bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of a Gene Encoding Glutamate Decarboxylase Involved in the Postharvest Fruit Ripening Process in Banana
Authors: Hu Wei , Liu Ju-Hua , Yang Xiao-Ying , Zhang Jian-Bin , Jia Cai-Hong , Li Mei-Ying , Xu Bi-Yu , Jin Zhi-Qiang
Published: February 2019

The banana, a typical climacteric fruit, undergoes a postharvest ripening process followed by a burst in ethylene production that signals the beginning of the climacteric period. Postharvest ripening plays an important role in improving the quality of the fruit as well as limiting its shelf life. To investigate the role of glutamate decarboxylase (GAD) in climacteric ethylene biosynthesis and fruit ripening in postharvest banana, a GAD gene was isolated from banana, designated MuGAD. Coincidently with climacteric ethylene production, MuGAD expression as well as the expression of the genes encoding the Musa 1-aminocyclopropane-1-carboxylate synthase (MaACS1) and Musa 1-aminocyclopropane-1-carboxylate oxidase (MaACO1) greatly increased during natural ripening and in ethylene-treated banana. Moreover, ethylene biosynthesis, ripening progress, and MuGAD, MaACS1, and MaACO1 expression were enhanced by exogenous ethylene application and inhibited by 1-methylcyclopropene (1-MCP). Taken together, our results suggested that MuGAD is involved in the fruit ripening process in postharvest banana.
Foliar Application of Sugar Alcohol Zinc Increases Sugar Content in Apple Fruit and Promotes Activity of Metabolic Enzymes
Authors: Zhang Yong , Fu Chunxia , Yan Yujing , Fan Xiaodan , Wang Yan’an , Li Ming
Published: February 2019

Application of sugar alcohol zinc (SA-Zn) spray to apple trees at certain developmental stages can improve fruit quality. Increasing the Zn concentration of fruit can improve nutritional content and promote human health. We conducted foliar application of SA-Zn to 13-year-old ‘Fuji’ apple trees at different developmental stages. The effects of SA-Zn application on Zn concentration, reducing sugar content, and carbohydrate metabolism-related enzyme activity in fruit were investigated. The foliar treatment increased Zn and reducing sugar concentrations significantly in mature fruit. Sorbitol dehydrogenase activity was higher in the fruit of trees treated before budbreak and 3 weeks after flowering compared with the control at the early fruit stage and was higher during fruit expansion in plants treated after termination of spring shoot growth. Mature fruit of trees treated during the fruit expansion stage showed higher sorbitol dehydrogenase activity than the control. Foliar SA-Zn treatment did not have a significant effect on sorbitol oxidase activity in apple fruit. Treatment before budbreak and at 3 weeks after flowering led to a significant increase in the activity of sucrose synthase and acid invertase at the early fruit stage. Treatment during the fruit expansion stage significantly increased the activity of acid invertase at maturity but had no effect on the activity of neutral invertase. Our results indicate that foliar SA-Zn application resulted in biofortification of Zn in apples, which led to higher activity of carbohydrate metabolism-related enzymes and accumulation of sugars.
Nitrogen and Trinexapac-ethyl Applications for Managing ‘Diamond’ Zoysiagrass Putting Greens in the Transition Zone, U.S.
Authors: Menchyk Nicholas , Bielenberg Douglas G. , Martin Samuel , Waltz Clint , Luo Hong , Bethea Frank , Liu Haibo
Published: February 2019

As a result of the increasing popularity of fine-leafed zoysiagrasses on golf courses, a 2-year field study was conducted to assess ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] putting green performance at The Cliff’s Communities Turfgrass Research Facility in Marietta, SC. Factors included four nitrogen (N) fertility rates and two trinexapac-ethyl (TE) regimes. Foliar applications of 0, 4.9, 9.8, and 14.7 kg·ha−1 N were made once weekly for 7 and 15 weeks in 2009 and 2010, respectively. Trinexapac-ethyl was tank-mixed and applied weekly for 7 weeks during July to August at 0 or 0.017 kg a.i./ha totaling 0.120 kg a.i./ha for both growing seasons. Putting green performance was measured by assessing turf quality (TQ), ball roll distance (BRD), surface firmness (SF), leaf tissue nutrient concentrations, and thatch accumulation. Turfgrasses receiving 4.9 kg N/ha weekly exhibited acceptable TQ and greater SF and BRD than plots receiving 14.7 kg N/ha weekly on all rating dates in 2010 before seasonal dormancy. Trinexapac-ethyl reduced clipping yield by 15% to 43% and influenced BRD, SF, and tissue nutrient concentration across the 2-year study. Surface firmness decreased as total N input increased during the 2010 growing season and is presumably the result of an increase in leaf tissue causing a cushioned putting surface. Linear regression of thatch accumulation and SF were analyzed and found to be significant at four rating dates in 2010 indicating that as thatch organic matter increased, SF decreased. Nitrogen input for ‘Diamond’ zoysiagrass putting greens grown in the transition zone should begin at 73.5 kg·ha−1/year with supplemental N applications applied as needed.
Small Heat Shock Proteins Can Confer Tolerance to Nanomaterial-induced Toxicity
Authors: Park Hanseul , Ko Eunhye , Ahn Yeh-Jin
Published: February 2019

The expression of a small heat shock protein (sHSP) in plants and its possible function in conditions related to nanomaterial exposure were examined. Multiwalled carbon nanotubes (MWCNTs) and silver nanoparticles (AgNPs) induced toxicity that was indicated by the bending and curling of carrot leaf tissues. Both nanomaterials induced the expression of a small heat shock protein in carrot, DcHsp17.7, but reduced the level of a constitutive heat shock cognate 70. To examine the possible function of DcHsp17.7, the coding gene was heterologously expressed in Escherichia coli. Both nanomaterials reduced the viability of E. coli cell lines. However, the transgenic cell line heterologously expressing DcHsp17.7 showed higher levels of cell viability, compared with vector controls, when exposed to MWCNTs and, more notably, to AgNPs. To the best of our knowledge, this is the first study reporting the influence of nanomaterials on the expression of a plant sHSP and its possible function in conferring tolerance to nanomaterial stress.
Effect of Shading on Anthocyanin and Non-flavonoid Polyphenol Biosynthesis of Gynura bicolor Leaves in Midsummer
Authors: Fukuoka Nobuyuki , Suzuki Takamoto , Minamide Keisuke , Hamada Tatsuro
Published: February 2019

The effect of shading in midsummer on anthocyanin and non-flavonoid polyphenol biosynthesis of Gynura bicolor DC leaves was examined using a control (full solar radiation) and a shade treatment (50% shading of full solar radiation). Leaf temperature in the shade plot remained ≈40 °C in the daytime, ≈6 °C lower than in the control. Plants in the shade plot grew better than the control. The content of chlorogenic acid (CGA) in leaves decreased with leaf maturation for both treatments, and a larger amount of CGA was detected in leaves from the control than the shade treatment. The profiles of reactive oxygen species (ROS) scavenging activity exhibited an identical pattern to the content of CGA. Although there was an abrupt increase in the content of anthocyanin in the early stage of leaf expansion, the content decreased rapidly as the leaves matured. The increase in anthocyanin early during leaf expansion was much more limited in control leaves than shaded leaves. There were no correlation between the profiles of anthocyanin and gene expression such as GbPAL, GbC4H, Gb4CL, GbCHS, GbCHI, GbF3H, and GbUFGT. However, the profiles of expression of genes such as GbMYB2, GbF3′H, GbDFR, and GbANS were similar to the anthocyanin profiles. These results suggest that artificial shading in midsummer is an effective method to promote anthocyanin accumulation but reduces ROS scavenging capacity as a result of lowered CGA production.
Salinity Tolerance of Three Commonly Planted Narcissus Cultivars
Authors: Veatch-Blohm Maren E. , Sawch Douglas , Elia Nicole , Pinciotti Dominic
Published: February 2019

Salinity is a problem for crop production worldwide and may be particularly problematic for ornamental plants because it has the potential to degrade visual quality. Daffodils [Narcissus sp. (L.) Amaryllidaceae] are a popular bulb plant, in demand for both landscapes and cut flowers. In this study, we examined how salinities ranging from 0 to 300 mm NaCl affected growth, flower production, and leaf physiology of three of the most popular cultivars of daffodil (‘Dutch Master’, ‘Ice Follies’, and ‘Tete-a-Tete’). Salinity reduced growth rate and biomass production at salinities greater than or equal to 100 mm NaCl with the greatest reductions in the highest salinity treatments (200 and 300 mm NaCl). Despite reductions in biomass, there was no significant chlorosis of the leaves. Flower quantity was unaffected by salinity in ‘Dutch Master’ and ‘Ice Follies’, but anthesis was delayed and flower duration was reduced by 40% to 70% at salinities of 150 mm NaCl and above. Anthesis and flower duration in ‘Tete-a-Tete’ were unaffected by salinity, but the number of flowers produced was negatively affected (reductions of 50% or more) by salinities of 150 mm NaCl and above. Sodium concentration in the leaves and bulbs increased 53% to 400% compared with the 0 mm NaCl control with lower accumulation in the bulbs than in the shoots. Sodium accumulation occurred at or above 50 mm NaCl in ‘Tete-a-Tete’, but at salinities greater than 150 mm NaCl in ‘Dutch Master’ and only in the 300-mm NaCl treatment in ‘Ice Follies’. Despite the Na+ accumulation in the leaves, the plants in most of the salinity treatments were able to maintain a K+:Na+ ratio above 1 (except in ‘Tete-a-Tete’ at salinities 150 mm NaCl or greater), which may have helped the daffodils tolerate the negative affects of Na+ and maintain good visual quality. ‘Dutch Master’, ‘Tete-a-Tete’, and ‘Ice Follies’ can be considered highly salt-tolerant because they maintain visual quality (leaf greenness, flower production, and flower duration) at soil NaCl-induced electrical conductivities greater than 6 dS·m−1.
The Horticultural Spray Oil, Civitas™, Causes Chronic Phytotoxicity on Cool-season Golf Turf
Authors: Kreuser William C. , Rossi Frank S.
Published: February 2019

Petroleum-derived spray oils (PDSOs) have been used for pest management in horticulture and agronomy for over a century. Civitas™ is a new PDSO designed for use in the turfgrass industry. It is commonly mixed with low rates of pesticides to reduce the environmental impact and improve plant stress tolerance. Civitas can cause phytotoxicity, which has limited its acceptance by the turfgrass industry. Civitas is mixed with a green pigment called Harmonizer™ to sustain acceptable turfgrass color. A field study and a growth chamber study were designed to quantify phytotoxicity, understand the role of Harmonizer, and isolate the cause of Civitas-induced phytotoxicity. Civitas, Harmonizer, their combination (Two-Pack), and a water-only control were applied to a research putting surface in Ithaca, NY, during 2012 and 2013. Civitas and Harmonizer were applied every 2 weeks at the rates of 5.0 and 0.3 mL·m−2, respectively. Visual turfgrass quality rating and canopy temperature were quantified several times weekly. Civitas caused chlorosis and decline in visual quality during both years. Harmonizer masked chlorosis but did not prevent a drop in stand density during the second field season. Treatments were replicated on annual bluegrass (Poa annua L.) in a growth chamber experiment. Civitas did not increase electrolyte leakage or alter the composition of cuticle; however, there were signs of oil persistence on the leaves and stomata and evidence of reduced gas exchange. Chlorosis resulting from oil persistence and reduced gas exchange is consistent with chronic PDSO phytotoxicity. This research demonstrated the potential for phytotoxicity with high rates of Civitas. Lower application rates likely reduce the potential for phytotoxicity but may also minimize the pest control benefits associated with the product.
Growth Responses of Tomato Seedlings to Different Spectra of Supplemental Lighting
Authors: Gómez Celina , Mitchell Cary A.
Published: February 2019

Seedlings of six tomato (Solanum lycopersicum) cultivars (‘Maxifort’, ‘Komeett’, ‘Success’, ‘Felicity’, ‘Sheva Sheva’, and ‘Liberty’) were grown monthly for 2-week treatment periods to determine photomorphogenic and developmental responses to different light-quality treatments from supplemental lighting (SL) across changing solar daily light integrals (DLIs). Seedlings were grown in a glass-glazed greenhouse at a midnorth latitude (lat. 40° N, long. 86° W) under one of five lighting treatments: natural solar light only (control), natural + SL from a 100-W high-pressure sodium (HPS) lamp, or natural + SL from arrays of red and blue light-emitting diodes (LEDs) using 80% red + 20% blue, 95% red + 5% blue, or 100% red. Varying solar DLI occurred naturally for all treatments, whereas constant DLI of 5.1 mol·m−2·d−1 was provided for all SL treatments. Supplemental lighting increased hypocotyl diameter, epicotyl length, shoot dry weight, leaf number, and leaf expansion relative to the control, whereas hypocotyl elongation decreased when SL was applied. For all cultivars tested, the combination of red and blue in SL typically increased growth of tomato seedlings. These results indicate that blue light in SL has potential to increase overall seedling growth compared with blue-deficient LED SL treatments in overcast, variable-DLI climates.
Potential Sources of Whitefly (Hemiptera: Aleyrodidae) Resistance in Desert Watermelon (Citrullus colocynthis) Germplasm
Authors: Coffey John L. , Simmons Alvin M. , Shepard B. Merle , Tadmor Yaakov , Levi Amnon
Published: February 2019

Selection for and incorporation of host plant resistance into cultivars is a fundamental strategy to control insects and diseases and may help reduce reliance on synthetic pesticides. The sweetpotato whitefly, Bemisia tabaci (Gennadius), is an important pest of watermelon [Citrullus lanatus (Thunberg) Matsum. and Nakai var. lanatus] and is among the most damaging pests in many agricultural systems worldwide. Citrullus colocynthis L., a perennial melon species indigenous to arid regions of northern Africa, the Mediterranean region, and southwestern Asia, is a valuable source of resistance to insect pests and diseases of watermelon. Laboratory and greenhouse experiments were conducted to evaluate selected C. colocynthis genotypes for sources of resistance to B. tabaci. Thirty genotypes of C. colocynthis, collected in different geographic regions, were evaluated against the heirloom cultivar Calhoun Gray using first a horizontal Y-tube olfactometer in the laboratory. A selected subset of the genotypes was evaluated in a second experiment in the laboratory using a vertical monitoring assay. In this assay, whiteflies could freely move upward to feed and oviposit on leaves placed in the upper portion of a Y-tube. In a third experiment, a choice assay was conducted on selected genotypes in cages in the greenhouse. Of the 30 C. colocynthis genotypes evaluated, PI 346082 (collected in Afghanistan) exhibited the highest level of resistance against B. tabaci based on all three experiments. PI 537277 (collected in Pakistan) exhibited a significantly high level of whitefly resistance based on low survival of adult whiteflies and a low ratio of nymphs to eggs. PI 346082 and PI 537277 should be a useful source for breeding projects aiming to improve whitefly resistance in watermelon cultivars.
Kentucky Bluegrass and Perennial Ryegrass Mixtures for Establishing Midwest Lawns
Authors: Proctor Christopher A. , Weisenberger Daniel V. , Reicher Zachary J.
Published: February 2019

Mixtures of turfgrass seed are commonly used to establish lawns, with kentucky bluegrass (KBG) and perennial ryegrass (PRG) comprising two of the more commonly used species. In the humid regions of the Midwest United States, KBG is a desirable species, but slow germination makes it difficult to establish compared with PRG. The objective of our study was to evaluate establishment rate and species composition over 3 years of a turf stand seeded with different ratios of KBG and PRG (wt:wt) maintained as a lawn. Repeat experiments were initiated in 2007 and 2008 and conducted for 3 years in West Lafayette, IN, with seed mixtures of KBG:PRG of 100:0, 90:10, 80:20, 70:30, 50:50, and 0:100 wt:wt of pure live seed. Plots were seeded late August each year and percent turfgrass cover was rated up to 6 weeks after seeding (WAS). To evaluate stand composition after establishment, percent KBG cover was rated annually in August for 3 years using transect counts after selective removal of PRG with the herbicide chlorsulfuron. Likely as a result of greater crabgrass (Digiaria sp.) competition during establishment in 2007, 100% PRG, 50:50, 70:30, or 80:20 KBG:PRG ratio had the highest percentage turf cover at 6 WAS, whereas there was no difference between treatments at 6 WAS in 2008 when crabgrass competition was lower. Regardless of turf cover during establishment, all treatments except 100% PRG shifted to greater than 95% KBG cover by 3 years after establishment. For the region in which our study was conducted, it may be desirable to seed with a higher proportion (greater than 50%) of PRG to speed initial establishment for customer satisfaction, erosion control, and/or to offset years with high weed pressure. Under lawn conditions similar to our study, seeding ratios with high KBG (80:20 or 90:10 KBG:PRG) will likely shift to a stand composition of greater than 95% KBG within 2 years, whereas all other ratios lower in KBG will likely shift similarly within 3 years. Chemical names used: 2-chloro-N-{[(4-methoxy-6-methyl-1,3,5-triazin-2 yl)amino]carbonyl}benzenesulfonamide (chlorsulfuron)
New Training Systems for High-density Planting of Sweet Cherry
Authors: Musacchi Stefano , Gagliardi Federico , Serra Sara
Published: February 2019

We assessed the vegetative growth and fruit production behavior of different sweet cherry cultivars grown using multiple new ultra-high-density planting (HDP) and training systems. An experimental orchard established in 2007 in the Ferrara province of Italy was used for this trial. The sweet cherry cultivars under evaluation were ‘Giorgia’ and ‘Grace Star®’ grafted on Gisela® 6; and ‘Black Star®’, ‘Early Bigi®’, ‘Early Star®’, ‘Ferrovia’, ‘Grace Star®’, ‘Kordia’, ‘Regina’, ‘Summit’, ‘Sweet Early®’, and ‘Sylvia’ grafted on Gisela® 5 rootstock. Each cultivar–rootstock combination was trained to spindle, V-system, or Super Spindle Axis (SSA). Planting densities ranged from 1905 trees/ha for spindle with Gisela® 6 to 5714 trees/ha for V-system and SSA with Gisela® 5. Vegetative growth, yield productivity, and fruit quality were evaluated. Among the three systems grafted on Gisela® 5, trees trained to the spindle system had the highest trunk cross-sectional area (26.2 cm2), followed by V-system (21.8 cm2) and SSA (20.2 cm2). Seven years after planting, ‘Ferrovia’ had the highest cumulative yield per hectare among cultivars on Gisela® 5, especially with V-system (50.5 t·ha–1) and SSA (52.2 t·ha–1) training systems. For cultivars on Gisela® 6, ‘Giorgia’ on had the highest cumulative yield per hectare after 7 years, but ‘Grace Star®’ on had higher production (≈14.0 t·ha–1 with V-system and SSA and 12.8 t·ha–1 with spindle) than ‘Giorgia’ in 2013.
Production of Baby-leaf Salad Greens in the Spring and Fall Seasons of Northwest Washington
Authors: Grahn Charlene M. , Benedict Chris , Thornton Tom , Miles Carol
Published: February 2019

Baby-leaf salad green crops such as lettuce (Lactuca sativa), kale (Brassica oleracea), arugula (Eruca sativa), and mustard greens (Brassica juncea) thrive in the cool, humid climate of the maritime Pacific Northwest, particularly in the extended spring and fall seasons. To identify cultivars best suited for extended-season production in northwest Washington, nine leafy green cultivars were grown at two locations in the spring and fall seasons for 2 years. A high level of variability in crop performance was observed between seasons, locations, years, planting dates, and cultivars, indicating low-yield stability in baby-leaf salad crops across diverse environments and conditions. Overall, cultivars had a higher marketable weight in the spring than in the fall. Marketable weight was higher in Spring 2013 than in Spring 2014, and was higher in Fall 2013 than in Fall 2012. Days to harvest (DTH) were shorter in the spring than in the fall both years, and in both seasons DTH varied by ≈1 week between the two trial locations. Fresh weed biomass was almost 5.5 times higher in spring than in fall both years. Overall, pak choi ‘Joi Choi’ and mustard ‘Komatsuna’ had the highest marketable weight, lowest DTH, and lowest weed biomass across the widest range of environments and conditions, while beet ‘Bull’s Blood’ had the lowest marketable weight, relatively long DTH and highest weed biomass. These results suggest that baby-leaf salad crop cultivar selection differs for spring and fall seasons, and production can be highly variable between years and locations. Further, results suggest that growers should plant a diversity of crop cultivars each season to protect from crop loss and to achieve overall yield stability.
Effects of Timing and Intensity of Summer Pruning on Reproductive Traits of Two Southern Highbush Blueberry Cultivars
Authors: Kovaleski Alisson P. , Darnell Rebecca L. , Casamali Bruno , Williamson Jeffrey G.
Published: February 2019

Blueberry (Vaccinium spp.) summer pruning can increase yield by promoting healthy fall foliage to support the reproductive development. However, there has been little research to examine the effects of timing and intensity of summer pruning in subtropical conditions. The objective of this study was to determine the effects of summer pruning timing and intensity on reproductive traits of mature ‘Jewel’ and ‘Emerald’ southern highbush blueberry (SHB) plants (V. corymbosum L. interspecific hybrid) in subtropical Florida. The effect of pruning time was evaluated by removing 30% of the canopy in June or July. The effect of intensity was evaluated by pruning either 30% or 60% of the canopy in June, followed by removal of the upper 5 cm of regrowth (“tipping”) in July. Both timing and intensity used nonpruned plants as a control. The same plants were evaluated over three consecutive seasons (June 2011–May 2014). Main effects of pruning time, intensity, and tipping were evaluated. Tipping did not affect the reproductive traits evaluated. ‘Emerald’ reproductive traits were unaffected by either summer pruning time or intensity over the 3-year study. ‘Jewel’ yield was unaffected in the first year, but was increased by 48% and 65% in years 2 and 3, respectively, in the 30% pruning treatment compared with the nonpruned control. Lack of pruning in ‘Jewel’ decreased inflorescence bud number compared with moderate pruning likely due to more diseased foliage that increased defoliation. Thus, pruning effects on reproductive traits were cultivar dependent. Leaving ‘Jewel’ plants unpruned for two or more seasons reduced inflorescence bud number and yield.
Plant and Leaf Physiological Responses to Water Stress in Potted ‘Vignoles’ Grapevine
Authors: Lanari Vania , Silvestroni Oriana , Palliotti Alberto , Green Alan , Sabbatini Paolo
Published: February 2019

Several studies have investigated water relationships in grapevines, but the responses to water limitation on individual leaves developed in different shoot positions are scarce in the literature. To begin to fill-in this gap, we examined the adaptive responses of vines at the leaf level to varying amounts of water stress using young hybrid ‘Vignoles’ in a controlled growth chamber. We found that the reduction in water availability to 40% of daily evapotranspiration limited shoot and leaf growth, affecting leaf number, shoot elongation, and leaf area. After 2 days of water stress we observed young developing leaves (nodes six to eight from the shoot apex) to have drastically reduced stomatal conductance (gS, about 20 mmol H2O/m2/s) and net photosynthesis (Pn, 2 μmol CO2/m2/s). On the 4th day Pn in mature leaves (nodes 9 to 12 from the shoot apex) fell to values below 2 μmol CO2/m2/s. After 6 days, both Pn and gS stabilized at lower values with fluctuations related only to leaf position along the shoot axis. Young leaves revealed substantial enrichment of carbon-13 (13C) and high water-use efficiency suggesting a higher and faster adaptive capacity to water shortage conditions as compared with mature leaves.
Morphological Changes Associated with Postharvest Fruit Deterioration and Physical Parameters for Early Determination of Shelf Life in Capsicum chinense Jacq.
Authors: Elibox Winston , Meynard Charles P. , Umaharan Pathmanathan
Published: February 2019

Thirty four pepper accessions (Capsicum chinense Jacq.) from the Caribbean were evaluated under controlled environmental conditions viz. darkness, 21.8 °C, and 90% relative humidity (RH) to determine the genetic variation and morphophysiological changes associated with loss of shelf life. The experiment was arranged in a randomized complete block design with three replications and 10 fruits per replication. The following parameters were recorded over a period of 20 days: fruit weight, shrivelling score, and proportion of fruits showing incipient pedicel necrosis, up to 20% pedicel necrosis, total pedicel/calyx necrosis (but with no pericarp necrosis), incipient pericarp necrosis. Water loss overtime, water loss slope and intercept, and days to incipient pedicel necrosis, 20% pedicel necrosis, total pedicel/calyx necrosis, and incipient pericarp necrosis were derived from the data. There were significant differences (P < 0.05) among accessions with respect to all parameters measured. Deterioration under storage initiated as incipient necrosis of the pedicel tip, which proceeded along the entire pedicel and calyx and subsequently into the pericarp. Shelf life varied from 6.6 to 16.9 days based on days to 20% pedicel necrosis and up to 19.5 days based on days to incipient pericarp necrosis. Shelf life based on days to 20% pedicel necrosis, total pedicel/calyx necrosis, and incipient pericarp necrosis were highly autocorrelated (r = 0.94 to 0.99, P < 0.01) and paralleled water loss from fruits. Pepper accessions with heavier fresh fruit weights had lower water loss rates and longer shelf lives than those with lighter fruits. Days to 20% pedicel necrosis and incipient pericarp necrosis were the best measures of shelf life as they best predicted marketability and usability of fruits as early as 8 days after harvest (DAH) (R2 = 0.94) and 9 DAH (R2 = 0.82), respectively, thus reducing the time of shelf life studies by half. Based on days to 20% pedicel necrosis, five accessions with shelf lives over 15 days were identified.
Field and Greenhouse Evaluations of Cucurbit Rootstocks to Improve Verticillium Resistance for Grafted Watermelon
Authors: Wimer Jesse , Inglis Debra , Miles Carol
Published: February 2019

Grafting watermelon (Citrullus lanatus Thunb.) onto resistant rootstocks is used in many areas of the world to overcome soilborne disease losses including verticillium wilt caused by Verticillium dahliae Kleb. Currently, this disease poses a serious risk to watermelon growers in Washington State. To identify resistant rootstocks, the verticillium wilt reactions (chlorosis, necrosis, and wilting) of 14 nongrafted PI accessions including Benincasa hispida Thunb., Cucurbita moschata Duchesne ex Poir., and Lagenaria siceraria Molina Standl. from the U.S. Department of Agriculture National Plant Germplasm System (USDA NPGS); 11 nongrafted commercially available rootstocks; and, nongrafted ‘Sugar Baby’ watermelon (verticillium wilt–susceptible control) were visually assessed in a field naturally infested with V. dahliae at a rate of 17 colony-forming units (cfu) per gram of soil. Typical symptoms of verticillium wilt were observed on all entries. ‘Sugar Baby’ had the highest relative area under disease progress curve (RAUDPC) value (26.80), which was not significantly different from ‘64-19 RZ’, ‘Marvel’, PI 368638, PI 634982, and PI 642045 (average = 10.16). PI 419060 (1.46) had the lowest RAUDPC value, which was not significantly different from ‘Miniature Bottle Gourd’, PI 326320, PI 419016, PI 536494, PI 636137, ‘Strong Tosa’, ‘Strongtosa’, and ‘TZ 148’ (average = 3.36). The mean RAUDPC value of PI accessions (5.49) did not differ significantly from the mean value of the commercial rootstocks (5.68). Microsclerotia typical of Verticillium spp. were observed in the stems of all but one entry (PI 181913). In a greenhouse study, a subset of 12 entries were inoculated with V. dahliae, and by 22 days after inoculation (DAI), ‘Sugar Baby’ had a significantly higher disease rating than all entries except PI 419060, PI 438548, and ‘Titan’. A strong positive correlation was observed between the field and greenhouse studies. Results indicate that commercial rootstocks as well as PI accessions could be used to successfully manage verticillium wilt in Washington; however, grafting compatibility with watermelon must first be ascertained for the promising PI accessions. Although greenhouse-based verticillium wilt assays can be used to help predict rootstock performance in the field, accurate assessment may require manipulating environmental conditions (e.g., temperature and humidity) to approximate field conditions.
Eggplant (Solanum melongena L.) Plant Growth and Fruit Yield as Affected by Drip Irrigation Rate
Authors: Díaz-Pérez Juan Carlos , Eaton Touria E.
Published: February 2019

Eggplant (Solanum melongena L.) is an increasingly popular crop in the United States. In the southeastern United States, eggplant is often produced with high levels of irrigation water [above the rate of crop evapotranspiration (ETc)], resulting in water waste and nitrogen (N) leaching. The objective of this research was to assess the effects of irrigation rate on plant growth and fruit yield in eggplant. The study was conducted in Tifton, GA, in the fall of 2010 and 2011. Eggplant plants cv. Santana were grown on raised beds (1.8 m centers) covered with white plastic film mulch. There was a single drip tape along the center of the bed. The design was a randomized complete block with five treatments and four replications. Treatments consisted of irrigation rates based on ETc (33%, 67%, 100%, 133%, and 167% ETc). Plant growth, chlorophyll index (CI), and volumetric soil water content (SWC) were monitored over the season. In 2010, SWC (0–30 cm deep) increased and soil nitrate levels decreased with increasing irrigation rates. Foliar N and potassium (K), and CI decreased with increasing irrigation rate, probably due to a dilution effect. Stem diameter, leaf dry weight (DW), and vegetative top DW increased with increasing irrigation rate. Net photosynthesis and stomatal conductance (gS) were lowest at 33% ETc. Fruit number and fruit yields (marketable and total) were also lowest at 33% ETc and there were little yield differences among irrigation rates higher than 33% ETc. In 2011, irrigation rate had minor or no effect on SWC, plant growth of mature plants, leaf gas exchange, and fruit number and yield. The no treatment effect observed for eggplant in 2011 was likely because study was conducted in a low field that remained moist most of the time, nullifying the treatment effects. Results suggested that eggplant may tolerate mild water stress, since plants irrigated at 67% ETc produced fruit yields similar to those of plants irrigated at 100% ETc or higher rates. Thus, there is a potential to save water by reducing current irrigation rates without negatively impacting fruit yields.
Genome Size and Seed Mass Analyses in Cicer arietinum (Chickpea) and Wild Cicer Species
Authors: Kim Sumin , Han Mengqiao , Rayburn A. Lane
Published: February 2019

The genome size of cultivated Cicer arietinum and 12 wild Cicer sp. including seven annual and five perennial species were analyzed using flow cytometry. A significant 2C genome size variation was observed among the Cicer sp. The 2C genome size ranged from 1.00 pg in wild species, Cicer judaicum, to 1.76 pg in cultivated species, C. arietinum. The wild perennial species all had a genome size of ≈1.6 pg. Most if not all of this genome size variation occurred among wild annual species. A significant positive correlation between 2C genome size and seed mass was observed among 12 wild Cicer sp. at α = 0.05. However, artificial selection appears to decrease nucleotype effects in cultivated C. arietinum, which resulted in no correlation between seed mass and genome size at α = 0.05.
Rowcovers and Strip Tillage Provide an Alternative to Plasticulture Systems in Summer Squash Production
Authors: Tillman Jennifer , Nair Ajay , Gleason Mark , Batzer Jean
Published: February 2019

Plastic mulch is often used in cucurbit production, but it has negative soil health and environmental implications due to use of tillage for installation and generation of plastic waste. This 2-year study aimed to find a viable alternative to plastic mulch through the use of strip tillage and rowcovers, as rowcovers could help minimize yield loss from strip tillage by providing warmer air and soil as well as providing insect protection. A split-plot design was used in both conventionally and organically managed summer squash (Cucurbita pepo), with production system as the whole-plot factor [conventional tillage with black plastic mulch also referred to as plasticulture (PL) and strip tillage into rolled cereal rye (Secale cereale) (ST)] and rowcover use as the subplot factor (rowcover until anthesis or no rowcover). Rowcovers reduced the incidence of squash vine borer (Melittia cucurbitae) and eliminated the need for insecticide sprays to control this insect pest, but did not reduce the incidence of yellow vine decline or the sprays needed to control squash bug (Anasa tristis). Rowcovers increased average air temperature by 1.6 to 4.0 °C and increased maximum air temperature by up to 10.3 °C. Rowcovers decreased average light intensity by 33% to 39%. Though soil temperature in PL tended to be higher than in ST, in 1-year rowcovers helped bridge the gap. Plant biomass was consistently higher in the PL than the ST system. Averaged across rowcover treatments, plants in PL had higher marketable yields than those in ST; however, the use of rowcovers often led to comparable yields between the production system treatments. Rowcover was a significant factor explaining marketable yield for the organically managed fields both years. There was no consistent effect of production system on soil microbial biomass carbon (MBC). Based on our results, strip tillage into rolled rye could be a viable alternative to plasticulture for summer squash production in Iowa, and rowcovers could help increase yields in ST especially in an organic management system.
Prestorage Application of Oxalic Acid to Alleviate Chilling Injury in Mango Fruit
Authors: Li Peiyan , Zheng Xiaolin , Chowdhury Md. Golam Ferdous , Cordasco Kim , Brecht Jeffrey K.
Published: February 2019

Effects of postharvest oxalic acid (OA) application on chilling injury (CI) in harvested mango fruit (Mangifera indica L.) were investigated using ‘Tommy Atkins’ fruit from Florida and ‘Zill’ fruit from Panzhihua. The OA was applied to harvested fruit as a 5 or 10 mm drench for 10 or 15 minutes at 25 °C. ‘Tommy Atkins’ fruit typically develop external CI symptoms while ‘Zill’ develops internal symptoms. Development of CI symptoms was significantly reduced in OA-treated ‘Tommy Atkins’ fruit stored for 18 days at 5 °C as was the rate of softening upon transfer to 25 °C for 4 days. However, OA treatment did not substantially control fruit decay. For ‘Zill’, CI development was significantly reduced in OA-treated fruit during storage at 10 °C for 49 days and subsequently for 4 days at 25 °C. In addition, membrane integrity was enhanced and the activities of the antioxidant system enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were elevated, although there were decreases in both hydrogen peroxide (H2O2) content and superoxide radical production in OA-treated fruit. The activities of some enzymes of the energy cycle were also elevated in the OA-treated fruit, including succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), H+-adenosine triphosphatase (H+-ATPase), and Ca2+-adenosine triphosphatase (Ca2+-ATPase). Thus, OA may enhance CI tolerance in mango fruit by maintaining membrane integrity associated with enhanced antioxidant activity and regulation of energy metabolism. Application of 5 mm OA appears to be beneficial in controlling postharvest CI in mango fruit.
An Image-based Method to Study the Fruit Tree Canopy and the Pruning Biomass Production in a Peach Orchard
Authors: Lordan Joan , Pascual Miquel , Fonseca Francisco , Montilla Víctor , Papió Josep , Rufat Josep , Villar Josep M.
Published: February 2019

The feasibility of two nondestructive methods based on image processing techniques was assessed for fruit tree research. The methods were evaluated in a 2-year (2011 and 2012) field experiment, during which various irrigation and soil management treatments were set up in a commercial peach orchard. Canopy image analysis was conducted using two approaches, namely the orthoimage and the lateral image technique. The proposed methods were compared with other classical measurements such as trunk diameter (TD) increase and pruning weight (PW). Orthoimage canopy area (OCA) analysis resulted in a reliable and sensitive technique to study the active crop growth along the growing season. The OCA values obtained were highly correlated with TD measurements (r2 = 0.88), thus describing an exponential significant model (y = 0.0997 e0.0521x). Cumulative crop growth was determined using the virtual pruning (VP) technique. VP estimates were well correlated with fruit tree PWs during 2011 (r2 = 0.86) and 2012 (r2 = 0.80). The nondestructive image-based techniques proved sensitive to crop growth and useful for the study of fruit tree canopies. On the basis of our results, we conclude that the proposed image analysis methods are valuable new approaches with wide applications in fruit tree research.
Effect of Detergent on the Quantification of Grapevine Downy Mildew Sporangia from Leaf Discs
Authors: Kono Atsushi , Sato Akihiko , Reisch Bruce , Cadle-Davidson Lance
Published: February 2019

Grapevine downy mildew (DM), caused by the oomycete Plasmopara viticola (Berk. & Curt.) Berlese & de Toni, is a major disease, especially in humid viticultural areas. Development of resistant cultivars is an important objective for grapevine breeding. To establish a reliable and inexpensive quantitative method to aid in breeding for DM resistance, we improved the method for counting the number of sporangia on leaf discs, and developed a method for counting the number of sporangia in solution. To prevent the loss of DM sporangia from adhesion onto plastic ware, we found as little as 0.01% Tween 20 was effective. On the other hand, this detergent was shown to have a severe inhibitory effect upon DM infection of leaves. We developed a sporangia counting method using dried droplets of DM suspensions, and the method was highly correlated with counting by hemacytometer (R2 > 0.96). The nonparametric Spearman’s rank correlations between visual rating and the number of the sporangia were as high as ρ = 0.82 to 0.91, suggesting that evaluation by the visual rating could provide a good estimate of the sporangia numbers on leaf discs. We established a high-throughput and inexpensive method with acceptable accuracy for DM resistance evaluation based on a leaf disc assay, and our results suggested that visual ratings of infected leaf discs provide a good estimate of sporangia numbers.
Performance of Bell Pepper Seeds in Response to Drum Priming with Addition of 24-Epibrassinolide
Authors: Barboza da Silva Clíssia , Marcos-Filho Julio , Jourdan Pablo , Bennett Mark A.
Published: February 2019

Drum priming systems are among the most common methods of seed priming for commercial treatment. The supply of water to the seeds is controlled by physical means, and seeds are able to reach a desired moisture content without the use of osmotic solutions for hydration control. The brassinosteroid (BR), 24-epibrassinolide (24-EpiBL), has been shown previously to have a significant effect on seed performance. Therefore, the aim of this study was to verify the feasibility of drum priming associated with added 24-EpiBL on enhancement of bell pepper seed performance. Two bell pepper cultivars (AF-6 and AF-7) were tested, and each cultivar represented, respectively, by three and four seed lots with different initial physiological potentials. Seed performance was determined by evaluating standard germination, initial seedling growth, and changes on the antioxidant activity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). Seed Vigor Imaging System (SVIS®) was used to assess the initial seedling growth. The nondenaturing polyacrylamide gel electrophoresis (PAGE) technique was used to evaluate possible changes in the enzymatic antioxidant system. Several advantages were verified in the drum priming technique with added 24-EpiBL compared with the traditional procedure (water alone). Germination time was reduced followed by a seedling growth increase. Concomitantly, seed enzymatic activity was improved. However, results showed different response for each enzyme. Drum priming with 24-EpiBL demonstrates viability for commercial treatment and enhancement of bell pepper seeds.
Status of Bacterial Leaf Spot Disease of Anthurium in Trinidad and Characterization of Native Isolates of the Causal Organism, Acidovorax anthurii
Authors: Holder Annelle W.B. , Elibox Winston , Umaharan Pathmanathan
Published: February 2019

Bacterial leaf spot disease (BLS) of anthurium (Anthurium andraeanum Linden ex André), caused by Acidovorax anthurii has contributed to the decline of the anthurium industry in Trinidad along with bacterial blight disease caused by Xanthomonas axonopodis pv. dieffenbachiae. This study investigated the status of BLS 12 years after its first discovery in 10 commercial anthurium farms located in nine geographically isolated areas in Trinidad. The disease was prevalent in only four farms located in Arima, Carapo, Brazil, and Grand Couva, and was a problem only in the wet season. Severity of BLS showed a strong association with prevalence of BLS (r = 0.92; P < 0.01) and rainfall (r = 0.64; P < 0.05). Cultivar differences in susceptibility to BLS were manifested as variation in the severity of foliar symptoms in adult plants and as frequency of systemic infection and plant death in juvenile plants. The native A. anthurii isolates showed morphophysiological and biochemical properties similar to isolates reported from the French West Indies, but with some differences. Native isolates did not grow at 41 °C or produce acid from arabinose, although some isolates produced acid from sucrose and mannitol. Two isolates were negative for urease activity, and one isolate did not elicit a hypersensitive reaction on the tobacco variety, ‘Samsun NN’. The native A. anthurii isolates were positive for Tween 80 hydrolysis, negative for acid production from potassium tartrate, and variable for production of acid from ethanol. There were significant differences between isolate colony diameters on minimal media, potassium tartrate, mannitol, ethanol, and glycerol. However, growth in minimal media amended with glycerol produced the largest colony diameters (mean of 8.6 mm). Although there were differences (P < 0.001) between the native isolates with respect to aggressiveness, significant cultivar × isolate interaction was not observed. Isolates collected from different geographical regions did not differ in aggressiveness. These results show that there is greater variation in morphophysiology of A. anthurii isolates than previously reported.
Rhizosphere Acidification is Not Part of the Strategy I Iron Deficiency Response of Vaccinium arboreum and the Southern Highbush Blueberry
Authors: Nunez Gerardo H. , Olmstead James W. , Darnell Rebecca L.
Published: February 2019

Vaccinium arboreum (VA) is a wild blueberry species that exhibits wider soil pH tolerance and greater ability for iron and nitrate uptake than cultivated Vaccinium species, including southern highbush blueberry (SHB, V. corymbosum interspecific hybrids). The ability of VA and SHB to respond to iron deficiency by rhizosphere acidification was investigated. Rooted cuttings of the VA genotype FL09-502 and SHB ‘Emerald’ were transplanted to a hydroponic system filled with complete nutrient solution. After 14 days of acclimation at 45 µm iron, plants were transferred to unbuffered nutrient solutions containing 90 or 10 µm iron. ‘Emerald’ and FL09-502 plants grown in 10 µm iron exhibited less iron uptake and lower chlorophyll, total iron, and active iron contents than plants grown in 90 µm iron. Generally, there were no species-level differences in iron or nitrate uptake. Neither FL09-502 nor ‘Emerald’ acidified the rhizosphere in either the nutrient solution or in a gel-based assay, regardless of external iron concentration. A screen of 18 additional genotypes of VA and SHB confirmed that this response is absent in these taxa. Thus, rhizosphere acidification is not part of the iron deficiency response of SHB and VA. In addition, the ability to acidify the soil is not likely to be responsible for the wider soil pH tolerance of VA.
Irrigation Water Management for Pecans in Humid Climates
Authors: Wells Lenny
Published: February 2019

Pecan [Carya illinoinensis (Wangenh.) K. Koch] tree stem water potential (ψ), shoot length, nut yield, and nut quality for the following treatments were evaluated in a commercial pecan orchard in Berrien County, GA; 1) current recommended irrigation schedule, 2) a reduced early season irrigation schedule, and 3) non-irrigated control. Water Stress on pecan occurred at ≈−0.78 MPa using the pressure chamber to measure stem water potential. Regression analysis suggests that irrigation scheduling for mature pecan trees may be needed when volumetric water content reaches 10% on Tifton loamy sand soil. Water stress in pecan is correlated with soil moisture from budbreak through the end of nut sizing. Pecan trees bearing a moderate to heavy crop load may undergo water stress during the kernel-filling stage regardless of soil moisture level. Therefore, it is suggested that water stress during the kernel-filling period is a function of nut development, crop load, or both in addition to soil moisture. The reduced early season irrigation schedule provided a 38% reduction in irrigation water use with no significant effect on pecan tree water stress, yield, or quality, suggesting that pecan trees can tolerate moderate early season water stress with no effect on pecan yield or quality under southeastern U.S. environmental conditions.