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The influence of the foliar nutrition on the pear fruit quality (Pyrus communis L.) cv. 'Williams' was studied in years 1997 and 1998. We determined the contents of individual sugars (glucose, fructose, sucrose and sorbitol) and organic acids (malic, citric, fumaric and shikimic) by HPLC (High Performance Liquid Chromatography). The sizes of the fruits (diameter, length, weight) were measured as well as the amounts of soluble solids and titrable acids. The experiment comprised two treatments: the foliar nutrition and the control. In the treatment of foliar nutrition the trees were sprayed five times (from May 22 to July 7) with a foliar fertilizer, which contained 15% of P205, 20% of K20, 0.1% of Mn, 0.1% of B and 0.1% of Mo. The foliar nutrition influenced higher quantities of sugars (glucose, sorbitol, soluble solids) and organic acids (malic, citric) but had no effect on the contents of shikimic acid, pH juice and titrable acids. At the treatment of foliar nutrition a trend of decrease in the contents of fructose, sucrose, fumaric acid, boron, and zinc was noticed.

Twenty-eight 'Bosc' rootstock training system combinations were studied over a 3-year period to determine if differences observed in post-storage problems were related to peel nutrient content. Few significant relationships between peel nutrient content and poststorage problems were found, and none of the relationships were significant over each of the three years of the study as well as the overall three-year period. Stepwise multiple regression analysis likewise found no equations that could effectively predict storage problems over each of the 3 years of the study. The lack of consistent and significant relationships or multiple regression equations strongly suggests that random fruit peel nutrient sampling can not be utilized to predict the occurrence of post-storage problems in 'Bosc' pears. [ABSTRACT FROM PUBLISHER]

Thirty 'd'Anjou' rootstock training system combinations were studied over a 3-year period to determine if differences observed in post-storage problems were related to peel nutrient content. Few significant relationships between peel nutrient content and post-storage problems were found, and none of the relationships were significant over each of the three years of the study. Stepwise multiple regression likewise found no equations that could effectively predict storage problems over each of the 3 years of the study. The lack of consistent and significant relationships strongly suggests that random fruit peel nutrient sampling cannot be utilized to predict the occurrence of post-storage problems in 'd'Anjou' pears. [ABSTRACT FROM PUBLISHER]

Modelling in vivo ethylene production rate in relation to O2 partial pressure was used to improve understanding of enzyme kinetics of 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase). Tomato fruit were stored in an extensive range of O2 partial pressures at 8, 13 and 18 °C. Ethylene production was related to O2 partial pressure using a model based on Michaelis–Menten enzyme kinetics including a term resembling cooperativity. This cooperative model explains the measured data better than two models that were previously used: a logistic model and a model based on Michaelis–Menten kinetics. The model was also used for pear fruit, which had been stored for 0, 13 and 25 weeks. The high accuracy of the cooperative model indicates that ACC oxidase in vivo does not always obey simple Michaelis–Menten kinetics. The possibility of true cooperativity is discussed. [Copyright &y& Elsevier]

A respiration–diffusion model for ‘Conference’ pears was used to simulate three-dimensional internal O2 and CO2 concentration profiles for intact pears as a function of the storage conditions. Although the skin was the major barrier to gas transport, the internal gas gradients in the fruit could not be neglected. Especially at high temperatures, when the respiration rate is high, the internal gradients increased considerably. A sensitivity analysis was carried out to assess the effect of biological variability present on the respiration and diffusion parameters, and on the gas concentration profiles. It was found that at room temperature, the O2 concentration underneath the fruit skin is mainly determined by the O2 transfer coefficient and consumption rate. However, for typical storage temperatures this dependency is less pronounced. A comparison of simulated gas concentration contours of pears stored with delayed controlled atmosphere and those immediately stored under controlled atmosphere (CA), illustrated the importance of an appropriate storage management right after harvest. When CA storage was applied immediately after harvest, the O2 and CO2 concentrations reached very low and very high values, respectively, possibly causing irreversible membrane damage and inducing core breakdown. These values were not found for delayed controlled atmosphere. A model validation experiment on affected pears indicated that the diffusion and respiration parameters for affected tissue were different from those for healthy tissue. [Copyright &y& Elsevier]

A respiration–diffusion model based on Fick''s second law of diffusion and Michaelis–Menten kinetics, including non-competitive CO2 inhibition, was developed to predict the internal O2 and CO2 concentrations in ‘Conference’ pears. The ‘respiration-free’ diffusion and ‘diffusion-free’ respiration parameters, determined in previous independent experiments, were incorporated in the respiration–diffusion model. The system of coupled non-linear partial differential equations was solved numerically for a three-dimensional pear geometry, by means of the finite element method. When Michaelis–Menten kinetics are used to describe a process like gas exchange of fruits, which involves both gas diffusion and respiration, the Michaelis–Menten parameters were assigned a higher value than those obtained when respiration was first uncoupled from the diffusion process and then described by means of Michaelis–Menten kinetics. The maximal O2 consumption and fermentative CO2 production were diffusion-independent, but the Michaelis–Menten constants measured on cell protoplasts were considerably smaller when compared with the corresponding apparent Michaelis–Menten constants determined from respiration measurements on intact pears. The model was successfully validated for its prediction of the total pear gas exchange and the gas concentration under the skin, and is suited to simulating three-dimensional internal O2 and CO2 dioxide profiles in pears as a function of the storage atmosphere. [Copyright &y& Elsevier]

Ethylene production in pear fruit was studied at 2 °C. Several observations showed that the inhibiting effect of CO2 on ethylene production did not operate only via the binding site of the ethylene binding protein. Ethylene production of freshly harvested pears was stimulated by 1‐methylcyclopropene (1‐MCP), but unaffected or inhibited by CO2 which points to different action sites for both molecules. In climacteric pears, where ethylene production was strongly inhibited by 1‐MCP, a range of applied CO2 partial pressures was able to inhibit ethylene production further, to an extent similar to untreated pears. In the case of pears that had been stored for a period of 25 weeks, CO2 only had a clear effect after 1‐MCP pretreatment. Respiration measurements showed that the effect of CO2 on ethylene production did not operate via an effect on respiration. Ethylene production models based on measurements of whole pears were used to study CO2 effects. Kinetic parameters derived from the models point to the conversion from ACC to ethylene by ACC oxidase as a possible action site for CO2 inhibition. [ABSTRACT FROM PUBLISHER]

The dynamics of daily nectar secretion was studied in 28 local pear cultivars in a Hungarian cultivar collection and three main types were distinguished. 1. Cultivars secreting nectar continuously are the most favourable for pollinators, rewarding them both with nectar and pollen. 2. Cultivars with discontinuous nectar secretion have sufficient insect attraction only if anther dehiscence is continuous during the day. In the first two types nectar secretion peaks usually appeared at 9:00 or 10:00, 14:00 or 15:00 and 18:00 or 19:00, with 4–5-hour intervals. 3. In some cultivars no nectar secretion was observed in any or some of the studied years, these being the least attractive for pollinators. The cultivars studied did not necessarily show the same type of nectar secretion dynamics in each season. From the viewpoint of pollination it is also of high importance, in which developmental phase nectar secretion begins. [ABSTRACT FROM AUTHOR]

Two-year-old branches of Pyrus communis L. were classified into groups according to the proleptic (from dormant buds) branching habit, indirectly quantifying the degree of apical control. In winter 1998 upright and flat, 2-year-old branches were randomly sampled from trees of seven pear cultivars, i.e., Forelle (on Quince A and BP1 rootstocks), Abate´ Fetel, Flamingo, Packham’s Triumph, Golden Russet Bosc, Rosemarie and Beurre D’Anjou on BP1 rootstock. For each branch the length and position of the 1-year-old shoots on the 2-year-old axis was determined. Laterals were classified according to length (<1, 1–5, 5–20 and >20 cm) and position (distal to proximal quadrants on the 2-year-old axis); 16 classes in total. The number of shoots per length class per cm quadrant length for each cultivar was subjected to a cluster analysis, then a canonical and a stepwise discriminant analysis. The cultivars were grouped into four groups from group 1 (‘Flamingo’), which resembles a spurred growth habit with strong apical control, to group 4 (‘Packham’s Triumph’ and ‘Golden Russet Bosc’), which resembles a spreading growth habit and weak apical control. Groups 2 and 3 were intermediate. The gravimorphic influences on the branching habit were investigated. [Copyright &y& Elsevier]

The bearing habit of seven pear cultivars was quantified according to the ontogenetic development from axillary buds, i.e. developmental changes in the terminal position of laterals on fruiting branches. Ten non-pruned branches of seven pear cultivars, i.e. Forelle (on Quince A and BP1 rootstocks), Abate´ Fetel, Flamingo, Packham’s Triumph, Golden Russet Bosc, Rosemarie and Beurre D’Anjou (all on BP1 rootstock) were observed. Description started with the development of the main fruiting branch, forming several leaves in the first year of growth (designated year Y), with meristems developing in the leaf axils. In the following season (year Y+1), these buds had five developmental alternatives: to remain as a latent bud (L), to develop as a vegetative bud (V), to become a flower bud without fruit (F), to become a flower bud setting a fruit (P), or to abort and leave a scar (S). Each year the development of these buds was observed and classified anew, giving rise to sequences describing up to 5 years of development. From 44% (‘Beurre D’Anjou’) to 79% (‘Flamingo’) of laterals remained in the growing phase (phase G comprising of V, F or P buds). This coincided with low proportions of buds remaining in the latent phase (L), with even fewer buds moving to the ending state (S; extinction mechanism). A relatively large proportion of growing laterals went from the growing phase back to the latent phase (up to 21% in the case of ‘Beurre D’Anjou’), probably due to inadequate winter chilling. The predominant bud type in the growing stage was vegetative (V). Although flowering was generally low, ‘Flamingo’ and ‘Abate´ Fetel’ became reproductive (F or P) in year Y+3. ‘Packham’s Triumph’ and ‘Rosemarie’ displayed F and P buds in year Y+1, corresponding to the ability of these cultivars to bear fruit on longer 1-year-old shoots. Although the occurrence of the extinction mechanism was low, the higher proportion of latent buds may aid in reducing the number of growing buds, thereby increasing the allocation of assimilates to fruiting structures. This, in combination with the tendency of ‘Packham’s Triumph’ and ‘Rosemarie’ to develop longer, more autonomous shoots, may explain their higher productivity and the occurrence of bourse-over-bourse bearing. [Copyright &y& Elsevier]

The effect of lowering O2 concentration on chlorophyll fluorescence was continuously monitored in apple (Malus x domestica Borkh.), pear (Pyrus communis L.), banana (Musa L. Cavendish subgroup), kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson), mango (Mangifera indica L.), and avocado (Persea americana Mill.) fruit, using a large surface-area sensor. In all of the six fruit, there were specific O2 concentrations at which the Fo and Fv/Fm chlorophyll fluorescence values suddenly increased and decreased, respectively. When the O2 concentrations were increased, the Fo and Fv/Fm signals returned to their previous values. Since the O2 concentrations at which this phenomenon occurred were close to known low O2 thresholds for these fruit, it may be that chlorophyll fluorescence can rapidly and non- destructively determine the lowest acceptable O2 concentration for stored chlorophyll-containing plant products. [Copyright &y& Elsevier]

The genetic diversity of pear local varieties prospected in mountainous areas from Northeastern Spain (Pyrenees and Iberian Cordillera) is not well known so far. In this study, an overall set of 252 accessions (178 prospected in mountainous areas from Aragon and a diverse set of 74 reference cultivars) was analyzed using 14 SSRs in order to estimate its genetic diversity and to identify the genetic structure and relationships among the pear germplasm studied. A total of 251 distinct alleles were successfully amplified with an average of 17.9 alleles per locus and with a wide genetic diversity (mean expected heterozygosity of 0.82). In total, 228 unique genotypes were identified and 210 genotypes were represented by a single accession indicating a situation of extreme vulnerability of these pear genetic resources held in the CITA collection. An amount of 32.9% of accessions were considered triploids displaying three alleles at least into two loci. Genetic analyses performed by a model-based Bayesian procedure, principal coordinate analysis and analysis of molecular variance supported the presence of a genetic stratification with the existence of four sub-groups among the accessions, with a highly significant differentiation (FST = 0.132; p < 0.001). These results shed light on the characterization and genetic relatedness between these local accessions and currently cultivated pear cultivars and highlight the importance to safeguarding this diversity that might be essential for new breeding programs. [ABSTRACT FROM AUTHOR]

Climate change is leading to higher plant water requirements and rootstock can play a role in tree adaptation, since the more vigorous ones are also likely to be more stress resistant. Pear trees of the cv. Abbé Fetél grafted on BA29 (more vigorous) and SYDO (more dwarfing) quince were irrigated according to three different treatments: 110 C, 80 DI and 60 DI, corresponding to 110%, 80% and 60% of the crop evapotranspiration rate (ETc), respectively. Shoot and fruit growth, water potentials, leaf gas exchanges and dry matter content were monitored during the season. Fruit quality was evaluated at harvest and after 6 months of storage at 1 °C. Results show how for both rootstocks, 60 DI significantly decreased their stem (Ψstem) and leaf (Ψleaf) water potentials as well as leaf gas exchanges. In SYDO, final fruit size was affected by irrigation, with lower values on 60 DI, but in BA29, no differences were found between treatments. After storage, BA29 60 DI fruit showed a higher soluble solid content, while in SYDO fruit, firmness was more affected by irrigation level. In conclusion, despite a slight decrease in fruit size, reduced irrigation led to fruit with higher quality features that were also maintained after a long period of storage. [ABSTRACT FROM AUTHOR]

The diploid Celina/QTee® ('Colorée de Juillet' × 'Williams'), one of the most promising pear cultivars developed by the Norwegian breeding program Graminor, was launched in 2010. In Norway, the flowering is medium to late, while the fruits ripen in the beginning of September. The fruits are attractive with an intense red blush (50%) on a green background. Although, 'Celina' is cultivated in the most climatically suitable regions for fruit cultivation, present in Norway, unfavorable environmental conditions for pear pollination can have a very negative effect on fruit set and consequent yield. The aim of this study was to determine the S-alleles of 'Celina', as well as its frequently used pollinizers, and, through paternity testing of 'Celina' seeds, give a recommendation regarding the most important pollinizers of this pear cultivar. In order to accomplish this, 'Celina' and its potential pollinizers were all S-genotyped. After harvest, seeds collected from 'Celina' fruit in 2017 and 2018 were genotyped using eleven microsatellite markers. Genomic DNA was also extracted from leaf material collected from 'Celina', as well as from five pear cultivars used as pollinizers in the three examined orchards, and analyzed using the same marker set. Subsequently a simple sequence repeat (SSR) database was constructed and used for gene assignment analyses with the aim of quantifying pollen donor contribution from individual pollinizers. The obtained results indicate that 'Anna', the only examined pollinizer that was fully cross-compatible with 'Celina', together with 'Fritjof', the genotype which had the highest flowering overlap with 'Celina', proved to be the most successful pollinizers across all seasons and orchards. Although both cultivars were ubiquitous in the examined orchards, either as planted trees or as branches introduced during the flowering period, they were the most abundant pollinizers in only one orchard each. It is therefore possible to conclude that pollinizer abundance has a secondary significance in pollinizer success within investigated 'Celina' orchards. [ABSTRACT FROM AUTHOR]

Precision Agriculture (PA) is a crop site-specific management system that aims for sustainability, adopting agricultural practices more friendly to the environment, like the variable rate application (VRA) technique. Many studies have dealt with the effectiveness of VRA to reduce nitrogen (N) fertilizer, while achieving increased profit and productivity. However, only limited attention was given to VRA's environmental impact. In this study an International Organization for Standardization (ISO) based Life Cycle Assessment (LCA) performed to identify the environmental effects of N VRA on a small pear orchard, compared to the conventional uniform application. A Cradle to Gate system with a functional unit (FU) of 1 kg of pears was analyzed including high quality primary data of two productive years, including also the non-productive years, as well as all the emissions during pear growing and the supply chains of all inputs, projecting them to the lifespan of the orchard. A methodology was adopted, modelling individual years and averaging over the orchard's lifetime. Results showed that Climate change, Water scarcity, Fossil fuels and Particulate formation were the most contributing impact categories to the overall environmental impact of the pear orchard lifespan, where climate change and particulates were largely determined by CO2, N2O, and NH3 emissions to the air from fertilizer production and application, and as CO2 from tractor use. Concerning fertilization practice, when VRA was combined with a high yield year, this resulted in significantly reduced environmental impact. LCA evaluating an alternative fertilizer management system in a Greek pear orchard revealed the environmental impact reduction potential of that system. [ABSTRACT FROM AUTHOR]

• A lumped three-compartment gas exchange model of pear fruit under CA was developed. • In-cell O 2 and CO 2 concentrations are in equilibrium with pore space concentrations. • RQ observed in storage headspace underestimates cellular RQ. A three-compartment non-equilibrium gas transport model of 'Conference' pear fruit under controlled atmosphere (CA) storage was developed. The model fruit tissue consists of cells, in which the concentrations of respiratory gasses can show gradients, and intercellular space, in which gasses are uniformly distributed. Non-equilibrium of gas concentrations in the cell compartment and intercellular space is assumed. A respiration model based on Michaelis-Menten respiration kinetics without inhibition of respiration by CO 2 and incorporating down-regulation of the maximal O 2 consumption rate in response to O 2 was developed. Conversion of CO 2 dissolved in the cell compartment to hydrogen carbonate at a constant pH of 5.0 was included. The model was validated based on experimental data of 'Conference' pear fruit during a complete depletion experiment starting from 3.58 mol m−3 O 2 and 0.00 mol m−3 CO 2. Model predictions match experimental observations well. Gas concentrations in the cell compartment were found to be in equilibrium with the gas concentrations in the intercellular space. The model was used to calculate apparent respiration rates and RQ as if measured in the storage headspace. Apparent values were compared to actual values in the fruit cells and it was found that apparent respiration rates and RQ, calculated based on headspace measurements, underestimated the actual respiration rate and respiratory quotient in the fruit cells. Relative differences of 4 %, 41 % and 41 % were found for the apparent O 2 consumption rate, CO 2 production rate and RQ, respectively. This affects the design of commercial RQ based DCA systems. [ABSTRACT FROM AUTHOR]

Arabinogalactans (AGs) and arabinogalactan-proteins (AGPs) were partially purified from an extract of fruits of the European pear (Pyrus communis L.) by DEAE-cellulose ion-exchange and Sepharose 6B gel-filtration chromatography. Among 7 AG(P)-containing fractions, a neutral AGP (SE-1) was confirmed to be highly purified (M r 67,000) and rich in L-Ara and Gal; this fraction included a small amount (2.6%, w/w) of protein and showed the highest reactivity forming precipitate with β-Glc Yariv reagent among the 7 fractions, the intensity of which was comparable to that of gum arabic, a standard AGP. Another accompanying minor low- M r neutral AGP (SE-2; M r approx. 7200) still contained other polysaccharide (starch fragments) and did not show Yariv reactivity. The carbohydrate moieties of SE-1 consisted of consecutive (1 → 3)-linked β-galactosyl backbone chains substituted with side chains of (1 → 6)-linked β-galactosyl residues at O -6, to which mainly single α- l -arabinofuranosyl residues were attached through O -3. This structural feature was also observed for SE-2. Successive digestion of SE-1 with α- l -arabinofuranosidase and exo-β-(1 → 3)-galactanase with the aid of endo-β-(1 → 3)-galactanase released most (more than 98%, w/w) of the carbohydrate moieties as low- M r fragments. These consisted of free L-Ara and Gal, and a series of β-(1 → 6)-galactooligosaccharides with degree of polymerization (dp) up to at least 17, indicative of attachment of (1 → 6)-linked β-galactosyl side chains of varying length along the (1 → 3)-linked β-galactosyl backbone chains. Image 1 • Arabinogalactan-proteins (AGPs) in European pear (Pyrus communis L.) fruits. • Structure of AG moieties was analyzed by digestion with exo-β-(1 → 3)-galactanase. • Liberated β-(1 → 6)-galactosyl side chains ranged from single Gal up to at least Gal 17. • Single L-Ara f and/or sparse Ara•Ara disaccharide units were attached to the side chains. [ABSTRACT FROM AUTHOR]

ABSTRACT The pear consumption in Brazil is significant and the country is dependent on the import of this fruit to meet the internal market. The aim of this study was to evaluate the vegetative growth of European pear trees grafted on quince with two application forms of nutrients. The study was conducted during the 2012/13, 2013/14 and 2014/15 harvests, in the experimental area of the Universidade do Estado de Santa Catarina / UDESC, in Lages. The cultivars used were Rocha, Santa Maria and Abbé Fétel. The quinces were ‘Adams’ and ‘EMA’. The application forms of the nutrients were conventional and fertigation. The experiment was carried out in a randomized block design and the arrangement of treatments was sub subdivided plots. The application form of nutrients and rootstocks of quince little influenced on the vegetative growth of the plants, being more influenced by the scion in the soil conditions of this study.

ABSTRACT Pear is among the fruits of major commercial interest in the world and one of the most imported in Brazil. Brazilian production is very small and the fruit quality is low, due to production problems. The success of culture in the country, among other factors, may be linked to the choice of cultivars, pollinating and rootstocks better adapted to local conditions, and thus depend on the particulars of an agricultural zoning. The aim of this study was to identify, in southern Brazil, homogeneous climatic zones with potential for growing of European and Asian pears, through climate risk studies. The regions were defined by the seasonal availability of chilling hours (

ABSTRACT The aim of this work was to evaluate the effect of passive modified atmosphere packaging (MAP) on the maintenance of fruit quality during the extended storage of ‘Rocha’ and ‘Packham’s Triumph’ pears. Fruit were packed in linear low density polyethylene (100 mm), with 6% BIF 1500 additive placed into perforated plastic boxes and kept at 0 ± 1 °C and 90 ± 5% RH for up to 180 days. MAP reduced weight loss by 14.8% for ‘Rocha’ and 11.5% for ‘Packham’s’ pears after 180 days in cold storage and retained the green color of the skin, which means that the yellowing visual perception was delayed in 60 and 90 days for ‘Rocha’ and ‘Packham’s’ pears, respectively. A strong softening was observed for ‘Packham’s’ pears after being kept for 150 days at 0° C followed by 5 days at room temperature, which did not limit the storage of both pear cultivars under modified atmosphere packaging. MAP created by linear low density polyethylene (100 mm), with 6% BIF 1500 additive extended in 30 days the cold storage for ‘Rocha’ and 60 days for ‘Packham’s’ pears.