bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of 1-Aminocyclopropane Carboxylic Acid and Metamitron for Delayed Thinning of Apple Fruit
Authors: McArtney Steven J. , Obermiller John D.
Published: February 2019

The normal window for application of thinning chemicals in apple extends from bloom until 3 weeks after bloom, when the fruit reach a mean diameter of ≈16 mm. After this time fruit are generally insensitive to standard chemical thinning sprays. The potential for the photosystem II (PSII) inhibitor metamitron and the ethylene precursor 1-aminocyclopropane carboxylic acid (ACC) to thin apple fruit after the traditional thinning window was investigated in field experiments over three years. A standard rescue thinning spray of carbaryl plus ethephon plus naphthaleneacetic acid (NAA) reduced fruit set of Gale ‘Gala’ if applied when the mean fruit diameter was 18, 20, and 27 mm in 2010, 2011, and 2012, respectively. The thinning activity of 400 mg·L−1 ACC was equivalent to the standard rescue thinning spray in 2010, whereas 350 mg·L−1 metamitron reduced fruit set more effectively than either the standard or ACC in 2010. Application of 400 mg·L−1 ACC plus 350 mg·L−1 metamitron when the mean fruit diameter was 18 mm reduced fruit set to almost no crop in 2010. The combination of metamitron plus ACC exhibited thinning activity after application at 25 and 33 mm mean fruit diameter in 2011 and 2012, respectively. Increased ethylene evolution was found in detached ‘GoldRush’ fruit 24 h after applications of ACC from 11 mm to 27 mm mean fruit diameter, but not when ACC was applied at 31 mm mean fruit diameter. Ethylene evolution was much higher after application of ACC at the 11 mm or 17 mm mean fruit diameter stage compared with application when fruit diameter was 23 mm or 27 mm. The thinning activity of ACC was related to the period of maximum ethylene response. The effects of delayed applications of ACC and metamitron on fruit set tended to be greater when these two chemicals were combined, suggesting that the creation of a carbohydrate stress and the capacity to convert ACC to ethylene are both required to trigger abscission of apple fruit larger than 18 mm in diameter.
Effect on Yield and Quality of a Simple System to Recycle Nutrient Solution to Greenhouse Tomato
Authors: Gent Martin P.N. , Short Michael R.
Published: February 2019

Recycling the nutrient solution used for greenhouse vegetable production can prevent groundwater pollution. Recycling could result in an accumulation or deficiency of elements that would be deleterious to plant growth, product quality, and the dietary value of vegetables. Complex fertilizer systems have been developed to maintain appropriate concentrations of all elements in recycled systems. We compared a much simpler system in which all excess solution drained from the plants was recycled without adjustment or dilution compared with a system with no recycling as a control. Crops of greenhouse tomato (Solanum lycopersicon L.) were grown in two years to compare these systems. Differences in composition of solution drained from the plants developed gradually over more than one month. The transition from vegetative to fruit growth, which coincided with warmer weather, resulted in a decreased demand for nitrate, and other nutrients, and an increase in electrical conductivity (EC) of water drained from the root zone. The composition of the fresh solution supplied to the plants was adjusted accordingly. It took a longer time to re-establish an optimum composition for recycled compared with control watering. EC tended to increase in the recycled system. Recycling decreased total yield and fruit size, but marketable yield was unaffected. The marketable fraction increased in the recycled treatment, primarily as a result of fewer fruit with cracked skin. This effect was consistent across seven cultivars. The cultivars differed in this and other defects, but they did not differ in their response to the two watering systems.
Yield and Phytochemical Compounds of Broccoli as Affected by Temperature, Irrigation, and Foliar Sulfur Supplementation
Authors: Pék Zoltán , Daood Hussein , Gasztonyi Nagyné Magdolna , Berki Mária , Tóthné Marianna Márkus , Neményi András , Helyes Lajos
Published: February 2019

Two experiments were carried out in 2010 to determine how cultivation period/harvest season, plant water status/irrigated, or rainfed and foliar sulfur supplementation influences the yield, sulforaphane, phenolics content, and polyphenol composition of broccoli cultivar Parthenon. Yield was significantly higher in the fall harvests. Foliar sulfur treatment induced earliness in irrigated broccoli in the fall harvest season of main florets by 44%. Sulforaphane content was higher in the fall harvests regardless of treatments. Harvest season also influenced total polyphenol content with the highest values measured in the spring season. Sulfur treatment in combination with irrigation increased total polyphenol content by 24% in spring and this change was statistically significant. Harvest season also affected trolox equivalent antioxidant capacity (TEAC) values with the highest values (4.3 mmol·kg−1) also measured in spring. In the irrigated treatment alone or irrigated treatment combined with sulfur treatment, spring season values were higher by 24% and 11%, respectively, compared with fall values and the difference between treatments was significant. Caffeic acid glucoside was one of the major phenolic components in both spring and fall season harvests, whereas ferulic acid glucoside could only be detected in spring florets. From the measured phenolic components, gallic acid content was the only one that was significantly raised by foliar sulfur supplementation in both spring and fall harvests in irrigated or rainfed treatments. Maximum gallic acid values (7.1 to 7.2 mg·kg−1) occurred in the irrigated combined with foliar sulfur treatment of the fall harvest in side and main florets, respectively. The season, irrigation, and foliar sulfur supplementation were related changes in other phenolic component contents and are also described in detail.
Olive Seed Germination and Initial Seedling Vigor as Influenced by Stratification Treatment and the Female Parent
Authors: Morales-Sillero Ana , Paz Suárez María , Rocío Jiménez María , Casanova Laura , Ordovás José , Rallo Pilar
Published: February 2019

The germination of seeds and the growth of the generated plant are two phases of great importance in an olive breeding program. In this work, three stratification treatments and five cultivars (Hojiblanca, Manzanilla Cacereña, Manzanilla de Sevilla, Toffahi, and Uovo di Piccione) used as female parents in a breeding program for table olive were evaluated along two years to improve germination protocols. The stratification treatments affected seed germination (percent seeds with radicle), radicle length, seedling emergence (percent emerged hypocotyls), and the average time of emergence. The cultivars have shown great variability with respect to the requirements of the seeds and seedling growth performance. None of the treatments with heat application (25 °C) after chill (14 °C) improved the percentage of germinated seeds and seedling emergence in any year compared with the control treatment (30 days at 14 °C). Cultivars such as Manzanilla de Sevilla and Toffahi seem to be a good choice of female progenitors to improve emergence rates and to obtain early vigorous progenies, a character that has been related to a shorter juvenile period of the seedlings. Moreover, in these progenies, a clear lower apical dominance was found from the first stages of seedling growth. The olive fruit and seed traits were also influenced by the female parent. In fact, ‘Hojiblanca’ and ‘Uovo di Piccione’ showed a higher number of empty seed fruits and double seed fruits compared with the other studied cultivars.
Biochar Amendment Increases Resistance to Stem Lesions Caused by Phytophthora spp. in Tree Seedlings
Authors: Zwart Drew C. , Kim Soo-Hyung
Published: February 2019

Soil amendment with biochar is thought to confer multiple benefits to plants including induction of systemic resistance to plant pathogens. Pathogens in the genus Phytophthora cause damaging diseases of woody species throughout the world. The objective of this study was to test 1) whether biochar amendment induces resistance to canker causing Phytophthora pathogens; and 2) how this resistance is related to the amount of biochar amendment in two common landscape tree species: Quercus rubra (L.) and Acer rubrum (L.). Seedlings of Q. rubra and A. rubrum were planted in peatmoss-based potting mix uniformly amended with 0%, 5%, 10%, or 20% biochar by volume. Plants in each treatment group were stem wound-inoculated with an isolate of Phytophthora cinnamomi Rands (host: Q. rubra) or P. cactorum (Leb. and Cohn) Schröeter (host: A. rubrum) using standard agar-plug inoculation procedures. Amendment of potting media with 5% biochar reduced horizontal expansion of lesions in both hosts, whereas the same treatment significantly reduced vertical expansion of lesions in A. rubrum (P < 0.05). In addition, 5% biochar resulted in a higher midday stem water potential in Q. rubra (P = 0.066) and significantly greater stem biomass in A. rubrum compared with inoculated control plants (0% biochar, P < 0.05). Our results suggest that biochar amendment has the potential to alleviate disease progression and physiological stress caused by Phytophthora canker pathogens and there is likely an optimal level of biochar incorporation into the root media beyond which the effects may be less pronounced.
1-Methylcyclopropene Has a Variable Effect on Adventitious Root Emergence from Cuttings of Two Sweetpotato Cultivars
Authors: Villordon Arthur , Clark Christopher , LaBonte Don , Firon Nurit
Published: February 2019

This study aimed to investigate the effect of 1-methylcyclopropene (1-MCP) on adventitious rooting in two sweetpotato cultivars. Experiments with ‘Beauregard’ and ‘Evangeline’ sweetpotato cuttings revealed differential adventitious root (AR) emergence responses to 1-MCP application. ‘Beauregard’ AR count and length decreased with 1-MCP application in two of four experiments. In contrast, 1-MCP did not influence ‘Evangeline’ root count. However, ‘Evangeline’ root length decreased in three of four experiments. Trypan blue staining of ‘Beauregard’ nodal tissue with delayed AR primordia emergence showed localized dead tissue in the general area where ARs emerge. The degree of staining appeared to correspond with the stage of AR emergence with the staining becoming more intense around the time an AR primordium eventually emerged through a crack in the epidermis. This response agrees with reported results of ethylene-mediated AR emergence in other plant species. These results also appear to suggest that ‘Beauregard’ and ‘Evangeline’ cuttings differ in ethylene sensitivity. This represents the first evidence of genotype-specific ethylene involvement in adventitious rooting of sweetpotato cuttings.
Turfgrass Performance of Diploid Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] Half-sib Populations
Authors: Serba Desalegn D. , Gulsen Osman , Abeyo Bekele G. , Amundsen Keenan L. , Lee Donald J. , Baenziger P. Stephen , Heng-Moss Tiffany M. , Eskridge Kent M. , Shearman Robert C.
Published: February 2019

Hybridization and selection has been one of the methods used to generate turfgrass cultivars in buffalograss improvement. Three half-sib populations were developed by crossing three buffalograss female genotypes, NE 3296, NE 2768, and NE 2769, with NE 2871, a male genotype, to 1) investigate the pattern of genetic variability generated for turfgrass characteristics through hybridization; 2) assess the effect of parental change on the level of genetic variability generated in a buffalograss diploid population; and 3) predict the performance of a progeny generated from two heterozygous parents for turfgrass performance. The four parents and 20 random F1 progeny selected from each population were established in 2006 at the John Seaton Anderson Turfgrass Research Facility located near Mead, NE. A randomized complete block design (RCBD) was used with the progeny nested in the crosses. A visual rating scale of 1–9 was used to evaluate the population. Mean population lateral spread, genetic color, density, and turfgrass quality from early summer to fall ranged from 3.5 to 4.5, 7.1 to 7.9, 6.9 to 8.1, and 5.2 and 6.8, respectively. There were significant differences among the crosses and the parents for all the traits studied except quality in June and August. The progeny nested within crosses differed for turfgrass genetic color and quality. Best linear unbiased prediction (BLUP) indicated a high improvement potential for turfgrass lateral spread and spring density in NE 2768 × NE 2871 and for turfgrass genetic color in NE 3296 × NE 2871. From these findings, it can be concluded that hybridization breeding is a worthwhile approach for generating and identifying transgressive segregants for specific buffalograss traits.
Irrigation Frequency Alters Nutrient Uptake in Container-grown Rhododendron Plants Grown with Different Rates of Nitrogen
Authors: Scagel Carolyn F. , Bi Guihong , Fuchigami Leslie H. , Regan Richard P.
Published: February 2019

The influence of irrigation frequency (same amount of water per day given at different times) on nutrient uptake of container-grown evergreen Rhododendron ‘P.J.M. Compact’ (PJM) and ‘English Roseum’ (ER) and deciduous Rhododendron ‘Gibraltar’ (AZ) grown with different rates of nitrogen (N) fertilizer was evaluated. Increased N application rate increased nutrient uptake and plant dry biomass. Irrigation frequency did not significantly influence total plant dry biomass; however, more frequent irrigation decreased net uptake of several nutrients including phosphorus (P), boron (B), and manganese (Mn) uptake in all cultivars; potassium (K), copper (Cu), and zinc (Zn) uptake in AZ and ER; sulfur (S) uptake in ER and PJM; and iron (Fe) uptake in AZ. Additionally, more frequent irrigation of evergreen cultivars increased calcium (Ca) uptake. Covariate analyses were used to compare nutrient uptake among cultivars and irrigation treatments after accounting for the variability in nutrient uptake attributable to differences in biomass and N uptake. For most nutrients, the influence of irrigation frequency on uptake was partially attributable to differences in biomass and N uptake. After accounting for the variability in nutrient uptake associated with biomass or N uptake, increased irrigation frequency decreased P, S, B, Cu, and Mn uptake only in ER and increased Ca uptake in the two evergreen cultivars. Differences in nutrient uptake among cultivars in response to irrigation treatments were related to water and N availability during production and their combined influence on water stress, nutrient uptake, and biomass partitioning. Estimates of nutrient demand and uptake efficiency using nutrient concentrations and ratios are discussed in relation to nutrient management differences for different cultivars and irrigation treatments.
Organic Fertilization and Its Effect on Development of Sweet Pepper Transplants
Authors: Gravel Valérie , Dorais Martine , Ménard Claudine
Published: February 2019

Organically grown greenhouse sweet pepper crops, as is the case with most year-around greenhouse crops, rely on pre-grown transplants. Production of adequately balanced (source and sink strength potential) healthy organic sweet pepper transplants is a challenge and is often related to early and total harvested yields. Liquid and/or solid organic fertilizers for greenhouse sweet pepper transplants were compared with a conventional liquid fertilizer. Transplants were grown under greenhouse conditions and inoculated, or not, with a beneficial microbial agent, Trichoderma harzianum Rifai, strain KRL-AG2 (Rootshield®). Medium respiration (CO2 efflux) and fluorescein diacetate (FDA) hydrolysis analysis showed a higher microbial activity in the liquid organic fertilizer treatment. Higher microbial activity was observed after 10 weeks than at 5 weeks after transplanting. Transplant development was greater in the liquid conventional fertilizer treatment compared with the two organic treatments. Transplants that received liquid organic fertilizer had greater development compared with transplants that only received water in addition to the initial solid fertilizer. Organic amendment mineralization did not completely fulfill transplant nutrient requirement compared with conventional transplants. Solid fertilization in the growing medium affected plant growth during the first 5 weeks but not after 10 weeks after transplanting. Solid and liquid organic fertilizers at a higher concentration should be provided to reach a similar transplant development because conventional seedlings or other slow-release sources of solid amendments should be added to the growing medium to keep an adequate and constant nutrient release. Providing a beneficial agent to the organic growing medium increased its biological activity but had no effect on seedling growth during this study. Solid organic fertilization (1600 mL·m−3 of shrimp meal with 50 mL·m−3 of kelp meal) combined with an organic liquid fertilization should be used in combination with inoculation with T. harzianum to obtain high-quality organic sweet pepper transplants.
Ethylene Analog and 1-Methylcyclopropene Enhance Black Spot Disease Development in Pyrus pyrifolia Nakai
Authors: Itai Akihiro , Igori Takaaki , Fujita Naoko , Egusa Mayumi , Kodama Motoichiro , Murayama Hideki
Published: February 2019

Black spot disease is one of the most serious diseases in Asian pear cultivation, with the commercial cultivar Nijisseiki being susceptible. Ethylene is known to play major roles in regulating plant defense responses against various pathogens. We investigated the relationship between ethylene synthesis and black spot disease in ‘Nijisseiki’ pear leaves by treatment with an analog of ethylene and 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action. Interestingly, both treatments enhanced black spot disease symptoms. Both treatments also increased ethylene production in accordance with disease symptoms through altered gene expression of ethylene biosynthetic enzymes, especially 1-aminocyclopropane-1-carboxylate (ACC) synthase genes (PpACS3 and 4). Chemical names used: 1-methylcyclopropene (1-MCP), 1-aminocyclopropane-1-carboxylate (ACC).
Developmental Stage and Growth Regulator Concentration Differentially Affect Vegetative Propagation of Select Clones of Taxodium Rich.
Authors: King Andrew R. , Arnold Michael A. , Welsh Douglas F. , Watson W. Todd
Published: February 2019

In previous studies, baldcypress [Taxodium distichum (L.) Rich.] clones were selected for improved field tolerance to alkaline soils, drought, foliar or soil salinity exposure, and for ornamental traits. Objectives of the current research were to 1) determine the clonal responses to potassium salt of indole-3-butyric acid (K-IBA) across seasonal developmental stages of cuttings; and 2) to determine whether rooting and callus percentages and rooted cutting quality (root number, length, and mass) would be sufficient for commercial production should these clones be released to industry. Cuttings were taken from 24 clones at three distinct stages of stem maturity (softwood, semihardwood, and hardwood). Three concentrations of K-IBA were tested [0, 7,500, and 15,000 mg·L−1 (0, 31.1, 62.2 mm, respectively)] on each clone at each stage. Rooting percentages ranged from ≈94% (clone MX1MC33) at the softwood stage to 0% for several clones at the hardwood stage. Some clones such as MX5MC17 rooted at statistically similar percentages in the softwood and semihardwood stages (88% and 83%, respectively). Clone EP3DC16 rooted at low levels (less than 20%) in all stages. Significant (P ≤ 0.05) interactions occurred between growth stage and clone in some cases. Clone EP8DC14 rooted at 59% at the softwood stage but only 37% at the semihardwood stage. Root number and length exhibited three-way interactions (P ≤ 0.05) among clone, developmental stage, and K-IBA concentration. Mean total root length ranged from 2 cm per cutting on semihardwood cuttings of MX2MC31 treated with no growth regulator to 81 cm per cutting on softwood cuttings of TX8DC38 treated with 7500 mg·L−1 K-IBA. Mean root length varied from 2 cm for several clones at the semihardwood stage to 11 cm for softwood cuttings of MX2MC31 treated with 15,000 mg·L−1 K-IBA. The greatest rooting percentages across K-IBA concentrations were typically at the softwood stage. Cuttings treated with either 7,500 or 15,000 mg·L−1 K-IBA rooted at the greatest percentages across stem maturity stages. No clone rooted well in the hardwood stage. The high concentration of K-IBA (15,000 mg·L−1) sometimes induced basal stem damage.
Qualitative Changes of Olive Oils Obtained from Fruits Damaged by Bactrocera oleae (Rossi)
Authors: Gucci Riccardo , Caruso Giovanni , Canale Angelo , Loni Augusto , Raspi Alfio , Urbani Stefania , Taticchi Agnese , Esposto Sonia , Servili Maurizio
Published: February 2019

Mature fruits of Olea europaea L. ‘Frantoio’ with different degrees of damage [from 0% to 100% of fruits with exit holes (EHs)] caused by the olive fruit fly (Bactrocera oleae), the key pest in Mediterranean olive orchards, were sampled to quantify the effects on free acidity, peroxide value (PV), and concentrations of secoiridoids and lignans of virgin olive oil (VOO). The total concentration of phenolic compounds and that of individual secoiridoids were negatively related to the degree of fruit damage, whereas the concentration of lignans, namely (+)-pinoresinol and (+)-1-acetoxypinoresinol, was unaffected. Free acidity was similar for the 0% and 10% EH treatments, increased sharply between 10% and 30% EH, and was similar again for the 60% and 100% EH treatments. Free acidity values were low and well within the limit for VOO classification even after 6 months of oil storage. Peroxide value responded to both B. oleae damage and storage conditions. Peroxide values increased between 10% and 30% EH treatments but changed little between the 30% and 100% EH treatments regardless of oil storage conditions. Secoiridoid concentrations closely reflected the degree of B. oleae damage when sources of variability such as cultivar and cultural practices were kept under control and conditions of processing and oil storage were optimal.
The Effect of Olive Tree Stock Plant Nutritional Status on Propagation Rates
Authors: Dag Arnon , Erel Ran , Ben-Gal Alon , Zipori Isaac , Yermiyahu Uri
Published: February 2019

The global production of olives (Olea europaea L.) has increased rapidly over the last decade as a result of the expansion of orchards with high tree densities. Most olives are propagated from rooted cuttings. The present study evaluated the propagation rate of rooted cuttings as a function of the nutritional status of the stock trees. Rooting ability was evaluated for cuttings taken from container-grown stock plants exposed to eight concentrations of nitrogen (N) (ranging from 0.4 to 14.1 mm), seven concentrations of phosphorus (P) (ranging from 0.01 to 0.62 mm), and five concentrations of potassium (K) (ranging from 0.25 to 5.33 mm). Increases in N level negatively affected rooting rate and cutting survival. Propagation success was increased threefold as N in irrigation water was reduced from the highest to the lowest treatments. Enhanced root development under low N concentrations resulted in higher root weight compared with the high N concentrations. The high concentration of N fertilization negatively affected the propagation rate but was not reflected in N concentration of diagnostic leaves. There was, however, a significant negative correlation between N in twigs and propagation rate. Regarding response to K concentration, no effect was found on rooting rate or cutting survival. Except for reduced rooting at the lowest concentration, P had a negligible effect on rooting rate. The experimental results indicate the need to avoid overfertilization of olive stock trees with N to promote successful propagation.
Identification of Resistance to Fusarium oxysporum f. sp. niveum Race 2 in Citrullus lanatus var. citroides Plant Introductions
Authors: Wechter W. Patrick , Kousik Chandrasekar , McMillan Melanie , Levi Amnon
Published: February 2019

Fusarium wilt (FW) is a major disease of watermelon in North America and around the world. Control of this disease is difficult because the soilborne causal agent Fusarium oxysporum f. sp. niveum (Fon) produces chlamydospores that remain infectious in the soil for many years. Although various levels of resistance to Fon Races 0 and 1 exist in watermelon cultivars, no resistance to Race 2 or 3 has been reported. In this study, we used seed and seedling inoculation procedures to screen 110 U.S. PIs of wild watermelon (Citrullus lanatus var. citroides) for resistance to Race 2 FW. Of these 110 accessions, 15 showed significantly higher resistance to Fon Race 2 than that found in the watermelon cultivars Sugar Baby or Charleston Grey as well as in the C. lanatus var. citroides PI 296341 that was reported to contain resistance to FW. PI 271769, another C. lanatus var. citroides that was previously reported as containing resistance to FW, is among the 15 resistant accessions described here. These 15 accessions are potential sources for resistance to Race 2 FW in watermelon breeding.
Liverwort Control: An Ancillary Role for Ozone-based Irrigation Water Treatment Systems?
Authors: Graham Thomas , Dixon Michael A.
Published: February 2019

Marchantia polymorpha L. (a thalloid liverwort) is a common plant pest in nursery and greenhouse production systems. The rapid growth and dissemination of this pest can result in heavy mats of thallus tissue on the surface of pots, which restrict water penetration, compete for nutrients, and provide a habitat for other pests and disease vectors. The sensitivity of liverwort to aqueous ozone was examined to determine if routine use of ozone, as a component of an irrigation water remediation strategy, could provide ancillary services in the form of liverwort management. Three experiments were performed to evaluate contact time (CT) thresholds and application frequencies suitable for liverwort management applications. The first two experiments confirmed that CT is a suitable process control parameter with a base liverwort management threshold occurring between CT 0.84 and 1.68 mg·L−1·min under the conditions used. The third experiment examined the effect of application frequency at a CT of 3.75 mg·L−1·min, which was previously determined to be compatible with select woody perennial species. Three and five applications per week resulted in reduced liverwort growth and fecundity.
Expression of Expansin Gene (CDK-Exp3) and Its Modulation by Exogenous Gibberellic Acid During Ripening and Softening of Persimmon Fruit
Authors: Zhang Zhengke , Fu Runshan , Huber Donald J. , Rao Jingping , Chang Xiaoxiao , Hu Meijiao , Zhang Yu , Jiang Nina
Published: February 2019

Expansins are proteins that have been reported to contribute to fruit softening. In this study, an expansin gene, CDK-Exp3, was identified from persimmon fruit, and the mRNA accumulation of CDK-Exp3 during postharvest softening was examined using real-time polymerase chain reaction (PCR). Sequence analysis showed that CDK-Exp3 contained a putative open reading frame of 765 bp encoding a polypeptide of 254 amino acid residues, which had all the characteristics of α-expansin. As fruit softened, the expression of CDK-Exp3 increased dramatically within the initial 8-day ripening at 20 °C followed by a gradual decline at the late stages of ripening. The expression of CDK-Exp3 was inhibited by gibberellic acid, and the maximum transcript abundance was delayed by 20 days compared with that of the control fruit. The results suggest that CDK-Exp3 might be closely related to softening of persimmon fruit during postharvest ripening.
Microbiological and Physicochemical Quality of Enzymatically Peeled Persimmon Fruit for Fresh-cut Slices
Authors: Murakami Yukari , Ozaki Yoshihiko , Izumi Hidemi
Published: February 2019

Enzymatic peeling of ‘Fuyu’ and ‘Tone-wase’ persimmon fruit was conducted for production of fresh-cut slices, and the microbiological and physicochemical quality of enzyme-peeled fresh-cut slices was compared with that of slices manually peeled with a knife. The enzymatic peeling process involved a porous treatment of the peel, heating at 100 °C for 45 s, infusion with 3% protopectinase at 37 °C for 3 h, and rinsing under running tap water. Initially, the peel of ‘Fuyu’ persimmon fruit had microbial counts ranging from 3.9 to 4.2 log cfu·g−1 and a diverse microflora. The heating treatment before the enzymatic peeling process reduced the microbial counts in both the peel and flesh of all fruits to levels below the lower limit of detection. After the enzyme infusion followed by gentle rinsing with tap water, microbial counts of enzyme-peeled fruit were close to or below the level of detection. When microbial contamination of enzyme-peeled and knife-peeled ‘Fuyu’ and ‘Tone-wase’ persimmon slices was compared, the bacterial counts and diversity of bacterial and fungal flora were less in enzyme-peeled slices than in knife-peeled slices. With ‘Tone-wase’ slices, the color index, pH, and texture were unaffected by enzymatic peeling, except for surface lightness, which was lower in enzyme-peeled slices than in knife-peeled slices. These results indicate that enzymatic peeling could be an alternative to knife-peeling of ‘Tone-wase’ persimmon fruit for fresh-cut production from the point of microbiological and physicochemical quality.
Impact of High-temperature Forced-air Heating of Navel Oranges on Quality Attributes, Sensory Parameters, and Flavor Volatiles
Authors: Obenland David , Collin Sue , Sievert James , Arpaia Mary Lu
Published: February 2019

Navel oranges were subjected to high-temperature forced-air (HTFA) treatment to evaluate the effect on quality and sensory attributes as well as flavor volatiles of a treatment protocol designed to disinfest citrus of Anastrepha spp. fruit flies. The treatment consisted of heating the fruit to a core temperature of 44 °C and then holding it there for 100 min, after which the fruit were placed into storage for 4 weeks. The fruit were removed from storage and evaluated for surface injury, soluble solids concentration (SSC), titratable acidity (TA), and then judged for sensory characteristics by a semiexpert panel. In a separate experiment, fruit were removed at 30-min intervals from the treatment chamber and sensory quality as well as flavor volatiles determined to obtain an estimate of when the flavor changes occurred. It was found that the HTFA treatment caused a significant loss in flavor quality that was most closely linked to a loss in the fresh flavor of the fruit. The HTFA-treated fruit were also determined by panelists to be less sweet, although the SSC/TA ratio was increased by treatment. Neither storage nor waxing after treatment appeared to alter the HTFA effect, although waxing before treatment greatly enhanced the negative effect on flavor. Flavor began to be significantly affected during the final 30 min of treatment. The flavor changes occurred at the same time as large increases in the amount of four esters, two of which were present in concentrations exceeding aroma thresholds and are likely involved in the loss in flavor quality induced by HTFA treatment.
Pak Choi (Brassica rapa, Chinensis Group) Yield, Phytonutrient Content, and Soil Biological Properties as Affected by Vermicompost-to-water Ratio Used for Extraction
Authors: Pant Archana P. , Radovich Theodore J.K. , Hue Nguyen V. , Miyasaka Susan C.
Published: February 2019

Previous work has demonstrated the potential of compost tea to enhance plant growth and nutritional status. One factor thought to contribute to variability in the efficacy of compost tea is the amount of compost per unit volume of water. To address these gaps in our understanding, two greenhouse trials and two field trials were conducted to investigate the effects of various extraction ratios on the growth, mineral nitrogen (N), and phytonutrient content of pak choi (Brassica rapa, Chinensis) and on soil biological properties. In greenhouse experiments, plants were fertilized with a single rate of chicken manure-based thermophilic compost. In field trials, three fertilizer treatments: 1) rendered meat byproduct or Tankage (Island Commodities, Honolulu, HI); 2) soluble fertilizer (16:16:16); and 3) chicken manure-based thermophilic compost were applied. Aerated vermicompost teas were prepared using chicken manure-based vermicompost and water at various ratios. Pak choi plants were treated weekly for 4 weeks with 10%, 5%, 3%, and 1% vermicompost teas in the greenhouse experiments and 10% and 5% teas in the field trials. Applications of vermicompost tea significantly increased plant growth, N content, total carotenoids, and total glucosinolates in plant tissue; this response was greatest in chicken manure-fertilized treatments. Increases in yield and phytonutrient content were associated with increased N uptake. Vermicompost tea also increased soil respiration and dehydrogenase activity over the control (water). Plant growth, phytonutrient content, and microbial activities in soil increased with increasing concentrations of vermicompost tea. Within the range of concentrations evaluated (1%–10%), greatest plant growth response was observed with 5% and 10% vermicompost tea, indicating that the optimal water-to-vermicompost ratio for extraction is lower than 50:1 and is likely in the range of 10:1 to 20:1. The findings suggest that vermicompost tea could be used to improve plant nutrient status and enhance soil biological properties in vegetable production.
Interstock of ‘Valencia’ Orange Affects the Flooding Tolerance in ‘Verna’ Lemon Trees
Authors: Gimeno Vicente , Syvertsen James P. , Simon Inma , Martinez Vicente , Camara-Zapata Jose M. , Nieves Manuel , Garcia-Sanchez Francisco
Published: February 2019

Previous work on citrus trees has shown that an interstock, grafted between the rootstock and scion combination, not only can improve tree growth, longevity, fruit production, and quality, but also can increase salinity tolerance. This research was designed to evaluate flooding responses of 2-year-old ‘Verna’ lemon trees [Citrus limon (L.) Burm.; VL] either grafted on ‘Sour’ orange (C. aurantium L.; SO) rootstock without an interstock (VL/SO) or interstocked with ‘Valencia’ orange (C. sinensis Osbeck;VL/V/SO) or with ‘Castellano’ orange (C. sinensis Osbeck; VL/C/SO). Well-watered and fertilized trees were grown under greenhouse conditions and half were flooded for 9 days. At the end of the flooded period, leaf water relations, leaf gas exchange, chlorophyll fluorescence parameters, mineral nutrition, organic solutes, and carbohydrate concentrations were measured. Leaf water potential (Ψw), relative water content (RWC), net CO2 assimilation rate (ACO2), and stomatal conductance (gS) were decreased by flooding in all the trees but the greatest decreases occurred in VL/V/SO. The Ci/Ca (leaf internal CO2 to ambient CO2 ratio), Fv/Fo (potential activity of PSII) and Fv/Fm (maximum quantum efficiency) ratios were similar in flooded and non-flooded VL/SO and VL/C/SO trees but were decreased in VL/V/SO trees by flooding. Regardless of interstock, flooding increased root calcium (Ca), iron (Fe), copper (Cu), and manganese (Mn) concentration but decreased nitrogen (N) and potassium (K) concentration. Based on the leaf water relations, gas exchange, and chlorophyll parameters, ‘Verna’ lemon trees interstocked with ‘Valencia’ orange had the least flooding tolerance. Regardless of interstock, the detrimental effect of flooding in ‘Verna’ lemon trees was the leaf dehydration which decreased ACO2 as a result of non-stomatal factors. Lowered ACO2 did not decrease the leaf carbohydrate concentration. Flooding decreased root starch in all trees but more so in VL/V/SO trees. Sugars were decreased by flooding in roots of interstocked trees but were increased by flooding in VL/SO roots suggesting that the translocation of carbohydrates from shoots to roots under flooded condition was impaired in interstocked trees.
Inhibition of Bacterial, Fungal, and Plant Growth by Testae Extracts of Citrullus Genotypes
Authors: Harrison Howard F. , Wechter W. Patrick , Kousik Chandrasekar S.
Published: February 2019

Watermelon [Citrullus lanatus var. lanatus (Thunb.) Matsum & Nakai] seed and root exudates inhibit germination and seedling growth of plants and growth of pathogenic fungi and bacteria. This study was conducted to determine if extractable components in the testa (seedcoat) contribute to the inhibition previously reported. Testae of eight genetically diverse Citrullus genotypes were extracted first with dichloromethane to remove less polar components and then with 70% methanol to remove more polar components. The dichloromethane extracts were not inhibitory in a Proso millet radicle growth bioassay; however, they were highly inhibitory to the growth of the fruit blotch bacterial pathogen Acidovorax avenae subsp. citrulli (Aac). All dichloromethane extracts were highly inhibitory to Aac except those from a watermelon breeding line, 406-1-x 7 and a C. lanatus var. citroides accession, PI 500354. The more polar components extracted in 70% methanol inhibited Proso millet radicle and Aac growth and Phytophthora capsici zoospore germination. The greatest inhibition of radicle growth was found with 70% methanol extracts from two watermelon relatives, C. lanatus var. citroides [Bailey (Mansf.)] (PI 532738) and C. colocynthis [(L.) Scrad.] (PI 432337). They reduced radicle elongation by 90% at an extract concentration of 250 mg of tissue extracted per mL water. The 70% methanol extracts of several genotypes partially inhibited Aac colony formation, but the C. lanatus var. citroides accession, PI 532738, was the only genotype with 70% methanol extracts that completely inhibited the bacterium at 100 mg·mL−1. The 70% methanol extracts of Charleston Gray, 406-1-x 7, PI 500354, PI 532738, and PI 167125 were highly inhibitory in a Phytophthora capsici zoospore germination bioassay. These results indicate that the testae of Citrullus genotypes contain at least two compounds that are inhibitory to microorganisms and plants in bioassay, and the amount of inhibition caused by the extracts varied among Citrullus genotypes.
Comparison of Light-emitting Diode and High-pressure Sodium Light Treatments for Hydroponics Growth of Boston Lettuce
Authors: Martineau Vincent , Lefsrud Mark , Naznin Most Tahera , Kopsell Dean A.
Published: February 2019

Recent irradiance level improvements in light-emitting diode (LED) technology has allowed this equipment to compete as suitable replacements to traditional high-pressure sodium (HPS) lamps in hydroponics growth environments. The current study compares LED and HPS lighting technologies for supplemental lighting in a greenhouse at HydroSerre Mirabel (Mirabel, Quebec, Canada) for the growth of Boston lettuce (Lactuca sativa var. capitata). The light treatments were applied for 2 hours before sunset and 8.5 hours after sunset to extend the photoperiod to 18 hours. An average total light irradiance (natural and supplemental) of 71.3 mol·m−2 for HPS and 35.8 mol·m−2 for LED were recorded over the 4 weeks of each experimental run. Wet and dry biomass of the shoots was recorded. On average, HPS light treatments produced significantly similar shoot biomass compared with LED light treatment, although the LED lamps provided roughly half the amount of supplemental light compared with the HPS lamps during the 4 weeks of the experimental treatment. Analysis of the lettuce samples showed no significant difference in concentrations of β-carotene, chlorophyll a, chlorophyll b, neoxanthin, lutein, and antheraxanthin among the light treatments; however, violaxanthin concentrations showed a statistical difference resulting from light treatment. When measured on an energy basis, the LED lamps provide an energy savings of at least 33.8% and the minimal “regular” HPS provided an energy savings of 77.8% over the HPS treatment.
Greenhouse Energy Curtains Influence Shoot-tip Temperature of New Guinea Impatiens
Authors: Blanchard Matthew G. , Runkle Erik S. , Both Arend-Jan , Shimizu Hiroshi
Published: February 2019

Many greenhouse growers have installed retractable energy curtains to reduce energy losses and heating costs. We performed experiments to quantify the effect of retractable nighttime curtains on plant shoot-tip temperature of New Guinea impatiens (Impatiens hawkeri Bull.) grown in glass-glazed greenhouses during winter. Plants were grown in separate greenhouses under different curtain materials and the following measurements were collected: plant shoot tip, aerial wet and dry bulb, and cover (glazing and superstructure or curtain) temperature; net canopy radiation (250 to 60,000 nm); transmitted shortwave radiation (SWR; 300 to 3,000 nm); and air velocity. At night, plants under an extended curtain had a higher (by 0.5 to 2.3 °C) shoot-tip temperature and the net longwave radiation (LWRnet; 3,000 to 100,000 nm) was 70% to 125% greater than plants without a curtain. Shoot-tip temperature was 0.2 to 0.6 °C lower under a shading curtain with open-weave construction (high air permeability) compared with closed-weave constructed curtains (e.g., blackout). As cover temperature decreased from 21 to 12 °C, measured shoot-tip temperature and LWRnet decreased by a mean of 3.0 °C and 39.1 W·m−2, respectively. Under a vapor pressure deficit (VPD) of 0.4 to 0.9 kPa, plant shoot-tip temperature was a mean of 1.0 °C closer to dry-bulb temperature compared with plants under a VPD of 1.4 to 1.8 kPa as a result of decreased transpiration. During the day, shoot-tip temperature was 1.2 °C lower than dry-bulb temperature when transmitted SWR was less than 100 W·m−2 and on average 1.6 °C higher than the dry-bulb temperature when SWR was more than 100 W·m−2. Therefore, in addition to reducing greenhouse heating costs, a curtain extended at night over a crop of New Guinea impatiens could increase plant shoot-tip temperature and accelerate development.
Fruit Production Characteristics of ‘Pawnee’ Pecan
Authors: Smith Michael W.
Published: February 2019

Yield and selected nut quality characteristics were monitored on hedge pruned ‘Pawnee’ pecan [Carya illinoinensis (Wangenh.) K. Koch.] trees over a 5-year period to characterize optimum production defined as equal crops 2 successive years. Previous year yield was linearly or quadratically related to current-season yield in three of four instances. Optimum yield ranged from 18 kg/tree to 29 kg/tree among years. Weight/nut, weight/kernel, and percent kernel were negatively related to yield/tree. Weight/nut and weight/kernel were more closely related to yield/tree than percent kernel, indicating that as cropload increased, shell weight and kernel weight were disproportionately affected. Increasing croploads reduced kernel weight more than shell weight, thus reducing the correlation between percent kernel and yield. Twenty-seven percent of the trees in the study produced greater than average yields with a lower than average alternate bearing index.
Biomass Effects and Selenium Accumulation in Sprouts of Three Vegetable Species Grown in Selenium-enriched Conditions
Authors: Arscott Sara , Goldman Irwin
Published: February 2019

Foods that can aid in prevention of disease are of increasing interest. Some vegetables experimentally enriched with selenium (Se) accumulate selenium as Se-methylselenocysteine (MeSeCys), a non-protein amino acid implicated with superior chemopreventive properties. The effects of increasing concentrations of Se on the gain in biomass (GIB) and total Se concentration of broccoli (Brassica oleracea), mung bean (Vigna radiata), and onion (Allium cepa ‘Red creole’) sprouts were evaluated against sulfur (S) as control. Trial 1 included treatments of selenate-Se and sulfate-S at levels of 127 μmol·L−1 and 1270 μmol·L−1. Trial 2 used additional treatments of 635 μmol·L−1 for broccoli and mung beans and 12,700 μmol·L−1 for onion. Sprouts were harvested at 3 and 5 days for broccoli and mung bean and at 5 and 7 days for onion. Broccoli was the most sensitive to Se, showing ≈45% GIB reduction at 635 μM Se. Mung bean GIB was 23% lower at 1,270 μM Se and onion GIB showed a small 16% reduction at 12,700 μM Se, suggesting high Se tolerance. These data clearly demonstrated species variation in tolerance to and uptake of Se during sprout production. The lowest treatment level, 127 μM selenate-Se, resulted in Se concentrations that exceeded the level desirable for fresh sprout consumption, suggesting that Se-biofortified sprout production for fresh consumption could be easily accomplished with little effect on growth rate or yield. Chemical name used: selenate (SeO42–) sulfate (SO42–).
Comparison of the Effects of Metamitron on Chlorophyll Fluorescence and Fruit Set in Apple and Peach
Authors: McArtney Steven J. , Obermiller John D. , Arellano Consuelo
Published: February 2019

The effects of foliar applications of the photosystem II (PSII) inhibitor metamitron on chlorophyll fluorescence and fruit set were compared in peach and apple trees. Metamitron increased dark-adapted chlorophyll fluorescence, measured as a reduction in Fv/Fm values, in both peaches and apples. Maximum suppression of the normalized ratio of variable fluorescence to maximum fluorescence (Fv/Fm) in peaches occurred 1 to 2 days after application and Fv/Fm values recovered by 7 days after treatment. The effects of metamitron on chlorophyll fluorescence were more persistent in apples compared with peaches. Fv/Fm values in apple declined within 2 days of treatment and did not start recovering until 5 days after treatment or longer. Concentrations of metamitron greater than 200 mg·L−1 were phytotoxic to peach leaves, reducing the leaf chlorophyll concentration as determined by SPAD measurements. At 300 mg·L−1, metamitron reduced fruit set in apple but not in peach. Inclusion of a non-ionic surfactant (Silwett L-77) with metamitron greatly increased its negative effect on Fv/Fm, quantum photosynthetic yield of PSII (ΦPSII), and relative electron transport rate (ETR). These results suggest that metamitron may be a useful thinner in apple but not in peach. Additional information is needed to understand how combining metamitron with existing thinning chemicals might enhance their activity. In particular, caution may be necessary if metamitron is applied as a tank mixture with commercial thinning products that have been formulated with a wetting agent.