Pears are the third most important temperate fruit species after grapes and apples ( Itai, 2007 ). There are three major species of pear, Pyrus communis (European pear), P. bretschneideri Rehd. or P. ussuriensis Maxim. (Chinese pear), and P
A total of 118 Pyrus sp. (pear) and cultivars native mainly to east Asia were subjected to randomly amplified polymorphic DNA (RAPD) analysis to evaluate genetic variation and relationships among the accessions. Two hundred fifty RAPD markers were scored from 20 decamer primers. RAPD markers specific to species were identified. Clustering analysis revealed two divisions: one comprising cultivars of P. communis L., and the other including all accessions of Pyrus native to east Asia. The grouping of the species and cultivars by RAPD data largely agrees with morphological pear taxonomy. However, some noted incongruence existed between two classification methods. Pyrus calleryana Dcne. clustered together with P. koehnei Schneid., P. fauriei Schneid. and P. dimorphophylla Makino. Pyrus betulaefolia Bge. clustered with P. ×hopeiensis Yu and P. ×phaeocarpa Rehd. A noncultivated clone of P. aromatica Kikuchi et Nakai grouped with P. aromatica cultivars. Pyrus hondoensis Nakai et Kikuchi and cultivars of P. ussuriensis Max. formed a single group. Some accessions from Korea (named Korean pear) had species-specific RAPD markers and comprised an independent group. Most of the Chinese white pears clustered together with most of the Chinese sand pears. Based on the present results, the new nomenclature P. pyrifolia var. sinensis (Lindley) Teng et Tanabe for Chinese white pear was suggested. Most accessions of Japanese pears fell into one main group, whereas pear cultivars from Kochi Prefecture of Japan subclustered with some Chinese sand pears and one accession from Korea. Our results infer that some local Japanese pear cultivar populations may have been derived from cultivars native to Kochi Prefecture in Shikoku region, and that the latter may have been introduced from ancient China and/or Korea.
). Mianli is a cultivar of the Xinjiang pear ( Pyrus sinkiangensis Yü) that belongs to the family Rosaceae (Li and Zhang, 2021). The precise origin of ‘Mianli’ is obscure, but it appears to have been developed in 1987 at the Luntai National Fruit Germplasm
A collection of 60 genotypes-of pear (Pyrus sp.) from East Europe were assayed for ovipositional antixenosis in no-choice cage tests. Five single plant replicates of each genotype, 'Bartlett' (P. communis L.), a susceptible and NY10352 (P. ussuriensis × P. communis BC1 hybrid)' as a resistant control, were stripped to the 6 youngest, but fully expanded leaves, and enclosed in single-plant cages. Four mating pairs of summer-morph adult pear psylla were introduced into each cage. The number of eggs laid on each plant was counted after 5 days. Egg hatch was determined 7 days later, and leaf area was measured. Twelve genotypes, 8 of which are P. communis, were found to be highly resistant to oviposition. These same genotypes had previously been found to exhibit high levels of nymphal feeding antixenosis and antibiosis. The results will be discussed in light of ovipositional cues and host acceptance-related behavior of the pear psylla.
Shoot tips of ‘Almey’ crabapple [Malus baccata (L.) Borkh. × M. pumila var. niedzwetzkyana (Dieck) Schneid.] and ‘Secke!’ pear (Pyrus communis L.) were cultured on Murashige and Skoog medium supplemented with 2 mg/liter 6-benzylamino purine and agar levels ranging from 0 to 1.2%. The greatest shoot proliferation and shoot growth in ‘Almey’ occurred on medium containing 0.3% agar. Higher agar concentrations decreased both shoot proliferation and shoot growth. Increasing agar concentrations resulted in decreased shoot growth in ‘Seckel’, but shoot proliferation was significantly greater at concentrations of 0.6% and higher as compared to 0.3% or lower. Autoclaving caused an acidification of the medium. The addition of agar reduced media acidification. This pH variation does not explain the effect of agar on shoot proliferation and growth.
descriptors on GRIN use a 1 to 9 scale. A high number on both scales corresponds to high susceptibility. Pear powdery mildew. Serdani et al. (2005 , 2006) evaluated 200 core accessions in the USDA Pyrus germplasm collection for susceptibility to
Concentrations of abscisic acid (ABA), dihydrophaseic acid (DPA), and their metabolites were measured in mature pear seeds, using gas-liquid chromatography (GLC). ABA content of Pyrus communis L. cv. Bartlett seeds fell during imbibition, but was not affected by temperature (4 vs. 21°C) or time (0 to 4 weeks) of stratification in a moist medium. Levels of DPA and 3 of its metabolites were not correlated with dormancy. The amount of chilling required to break dormancy was not correlated with ABA or DPA content in imbibed, non-stratified seeds of 6 Pyrus species.
disorders after removal from cold storage. Materials and Methods Plant material. ‘d’Anjou’ ( Pyrus communis L.) pear fruit were obtained from three commercial orchards in central Washington State. Pears determined to be commercially mature by the growers
compared with other plants, including Arabidopsis, tobacco, and tomato. Pear ( Pyrus spp.) is one of the most important fruits in the world and the content of AsA in pears is quite low compared with other plants, such as kiwifruit ( Koutinas et al., 2010
The Tatura Trellis consists of V-shaped trees planted closely together in single rows. Each tree has 2 limbs trained at 60° from the horizontal across the inter-row alley-way. No dwarfing rootstock is used and trees fill their allotted space rapidly and come into bearing early. The system, which employs a high tree density but does not require dwarfing rootstocks, has most of the advantages ascribed to other intensive orchards. Furthermore, it facilitates rapid and easy hand-harvesting and meets the requirements for simple mechanization (2, 8). We previously have reported experimental results (2) and commercial experience (6) with clingstone peach trees on Tatura Trellis. We report the results of a preliminary study of the planting and management approach for ‘Bartlett’ (‘Williams’ Bon Chretien’) pear trees in this paper.