bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Root Restriction on Ultrastructure of Phloem Tissues in Grape Berry
Authors: Xie ZhaoSen , Forney Charles F. , Xu WenPing , Wang ShiPing
Published: February 2019

In this study, the ultrastructure of phloem and its surrounding parenchyma cells in the developing grape berry produced under root restriction or without (control) was for the first time systematically investigated through transmission electron microscopy during the entire developmental process of the berry. The results showed that root restriction increased the number of plasmodesmata between sieve elements (SE) and companion cells (CC) and between the SE/CC complex and phloem parenchyma cells. Sieve elements in fruit produced under root restriction were smaller in size than those from the control treatment, but CC were bigger than in the control treatment. During the first rapid growth phase of the grape berry, there was denser cytoplasm in the CC produced under root restriction having more abundant mitochondria, endoplasmic reticulum, multivesicular bodies, vesicles, and plastids than in control fruit. During the second rapid growth phase of the grape berry, CC under root restriction showed more serious plasmolysis. Cytoplasmic contents such as vesicles were fused into the vacuole of which the tonoplast nearly disappeared in the phloem parenchyma cells, and cytoplasmic contents in fruit cells produced under root restriction became denser than the control treatment. These results demonstrated that grape berry adapted to the root restriction stress through ultrastructure variation of the phloem, and this variation explained the increase of photosynthate accumulation in the grape berry observed under root restriction.
Factors Affecting Growers' Willingness to Adopt Sustainable Floriculture Practices
Authors: Hall Tanya J. , Dennis Jennifer H. , Lopez Roberto G. , Marshall Maria I.
Published: February 2019

In June to Oct. 2008, a U.S. floriculture survey was conducted to examine the factors affecting growers' willingness to adopt sustainable practices. The factors affecting adoption of sustainable practices were evaluated in five areas: environmental regulations, customer value, growers' attitudes toward sustainability, age, and operation size. A logistic regression model was used to examine factors affecting growers' adoption of sustainable practices. Nearly two-thirds (65.2%) of respondents thought sustainability was very important to the environment. Similarly, more than half (63%) of the respondents had sustainable practices in their operations. Although respondents had positive attitudes toward sustainability and the environment, these positive attitudes alone were unable to predict adoption behaviors. The two most important factors that affected adoption of sustainable practices were the concerns about implementation and the risk perceived by growers. Neither perceived customer value nor the stringency of state regulations affected the adoption of sustainable practices. The results from this study provide original insight into growers' views of sustainability and identify the educational assistance needed by growers to overcome the factors affecting their adoption of sustainable practices.
Germination, Mineral Composition, and Ion Uptake in Walnut Under Salinity Conditions
Authors: Lotfi Naser , Vahdati Kourosh , Kholdebarin Bahman , Ashrafi Elaheh Najafian
Published: February 2019

Walnut (J. regia L.) is one of the most sensitive plants to abiotic stresses for which finding salt-tolerant genetic resources is very important. Effects of salt stress on seed germination of seven walnut cultivars (Serr, Lara, Pedro, Chandler, Hartely, Vina, and Roun de Montignac) were studied. Salt stress treatments were applied using NaCl solutions ranging from 50 to 250 mm. The increase in salinity levels resulted in a substantial decrease in root relative water content. The percent of germination was also affected by salinity level and cultivar and their interactions. The mean germination time differed among treatment media and cultivars and a significant interaction was observed between these two factors. According to the cluster analysis, ‘Chandler’ was classified as the most tolerant cultivar. ‘Hartley’, ‘Pedro’, and ‘Round de Montignac’ (‘RDM’) were also classified in another group (semisensitive), whereas ‘Vina’, ‘Serr’, and ‘Lara’ were classified as sensitive cultivars. With the increase in salt stress, resistant cultivars accumulated more potassium (K) and calcium, especially in their shoots. However, in the semitolerant cultivars, accumulation of K in the root was more than in the shoot. Differences in magnesium accumulation in roots and shoots of all samples were significant at all stress levels and were dependent on genotypes. Sodium levels in roots were higher than in the shoots in most cultivars, especially in the semisensitive and tolerant ones. There was a low correlation (r2 ≤ 0.15) between walnut seed traits (seed weight and kernel weight) and growth indices with respect to salinity tolerance.
Chemical and Hot Water Treatments to Control Rhizoctonia AG P Infesting Stem Cuttings of Azalea
Authors: Copes Warren E. , Blythe Eugene K.
Published: February 2019

In the southern and eastern United States, azalea stems cut during the spring for propagation may be infested with Rhizoctonia spp. Multiple methods were evaluated in a series of laboratory experiments for the purpose of eliminating Rhizoctonia from stem cuttings of Rhododendron L. ‘Gumpo White’ [‘Gumpo White’ (Satsuki) azalea] to prevent spread of azalea web blight during the propagation phase of nursery production. Leafless stem sections were inoculated with an isolate of binucleate Rhizoctonia anastomosis group P (AG P). Disinfestants (sodium hypochlorite, hydrogen dioxide, and quaternary ammonium chloride) or fungicides (chlorothalonil + thiophanate-methyl and flutolanil) applied at several rates (below, at, and above label rates) did not eliminate Rhizoctonia AG P from stem sections. Recovery of Rhizoctonia AG P was not reduced by submersing stem pieces in 45 °C water, but was eliminated at water temperatures of 50 °C or greater. Mortality of Rhizoctonia infesting azalea stem pieces was best explained by a cubic regression model. Mortality increased with increasing time (0, 1.5, 3, 4.5, 6, 7.5, 9, 10.5, 12, 15, 18, and 21 min) in water at 50 and 55 °C and with increasing temperatures (52, 55, 58, 61, 64, 67, and 70 °C) when stem pieces were submerged for 30 and 60 s. The duration of hot water treatment at which 99% of stem pieces were predicted to be free of Rhizoctonia was 20 min 16 s at 50 °C and 5 min 19 s at 55 °C. The average water temperature at which 99% of the stem pieces were predicted to be free of Rhizoctonia was 60.2 and 56.9 °C when stem pieces were submerged for 30 and 60 s, respectively. Only minor leaf damage occurred on terminal, leafy stem cuttings when submerged in 50 °C water after 40 min. Severe leaf damage did occur if cuttings were submerged long enough in water of 55 °C or greater. Leaf damage was predicted to exceed a proportional leaf damage value of 0.25 (indicating severe damage) when leafy stem cuttings were submerged in 55 °C water for longer than 13 min 54 s or for 30 and 60 s with water temperature greater than 57.4 and greater than 56.8 °C, respectively. Of the methods tested, submersion in hot water has the greatest potential for eliminating Rhizoctonia AG P from azalea stem cuttings. Submerging stem pieces in 50 °C water for 21 min eliminated Rhizoctonia and provided the least risk for development of severe leaf damage.
Maturity and Quality of ‘Liberty’ Apple Fruit Under Integrated and Organic Fruit Production Systems Are Similar
Authors: Peck Gregory M. , Merwin Ian A. , Watkins Christopher B. , Chapman Kathryn W. , Padilla-Zakour Olga I.
Published: February 2019

Maturity and quality of fruit harvested from an orchard of disease-resistant ‘Liberty’ apple (Malus ×domestica Borkh.) trees was investigated during and after the transition from conventional to integrated (IFP) and organic fruit production (OFP) systems. Over 4 years, internal ethylene concentration, starch pattern index, flesh firmness, soluble solids concentration (SSC), titratable acidity (TA), and percent of surface blush of fruit at harvest were not consistently different between fruit from IFP and OFP systems. Total phenolic content and antioxidant capacity of the fruit were also similar between treatments. IFP-grown fruit contained more potassium during the first 2 years and more calcium in all years than OFP-grown fruit. After fruit were stored in air at 0.5 °C for 9 weeks in 2007, OFP-grown apples were firmer and had higher SSC, TA, and SSC:TA ratios. In double-blind triangle taste tests, consumer panelists were able to discriminate between the fruit from each treatment, but in double-blind hedonic and intensity tests, panelists did not consistently rate one treatment more highly than the other. Overall, consumer panelists favorably rated internal quality of fruit grown under both IFP and OFP systems. In 2006, when weather and disease caused a high percentage of OFP-grown fruit to have cosmetic defects, the panelists rated the appearance of OFP-grown apples as less acceptable than the cleaner-looking IFP-grown apples. Our study of ‘Liberty’ apple fruit maturity and quality during a 4-year transition period from conventional to IFP and OFP systems showed that differences were small if present, whereas internal fruit quality was rarely different between systems.
Effects of Aminoethoxyvinylglycine Plus 1-Methylcyclopropene on ‘Royal Gala’ Apple Volatile Production After Cold Storage
Authors: Escalada Valeria Sigal , Archbold Douglas D.
Published: February 2019

Both aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP) are useful tools for managing apple fruit ripening, and their impacts on apple volatile production have been independently assessed. In this work, their combined effect, as might occur in commercial production and postharvest storage, on ‘Royal Gala’ apple volatile production at harvest and after air storage was compared with the effect of each alone. An aqueous solution of AVG was applied to ‘Royal Gala’ apple trees 4 weeks before the normal harvest date (H1) at 124 g·ha−1/a.i. in 2004 and 2005. Control and AVG-treated fruit were treated at H1 or after harvest of AVG fruit 2 weeks later (H2) for 20 h at 30 °C with 1-MCP at a final headspace concentration of 1 μL·L−1. Fruit were ripened for 7 d at room temperature immediately after harvest and treatment or after treatment and then cold storage at 4 °C for 6 or 12 weeks. Peel and cortex tissue of control and AVG plus 1-MCP-treated fruit was provided with butanol or hexanol and ester production was quantified. The combination of AVG plus 1-MCP was more effective in reducing internal ethylene concentration than either alone. Both total volatile production and that of the major individual esters, including hexyl acetate, butyl acetate, and 2-methylbutylacetate, which are considered key constituents of ‘Gala’ aroma, were consistently repressed by the combination of AVG plus 1-MCP after harvest and up to 12 weeks of cold storage. The effects of AVG plus 1-MCP were evident even with H2 fruit when the effects of AVG alone on fruit ripening were at least partially lost. Because alcohol–acyl transferase activity was unaffected by AVG plus 1-MCP, AVG plus 1-MCP-treated peel and cortex samples had similar total ester production when they were provided butanol or hexanol. Total alcohols showed recovery in most treatments except AVG plus 1-MCP, so precursor availability was likely the major factor limiting ester production. The results indicated a sustained adverse effect of the AVG plus 1-MCP treatment on aroma volatile production that could impact consumer acceptability.
Propagation and Establishment of Three Endangered Mexican Orchids from Protocorms
Authors: Mata-Rosas Martín , Salazar-Rojas Víctor M.
Published: February 2019

Protocols for in vitro propagation from protocorms of Mormodes tuxtlensis Salazar, Cuitlauzina pendula La Llave & Lex., and Lycaste skinneri (Batem. Ex. Lind.) Lind., three endangered species distributed in Mexico and highly appreciated as ornamentals, were developed. The effect of two different culture media, Murashige and Skoog (MS) and modified Knudson (KCm), combined with varying concentrations of N6-benzyladenine (0, 2.2, 4.4, 8.9, and 13.3 μM) and α-naphthaleneacetic acid (0, 0.5 and 2.7 μM), were investigated. Shoot formation and development of protocorm-like bodies were observed. For all three species, cultures in MS produced more shoots per explant than those in KCm, and those shoots were longer and more robust in appearance. Maximum number of shoots for M. tuxtlensis (1.5) and C. pendula (24.3) were obtained in media supplemented with 13.3 μM and 2.2 μM N6-benzyladenine, respectively. Conversely, for L. skinneri the greatest shoot production (16.4) was achieved in medium supplemented with 2.7 μM α-naphthaleneacetic acid. Subculturing explants in MS basal medium allowed further development and rooting of the shoots as well as growth of protocorm-like bodies. The effect of different potting mixes on ex vitro survival plantlets was also investigated; pine bark:oak charcoal:pumice (3:1:1) allowed the highest survival rates in all three species.
Nitrogen Fertigation Concentration and Timing of Application Affect Nitrogen Nutrition, Yield, Firmness, and Color of Apples Grown at High Density
Authors: Neilsen Gerry Henry , Neilsen Denise , Herbert Linda
Published: February 2019

A randomized complete block, split-plot experiment with six replicates was established and maintained for the first six fruiting seasons (1999 to 2004) in a high-density apple [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] orchard on M.9 rootstock planted in Apr. 1998. This report assesses responses to six main-plot fertigation treatments, each containing three tree subplots of five different cultivars (Ambrosia, Cameo, Fuji, Gala, and Silken). Fertigation treatments were a factorial combination of two nitrogen (N) rates and three N application timings. N was applied at low (28 mg N/L) or high (168 mg N/L) concentrations daily at 0 to 4, 4 to 8, or 8 to 12 weeks after full bloom (wafb). Under greater N inputs, all cultivars had increased midsummer leaf and harvested fruit N concentrations, decreased fruit firmness, and in heavy crop years, decreased percent red color. Annual yield of all cultivars was significantly increased by N rate in a single year, but their cumulative yields were not different between treatments as a result of rate or timing. Altering the timing of N application within 12 wafb only affected leaf and fruit tissue N concentration. Leaf N was higher after 4 weeks of fertigation any time, although concentrations declined over the growing season, reaching minimum values around harvest. Fruit N was increased by fertigation 4 to 12 wafb. Yield, fruit firmness, and color were unaffected by fertigation timing. Critical fruit quality issues for ‘Gala’ and ‘Silken’ were small fruit size, for Ambrosia low fruit numbers, and for ‘Cameo’ soft fruit. ‘Fuji’, which achieved high yield and leaf N concentration and firm fruit, had poor red color regardless of N treatments.
Substrate Type and Salinity Affect Growth Allocation, Tissue Ion Concentrations, and Physiological Responses of Carrizo Citrange Seedlings
Authors: García-Sánchez Francisco , Syvertsen James P.
Published: February 2019

To gain insight into salinity tolerance of citrus, we studied growth, leaf, and root Cl– concentrations and physiological responses of 5-month-old seedlings of the citrus rootstock Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliate L.] grown in a greenhouse in three different substrates: Candler sand soil, Floridana sandy clay soil, or a commercial soilless peat/perlite/vermiculite potting media. Plants were kept well-watered with a complete nutrient solution plus either no salt (control) or 50 mM NaCl for 9 weeks. Without salinity, substrate type did not affect total plant growth although there were differences in shoot/root dry weight ratio and mineral nutrient relationships attributable to substrate. Predawn leaf water potential, midday CO2 assimilation, and leaf water use efficiency were highest in seedlings grown in the soilless peat. The salt treatment decreased leaf and root growth, reduced leaf Ca2+, and increased leaf K+ concentration in all the three substrates. Overall, plant growth was negatively related to leaf Cl–. Leaf growth reductions were least in Candler-grown seedlings and greatest in Floridana soil as Cl– concentrations were lowest in Candler sand and highest in Floridana soil. Leaf Na+ was also highest in Floridana seedlings. In contrast to salt ions in leaves, roots of salinized seedlings in Candler sand had the highest Na+ and Cl– concentration. Salinity reduced net gas exchange of leaves similarly in all three substrates. Salinity reduced both leaf water potential and osmotic potential such that leaf turgor was increased. Thus, salinity-induced reductions in growth and net gas exchange were not the result of loss of turgor but more likely resulting from toxic ion accumulation in leaves. Based on the relative rankings of leaf growth and leaf Cl– concentrations, Carrizo seedlings from Candler sand had the highest salt tolerance and those grown in Floridana soil had the lowest salt tolerance. Substrate type should be considered when characterizing plant growth and physiological responses to salinity.
Evaluation of Zoysiagrass Genotypes for Shade Tolerance
Authors: Sladek Bradley S. , Henry Gerald M. , Auld Dick L.
Published: February 2019

Establishing turfgrass in shaded environments can create a unique maintenance challenge. Shading reduces zoysiagrass (Zoysia spp.) photosynthesis and results in reduced turfgrass aesthetic quality. Zoysiagrass is a warm-season, perennial turfgrass that forms a dense, uniform turf through the production of rhizomes and stolons. It has demonstrated good tolerance to growth in reduced light intensity environments. Greenhouse experiments were conducted in 2006 and 2007 to evaluate the relative difference in growth response to three light intensities (0%, 50%, and 90% shade) among six zoysiagrass genotypes under artificial shade conditions. Percent change in zoysiagrass plug diameter decreased as shade level increased 6 and 12 weeks after planting (WAP) regardless of year or genotype. ‘Diamond’ and ‘Shadow Turf’ exhibited the greatest percent change in plug diameter 12 WAP (60% to 69%) followed by the remaining zoysiagrass genotypes (21% to 56%) when grown under 50% shade, regardless of year. In 2006, no zoysiagrass genotype maintained acceptable turfgrass quality (6 or greater) 12 WAP when grown under 50% shade. However, ‘Diamond’ and ‘Shadow Turf’ exhibited acceptable turfgrass quality ratings (7.0 and 6.3) 12 WAP in 2007, whereas all other genotypes exhibited unacceptable turfgrass quality ratings (5.0 to 5.7). In 2006, ‘Shadow Turf’ zoysiagrass exhibited the greatest percent increase in plug diameter (21%) followed by ‘DALZ 0501’ (15%) and ‘Diamond’ (5%) 12 WAP when grown under 90% shade. All other zoysiagrass genotypes exhibited decreases in plug diameter (31% to 87%). In 2007, ‘Shadow Turf’ and ‘Diamond’ exhibited the greatest percent change in plug diameter (11%) followed by ‘DALZ 0501’ (7%) 12 WAP when grown under 90% shade. All other zoysiagrass genotypes exhibited decreases in plug diameter (17% to 38%). Turfgrass quality declined as shade level increased 6 and 12 WAP regardless of year or genotype. ‘Shadow Turf’ and ‘Diamond’ exhibited the highest turfgrass quality ratings (4.7 and 3.7, respectively, in 2006 and 5.3 in 2007) 12 WAP when grown under 90% shade. Proper zoysiagrass cultivar selection may improve turfgrass growth and quality under low light intensity while increasing turfgrass options for shaded environments.
Differential Resistance of Gordonieae Trees to Phytophthora cinnamomi
Authors: Meyer Elisabeth M. , Ranney Thomas G. , Eaker Thomas A. , Ivors Kelly
Published: February 2019

Trees in the Theaceae tribe Gordonieae are valuable nursery crops, but some of these taxa are known to be highly susceptible to root rot caused by Phytophthora cinnamomi Rands. The objective of this study was to evaluate a collection of Gordonieae taxa for resistance to this pathogen. These taxa included Franklinia alatamaha Bart. Ex Marshall, Gordonia lasianthus (L.) Ellis, Schima wallichii Choisy, S. khasiana Dyer, ×Schimlinia floribunda Ranney & Fantz, and ×Gordlinia grandiflora Ranney & Fantz. Abies fraseri (Pursh) Poir. was also included in the study as a positive control. Container-grown trees were inoculated with three isolates of P. cinnamomi and symptoms were rated over an 84-day period during the summer of 2008. Disease symptom ratings from 1 (healthy) to 4 (dead) were collected twice weekly and area under the disease progress curve (AUDPC) values were calculated. None of the S. khasiana or S. wallichii exhibited any root rot symptoms or mortality, whereas the remaining species showed symptoms of infection at varying levels over time. Symptoms in F. alatamaha and A. fraseri were apparent before other taxa, and mortality for both species reached 100% by the end of the experiment. Comparison of AUDPC values indicated that F. alatamaha was the most susceptible followed by A. fraseri. There was no significant difference in AUDPC among the more resistant taxa, including G. lasianthus, both Schima species, and the intergeneric hybrids. Values for AUDPC in the hybrid taxa were similar to their more resistant parental genus, indicating that resistance to P. cinnamomi is a partially dominant trait in these plants. These results further suggest the potential to breed improved hybrids of Gordonieae trees with substantial resistance to P. cinnamomi.
Susceptibility of Geranium Cultivars to Ralstonia solanacearum
Authors: Norman David J. , Huang Qi , Yuen Jeanne M.F. , Mangravita-Novo Arianna , Byrne Drew
Published: February 2019

Sixty-one cultivars of geraniums, including zonal, regal, ivy, and scented, were tested for susceptibility to three strains of Ralstonia solanacearum: a race 1, biovar 1 (R1B1) strain P597 isolated from tomato in Florida, a R1B1 strain P673 obtained from pothos originated from Costa Rica, and a race 3, biovar 2 (R3B2) strain UW551 isolated from geranium imported from Kenya. These three strains represent populations of R. solanacearum found in the United States or imported with infected plant propagative material. A genomic comparison of the geranium cultivars was also done using amplified fragment length polymorphisms. Both R1B1 strains were more virulent than the R3B2 strain, producing wilt symptoms on most cultivars of zonal, regal, and ivy types. Variation in susceptibility of geranium cultivars to the two R1B1 strains was observed. The R3B2 strain UW551 had a much more restricted host range and was not able to infect most regal geranium cultivars when applied as a soil drench. Many of the scented cultivars were found to be resistant to all three strains of R. solanacearum when tested using the drench inoculation method. However, most scented cultivars were found to be susceptible when plants were wound-inoculated. The greatest variation in type of resistance was observed between the scented geranium cultivars and specific strains of R. solanacearum.
In Vitro Propagation of Viburnum treleasei Gand., an Azorean Endemic with High Ornamental Interest
Authors: Moura Mónica , Candeias Maria Irene , Silva Luís
Published: February 2019

The purpose of our research was to establish a protocol for the in vitro culture of Viburnum treleasei, a rare and endangered taxon with high ornamental potential endemic to the Azores islands. The surface sterilization of the explants was better achieved with a pretreatment of 0.1% (w/v) Benomyl for 2 h followed by 0.2% (w/v) HgCl2 for 10 min with agitation. Shoot tips were the most efficient explants for shoot development and single-node segments for proliferation. Woody plant medium (WPM) was adequate for all micropropagation stages. For culture establishment and shoot development, a hormone-free medium was adequate, whereas a 1.1 μM N6-benzyl adenine medium supplement was more efficient for shoot multiplication. Elongation and rooting could be carried out on a 1.3 μM 1-naphthaleneacetic acid-supplemented medium. Acclimatization of in vitro-produced plantlets was achieved after 1 month with a success rate of 50%. This in vitro propagation procedure will be useful for the conservation of Viburnum treleasei through production of morphologically true-to-type plants, allowing the recovery of depleted natural populations. Chemical names used: N6-benzyl adenine (BA); 1-naphthaleneacetic acid (NAA); HgCl2 (mercury bichloride).
Large-scale Micropropagation of Aloe vera
Authors: de Oliveira Enio Tiago , Crocomo Otto Jesu , Farinha Tatiana Bistaco , Gallo Luiz Antônio
Published: February 2019

A protocol for large-scale Aloe vera (L.) Burm. f. production was established using micropropagation of apical buds. The effects of two chlorine-based disinfectants were evaluated on the survival of the explants in different treatments in a semisolidified Murashige and Skoog (MS) medium in the presence of 6-benzylaminopurine (6-BAP; 2 mg·L−1). During 120 days, 136 green apical shoots bearing axillary buds were multiplied four times at 30-day intervals in the same MS medium, reinoculating seven to nine explants per flask each time. The elongation and rooting processes were carried out in the same MS medium without 6-BAP. A total of 40,495 Aloe vera microplants were obtained, a yield of 300 microplants per apical bud at a rate of 1:5.3 in every multiplication period of 30 days. From that total, 38,480 Aloe vera microplants were successfully acclimatized transferring to 36- and 64-cell polyethylene trays containing proper substrate in two different ex vitro greenhouse conditions. After a 3-month period, fresh and dry matter weights of the Aloe vera plants were determined. All the data from each experimental phase were statistically analyzed. The use of 64-cell (40 cm3/cell) trays represented an economy of 47.37% in greenhouse space and 50% in the amount of substrate per Aloe vera plant.
Posttransplant Irrigation Frequency Affects Growth of Container-grown Sweet Viburnum in Three Hardiness Zones
Authors: Shober Amy L. , Moore Kimberly A. , Wiese Christine , Scheiber S. Michele , Gilman Edward F. , Paz Maria , Brennan Meghan M. , Vyapari Sudeep
Published: February 2019

The survival and quality of shrubs planted in the landscape from containers is dependent on irrigation to ensure the development of a healthy root system. This study determined the effect of irrigation frequency on survival, quality, canopy growth index, root to canopy spread ratio, and dry root and shoot biomass of Viburnum odoratissimum Ker-Gawl. (sweet viburnum) planted in Florida in USDA hardiness Zones 8b (Citra, FL), 9a (Balm, FL), and 10b (Ft. Lauderdale, FL). Sweet viburnum shrubs were planted into the landscape from 11.4-L (#3) containers and irrigated with 3 L every 2, 4, or 8 days. Shrubs were planted on eight dates over a 2-year period (2004 to 2006). Irrigation frequency during the 12- to 22-week irrigation period had no significant effect on sweet viburnum survival or aesthetic quality at any location. In addition, there was no irrigation effect on root spread, root to shoot biomass ratio, or root biomass for shrubs planted in Zones 8b or 9a. However, sweet viburnum irrigated every 2 days had greater canopy growth index at 28 and 104 weeks after planting than shrubs irrigated every 4 or 8 days in Zone 8b and every 8 days in Zone 9a. When planted in Zone 10b, sweet viburnum irrigated every 2 days exhibited greater growth index, shoot biomass, and root biomass than plant receiving irrigation every 4 days. Although more frequent irrigation (every 2 days) resulted in more plant growth in Zones 8b and 10b, sweet viburnum survived and grew after planting under natural rainfall conditions provided they were irrigated with 3 L of water every 8 days during establishment until roots reached the canopy edge in hardiness Zones 8b and 9a and every 4 days in hardiness Zone 10b. Subsequent supplemental irrigation (hand-watering) was only needed after irrigation was ended when plants exhibited visible signs of drought stress and there was no measurable rainfall for 30 consecutive days.
Nitrogen and Phosphorous Removal by Ornamental and Wetland Plants in a Greenhouse Recirculation Research System
Authors: Chen Yan , Bracy Regina P. , Owings Allen D. , Merhaut Donald J.
Published: February 2019

A nutrient recirculation system (NRS) was used to assess the ability of four ornamental and three wetland plant species to remove nitrogen (N) and phosphorous (P) from stormwater runoff. The NRS was filled with a nutrient solution with total N and P concentrations of 11.3 and 3.1 mg·L−1, respectively, to simulate high levels of nutrient contaminations in stormwater. Nutrient removal abilities of herbaceous perennial ornamental plants, canna (Canna ×generalis Bailey) ‘Australia’, iris (Iris pseudacorus L.) ‘Golden Fleece’, calla lily [Zantedeschia aethiopica (L.) Spreng], and dwarf papyrus (Cyperus haspan L.) were compared with those of wetland plants arrow arum [Peltandra virginica (L.) Schott], pickerelweed (Pontederia cordata L.), and bulltongue arrowhead (Sagittaria lancifolia L.) in three experiments. ‘Australia’ canna had the greatest water consumption, total biomass production, and aboveground N and P content followed by pickerelweed. ‘Golden Fleece’ iris had higher tissue N concentrations than canna but much lower biomass production. Dwarf papyrus had similar total biomass as pickerelweed but less shoot biomass. N and P removed from the NRS units planted with canna (98.7% N and 91.8% P) were higher than those planted with iris and arrow arum (31.6% and 31.5% N, and 38.5% and 26.3% P, respectively). NRS units planted with dwarf papyrus had similar nutrient recovery rate as pickerelweed, but much less total N and P were removed as a result of less water consumption. The NRS units planted with calla lily had lower nutrient removal than canna and pickerelweed. Our results suggest that canna is a promising ornamental species for stormwater mitigation, and harvesting the aboveground biomass of canna can effectively remove N and P from the treatment system. However, more research needs to be done to evaluate factors that might affect plant performance in a floating biofiltration system.
Influence of Grafted Watermelon Plant Density on Yield and Quality in Soil Infested with Melon Necrotic Spot Virus
Authors: Huitrón-Ramírez María Victoria , Ricárdez-Salinas Marcia , Camacho-Ferre Francisco
Published: February 2019

One of the major problems of watermelon production is the decrease of fruit yield and quality caused by soil diseases. Soil disinfection with methyl bromide (MB) has been used to prevent fungus attacks; however, its use is being restricted because this substance damages the ozone layer. Searching for new MB alternatives, field experiments were carried out in open field in soils infested with Olpidium bornovanus and melon necrotic spot virus in Colima, Mexico, where watermelons had only been grown previously using soil fumigation with MB. Yield and quality of watermelon cultivar triploid Tri-X 313 grafted on two rootstocks of Cucurbita maxima × Cucurbita moschata (‘RS841’ and ‘Shintosa Camelforce’) were evaluated during 2 consecutive years. Each experiment had five treatments, two of them with nongrafted plants at a density of 3472 plants/ha with and without MB fumigation. The remaining three treatments had grafted plants in nonfumigated soil with plant densities of 2778, 2083, and 1740 plants/ha. The use of watermelon grafted on ‘RS841’ and ‘Shintosa Camelforce’ rootstocks significantly increased the average fruit weight and the total yield of watermelon in soil without the need for MB. Grafting may be considered as an alternative MB fumigation. With the use of grafted watermelon plants, planting density may be reduced by 50%, obtaining higher yields than those obtained from nongrafted plants grown on fumigated soil except for ‘Tri-X 313’ grafted on ‘Shintosa Camelforce’ in 2006–2007. Fruits harvested from grafted plants had higher firmness than those harvested from nongrafted plants without affecting the content of soluble solids.
Influence of Aminoethoxyvinylglycine on Pecan Fruit Retention
Authors: Wood Bruce W. , Lombardini Leonardo , Heerema Richard J.
Published: February 2019

Insufficient fruit retention limits profitability of certain pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars. The present study examined efficacy of aminoethoxyvinylglycine (formulated as ReTain®; Valent BioSciences, Libertyville, IL), a natural ethylene inhibitor, for increasing crop-load through increased fruit retention in pecan trees grown at three distinct locations within the U.S. pecan belt. Several years of field studies found that timely postpollination ReTain® sprays [132 mg·L−1 a.i. (11.7 oz./acre)] to canopies could increase fruit retention of ‘Desirable’ and increase crop yield by 16% to 38% in trees carrying a “moderate to heavy” crop. ReTain® did not detectably increase fruit retention on trees carrying a “light” crop-load. The ReTain®-associated increase in yield of “heavy” crop-load trees did not necessarily decrease subsequent year yield. ReTain® appears to offer commercial potential as a crop-load management tool for ‘Desirable’ through regulation of Stage II drop (i.e., June-drop), but may not be efficacious for all cultivars.
Spray Volume, Distribution, and Efficacy of 5-Chloro-3-methyl-4-nitro-1H-pyrazole for Loosening Sweet Orange
Authors: Ebel Robert C. , Burns Jacqueline K. , Morgan Kelly T.
Published: February 2019

The abscission compound CMNP (5-chloro-3-methyl-4-nitro-1H-pyrazole) was applied to fully mature sweet orange trees at different spray volumes using a vertical, multiple-fan air-blast sprayer to determine distribution of fruit loosening throughout the canopy and subsequent effects on mechanical harvester efficiency. CMNP was applied at 0, 935, 1871, and 2806 L·ha−1 in three ‘Valencia’ and one ‘Hamlin’ grove. Spray coverage was measured using water-sensitive paper and fruit loosening was measured by fruit detachment force (FDF). Spray coverage and FDF were measured at 1-, 2-, and 4-m height within the canopy and inside the canopy near the trunk and on the periphery of the canopy. Spray coverage increased with volume of CMNP applied. Spray coverage was higher at 4 m than 1 and 2 m, which were similar. Spray coverage within the canopy was decreased almost half compared with that of the periphery. FDF was unaffected by spray volume at the different heights except in one trial where fruit had higher FDF at 4 m. Fruit inside the canopy did not loosen as much as fruit outside the canopy in three of the four trials. FDF inside the canopy averaged 52 to 84 N, whereas fruit on the periphery of the canopy averaged 50 to 74 N. CMNP promoted fruit drop, but only in two trials was the amount over 5% of the total yield for the 2806-L·ha−1 treatment. The fruit were harvested by canopy shakers that captured fruit on catch frames, except one of the ‘Valencia’ trials in which the canopy shaker did not have a catch frame. The percent of the total crop removed by the harvesters increased when CMNP was applied at higher spray volumes except in the ‘Hamlin’ trial in which there was no difference among volume treatments. The percent of the total crop removed by the harvester but not captured by the catch frame increased at higher volumes of CMNP applied for two of the three trials in which catch frames were used. Fruit loss with greater volume of CMNP applied was promoted by peripheral canopy contact with the front shield of the harvester that knocked fruit down before the catch frame moved under that portion of the canopy. Recovery percentage, or the percentage of total yield that was caught and conveyed to bulk collection by the harvester catch frame, averaged 78.1% to 87.8% of total yield. Higher CMNP volume with increased removal rate compensated for higher catch frame loss, providing overall higher recovery percentage. Based on the goals of minimizing fruit drop and maximizing fruit recovery, the range of FDF that should be reached by harvest is 40 N to 65 N for canopy shakers equipped with catch frames. These trials underscore the importance of adequate CMNP coverage for reducing in-canopy variation of fruit loosening and maximizing fruit removal.
Characteristics of Sugar Content in Different Sections and Harvest Maturity of Bamboo Shoots
Authors: Thammawong Manasikan , Nei Daisuke , Roy Poritosh , Nakamura Nobutaka , Shiina Takeo , Inoue Yuuichi , Hamachi Hidenobu , Nonaka Shigeyuki
Published: February 2019

Bamboo shoots (Phyllostachys pubescens Mazel) harvested from two cultivation areas were used to investigate the amount of accumulated sugars (sucrose, glucose, and fructose) in four sections along the length of a bamboo shoot. Bamboo shoots harvested from above ground (emerged bamboo shoot) and underground of the same cultivation area were also used to study the changes in sugar content during storage at both 5 and 25 °C. The amounts of sucrose, glucose, fructose, and total sugar of underground bamboo shoots were higher than those of emerged shoots. Sucrose content in the apical section was significantly higher than that in other sections. Meanwhile, higher amounts of glucose, fructose, and total sugar (the sum of sucrose, glucose, and fructose) were observed in the basal section. Changes in sugar content were also observed during storage. The fresh, unpeeled bamboo shoots have particular cellular chemical properties and respond differently to storage duration and condition depending on harvest maturity.
Hot Water Treatment in Combination with Rachis Removal and Modified Atmosphere Packaging Maintains Quality of Table Grapes
Authors: Kou Liping , Luo Yaguang , Ding Wu , Liu Xinghua , Conway William
Published: February 2019

Alternatives to sulfur dioxide to maintain quality of table grapes, including various combinations of rachis removal, chlorinated wash, hot water treatment, and modified atmosphere packaging, were explored in this study. Grapes were prepared by cutting off the rachis 1 to 2 mm from the fruit or by keeping the clusters intact. After initial preparation, short-stem and cluster grapes were subjected to chlorinated wash and/or hot water (45 °C, 8 min) treatment and packaged in plastic trays sealed with a gas-permeable film. The treated grapes as well as the commercially packed grapes (COM) in their original packages were stored at 5 °C for up to 4 weeks. Hot water treatment resulted in significantly (P < 0.05) higher oxygen retention and lower carbon dioxide accumulation in package headspaces, maintained a firmer texture, higher overall visual quality, lower decay rate, and lower microbial populations than other treatments or COM during the entire storage period. Grapes that were cut from the rachis and treated with hot water and chlorine maintained the highest quality for 4 weeks with the least decay among all treatments. A chlorine prewash treatment significantly (P < 0.05) reduced microbial populations on cluster grapes and maintained better overall quality. Conventional COM grapes developed dark decay and lost turgidity and were of unacceptable quality at 28 days of storage.
Strawberry Bruising Sensitivity Depends on the Type of Force Applied, Cooling Method, and Pulp Temperature
Authors: Ferreira Marcos D. , Sargent Steven A. , Brecht Jeffrey K. , Chandler Craig K.
Published: February 2019

Strawberry (Fragaria ×ananassa Duch.) fruit are very susceptible to mechanical injury and for this reason are normally field-packed. Fruit of three cultivars (Chandler, Oso Grande, Sweet Charlie) were subjected to forced-air or hydrocooling to reach pulp temperatures between 1 and 30 °C and then individually subjected to compression and impact forces representative of commercial handling operations. Strawberries with a pulp temperature of 24 °C exhibited sensitivity to compression but greater resistance to impacts. As pulp temperature decreased, fruit were less susceptible to compression as shown by up to 60% reduction in bruise volume. In contrast, strawberries at 1 °C pulp temperature had more severe impact bruising with up to 93% larger bruise volume than at 24 °C depending on the cultivar. Strawberries also showed different impact bruise susceptibility depending on the cooling method. Impacted fruit that were forced-air cooled had larger bruise volumes than those that were hydrocooled. The impact bruise volume for strawberries forced-air cooled to 1 °C was 29% larger than for fruit hydrocooled to 20 °C, 84% higher than those forced-air cooled to 20 °C, and 164% higher than those hydrocooled to 1 °C. Because incidence and severity of impact and compression bruises are temperature-dependent, strawberry growers should consider pulp temperature for harvest scheduling and for potential grading on a packing line. Hydrocooling shows promise to rapidly cool strawberry fruit while reducing weight loss and bruising sensitivity.
Candidatus Liberibacter asiaticus and Huanglongbing Effects on Citrus Seeds and Seedlings
Authors: Albrecht Ute , Bowman Kim D.
Published: February 2019

Huanglongbing (HLB) is a devastating disease of citrus and threatens the citrus industry worldwide. The suspected causal agent of the disease is a phloem-limited bacterium of the genus Candidatus Liberibacter transmitted through insect vector or grafting with diseased budwood. Currently, most seed source trees for citrus rootstock propagation are located outdoors and unprotected from disease transmission. In addition, fruit from HLB-affected scion varieties in Florida containing seeds enter the commercial trade and move into other citrus-growing areas. The objective of this study was to determine how Ca. L. asiaticus infection affects seed quality and seedling development and whether the disease appears in seedlings grown from infected fruit. Two experiments were conducted involving thousands of seedlings produced from seeds from infected rootstock seed source trees and ‘Valencia’ sweet orange trees, respectively. Infection of trees and fruit with Ca. L. asiaticus significantly reduced seed weight, seed germination, and seedling height. Seedlings did not develop symptoms typical of HLB throughout the experiment. Polymerase chain reaction (PCR) analysis initially identified two of 686 rootstock seedlings and three of 431 sweet orange seedlings positive for the pathogen when they were very young. Resampling and PCR analysis of these five seedlings at older ages consistently indicated they were negative for the pathogen and none of these plants ever developed symptoms of HLB. It is suggested that Ca. L. asiaticus may have been translocated into some part of the embryo during seed development but that it was not present in cells or tissue, which permitted replication or disease development as the seedling grew.
Interactive Effects of Grafting and Manganese Supply on Growth, Yield, and Nutrient Uptake by Tomato
Authors: Savvas Dimitrios , Papastavrou Dimitrios , Ntatsi Georgia , Ropokis Andreas , Olympios C. , Hartmann Hagen , Schwarz Dietmar
Published: February 2019

Tomato (Solanum lycopersicum L. cv. Belladona F1) plants were either self-grafted or grafted onto the rootstock ‘He-Man’ and grown in recirculating nutrient solution with low, standard, or high manganese (Mn) concentrations (2, 15, and 100 μM, respectively). The concentrations of all nutrients except Mn were identical in all treatments. The objectives of the experiment were to test whether grafted tomato plants have a higher or lower ability to withstand deficient or toxic levels of Mn in the root zone and to study the effects of grafting on nutrient uptake and translocation to the aerial organs. Both excessive and insufficient Mn concentrations in the root zone significantly reduced the number of fruit per plant, whereas mean fruit weight was unaffected by external Mn concentrations ranging from ≈1 to 100 μM. The excessive external Mn concentration caused the leaf Mn concentration to increase beyond the critically high level at the expense of leaf and root iron and zinc concentrations but without significant differences between the grafting treatments. The fruit yield of plants grafted onto ‘He-Man’ was significantly lower than that of self-grafted plants when the Mn concentration in the root zone was excessively high. This response might be associated with the lower translocation of magnesium (Mg) to the leaves of plants grafted onto ‘He-Man’ in comparison with the self-grafted plants, resulting in lower Mg/Mn ratios in the leaves. Grafting onto ‘He-Man’ also restricted the leaf and root iron and copper concentrations but enhanced those of potassium. Overall, tomato cv. Belladona proved to be more tolerant to excess Mn than to Mn deficiency in terms of vegetative growth and fruit yield.
Nitrogen Requirements of Drip-irrigated Processing Tomatoes
Authors: Hartz Timothy K. , Bottoms Thomas G.
Published: February 2019

As growers of processing tomato (Lycopersicon esculentum Mill.) adopt drip irrigation, plant vigor and fruit yield typically increase, suggesting a need for re-evaluation of established nitrogen (N) fertilization practices. Trials were conducted in California in 2007–2008 to evaluate growth and N uptake dynamics of drip-irrigated processing tomatoes across N fertigation regimes ranging from deficient to excessive. Whole plants were collected at 2-week intervals for determination of biomass and N content, recently matured whole leaves for total N and petioles for NO3-N. Additionally, six commercial fields were sampled at 3- to 4-week intervals to document N uptake and crop N status under conditions representative of the industry. A seasonal N rate of ≈200 kg·ha−1 appeared adequate to maximize fruit yield across the range of field conditions encountered. The four highest-yielding fields (143 Mg·ha−1 mean fresh fruit mass) averaged 14 Mg·ha−1 of above-ground biomass with fruit representing 62%; these fields averaged 296 kg·ha−1 biomass N, of which 71% was in fruit. The rate of biomass development and N uptake peaked during the period between early fruit setting and early red fruit development (a period of ≈6 weeks) during which N uptake averaged 4 to 5 kg·ha−1·d−1. Leaf N concentration was highly correlated with whole plant N (r2 = 0.83) and provided a reliable indicator of plant N sufficiency throughout the season. Petiole NO3-N did not reliably discriminate between crops with adequate or deficient N availability; current petiole NO3-N sufficiency guidelines are unrealistically high.