °C in air or air + 20 kPa CO2 were observed. This change in the volatile aroma profile is probably the primary factor contributing to the loss of strawberry flavor during storage.
Effect of Time of Harvest on Postharvest Leaf Abscission in Lantana (Lantana camara L. ‘Dallas Red’) Unrooted Cuttings
Authors: Rapaka Vijaya Kumar , Faust James E. , Dole John M. , Runkle Erik S.
Published: February 2019

This study investigated the preharvest carbohydrate status and postharvest ethylene action of unrooted shoot-tip cuttings of lantana ‘Dallas Red’ harvested at three times during the day (0800, 1200, and 1600 hr) in relation to subsequent leaf abscission, shoot apices blackening, and adventitious root formation. The cuttings harvested at various times during the day were stored in darkness at 20 ± 1 °C for 4 days in sealed polyethylene bags. The cuttings harvested at 0800 hr had lowest total nonstructural carbohydrate concentrations; however, the amount of ethylene production during postharvest storage was similar among harvest times and increased during the storage period. After 4 days of storage, 69% of the leaves of cuttings harvested at 0800 hr abscised, but only 22% and 8% of the leaves abscised in cuttings harvested at 1200 and 1600 hr, respectively. Application of 1-methylcyclopropene (1-MCP) increased ethylene production and suppressed leaf abscission regardless of the harvest time, but cuttings harvested at 0800 hr developed blackened shoot apices. Leaf abscission was negatively correlated with total nonstructural carbohydrate concentration in the leaves, but no relationship was found with ethylene production. These results indicate that a high endogenous carbohydrate status decreases the postharvest ethylene sensitivity in unrooted shoot-tip cuttings of lantana. Time of harvest influenced subsequent rooting response; however, 1-MCP application did not inhibit rooting. Among various storage treatments, the best rooting response was observed in cuttings harvested at 1600 hr and treated with 1-MCP. Therefore, significant improvement of postharvest storage quality in vegetative lantana cuttings could be achieved by harvesting cuttings late in the day and treating with 1-MCP.
Postharvest Survey of Volatile Compounds in Five Tropical Fruits Using Headspace-solid Phase Microextraction (HS-SPME)
Authors: Laohakunjit Natta , Kerdchoechuen Orapin , Matta Frank B. , Silva Juan L. , Holmes William E.
Published: February 2019

The volatiles of longon (Lansium domesticum Corr. var Dongon), mangosteen (Garcinia mangostana L. var Native), durian (Durio zibethinus L. var Monthong), rambutan (Nephelium lappaceum L. var Rong-rien), and sapodilla (Manilkara zapota van Royer var Kai) were identified by headspace-solid phase microextraction with the gas chromatography-mass spectrometry technique. The headspace volatiles of fresh, unheated, salted out with NaCl, and NaCl + heated samples were determined. Salting out gave the highest number of volatile components with the longon headspace. High temperature did not have much affect on the amount of volatiles in the headspace. Major volatiles of the total 43 volatiles in longon were 1,3,5 trioxane, (E)-2-hexenal, 3-carene, α-cubebene, isoledene, δ-selinene, and α-calacorene. Major volatiles of mangosteen were 2, 2-dimethyl-4-octanal, E-2-hexenal, benzaldehyde, (Z)-3-hexen-1-ol, hexyl–n-valerate, 1,4-pentadiene, and 2-methyl-1, 3-buten-2-ol. Volatile compounds in durian consisted of a large number of sulfur-containing compounds, which included diethyltrisulfide, diethyldisulfide, dithiolane, dimetyl sulfide, and 3-methyl-thiozolidine. Nonsulfur compounds 2-methyl butanoate, butanedioic acid, and propyl-2-ethylbutanoate were also abundant. Isocitonellol, 3-hydroxy-2-butanone, pentanal, and 4-tridecyl valerate were most abundant in ‘Rong-rien’ rambutan. A total of 23 components were characterized in sapodilla with ethyl acetate, acetaldehyde, benzyl alcohol, and 2-butenyl benzene being the major volatiles.
Involvement of Both Subgroups A and B of Expansin Genes in Kiwifruit Fruit Ripening
Authors: Yang Shaolan , Xu Changjie , Zhang Bo , Li Xian , Chen Kunsong
Published: February 2019

Two complementary DNA fragments encoding expansin genes Ad-EXP1 and Ad-EXP2 were isolated from ripening kiwifruit (Actinidia deliciosa cv. Bruno) by reverse transcription–polymerase chain reaction amplification using a pair of degenerate primers. The homology between these two expansin family members was 50% in nucleotide sequence and 74% in amino acid sequence. It was revealed that Ad-EXP1 and Ad-EXP2 belong to subgroups A and B of an expansin gene family respectively. However, gene expression of these two members shared similar patterns. Both were upregulated by ethylene treatment and downregulated by acetylsalicylic acid treatment. The study suggests that members of both subgroups A and B of the expansin family are involved in kiwifruit fruit ripening.
Vegetative Propagation of American Beech Resistant to Beech Bark Disease
Authors: Ramirez Marianela , Krasowski Marek J. , Loo Judy A.
Published: February 2019

The objective of this study was to develop vegetative propagation techniques—using tissue culture and grafting—for American beech (Fagus grandifolia) resistant to beech bark disease. Resterilizing the buds after excising bud scales reduced contamination of in vitro cultures derived from dormant buds. Application of a 7-day dark treatment before transferring shoots to the rooting medium improved rooting success. Plantlets gradually acclimatized to nonsterile growth conditions and set buds but failed to survive the dormant period. The application of 6-benzyladenine enhanced sprouting from roots collected from mature trees, but the excised shoots rooted poorly in vitro despite low contamination. Success of grafting scions from mature trees varied among genotypes and differed each year (30% in 2003, 12% in 2004, and 18% in 2005). Applying the growth hormone indole butyric acid to the scion before joining it to the rootstock did not increase grafting success. Survival of grafts was independent of rootstock age (1 or 2 years old). Grafting success increased when scion diameter was slightly larger than rootstock diameter. The rooting of sucker cuttings was successful for only one genotype. Critical steps, in which most failures in the propagation of American beech occur, are identified.
Effects of Nitrogen, Phosphorus, and Potassium Nutrition on Total Polyphenol Content of Bush Tea (Athrixia phylicoides L.) Leaves in Shaded Nursery Environment
Authors: Mudau Fhatuwani N. , Soundy Puffy , du Toit Elsa S.
Published: February 2019

Bush tea (Athrixia phylicoides L.) contains high concentrations of polyphenols that are the primary indicator of antioxidant potential in herbal teas. The objective of this study was to determine the seasonal effect of nitrogen (N), phosphorus (P), and potassium (K) nutrition on total polyphenol content in bush tea leaves. Treatments consisted of 0, 100, 200, 300, 400 or 500 kg·ha−1 of N, P, or K in a randomized complete block design under 50% shade nets. Three (N, P, and K) parallel trials were conducted per season (autumn, winter, spring, and summer). Total polyphenols were determined using Folin-Ciocalteau reagents and analyzed in a spectrophotometer. The results of this study demonstrated that, regardless of season, application of nitrogenous, phosphorus, and potassium fertilizers increased quadratically the total polyphenols in bush tea, with most of the increase occurring between 0 and 300 kg·ha−1 N, 300 kg·ha−1 P, and 200 kg·ha−1 K. Linear relationships between percentage leaf tissue N, P, and K with total polyphenols in bush tea were also observed. Therefore, for improved total polyphenol content in bush tea leaves, 300 kg·ha−1 N, 300 kg·ha−1 P, and 200 K kg·ha−1 N is recommended.
Cation Exchange Capacity and Base Saturation Variation among Alberta, Canada, Moss Peats
Authors: Rippy Janet F.M. , Nelson Paul V.
Published: February 2019

Variations in moss peat cation exchange capacity (CEC) and base saturation (BS) can result in inconsistent initial pH in moss peat-based substrates created using standard formulas for limestone additions and can lead to subsequent drift from the initial pH in those substrates. This study was conducted to determine the extent of such variation. CEC and BS were measured in three replications on 64 moss peat samples that were selected from three mires across Alberta, Canada, to represent maximum gradients in plant species composition within six degrees of decomposition acceptable for professional peat-based substrates. CEC ranged from 108 to 162 cmol·kg−1 (meq·100 g). Averaged overall samples, BS ranged from 15% to 71% of CEC and calcium accounted for 68%, magnesium for 25%, sodium for 5%, and potassium for 1.4% of BS. CEC was positively correlated to the amount of Sphagnum fuscum (Schimp.) Klingrr. in the sample (r = 0.22). BS was positively correlated to the amount of sedge (r = 0.28). Neither CEC nor BS was influenced by degree of decomposition (r = 0.002 and r = 0.08, respectively). Moss peats with high CEC have a greater buffering capacity than those with low CEC, resulting in less pH drift. Moss peats with high BS should have a low neutralization requirement to achieve a target pH. Understanding the species composition in peat-based substrates can alleviate problems of inconsistent initial pH and subsequent pH drift.