Commercial Pear Cultivars Research Articles

Virusi i viroidi kruške

One of the most common fruit species in the world is the pears. Compared to stone and small fruit trees, pears and other pome fruits are infected by a lesser number of viruses and viroids. The majority of commercial pear cultivars do not exhibit symptoms on their leaves, fruits, or other plant parts due to viruses. Only foliage and fruits show symptoms in susceptible cultivars. Apple stem pitting virus (ASPV), apple stem grooving virus (ASGV), apple chlorotic leafspot virus (ACLSV), and apple mosaic virus (ApMV) are widespread and economically significant pear viruses. Pear blister canker viroid (PBCVd) and apple scar skin viroid (ASSVd) are the most dangerous viroids infecting pears.

A Comparative Study of Ten Pear (Pyrus communis L.) Cultivars in Relation to the Content of Sugars, Organic Acids, and Polyphenol Compounds.

Traditional pear cultivars are increasingly in demand by consumers because of their excellent taste, the possibility of use in sustainable food production systems, convenience as raw materials for obtaining products of high nutritional quality, and perceived health benefits. In this study, individual sugars, organic acids, and polyphenols in the fruits of nine traditional and one commercial pear cultivar during two growing seasons were determined by HPLC. A significant influence of cultivars, growing years, and their interaction on the content of analyzed primary and secondary metabolites was determined. The commercial pear cultivar ‘Président Drouard’ and traditional cultivars ‘Dolokrahan’, ‘Budaljača’, and ‘Krakača’ had a lower content of all analyzed sugars. Overall, traditional pear cultivars had higher total polyphenols in the peel and pulp than ‘Président Drouard’, with the exception ‘Takiša’ and ‘Ahmetova’. High polyphenol content detected in ‘Budaljača’, ‘Dolokrahan’, and ‘Krakača’ shows the utilization value of traditional pear germplasm. The obtained data can serve as practical supporting data for the use of traditional pears in the neutraceutical, pharmaceutical, and food industries.

Analysis of the Fruit Quality of Pear (Pyrus spp.) Using Widely Targeted Metabolomics.

Pear is a kind of common temperate fruit, whose metabolite composition that contributes to the difference in fruit quality is unclear. This study identified and quantified the metabolites using a widely targeted LC-MS/MS approach in three pear species, including Pyrus bretschneideri (PB), Pyrus usssuriensis (PU) and Pyrus pyrifolia (PP). A total of 493 metabolites were identified, consisting of 68 carbohydrates, 47 organic acids, 50 polyphenols, 21 amino acids, 20 vitamins, etc. The results of PCA and OPLS-DA demonstrated that the metabolite compositions differed distinctly with cultivar variability. Our results also involved some metabolic pathways that may link to the fruit quality based on KEGG pathway analysis, the pathway of phenylalanine metabolism revealed significant differences between PB and PP (p < 0.05). Furthermore, the study selected D-xylose, formononetin, procyanidin A1 and β-nicotinamide mononucleotide as the major differentially expressed metabolites in the three species. The present study can open new avenues for explaining the differences in fruit quality of the major commercial pear cultivars in China.

Qualitative and nutraceutical characterization of ancient Italian and commercial pear cultivars

Qualitative and nutraceutical characterization of ancient Italian and commercial pear cultivars

Growth and Nutrients Uptake in Commercial Pear Cultivars on Seedling, Pyrodwarf® and OH × F69 Rootstocks

Pyrodwarf and OH × F69 rootstocks are the main clonal rootstocks for pear trees in Iran. This research was conducted to compare growth and nutrient uptake in different commercial pear cultivars including; Louise Bonne, Dargazi and William`s Duchesse on Pyrodwarf, OH × F69 and Dargazi seedling rootstocks in two years in the nursery. Both clonal rootstocks inducted higher growth in cultivars. Cultivar Louise Bonne had the highest growth on Pyrodwarf rootstock. Calcium content varied from 1.4% to 1.5%, but nitrogen, phosphorus, potassium and manganese showed higher variation, and the highest content of these nutrients were observed in cultivar Dargazi on Pyrodwarf rootstock. The lowest and the highest variations were observed in zinc and iron content, respectively. In addition, about 30% of total iron of the leaves was active iron, indicating high level of active iron in pear in comparison with other fruit tree species. In all graft combinations, variation in micro and macro nutrients contents were in optimum range. Comparison of nutrient contents with active lime level in soil indicated that the range of 10-15% active lime in soil would not hinder growth and nutrients uptake of plants.

Success Rate of Individual Pollinizers for the Pear Cultivars “Ingeborg” and “Celina” in a Nordic Climate

Norwegian pear production is low due to climatic limitations, a lack of well-adapted cultivars and suitable pollinizers. However, nowadays it is increasing as a result of newly introduced and bred pear cultivars. Since cross pollination is necessary for high yields and good fruit quality, the aim of this investigation was to find the most suitable pollinizers for the pear cultivars “Ingeborg” (“Conference” × “Bonne Louise”) and “Celina” (“Colorée de Juillet” × “Williams”). Self-pollination of “Ingeborg” and “Celina”, together with “Conference”, “Belle Lucrative”, “Anna”, “Clara Frijs”, “Herzogin Elsa”, “Kristina” and “Fritjof” as potential pollinizers, were studied in this experiment during the 2017 and 2018 seasons in Norway. The success rate of each pollinizer was tested under field conditions, while the monitoring of pollen tube growth was done using the fluorescence microscopy method. All reproductive parameters (pollen germination, number of pollen tubes in the upper part of the style, pollen tube number in the locule of the ovary, number of fertilized ovules, initial fruit set, and final fruit set) in all crossing combinations were higher in 2018 due to much warmer weather. Based on the flowering overlap and success rate of each individual pollinizer and fruit set, the cultivars “Anna” and “Clara Frijs” can be suggested as pollinizers for the cultivar “Ingeborg”, while “Fritjof”, “Anna”, “Kristina” and “Herzogin Elsa” for the cultivar “Celina”. An even distribution of two compatible pollinizers having overlapping flowering times with the main commercial pear cultivar is a general recommendation for commercial pear production.

Changes in Sugar Metabolism and Fruit Quality of Different Pear Cultivars During Cold Storage

This study evaluated the changes in sugar metabolism and fruit quality of different pear cultivars during cold storage using seven major commercial pear cultivars belonging to different Pyrus species, such as P. bretschneideri Rehd. (“Huangguan,” “Yali”), P. pyrifolia Nakai. (“Wonhwang,” “Hosui”), P. ussuriensis Maxim. (“Jingbai,” “Nanguo”), and P. communis L. (“Bartlett”). The firmness, respiration rate, titratable acidity, total soluble solids, sugar content, and enzyme activity of the seven pear cultivars were investigated. SPSS was used for analyzing the significance of different indexes. Results showed that fructose was the dominant sugar, accounting for > 60% of total sugars, followed by glucose and sucrose. The respiration peak of almost all cultivars appeared within 60 days. The levels of fructose, glucose, sucrose, and total soluble solids increased within 90 days and then generally decreased. Acid invertase showed the highest activity among all pear cultivars, followed by neutral invertase, sucrose synthetase, and sucrose phosphate synthetase during storage.

Microsatellites as a tool for identifying successful pollinators of the pear cultivar ‘Ingeborg’ in Ullensvang, Norway

Due to their Mendelian inheritance, microsatellites or SSRs (simple sequence repeats) can readily be used for parentage analyses of pear seedlings, thus revealing the female and male parents of the plant. However, in cases where obtained pear seeds display low viability, conducting a parentage analyses on the pear seeds themselves could be used in order to identify the male parent (successful pollinator). In this study, batches of seeds were extracted from fruits of the triploid ‘Ingeborg’ pear (‘Conference’ × ‘Bonne Louise’), the main commercial pear cultivar in Norway. Mature pears were collected from eight commercial pear orchards located in Ullensvang, at 60° North and seeds were collected. Genomic DNA was subsequently isolated from the obtained seed batches and genotyped using 12 microsatellite markers. The same markers were also used for the genetic characterization of ‘Ingeborg’ and five pear genotypes used as pollinators in the sampled orchards (‘Clara Frijs’, ‘Herzogine Elsa’, ‘Anna’, ‘Coloree de Juillet’ and ‘Belle lucrative’). The obtained SSR profiles were used in paternity analyses, as well as for gene assignment analyses. Both approaches identified pear ‘Clara Frijs’ to be the most successful pollinator in most of the sampled orchards. Subsequent S allele genotyping of ‘Ingeborg’ and five pear genotypes used as pollinators in the sampled orchards revealed that the preferential pollination by individual genotypes was not caused by gametophytic incompatibility or semi-compatibility.

Study on Pollination and Selection of the Most Suitable Pollinizers for Commercial Pear Cultivars (Pyrus communisL.) in Iran

AbstractThe cultivated pear is an economically important fruit tree species of genusPyrusin which often gametophytic self-incompatibility occurs. Therefore, this species need to be pollinated by cross-compatible cultivars that bloom in the same time. Selection of appropriate pollinizers for pear cultivars is very important to produce commercial yield. ‘Sebri’, ‘ Shahmiveh’ and ‘Natanzi’ are the best commercial cultivars in Iran, but the lack of a suitable source of pollen can reduce productivity. In order to select the most suitable pollinizer for these pear cvs, an experiment was conducted in which they were considered as pollen recipients and ‘Coscia’, ‘Bartlett’ and ‘Sardroud’ along with ‘Sebri’, ‘Shahmiveh’ and ‘Natanzi’ were evaluated as pollen donors. This research was conducted as a factorial experiment in randomized complete block design for four years. Recipient and donor cultivars had almost overlapping flowering time. The flower buds on selected branches were emasculated at balloon stage and then were counted and isolated with cotton tissue bags. Pollen grains of these pollinizers were collected in the laboratory. Isolation bags were taken off from the branches and emasculated flowers were pollinated with pollen grains of listed pollinizers during receptibility of stigma. The number of pollinated flowers was counted, and branches were covered again with the bags. The results showed that for ‘Sebri’ the best pollinizer was ‘Coscia’ with 5.7% fruit set, for ‘Shahmiveh’ ‘Bartlett’ cv. with 5.8% of fruit set and for ‘Natanzi’, ‘Shahmiveh’ with 5.5% of fruit set.

Pollinizer Efficacy of Several ‘Ingeborg’ Pear Pollinizers in Hardanger, Norway, Examined Using Microsatellite Markers

‘Ingeborg’ is currently the main commercial pear cultivar grown in Norway. However, fruit set and subsequent yields of this cultivar have proven to be variable and overall low averaging 10–20 t·ha−1. Pear seeds found in ‘Ingeborg’ fruits are often underdeveloped, suggesting that incomplete fertilization might be a major cause of poor fruit set. In some years, sporadically unfavorable environmental conditions during and immediately after pollination in Hardanger district, western Norway, have resulted in poor fruit set of ‘Ingeborg’. In this study, the pollinizer efficacy of several pollinizers, namely ‘Clara Frijs’, ‘Herzogin Elsa’, ‘Anna’, ‘Colorée de Juillet’, and ‘Belle lucrative’, from several orchards located in the Hardanger district was investigated using 12 microsatellite markers for two growing seasons (2014 and 2016). Pollinizer efficacy was estimated by genotyping ‘Ingeborg’, each individual pollinizer, as well as normally developed seeds from ‘Ingeborg’ fruit, and conducting gene assignment analyses to identify the pollen contribution from each of the pollinizer cultivars. In addition, S-allele genotyping was conducted, and only one pollinizer, ‘Anna’, was identified as being semicompatible with ‘Ingeborg’, whereas all other pollinizers were fully compatible. ‘Clara Frijs’ and ‘Belle lucrative’ were identified as the most efficient pollinizers probably because these cultivars were abundant compared with all other pollinizers within all, but one of the examined orchards. Higher yields could not be attributed to a particular pollinizer, and genetic effects associated with the triploid nature of ‘Ingeborg’ are most likely implicated as a cause behind the low and variable yield of this cultivar.

Fruchtgewicht, Gesamt-Phenolgehalt, Säure- und Zuckergehalt zum Verzehr geeigneter Früchte der Wildbirne (Pyrus elaeagnifolia Pall. = Ölweidenblättrige Birne)

Wild pear (Pyrus eleagnifolia) is a naturally grown species mainly in inner Anatolia and its edible small fruits are traditionally consumed by local peoples and are called “Ahlat” in Turkey. Its seedlings are also used as rootstock for commercial pear cultivars. In this study, we reported first time pomological characteristics and biochemical compositions in fruits of a wide number selected wild pears genotypes (Pyrus eleagnifolia Pall.) from inner Anatolia. The obtained results revealed that there were significant differences among wild pear genotypes for all analyzed parameters. Fruit weight, total phenolics, total acidity and total sugar contents of the fruits varied from 4.71 to 27.09 g, 42.79 to 119.14 mg GAE/100 g, 0.20 to 1.40 g/100 g and 8.36 to 19.31 g/100 g, respectively. Considering these values, it was concluded that naturally grown wild pears of Anatolia with their rich salubrious biochemical compounds could reliably be used as a food source for humans.

Antioxidant and Antiinflammation Capacities of Some Pear Cultivars

Five commercial pear cultivars were investigated for total phenolics and flavonoids contents, the main phenolic compounds, and their antioxidant and antiinflammation capacities. Four in vitro oxidant and 2 in vivo antiinflammation models were used to evaluate the pharmacological activities of the different pears. The main phenolic compounds were determined by high-performance liquid chromatography with diode-array detector, which result indicated that gallic acid ranged from 5.23 to 10.72 μg/g, catechin from 0.41 to 28.83 μg/g, chlorogenic acid from 485.11 to 837.03 μg/g, caffeic acid from 0 to 1.16 μg/g, epicatechin from 6.73 to 131.49 μg/g, and rutin from 0.92 to 104.64 μg/g. The total antioxidant capacity was in descending order: Shuijing > Fengshui > Xuehua > Ya > Xiang pear, which was consistent with the total phenol and flavonoid contents. Thus, the antioxidant capacity of pears may be attributed to their high contents of phenolics and flavonoids. However, the antiinflammation activity was in decreasing order: Xuehua > Xiang > Ya > Fengshui > Shuijing pear, which indicates that compounds other than antioxidants may be responsible for the antiinflammation effect. The importance on antioxidant activities of phenolic compounds in foods and vegetables as natural antioxidants has reached a new high in recent years. In this study, the total phenol and flavonoid contents, and the antioxidant and antiinflammation activities of 5 different types of commercial pears in China were investigated, which may be the experimental basis for the further development and utilization of the pears.

First Report of Pear blister canker viroid in Pear Trees in Argentina.

During December 2009 and January 2010, pear trees (Pyrus communis L.) from five orchards located in Allen (Alto Valle) and one in Rio Colorado, both in Rio Negro Province in Argentina, were randomly sampled for Pear blister canker viroid (PBCVd). Ninety-six trees were tested, 20 of cv. Williams, 4 of Abate Fetel, 30 of D'Anjou, and 38 of Packhamn, that showed no symptoms of PBCVd, plus four trees of cv. Red Bartlett that exhibited symptoms of bark pustules and rounded, scaly cankers varying from 2 to 6 cm in diameter on the stems. Purified dsRNA from leaves of 96 trees were analyzed by dot-blot hybridization with a specific probe for PBCVd (2). Of the plants tested, 18 were positive for PBCVd. Three of the positive dsRNAs, with a higher dot-blot signal, were analyzed by electrophoresis in 5% nondenaturing polyacrylamide and a second denaturing polyacrylamide gel. A band, in the portion of viroids migration, was detected with ethidium bromide. The segment corresponding to the three bands was excised and electroeluted. Two-step reverse transcription (RT)-PCR was performed using Moloney-murine leukemia virus (M-MLV) reverse-transcriptase (Promega Corporation, Madison, WI), retrotranscriptase, and PBCVd primers F-5'-GCGGGACAGAAGACGAGGCTCAGGCAGGAAGCAAC-3' and R-5'-TATAAAAGAAAAAAGCGCTTCGGCGGTGCTCGGG-3' (3). The product was legated into pUC 19 vector (Fermentas Inc., Glen Burnie, MD) and cloned following the manufacturer's instructions. Four clones were sequenced by the Unidad de Genómica, Instituto de Biotecnología (Argentina) and the sequences were analyzed with the Lasergene Biocomputing Software for Windows (version 8.0.2; DNASTAR, Madison, WI). The four partial sequences of 296 nucleotides from the local sequences were identical to each other and had the highest nucleotide identity (99.7%) with the Spanish PBCVd (GenBank Accession No. D12823). The local sequence was submitted to GenBank (Accession No. HQ606079). PBCVd is a member of the genus Apscaviroid within the family Pospiviroidae. PBCVd is a 316-nucleotide viroid responsible for pear blister canker disease. It causes pustules, cankers, and/or bark symptoms on the pear indicators A 20 and Fieud 37, whereas infections on most commercial pear cultivars remain symptomless (1). These lesions are entry points for other pathogens to infect the plant. This research indicates the need to test pear propagation material in Argentina, since this is the primary way of spreading this pathogen. To our knowledge, this is the first report of PBCVd in Argentina.

Polymorphism of SSR alleles in pear cultivars grown in Belarus

Using SSR markers designed for Malus x domestica Borkh, genetic polymorphism of 43 pear accessions cultivated in Belarus was examined. A total of 217 alleles were identified with the mean number of 12.8 alleles per marker. The mean PIC value was 0.81; the mean number of informative alleles, 6.49. The heterozygosity level ranged from 0.30 to 0.84. Genetic diversity of SSR alleles in pear and apple genomes was compared. A method of identification of commercial pear cultivars using a set of six SSR markers was suggested.

Chemical compositional characterization of eight pear cultivars grown in China

The sugar, organic acid, amino acid and fatty acid compounds of eight commercial pear cultivars were identified and quantified using high-performance liquid chromatography (HPLC) equipped with RI and UV detectors and gas-chromatography (GC) equipped with FID detector. The mineral composition was determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed great quantitative differences in the composition of the pear cultivars. Fructose was the dominant sugar in the eight pear varieties, followed by glucose and sucrose, while malic acid was the principal organic acid. The C16:0, C18:0, C18:1, C18:2 and C18:3 fatty acids were clearly the most abundant fatty acids, and the C18 family comprised more than 70% of the total fatty acids content. Asparagine and serine were the principal amino acids. Potassium is the most abundant mineral, followed by magnesium and calcium. The results provide important information on how to make the best use of pear cultivars investigated for different uses, which is of significance for both technological research and processing practice.

(96) Sensory Evaluation of Alternative Pear Varieties for the U.S. West Coast

Assessing consumer acceptance is an important aspect of cultivar evaluation. Since 2002, about 2700 consumers have participated in pear preference surveys. Surveys were conducted on multiple dates and at multiple venues from 2002 to 2005 in Oregon and northern California. Survey participants were asked to indicate their preference for pears based on size, appearance, taste, and overall preference. They were also asked to indicate what attributes they liked or disliked about their favorite and least favorite varieties and to indicate their level of purchase intent. Each survey consisted of four to six cultivars, including at least one standard commercial comparison; i.e., Bartlett, Bosc, or Anjou. Data was analyzed (RCBD; Friedman Analysis of Rank or ANOVA/Tukey's HSD) at the OSU Food Innovation Center Experiment Station using Compusense® five v.4.6 software (Guelph, Ont., Canada). Results indicated several alternative possibilities for both summer and winter sales. Among the most preferred cultivars (variable between states) were Anjou (commercial standard winter pear), Bartlett (commercial standard summer pear and most-consumed cultivar), Blake's Pride, Cinnamon, Concorde, and 71655-014. Other major findings were preference for large pears for adults and small for children, overall liking based on sweetness and flavor rather than skin color, and general lack of knowledge of many commercial pear cultivars. Sensory evaluation surveys will be continued in 2006 in California, with focus on differential harvest times for selected preferred cultivars. Consumer preference data is being combined with production and postharvest quality data in order to provide the pear industry a comprehensive data set on potential alternative cultivars.

Pear Blister Canker Viroid: Host Range and Improved Bioassay with Two New Pear Indicators, Fieud 37 and Fieud 110.

An investigation was conducted to improve the biological detection of pear blister canker viroid (PBCVd), which over a period of 2 to 3 years induces pear blister canker disease on the perry pear (Pyrus communis) cv. A20. PBCVd was not detected by dot blot hybridization or bioassay in any of the tested species of Amelanchier, Aronia, Cotoneaster, Crataegus, and Pyracantha. However, some species of Chaenomeles, Cydonia, and Sorbus, five out of 13 species of Malus, 15 Pyrus species, and 16 commercial pear cultivars were susceptible to PBCVd, although none developed symptoms. Only in perry pear seedlings did approximately 5% of the population react to infection with pure PBCVd strains by developing petiole, leaf, or bark necrosis 2 to 3 years (cv. A20) or 3 to 5 months (cv. Fieudière) after inoculation. The selected Fieud 37 and Fieud 110 clones are proposed as PBCVd indicators to replace A20. Results from bioassays on the indicators and from detection by a PBCVd-cRNA probe were essentially in agreement except for some Malus species.