Pear aroma quality is predominantly governed by volatile organic compounds (VOCs), which are critically influenced by postharvest storage conditions. This study tracked VOCs, soluble solids content (SSC), and texture dynamics in Nanguoli, Jingbaili, and Korla pears during 105-day cold storage and a 15-day shelf life. A total of 301 VOCs were identified, with esters increasing dramatically (25.96- to 113.55-fold) after 75-day cold storage, especially in soft-fleshed cultivars. Texture declined in these cultivars during shelf life, whereas Korla pears maintained exceptional firmness (> 90% retention) and stable texture parameters. Multivariate analysis revealed a strong negative correlation (r < -0.8) between ester accumulation and textural integrity, highlighting a fundamental trade-off between tissue softening and aroma development. Furthermore, up to 85 VOCs were identified with variable importance in projection scores > 1. These compounds may help clarify the mechanistic basis of texture deterioration and inform strategies for postharvest quality preservation in future studies.

Wild pear resources are rich in phenolic metabolites and few studies have explored molecular mechanisms underlying polyphenol metabolism in wild pear fruit after storage. In this study, we analyzed changes in total phenolic content, total flavonoid content, antioxidant capacity, phenolic metabolites, and gene expression patterns in wild pear after storage. The results showed that both total phenols and total flavonoids increased after storage, accompanied by enhanced antioxidant capacity. Almost all differentially accumulated phenolic acids and flavonoids were upregulated, whereas almost all lignan-related metabolites were downregulated. Phenylalanine ammonia-lyase (PAL) and p-hydroxycinnamoyl-CoA (HCT) participated in the synthesis of phenolic acids, flavonoids, lignans, and coumarins; shikimate dehydrogenase (SKDH) and chorismate mutase (CM) contributed to phenolic acid formation; dihydroflavonol 4-reductase (DFR) and flavonol synthase (FLS) were associated with flavonoid biosynthesis; and dirigent protein (DIR) and β-glucosidase (BGLU) were implicated in lignan and coumarin production. Furthermore, we constructed ceRNA networks related to polyphenol metabolism, correlation networks between differentially expressed genes and metabolites, and metabolic pathways for phenolic acids, flavonoids, lignans, and coumarins. This study clarified variation patterns of polyphenols in wild pear germplasm after storage and might facilitate the breeding of polyphenol pear varieties.

Climate change is profoundly affecting global ecosystems and biodiversity, with fruit trees being one of the plant groups relatively sensitive to climate change. China is one of the centers of diversity for the genus Pyrus, harboring abundant wild and cultivated germplasm resources. However, systematic assessments of the responses of Pyrus species to future climate change at the national scale in China using species distribution modelling remain limited. In this study, we compiled 153 occurrence records of Pyrus betulifolia, 47 of Pyrus pyrifolia, and 117 of Pyrus ussuriensis, and integrated climatic, soil, topographic, and anthropogenic variables. A biomod2-based ensemble modelling framework was used to predict potential suitable habitats under current and future climate scenarios and to identify key environmental drivers. The results showed that temperature seasonality (Bio4) was the dominant factor influencing the distributions of P. betulifolia and P. ussuriensis, whereas precipitation of the warmest quarter (Bio18) was the primary driver of P. pyrifolia. Under current climatic conditions, highly suitable habitats accounted for 4.04

Pear (Pyrus L.) is a fruit tree of global commercial importance. Its genetic relationships, evolutionary history, dissemination routes, and genetic determinants of most agronomic traits remain to be elucidated. We conducted whole-genome resequencing of 495 Pyrus accessions. Phylogenetic and demographic analyses resolved geographic groupings of the accessions, identifying the Yunnan-Guizhou Plateau as the putative dissemination center for cultivated Pyrus pyrifolia and P. bretschneideri. Identification of two evolutionary bottlenecks provides insights into the population dynamics of pear species. Admixture and introgression analyses revealed both intraspecific and interspecific genetic exchanges, substantiating the complex emergence of cultivated populations. Genome-wide association study (GWAS) identified loci associated with nine crucial agronomic traits, together with eight candidate genes. The GWAS, molecular, and biochemical analyses suggested that PbeMADS25, PbeSPP, PbeDHQ-SDH, PbeARF2, PbePPO, PbePIN3, PbeCXE, and PbeMYB38 participate in the regulation of number of stigmas and number of locules, number of stamens, young leaf color, sepal persistence, astringency, acidity, aroma, and fruit skin color, respectively. Overexpression and metabonomic analysis of PbeCXE indicated that it affects the fruit aroma by affecting the balance between ester biosynthesis and substrate consumption. These findings expand our understanding of Pyrus evolution and provide a genomic foundation for genetic improvement of agronomic traits.

BACKGROUND:Pear is one of the most popular and widely cultivated fruits globally, with rich cultivar diversity. Pyrus species are characterized by self-incompatibility and the absence of reproductive barriers between species, leading to extensive gene flow and genetic recombination among different types of cultivars. As a result, cultivar identification technologies have considerable practical significance in pear production. Multiple nucleotide polymorphism (MNP) technology, which combines multiplex PCR amplification and high-throughput sequencing, offers high efficiency and accuracy in pear cultivar identification, and meets the needs of cultivar innovation and industry development. RESULTS:We applied MNP technology to pear cultivar identification for the first time, establishing fingerprints for major pear cultivars and exploring the feasibility of MNP markers for pear population structure analysis. Based on genomic resequencing data from 143 pear accessions, 558 marker loci were initially developed, and 310 core markers were retained after screening. The 310 MNP markers showed high polymorphism, with an average of 18.14 alleles per marker locus and PIC values ranging from 0.57 to 0.99. Validation using 76 representative pear cultivars demonstrated reproducibility and accuracy rates exceeding 99% for the 310 MNP markers. A total of 2,850 pairwise comparisons among the 76 cultivars showed an average genetic differentiation of 90.89%. Population structure analyses based on MNP markers effectively reflected the classification relationships among the 76 cultivars, clearly distinguishing European from Asian pears. CONCLUSION:In summary, the developed pear MNP markers possess high polymorphism, stability, and cultivar-discrimination capability, promising extensive future applications in pear cultivar identification and population genetic research.

Introduction:Wild Ussurian Pear germplasm resource has rich genetic diversity, which is the basis for genetic improvement of pear varieties. Accurately and efficiently identifying wild Ussurian Pear accession is a prerequisite for germplasm conservation and utilization. Methods:We proposed YOLOv10n-MCS, an improved model featuring: (1) Mixed Local Channel Attention (MLCA) module for enhanced feature extraction, (2) Simplified Spatial Pyramid Pooling-Fast (SimSPPF) for multi-scale feature capture, and (3) C2f_SCConv backbone to reduce computational redundancy. The model was trained on a self-made dataset of 16,079 wild Ussurian Pear leaves images. Results:Experiment results demonstrate that the precision, recall, mAP50, parameters, FLOPs, and model size of YOLOv10n-MCS reached 97.7(95% CI: 97.18 to 98.16)%, 93.5(95% CI: 92.57 to 94.36)%, 98.8(95% CI: 98.57 to 99.03)%, 2.52M, 8.2G, and 5.4MB, respectively. The precision, recall, and mAP50 are significant improved of 2.9%, 2.3%, and 1.5% respectively over the YOLOv10n model (p<0.05). Comparative experiments confirmed its advantages in precision, model complexity, model size, and other aspects. Discussion:This lightweight model enables real-time wild Ussurian Pear identification in natural environments, providing technical support for germplasm conservation and crop variety identification.

Located in the southwestern region of China, the Yunnan–Kweichow Plateau, is closely related to the origins of Pyrus L. Despite this important status, there has been relatively little population genetics research focused on the wild Pyrus species in this area. To address this gap in knowledge, the present study was conducted investigating wild Pyrus species distributions in the Yunnan–Kweichow Plateau region. These analyses entailed the collection of 80 accessions, whole-genome resequencing, and the detection of variants including SNPs, InDels, SVs, and CNVs. Genetic structure analyses revealed clear differences between P. pashia and P. calleryana, where the former was additionally subdivided into five groups. The genetic structure of these accessions was closely aligned with their geographic distribution, highlighting the fragmented nature of wild Pyrus populations on the Yunnan–Kweichow Plateau. Analyses of genetic diversity suggested that the central and easter portions of Yunnan Province are key centers of Pyrus diversity on the Yunnan–Kweichow Plateau, whereas the highest degree of differentiation was observed for wild Pyrus in the southwest and northwest regions. Demographic analyses indicated that wild Pyrus populations on the Yunnan–Kweichow Plateau are currently in a state of population contraction, with evidence of migration events between these populations.

Flesh texture is an important quality trait and is related to people’s preference for fruit, especially for crisp pears. Puncture tests were carried out on 156 crisp pear fruit germplasm samples to analyze the diversity level of texture traits, to clarify the correlation between sensory description evaluation and instrumental traits, and to explore the effects of fruit ripening, size, and shelf life on the change in flesh texture. The results showed that puncture parameters were significantly different between crisp pear cultivars, and the work associated with the flesh limit compression force had the highest coefficient of variation (0.281). There was a significant correlation between puncture parameters and sensory evaluation scores. The correlation between sensory score and flesh firmness was the highest, with a correlation coefficient of 0.708, indicating that hardness can significantly influence the sensory evaluation of texture. Cluster analysis based on sensory evaluation and puncture determination could divide the germplasm resources of crisp pear into five texture categories: loosen, crunchy, crisp, tight–crisp, and dense. A comprehensive texture score model, constructed by principal component analysis, showed consistency with sensory evaluation scores and proved that the combination of a puncture test and sensory evaluation is the best way to identify and evaluate the texture of crisp pear. Further analysis of the influencing factors of flesh texture showed that fruit maturity and shelf life had significant effects on flesh quality. This study provides an important reference for the standardization, evaluation, and utilization of crisp pear variety resources.

[Objective] Weixian has a long pear cultivation history with approximately 20 unique local pear cultivars, including the most famous Weixian Yali. Researchers have made significant progress in the collection, preservation and phenotypic evaluation on pear germplasm resources in Weixian, but the genetic relationship and background of these pears remain largely unexplored. To provide a theory basis for the efficient utilization of Weixian pears and the sustainable development of pear industry, it is needed to elucidate the genetic relationship and background of Weixian pear accessions. [Methods] Twenty local pear cultivars from Weixian and 10 representative local pear cultivars from other regions within Hebei province were selected as research materials. Based on the whole-genome resequencing data and chloroplast DNA variation, we investigated the genetic relationship and background of local pear cultivars in Weixian. The clean reads were aligned to the reference genome Yunhong No.1 using BWA v0.7.15 software for whole-genome alignment; SNP detection and filtering were performed using GATK v4.2.5.0 software; Population structure analysis was conducted using Admixture v1.3.0 and principal component analysis was carried out using GCTA v1.93.2 software; Treebest v1.9.2 software was used to calculate the distance matrix, and a phylogenetic tree was constructed using the neighbor-joining method. The chloroplast DNA sequencing results were aligned and manually corrected using the software MEGA X; the genetic parameters of chloroplast DNA sequence fragments were calculated using the software DnaSP 5.1; the evolutionary relationship between haplotypes was analyzed using the software NetWork 10. [Results] By comparing the resequencing data of 30 materials with the reference genome, a total of 30 041, 877 SNP loci were identified. We performed principal component analysis, population genetic structure and phylogenetic tree based on these SNPs. The results showed that local pear cultivars in Weixian exhibited a clear population genetic structure, which could be divided into two groups: Group 1 consisted of 9 materials including Weixian Hongli, Youqiu, Xiaohongmian, Baidunzili, Baihongli, Dunzili, Jinfeng Yali, Kaixinmian and Suanjiuli; Group 2 comprised the remaining 11 materials from Weixian, including Xiaobaimian, Xuehua, Wu'an Youqiu, Dabaimian, Yayamian, Teda Baimian, Baixuehua, Yinbai, Yali, Teda Yali, Meixiang Yali and Xiaobaimian, which can be further divided into two subgroups. Additionally, Group 2 included 10 local pear cultivars from northern Hebei, like Anli and Baihuaguan, indicating a close genetic relationship between Weixian pears in Group 2 and northern pear cultivars. In contrast, Weixian Hongli in Group 1 belonged to the Chinese Sand Pears, suggesting a closer genetic relationship between Weixian pears in Group 1 and southern pear cultivars. The sequencing results of the non-coding region of chloroplast DNA showed that three more evolved haplotypes were detected in Weixian pears. The haplotype of most Weixian pears was haplotype H_3, while Weixian Hongli exhibited the haplotype H_2. Additionally, Xuehua and the Yali group, with the exception of Jinfeng Yali, displayed the haplotype H_1. By analyzing the genetic relationship and haplotype categories, we identified the genetic background of bud sport mutations and hybrids of Weixian pears. Jinfeng Yali belonged to the Yali group and had the characteristic of high self-fertility. Whole-genome resequencing analysis and chloroplast haplotype results showed that Yali, Meixiang Yali and Teda Yali belonged to the same branch and had the same haplotype. The clustering results and haplotype of Jinfeng Yali were different from these three Yali pear varieties. Jinfeng Yali was more closely related to Suanjiuli, and both had the same chloroplast haplotype, indicating that Jinfeng Yali was not a bud sport of Yali but possibly a selection from Yali seedlings. Dunzili and Baidunzili had a close genetic relationship and shared the same haplotype, suggesting Baidunzili may be a bud sport of Dunzili. The chloroplast haplotypes of Baihongli and Weixian Hongli were inconsistent, but they had a close relationship, suggesting that Weixian Hongli was more likely to be its paternal variety. Kaixinmian and Xiaohongmian shared the same chloroplast haplotype, and Xiaohongmian and Dunzili were in the same group, suggesting that Kaixinmian was a hybrid between Xiaohongmian and Dunzili. There was a distinct genetic difference between Youqiu and Wu'an Youqiu, despite their similar names. [Conclusion] In this study, based on the information of single nucleotide polymorphisms (SNPs) revealed by whole-genome resequencing and chloroplast DNA variation, we clarified the genetic relationship and background of Weixian pears. This result provides valuable references for protection and rational utilization of Weixian pear germplasm resources, further aiding in advancing the genetic understanding of pear cultivation in the region. Additionally, it enriches the cultural significance of pear culture in Weixian and offers cultural support for rural revitalization efforts.

The impact of maturity on pear fruit quality directly affects consumer taste. Ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was used to determine the sugar and organic acid components of mature pear fruits with different texture types, a texture analyzer was used to determine the texture traits of pear fruits. The result revealed that the variation tendency of sugar and organic acid components affected by the texture types, ripening stages and shelf-life. The decrease in flesh firmness of pear fruits was related to sucrose and glucose during the shelf-life of 0-14 days (d) at different ripening stages. According to the principal component analysis, Nanguoli, Jingbaili and Chili achieved the highest fruit quality score when harvested at 136 days after flower bloom (DAFB); Gute Luise and Korla pear achieved the highest fruit quality score when harvested at 146 DAFB; Yali and Dangshan Suli achieved the highest fruit quality score when harvested at 156 DAFB. In conclusion, combination of texture, sugar and organic acid components could serve as powerful maturity indicator candidates, provided valuable references for determining appropriate harvesting period and the best shelf-life quality of pear fruits.

Pear (Pyrus L.) is abundant in phenolic compounds which significantly contribute to functional properties. This study analyzed the phenolic profiles in the leaves of 460 pears using UPLC-MS/MS. A total of 28 phenolic compounds were identified, including one hydroxyphenyl-glucopyranoside, two hydroxycinnamates, five flavanols, four flavonoids, and sixteen flavonols, displaying pronounced species-specific and spatial variation. Arbutin emerged as the predominant phenolic component, accounting for 60.36 % of total phenolics, but was significantly less abundant in P. calleryana compared to others. European pears were richer in rutin, while Asian pears had higher concentrations of luteolin 7-O-glucoside. Chlorogenic acid levels showed a positive correlation with the varietal-origin altitude, while luteolin 7-O-glucoside and chrysoeriol 7-O-glucoside were negatively correlated with latitude. Varieties BT, YBMY, and XH_js003 exhibited high phenolic diversity, whereas JT41H, CPS, and ZYX possessed high arbutin. This study provides a comprehensive profile of pear phenolics, thereby enhancing their utilization in bioactives and understanding of adaptations.

Pear belongs to the Rosaceae family, Pomaceae subfamily, Pyrus genus, and is cultivated all over the world. China has a long history of pear cultivation. It is generally believed that Pyrus originated in the mountainous areas of western or southwestern China during the Tertiary period, evolving and developing from east to west. The Pyrus plants are mainly distributed in Europe, North Africa, Asia Minor, Iran, Central Asia, China, Korea and Japan. In terms of geographical boundaries, the Pyrus plants distributing to the east of Tianshan and Xingdu Kush Mountains are called Oriental pears, while those to the west are called Occident pears. With the change of geographical environment, Pyrus plants gradually evolved into two major pear families and formed three secondary centers: China center, Central Asia center and Near East center. The scientific classification of Pyrus germplasm is of great significance for the collection, preservation, identification, evaluation and shared utilization of Pyrus germplasm resources. China has abundant and diverse Pyrus germplasm resources, which provide important material guarantees for pear breeding and pear industry development. The National Pear and Apple Germplasm Repository (Xingcheng) is one of the earliest established national fruit tree resource preservation repository in China, with the total collection and preservation of over 1600 Pyrus germplasm accessions. It has provided a large amount of resources for pear research, production and popular science education in China, and has played an important role in talent training, rural revitalization and pear industry development. During the past 20 years, with the increase and stable support of scientific research funding, pear researchers in China have carried out a large amount of research work on pear germplasm resources phenotype identification, resistance identification, fruit traits evaluation, functional component identification, molecular marker evaluation, transcriptome, genomics research and so on. Over the past 20 years, we have formulated 4 agricultural industry standards and 1 local standard related to pear germplasm resources evaluation, published 6 books on pear, published over 100 academic papers both domestically and internationally, acquired 13 national invention patents granted, obtained 5 software copyrights, and registered 22 hybrid pear varieties. Since the establishment of China Agriculture Research System of pear industry in 2009, the supply and utilization of pear germplasm resources have significantly increased, effectively supporting the implementation of scientific research projects and talent training. This article briefly introduces the development process and preservation status of the National Pear and Apple Germplasm Repository (Xingcheng), focusing on the excellent pear germplasm resources, phenotype evaluation, phylogenetic analysis, fruit traits evaluation, resistance evaluation and genome. It summarizes the relevant scientific research progress on the utilization of pear germplasm resources and the scientific researches in the National Pear and Apple Germplasm Repository (Xingcheng) during the past 20 years, and reviews the technical supports for industrial development, and looks to future research directions, in order to provide reference information for the effective utilization of pear germplasm resources and industrial development in the future.

BACKGROUND:Pyrus ussuriensis Maxim. are rich in nutrients, with a pleasant aroma and postharvest softening properties. Postharvest softening influences shelf life of fruit and fruit quality. Melatonin is a natural and safe preservative, which can effectively maintain fruit quality after harvesting, and delay softening of fruit. The aim of study was to elucidate mechanism of pear fruit softening and fruit aroma during postharvest storage and effect of melatonin. RESULTS:Ethylene production rate, respiration rate, weight loss of fruit, soluble solid content, titratable acidity were assessed, and transmission electron microscopy, metabolite profiling, and whole-transcriptome RNA-sequencing were performed. Four important pathways that pentose and glucuronate interconversion, galactose metabolism, sphingolipid metabolism and the starch and sucrose metabolism pathway were involved in pear fruit softening. Ethylene production pathway-related genes, such as ACS and ACO were involved in pear fruit softening and expression of that under exogenous melatonin treatment were slightly inhibited. Fruit aroma changed after storage mainly through lipoxygenase pathway under ddH2O treatment and exogenous melatonin treatment changed composition of volatile organic compounds. CeRNA networks associated with pear softening and aroma were established. Mdm-miR159a, mdm-miR396a/b-p3 and mdm-miR408a were found to modulate both fruit softening and aroma formation through ceRNA analysis. Mdm-miR10988-p3 was functionally diverse and as major regulatory components in ceRNA network. CONCLUSIONS:This study indicated that degradation of cell wall caused pear fruit softening, lipoxygenase pathway mainly affected change of fruit aroma during postharvest storage and exogenous melatonin treatment could improve fruit firmness after storage and alter pear's aroma. The mechanism underlying these effects was elucidated, providing theoretical basis for study of pear fruit softening and preservation technology.

Cold-storage is a widely-used technique for effectively maintaining pear quality. In this study, ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was employed to determine sugar and organic acid components in pears of different textures after different cold-storage times, while texture analyzer was adopted to assess the texture traits of pear fruits. Different cold-storage times affected the quality of fruits from different pear varieties, whereas extended cold-storage led to quality deterioration. After cold-storage, the difference in sucrose between soft-flesh pears and crispy-flesh pears decreased and eventually faded with extended storage. Based on principal component analysis (PCA), Nanguoli, Jingbaili, Ruanerli, Korla pear, Chili and Yali achieved the highest fruit quality after 2 months of cold-storage, while Dangshan Suli and Shuihongxiao peaked after 4 months. This work provides a better strategy for determining suitable cold-storage time and shelf-life for pear varieties by comprehensively considering sugars, organic acids and texture variation.

As the third most important temperate fruit, Pear (Pyrus spp.) exhibits a remarkable genetic diversity and is classified into two mainly categories known as Asian pear and European pear. Although several pear genomes are available, most of the released versions are fragmented and not chromosome-level high-quality. In this study, we report two high-quality genomes for Pyrus bretschneideri Rhed. cv. ‘Danshansuli’ (DS) and Pyrus communis L. cv. ‘Conference’ (KFL), which represent the predominant Asian and European cultivars, respectively, with nearly telomere-to-telomere (T2T) gap-free level. The finally assembled genome sizes for DS and KFL were 510.98 Mb and 510.71 Mb, respectively, with Contig N50 of 29.47 Mb and 30.47 Mb, where each chromosome was represented by a single contig. The DS and KFL genomes yielded a total of 46,394 and 44,702 protein-coding genes, respectively. Among these genes, the functional annotation accounted for 96.47% and 96.46% in the DS and KFL genomes. The two novels nearly T2T genomic information offers an invaluable resource for comparative genomics, genetic diversity analysis, molecular breeding strategies, and functional exploration.

The UGT72 gene family encodes proteins that glycosylate phenylpropanoids, and thus contribute to the synthesis of various phenolic substances. However, their functional role and evolutionary history in Pyrus spp. remains poorly understood. Here we explored the evolution, amplification, coding region structural variation, and functional divergence of the UGT72 gene family and its subfamilies. Further, we identified functional genes involved in arbutin synthesis and functionally validated the key genes. 15 UGT72 genes were identified in the complete genome sequence and classified into two subfamilies of Pyrus betulifolia. Significant expansion of the UGT72 gene family occurred after genome duplication in P. betulifolia. 53.33 % of all UGT72 family genes were found to have undergone expansion via WGD/segmental duplication. A noteworthy discovery was that the amplification of functional genes such as PbUGT72B1714 during polyploidization, combined with the loss of vital motifs and variations at important sites within these genes, significantly impacted the diversification of arbutin metabolism. These findings offer novel insights into how gene gains and losses caused by WGDs have contributed to metabolic diversification and evolutionary adaptation in Pyrus, as well as a groundwork for more detailed investigations into the mechanisms of arbutin metabolism.

Pears are popular among consumers for their juicy and delicious taste. In this study, the sugar and organic acid compositions of pear fruits with different texture types during development were determined by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), and fruit texture traits were determined by a texture analyzer. The results showed that the dominant sugar in soft and crispy types of pear fruits was fructose. The main difference between pears was the second-highest sugar component; glucose content was higher in crispy-flesh pear fruits while sucrose content was higher in soft-flesh pear fruits. The composition of organic acid components in both texture types of pear fruits was similar. The turning points of changes in the content of sucrose, sorbitol, glucose and quinic acid were different between different-textured pear varieties. A Pearson correlation analysis showed that sugar and organic acid components were significantly correlated with single fruit weight and soluble solid contents (SSCs), respectively. There was a high correlation among texture traits, individual sugars and organic acids. A partial least squares discriminant analysis (PLS-DA) VIP score plot showed that the differential traits with scores greater than 1 were total soluble sugars/total organic acids (TSSs/TAs), fracture and malic acid/citric acid (MA/CA), which could distinguish pear fruits of different texture types better and reflect the uneven quality differences among pear fruits adapted to different origins. The comprehensive analysis results of the flesh texture parameters and sugar and organic acid components are in line with objective reality and will provide a reference for quantitative indicators of the sensory evaluation of pear varieties as well as for molecular mechanism research on trait differences.

[目的]进一步完善我国梨种质资源描述评价体系,确定梨若干果实数量性状的分级评价指标及参照品种.[方法]对国家果树种质兴城梨圃保存的梨11个种456份资源和114份新品种共570份材料的9个果实数量性状进行数据采集及整理,使用SPSS 19.0软件进行数据统计分析,绘制各数量性状频率分布直方图,进行分级评价并选取参照品种.[结果]梨种质资源果实数量性状变异系数最大的是可滴定酸含量,为128.43％.9个果实数量性状数据均为偏正态分布.使用等距法绘制各果实数量性状频率分布图,果梗长度和果梗粗度采用5级分级,果心大小采用4级分级.由于脆肉型梨(含白梨、砂梨和脆肉型梨新品种)、西洋梨和秋子梨单果质量、果实横径、果实纵径、果肉硬度、可溶性固形物含量、可滴定酸含量6个性状差异显著,因此分别进行分级,相应分级标准为:脆肉型梨和西洋梨的单果质量、果实横径和果实纵径采用4级分级方法,秋子梨的单果质量、果实横径和果实纵径采用3级分级方法;果肉硬度均采用3级分级方法;可溶性固形物含量和可滴定酸含量均采用5级分级方法.每个性状的各等级选取2个参照品种.[结论]梨种质资源9个果实数量性状中可滴定酸含量的变异系数最高,更能体现梨品种间的差异.9个性状均不符合标准正态分布,其原因可能是长期人为选择的结果.软肉型梨(秋子梨和西洋梨)的平均可溶性固形物含量和可滴定酸含量高于脆肉型梨.9个果实数量性状采用了3级、4级和5级等3种不同的分级方法.