Triumph Pears Research Articles

Early impact assessment of the paninvasive polyphagous shot hole borer beetle on commercial pear production

AbstractThe polyphagous shot hole borer (PSHB) beetle, Euwallacea fornicatus (Eichhoff) (Coleoptera: Curculionidae, Scolytinae), and its phytopathogenic fungal symbiont (Fusarium euwallaceae Freeman et al.) threaten commercial and urban tree species worldwide. This pest–fungus complex has been newly discovered in the commercial deciduous fruit industry (Western Cape, South Africa), where its effect is still unknown. This study explored the impact of PSHB infestation on fruit quality and plant water‐use efficiency (WUE) – as indicated by carbon and nitrogen stable isotope ratios – of commercially cultivated Packham's Triumph pear trees within the first year of invasion, as well as changes in phenotypic plasticity (trait expression range). The impact of PSHB infestation is currently most evident in fruit quality traits, with a clear distinction between the control and most densely attacked tree categories. Fruit and leaf traits showed high variation and a significant change in phenotypic plasticity. Increased PSHB attack density was associated with smaller, duller‐toned, sweeter fruit at the time of harvest and data tended towards reduced plant WUE. Producers can expect significant variation in fruit quality and plant WUE even in hosts without branch dieback, visible plant stress or extensive beetle breeding, especially in orchards where infestations persist beyond the first year. These findings necessitate additional research to describe the long‐term impact, examine the threat to other deciduous fruit crops and cultivars and assess the need for adapted management or harvesting methods.

Statistical media optimization using cheese whey powder for production of Vishniacozyma victoriae postharvest biocontrol yeast in pears

Vishniacozyma victoriae NPCC 1263 was selected for this work because of the active antagonistic effect over several fungi. A cheese whey powder (CWP) based medium for the maximum biomass production of biocontrol agent was statistically optimized using a central composite design based on response surface methodology (RSM). The optimization condition was found to be in g/L: CWP 80, KH2PO4 10, (NH4)2SO4 1.2 and, under optimum conditions, the biomass production in a 15-L fermenter was about 15 g/L after 74/78 h cultivation. The efficacy of V. victoriae NPCC 1263 for controlling postharvest decay of pear fruits was evaluated in semicommercial packing-house conditions with the application of 108 CFU mL−1 yeast cells, with CaCl2 (2 % w/v) addition in two treatments, fresh and lyophilized-rehydrated biomass on Packham's Triumph pear cultivars. After 150 days of storage, lyophilized-rehydrated biomass treatment reduced the incidence caused by B. cinerea, P. expansum and Cladosporium spp., reaching 36 %, 71 % and 55 % of control respectively. The fresh biomass treatment reached 47 % and 58 % of control for B. cinerea and P. expansum, but no control for Cladosporium spp. was observed. The two treatment yeasts were able to control decay and colonize the surface of the fruits during the postharvest period, with an estimated increase in the population density of approximately-three log units independently of the treatment applied.

Packham's Triumph Pears (Pyrus communis L.) Post-Harvest Treatment during Cold Storage Based on Chitosan and Rue Essential Oil.

Pears (Pyrus communis L.) cv. Packham’s Triumph are very traditional for human consumption, but pear is a highly perishable climacteric fruit with a short shelf-life affected by several diseases with a microbial origin. In this study, a protective effect on the quality properties of pears was evidenced after the surface application of chitosan-Ruta graveolens essential oil coatings (CS + RGEO) in four different concentrations (0, 0.5, 1.0 and 1.5 %, v/v) during 21 days of storage under 18 °C. After 21 days of treatment, a weight loss reduction of 10% (from 40.2 ± 5.3 to 20.3 ± 3.9) compared to the uncoated pears was evident with CS + RGEO 0.5%. All the fruits’ physical-chemical properties evidenced a protective effect of the coatings. The maturity index increased for all the treatments. However, the pears with CS + RGEO 1.5% were lower (70.21) than the uncoated fruits (98.96). The loss of firmness for the uncoated samples was higher compared to the coated samples. The pears’ most excellent mechanical resistance was obtained with CS + RGEO 0.5% after 21 days of storage, both for compression resistance (7.42 kPa) and force (22.7 N). Microbiological studies demonstrated the protective power of the coatings. Aerobic mesophilic bacteria and molds were significantly reduced (in 3 Log CFU/g compared to control) using 15 µL/mL of RGEO, without affecting consumer perception. The results presented in this study showed that CS + RGEO coatings are promising in the post-harvest treatment of pears.

The antimicrobial activity of biogenic silver nanoparticles synthesized from extracts of Red and Green European pear cultivars

Green nanotechnology stands amongst the leading giants of innovation for the twenty first century technological advances. More interesting, is the use of natural products as reducing agents. These could be recyclable materials from fruits and vegetables to produce nanoparticles (NPs) with novel properties. In the current study, silver NPs (AgNPs) were synthesized using the water extracts from the peel and flesh of two Pyrus communis L. cultivars, namely, the Forelle (Red) Pears (RPE) and Packham Triumph (Green) Pears (GPE). The AgNPs were characterized by UV-Vis spectrophotometry, Dynamic Light Scattering (DLS), High Resolution Transmission Electron Microscopy (HRTEM) and Fourier Transform Infra-Red Spectroscopy (FTIR). The antibacterial activities of the AgNPs were evaluated using agar well diffusion and microdilution assays. The cytotoxicity of the AgNPs was investigated on a rat macrophage (RAW 264.7) cells using MTT assay. Both the RPE and GPE were capable of synthesizing the AgNPs at high temperatures (70 and 100 °C). The AgNPs exhibited antibacterial activity against the test strains, and also had low toxicity towards the RAW 264.7 cells. Thus, the synthesized AgNPs have a potentially viable use in bio-applications for treatment of bacterial infections.

Understanding the key preharvest factors determining ‘Packham’s Triumph’ pear heterogeneity and impact in superficial scald development and control

Abstract Although superficial scald (SS) is well characterized on apples, there is still few information regarding the influence that initial fruit’s maturity heterogeneity may have on the development of this disorder on pears. In this study we aimed to understand the effect of growing season and site, harvest maturity, and their interaction with postharvest treatments on superficial scald development. Pears (Pyrus communis L.) cv ‘Packham’s Triumph’ were picked during three consecutive seasons at three harvest maturities (H1, H2, H3) from different commercial orchards. Different SS control treatments (DPA vs. 1-MCP; season # 2) and storage scenarios (RA, CA and RA + stepwise cooling (SWC); season # 3) were evaluated. Bioclimatic indices, superficial scald incidence, maturity indices and biochemical analysis associated with SS were carried out at harvest and periodically postharvest in all treatments. In general, bioclimatic indexes (GDA and HL10) were poorly correlated with SS incidence. Only in season #1, harvest maturity was positively correlated with SS after 140 and 180 d into storage (rs = 0.621* and 0.620*, respectively), the more mature fruit being more sensitive. The opposite was observed in season #3, and no pattern in season #2. There was a good and positive correlation between CTols dynamic (δCTols/δt) and SS development, with variation between seasons. DPA and 1-MCP effectively reduced SS up to 180 d regardless of years and orchard location. In contrast, the beneficial effect of CA storage was orchard dependent and SWC strategy did not control SS and affected fruit quality. Collectively our results suggest that initial fruit heterogeneity at harvest is an important factor that modulate SS development in ‘Packham triumph pears. Climatic and fruit maturity indexes are not reliable for a multi-year prediction of SS development. In contrast to CA storage that reduced the disorder in an orchard dependent manner, 1-MCP and DPA treatments effectively controlled SS independently of initial fruit heterogeneity.

Semi-commercial testing of regional yeasts selected from North Patagonia Argentina for the biocontrol of pear postharvest decays

The efficacy of two regional yeasts, Pichia membranifaciens NPCC 1250 and Vishniacozyma victoriae NPCC 1263, for controlling pear postharvest decay was evaluated at large scale (semi-commercial conditions) in two different packing houses. The human safety of the two yeast strains was initially assayed by assessing growth at body temperature, pseudohyphal growth, phospholipases production, and growth in simulated gastric juice. Subsequently, yeasts biomass was produced in a bioreactor (22 L) containing 18 L of culture medium based on sugarcane molasses plus urea. The produced biomass, with/without CaCl2 (2% w/v) addition, was used in biocontrol experiments carried out at semi-commercial scale on Beurre d'Anjou and Packham’s Triumph pears. Vishniacozyma victoriae NPCC 1263 plus CaCl2 showed high performance on controlling decay caused by Penicillium expansum and Botrytis cinerea. On Beurre d'Anjou cv, P. expansum and B. cinerea incidence was reduced by 70% and 100%, respectively, after 90 days of commercial storage. On Packham’s Triumph the incidence of the two decay forms was 63% after 150 days. The two antagonistic yeasts were able to establish and colonize the surface of the fruits, with an estimated increase in the population density of approximately three orders of magnitude during the postharvest period. This work is the first to evaluate and demonstrate the efficacy of local biocontrol experiments with regional yeasts under semi-commercial conditions.

The cell regeneration and connection of grafting between pear and quince trees are defined by the cortex and phloem

Pear cultivation in the tropics currently requires the complex use of Pyrus calleryana or Chaenomeles sinensis rootstocks with Cydonia oblonga interstocks. The objective of the present study is to quantify the different proportions of tissues in rootstock-interstock combinations established to obtain saplings. Packham's Triumph pear (scion) was double grafted by cleft grafting onto interstocks of C. oblonga and these combinations were subsequently grafted onto C. sinensis or P. calleryana rootstocks. The sprouting percentage was evaluated passed 150 days. Subsequently, the anatomy of the connections between the scion and interstock and the interstock and rootstock was examined. The following characteristics were evaluated: xylem parenchyma ray area of each grafting component (scion, interstock and rootstock); total connection area; connection areas between xylem-xylem, phloem-phloem, phloem-cortex, and cortex-cortex; percentage of xylem, phloem, and cortex for all materials; rootstock area; interstock area; scion area; rootstock/interstock connection area; interstock/scion connection area; and areas with no connection or with necrosis. The data were subjected to analysis of variance and the Scott-Knott test (P ≤ 0.05), and correlations between tissue percentages and connection areas were calculated and considered significant when R2 ≥ 0.6. Only the tissues composing the cortex and phloem were positively correlated with the connection area. The P. calleryana rootstock has greater compatibility with the interstock due to its greater proportion of cortex. The xylem parenchyma rays do not significantly influence cell regeneration or connection. Therefore, woody species that contain more cortex and phloem in the rootstock and/or scion will have greater potential for grafting success.

Effect of cutting and storage temperature on Packham’s Triumph pears (Pyrus communis L.)

En los frutos mínimamente procesados en fresco (MPF) el tipo de corte y la temperatura son factores por considerar para mantener una calidad y apariencia adecuada. El objetivo de este trabajo fue evaluar los efectos del corte y la temperatura de conservación sobre la actividad metabólica, color, firmeza, perfil aromático y concentración de ácidos orgánicos y azúcares de peras (Pyrus communis L. cv. Packham’s Triumph). Los frutos enteros fueron lavados, pelados, cortados en cascos o cubos, envasados en tarrinas y posteriormente almacenados 8 d a 5 o 8 ºC. El tipo de corte y la temperatura tuvieron un efecto significativo sobre los parámetros fisiológicos, color, firmeza y en el contenido de ácidos orgánicos y azúcares. Sin embargo, el contenido de compuestos aromáticos volátiles se redujo independientemente del tipo de corte y las temperaturas de conservación. Por tanto, esta variedad de peras Packham’s Triumph deben ser procesadas en cascos y deben almacenarse a 5º C para mantener una calidad general óptima durante 8 días.

AVALIAÇÃO FENOLÓGICA DA PEREIRA ‘TRIUNFO’ CULTIVADA EM CLIMA SEMIÁRIDO NO NORDESTE DO BRASIL NA SAFRA DE 2012

A fenologia representa uma ferramenta primordial para a inserção de culturas em áreas que apresentam condições diferentes daquelas nas quais estão adaptadas. Opresente trabalho objetivou caracterizar fenológica e produtivamente pereira ‘Triunfo’, sob condiçãosemiárida tropical, no Vale do São Francisco, Nordeste brasileiro. O experimento foi conduzido de 10 de fevereiro a 2 julho de 2012, em pomar experimental, na Estação Experimental de Bebedouro da Embrapa Semiárido,em Petrolina-PE, Brasil. Foram realizadas observações diárias, do estádio de gema dormente até o amadurecimento dos frutos, e foram avaliados os seguintes parâmetros de produção: i) vingamento: a relação entrenúmero de flores e de frutos (%); ii) o número de frutos por planta; iii) produção de frutos por planta (kg); e iv) produtividade (t/ha). O ciclo fenológico da pereira ‘Triunfo’ durou 144 dias, o vingamento obtido foide 11,43%, o número de frutos por planta de 162, produção por planta de 26,34 kg e produtividade de 26,33 t ha-1. Baseado nos resultados obtidos, foi constatada a possibilidade de produção de frutos de pereira emcondição semiárida tropical.

Evolución de Madurez en Pre y Postcosecha y Potencialidad de Almacenaje de Peras Packham's Triumph

A B S T R A C T Packham’s Triumph pears (Pyrus communis L.) were evaluated from four weeks before harvest for maturity and ethylene production. Firmness and soluble solids showed the highest correlations (r = -0.97 y 0.98, respectively) with days after full bloom (DDPF). Ethylene production was low (< 0.07 mg kg -1 ) and was not correlated with DDPF. Fruit harvested with 7.8 (E1) and 7.0 kg (E2) were stored in conventional cold air (0°C) and two controlled atmosphere conditions (AC1: 2-2.5% O 2 /1-1.5% CO 2 and AC2: 1-1.3% O 2 / 0.5-0.8% CO 2 ), -1°C, for six months. Changes in maturity, and ethylene production were measured (monthly) and incidence of physiological disorders was assessed (after four and six months). Additionally, the ethylene production rate (TPE) was monitored for seven days at room temperature, after each storage period. Fruit from both harvests, stored under AC1 and AC2 were firmer, greener and had lower ethylene production than those of FC. There were no significant differences in ripening between AC1 and AC2. Ethylene accumulation was exponential and occurred earlier and with higher values in FC (900 mg kg -1 maximum at the 5 th month), with respect to AC (146 and 230 mg kg -1 for E1 and E2 at the end of the storage period). At room temperature, the TPE of the three storage conditions increased from the second month, but the climacteric peak was observed only in FC. After six months, fruit from FC and from both harvests developed superficial scald (17% for E1 and 20% for E2).

The effect of temperature on infection and a warning system for pear blossom blast caused by Pseudomonas syringae pv. syringae

Blossom blast caused by Pseudomonas syringae pv. syringae van Hall, is a major disease of pears ( Pyrus spp.) in Chile. Freezing temperatures may predispose pears to infection; however, our results demonstrated that blossom blast infection might occur in the absence of frosts, at temperature higher than 5°C, provided that the appropriate inoculum concentration, moisture levels and the susceptible bloom stages were available. Regardless of the flower bud stage development, blossom blast was lowest at 5°C and highest at 20°C. The first symptoms appeared after 2–3 days at 20°C, and were delayed 2 days at 5°C. A significant and positive linear regression best explained the relationship between disease incidence and temperature. A warning system, based on temperature and free moisture conditions, was developed and found to be useful for prediction of blossom blast infection in the field. Antibiotic treatments applied after each warning significantly ( p<0.05) reduced blossom blast on Packham's Triumph pears.

Evaluation of a non-chemical disinfestation treatment on quality of pome fruit and mortality of lepidopterous pests

Australian pome fruit exports to northern America and Japan are rejected if they contain lightbrown apple moth (Epiphyas postvittana Walker) or codling moth (Cydia pomonella Linnaeus) respectively. A warm controlled atmosphere (CA) disinfestation treatment (72 h at 28˚C at 0, 1 or 2 kPa O2 ), followed by varying lengths of cold storage (5 weeks, 10 weeks or 6 months), is described. Four cultivars were studied: Packham’s Triumph pears (Pyrus communis Linnaeus); Royal Gala; Fuji and Pink Lady apples (Malus domestica Borkh.). Consumer panels found that fruit subjected to the 2 kPa O2 warm CA treatment and cold storage were as acceptable as control fruit. This is an important finding as previously published results for a harsher treatment described treated fruit (especially Pink Lady) as being less acceptable than controls. Some advanced ripening was observed for treated Packham’s Triumph pears. After 5 and 10 weeks cold storage, treated Royal Gala apples were generally firmer than the controls. Insects were also subjected to the 2 kPa O2 warm CA treatment. The most tolerant life stage (MTS) of lightbrown apple moth was the sixth instar with an LT95 of 37 days cold storage (0.5˚C) after the 2 kPa O2 warm CA treatment. Comparison with previous research suggests that the 2 kPa O2 warm CA treatment approximately halves the time required in cold storage for effective control of late instar lightbrown apple moth. A LT95 of 81 days was achieved for fifth instar codling moths (considered to be the MTS) and this may need to be reduced for export to Japan. Preliminary observations suggested that there may not be substantial difference between the resistance of non-diapausing and pre-diapausing codling moth larvae to the warm CA followed by cold treatment.

A high temperature/low oxygen pulse improves cold storage disinfestation

Short periods of elevated temperature under controlled atmospheres (CA) effectively control insect pests. Cold treatment is also an effective non-chemical disinfestation process. If synergistic effects can be found by combining treatments, these may provide opportunities for cost reduction. Tests were performed to evaluate the tolerance of Packham's Triumph pears (Pyrus communis L.) to a range of temperatures (30–40 °C) combined with low oxygen (O2 < 1 kPa). Treatment duration was 16–48 h and was followed by 1 month storage at 0 °C under air. When held at 30 °C, pears withstood up to 30 h of hypoxia. After cold storage, pears ripened slightly faster than controls but were undamaged. A temperature of 35 °C induced slight skin browning, and 40 °C resulted in substantial skin blackening. Some treatments were also tested on survival of lightbrown apple moth (LBAM), Epiphyas postvittana (Walker). All developmental stages were subjected to either 16 h at 30 °C, or 16 h under hypoxia, or 1 month at 0 °C, or a combination of the three treatments. With all treatments combined, all eggs, larvae and adults were killed. Only 4% of the pupae produced adults and combined treatments led to an increase in pupa mortality of 38%. A combined treatment (tolerated by pears) consisting of 30 h at 30 °C under low O2 plus 1 month cold storage under air, killed 100% of LBAM pupae, and 100% of 5th instar larvae of both codling moth, Cydia pomonella (L.), and oriental fruit moth, Grapholita molesta (Busck). Implementation of such treatments would not require substantial investments for fruit industries equipped with CA storage facilities.

Absorption and persistence of 2,4,5-TP in Packham's Triumph pear trees

Fruit set of the pear cultivar Packham's Triumph is significantly improved by a post-harvest application of 2-(2,4,5-trichlorophenoxy) propionic acid (2,4,5-TP), implying a persistence long enough to prevent fruitlet abscission the following spring. Since no literature regarding the persistence of 2,4,5-TP in higher plants could be found, it was decided to study its persistence in Packham's Triumph pear tissue following postharvest applications. Residual 2,4,5-TP in the tissues was determined by electron capture gas chromatography. It was found that 2,4,5-TP did not persist in detectable levels in the tissues of potted saplings until spring. However, significant amounts were found in buds of full-grown trees until bud break, as well as in leaves and fruitlets developing from these buds.

Possible metabolites of 2,4,5-TP in Packham’s Triumph pear tissue

This study was undertaken to identify metabolites of the side chain metabolism of 2-(2,4,5-trichlorophenoxy) propionic acid (2,4,5-TP) in leaf and fruit tissues of Packham’s Triumph pear trees by means of paper and thin-layer chromatography. The following compounds were postulated as possible metabolites: 2,4,5-trichlorophenoxyacetic acid (2,4,5- T), 2,4,5-trichlorophenol, 2,4,5-trichloroethoxybenzene and 2,4,5-trichloroanisole. The latter two compounds were not commercially available as standards and were thus synthesized from 2,4,5-trichlorophenol. Leaf and fruit extracts containing radioactive metabolites of 2,4,5-TP were obtained by incubating leaf discs and fruit slices with ring-labelled 14 C-2,4,5-TP. Chromatographic analyses of the extracts did not reveal any of the postulated compounds. However, the possibility that 2,4,5-trichlorophenol may exist as an intermediate that is immediately transformed into a glycoside or ester, cannot be excluded.

The effect of 2,4,5- TP on RNA and protein synthesis in bean explants during abscission

During this investigation the mechanism whereby 2-(2,4,5-trichlorophenoxy) propionic acid (2,4,5-TP) prevents abscission in Packham’s Triumph pears was studied with bean explants as a model system. An attempt was made to indicate a possible relationship between 2,4,5-TP and RNA and protein synthesis. It was found that 2,4,5-TP stimulated the incorporation of precursors into RNA and proteins of abscission zones during Stages I and II of abscission. Actinomycin D and cycloheximide (CHI) prevented abscission and inhibited the activities of cellulase and endo-polygalacturonase (endo-PG) in a similar way as 2,4,5-TP. The finding that 2,4,5-TP (which stimulates RMA and protein synthesis) and actinomycin D and CHI (which inhibits RNA and protein synthesis respectively) similarly affected abscission and enzyme activity, led to the conclusion that 2,4,5-TP probably exerts a selective gene repression during Stage I of abscission. It probably represses only the genes for enzymes involved in abscission, while stimulating the transcription of genes involved in growth and development. The stimulation of abscission following delayed applications of actinomycin D, CHI and 2,4,5-TP probably results from the ability of these compounds to stimulate ethylene evolution. Ethylene in turn could then stimulate enzyme synthesis, since adequate mRNA’s may have been formed prior to the application of the above compounds.

Timing, selectivity and varietal response to mechanical thinning of apples and pears

SummaryMechanical thinning of cv Delicious apples six to ten weeks after full bloom eliminated the need for hand thinning. Fruit removed earlier than six weeks would have shed naturally. Fruit removed after ten weeks was poorly distributed as increasing fruit weight caused the fruiting laterals to hang lower than 45° from the vertical. Mechanical thinning was non-selective for fruit size. Of five pear cultivars examined, Williams, Josephine and, to a lesser extent. Beurre Bosc could be mechanically thinned successfully. The long flexible peduncle was a major limitation in mechanically thinning Packham’s Triumph pears. Mechanical and hand thinning were equally effective in reducing the proportion of small fruit in Williams pears.

Further Studies on Pollination of Packham's Triumph Pears

SummaryThe availability and transport of pollen for fertilization of Packham's Triumph pears was studied in a commercial pear orchard at Doncaster East, Victoria, Australia. Parthenocarpy was found to be of importance in this variety. Temperature and humidity conditions during the trial period were conducive to ripening and dehiscence of the anthers and to high bee activity. Bees formed almost 53% of the insect visitors and were the most effective means of transport of pollen from flower to flower. Enclosing trees in bee-proof cages did not significantly lower fruit set or yield but reduced the mean number of seeds per fruit from 4·5 to 0·1. Airborne pollen concentrations inside and outside the cages were similar.Simulated pear nectar containing only about 7% of sugars was less attractive to bees than simulated apple nectar (about 23% sugars), and the total sugar concentration was more important in this respect than the proportion of sugars in the nectar.

A study on pollination of Winter Nelis pears

The roles of wind and honeybees in the transport of pollen for fertilization of Winter Nelis Pears was studied in a pear orchard at Doncaster East, Victoria. Concentrations of airborne pollen in the orchard were greater between 10.00 a.m. and 4.00 p.m. than during the remainder of the day but were similar inside and outside a 2.5 mm mesh cage. Enclosing the trees in beeproof cages caused a marked decline in fruit yields and in numbers of seeds per fruit. The results of this study are compared with those of a previous study with Packhams Triumph Pears.

A study on pollination of Packham's Triumph pears

The availability of pollen for fertilizing Packham's Triumph pear flowers and its dispersal aerially and by honeybees was studied in the laboratory and in a pear orchard. Ripening and dehiscence of anthers were promoted by higher temperatures and lower relative humidities. More airborne pollen was in the orchard between 10 a.m. and 4 p.m. than during the remainder of the day. Flight activity of bees was related to ambient temperature but not to visits to pear trees. Enclosing trees in beeproof cages did not cause significant effects on yield of fruit or seed counts. The apparent failure of bees to effect pollination of Packham's Triumph pear flowers is discussed.