In this study, the carotenoid profiles and content in 132 cultivars of yellow-flesh peach having different fruit developmental periods (short, middle, and long), fruit surface indumenta (glabrous and pubescent skin), and flesh colors (yellow, golden, and orange) were investigated. We simultaneously analyzed and compared the levels of five carotenoids (lutein, zeaxanthin, β-cryptoxanthin, α-carotene, and β-carotene) through high-performance liquid chromatography. Large differences in carotenoid content among germplasms were observed, with coefficients of variation ranging from 21.24% to 67.78%. The carotenoid content, from high to low, was as follows: β-carotene > zeaxanthin > α-carotene > β-cryptoxanthin > lutein. We screened several varieties with high carotenoid content, including zeaxanthin in ‘Ruiguang2’, β-cryptoxanthin in ‘NJN76’ and ‘TX4F244C’, and β-carotene and total carotenoids in ‘Jintong7’, ‘77-26-7’, and ‘77-20-5’. A longer fruit developmental period was associated with greater β-carotene accumulation but lowered the zeaxanthin and β-cryptoxanthin accumulation. The zeaxanthin, β-carotene, and total carotenoid concentrations significantly increased as the flesh color deepened, but the lutein and α-carotene levels remained similar among the three flesh colors. The classification index of the indumenta significantly affected the β-carotene and total carotenoid content (p < 0.05) and was higher in pubescent than glabrous skin.

Aroma profiling peach flowers can improve the landscape and ecological value of the surrounding environment. In order to preliminarily explore and screen the flower aromas of peach germplasms, the floral aroma profiles of 50 peach germplasms were analyzed by electronic nose detection. The clustering results from ten sensors showed that it was possible to identify each peach blossom aroma type. ‘Gansutao2’ was separately classified as cluster I; ‘Yuntaishanshantao’, ‘Dazhuanggansutao’, and ‘Zhouxingshantao’ as cluster II; ‘Xinjiangpantao’ and ‘Xinjianghuangrou’ as cluster III; and the remaining germplasms as cluster IV. The flower aromas of clusters I, II, and III were different from that of cluster IV and were mainly highlighted by the significant differences in the response values of the three main sensors, which were W1S (methane), W1W (hydrogen sulfide), and W5S (nitrogen oxides). The principal component analysis and significance analysis of the sensor response values showed that ‘Hua3’, ‘Hongfenjiaren’, and ‘Yuntaishanshantao’ had special flower aromas. The response values of these three varieties produced by the W1S, W1W, and W5S sensors and two aromatic sensors, W2W (aromatic components and organic sulfides) and W3S (methane-aliph), were significantly different from most of the other germplasms. The ‘Yuntaishanshantao’ response values produced by the five sensors’ were low, which showed that it had a light aroma, while the ‘Hongfenjiaren’ and ‘Hua3’ values were high, which showed that they had strong aromas. The results from this study provided basic data that could be used to screen peach germplasms with obvious floral aromas, cultivate new varieties with strong aromas, and aid the development and utilization of peach floral aroma substances.

This study investigates the aroma differences among various peach and nectarine varieties by sensory evaluation, electronic nose (E-nose) analysis, and metabolomics. Peach is a significant fruit crop in China, and identifying unique fragrances is essential for germplasm selection and cultivar improvement. Six peach and nectarine varieties were collected from the National Peach Germplasm Repository in Nanjing, China. Sensory evaluation revealed significant differences in aroma and taste, with ”Zi Jin Hong 3” and “Bai Mi Pan Tao” showing high scores for aroma, sweetness, and overall sensory quality, while “Tachibanawase” had the lowest overall impression score. E-nose analysis showed distinct response values among varieties, with sensors W1S, W1W, and W5S exhibiting the highest sensitivity. GC-MS identified 446 metabolites, including esters and terpenes. PCA and OPLS-DA differentiated metabolite profiles among varieties, revealing significant differences in metabolite expression. The integration of these techniques provides a comprehensive understanding of aroma differences, highlighting the potential for identifying unique germplasms for breeding high-quality cultivars with charming flavor, and offering a theoretical foundation for raw material selection and process optimization in the deep-processing industry of peach fruits in future research.

The flavour and mouthfeel of peaches are crucial qualities of peach germplasm resources that significantly influence consumer preferences. In this study, we utilized 212 peach germplasm resources from the Nanjing Peach Resource Repository, National Fruit Germplasm facility, Jiangsu Academy of Agricultural Sciences as materials for sensory analysis, electronic nose analysis, and composition analysis via high-performance liquid chromatography (HPLC). In the sensory analysis, we divided 212 peach germplasms into three clusters based on hierarchical cluster analysis (d = 5). No.27, No.151, and No.46 emerged as the most representative of these clusters. The electronic nose was used to conduct an evaluation of the aroma profiles of the 212 peach germplasms, revealing that the primary distinguishing factors of peach aroma can be attributed to three sensors: W1S (methane), W1W (terpenes and organosulfur compounds), and W5S (hydrocarbons and aromatic compounds). The primary differences in the aromatic substances were characterized by sensors W2W (aromatic compounds, sulphur, and chlorine compounds) and W1C (aromatic benzene). The HPLC analysis indicated that the persistence of peach sensory characteristics was positively correlated with acids and sourness and negatively correlated with sweetness and the ratio of sugar to acids. The overall impression of the 212 peach germplasms revealed a negative correlation with acids, while a positive correlation was observed between the overall impression and the ratio of sugar to acids. Therefore, this study substantially contributes to the preliminary screening of the analysed specific characteristics of peach germplasms such as No.27, No.46, No.151, and No.211. These selections may provide valuable information for the potential creation of superior germplasm resources.

Breeding early maturing cultivars is one of the most important objectives in pear breeding. Very early maturing pears provide an excellent parental material for crossing, but the immature embryo and low seed germination of their hybrid progenies often limit the selection and breeding of new early maturing pear cultivars. In this study, we choose a very early maturing pear cultivar ‘Pearl Pear’ as the study object and investigate the effects of cold stratification, the culture medium, and the seed coat on the germination and growth of early maturing pear seeds. Our results show that cold stratification (4 °C) treatment could significantly improve the germination rates of early maturing pear seeds. A total of 100 days of cold-temperature treatment in 4 °C and in vitro germination on White medium increased the germination rate to 84.54%. We also observed that seed coat removal improved the germination of early maturing pear seeds, with middle seed coat removal representing the optimal method, with a high germination rate and low contamination. The results of our study led to the establishment of an improved protocol for the germination of early maturing pear, which will greatly facilitate the breeding of new very early maturing pear cultivars.

Previous studies have shown a negative correlation between chilling accumulation (CA) and heat requirements (HRs) in peaches (Prunus persica (L.) Batsch), consistent with findings in other plants in spring events. However, there is a lack of comparative research on the CA–HR relationship in peach varieties with different chilling requirements (CRs), and the specific impact of CA on HR reduction remains poorly described. To address this, we investigated the effects of CA on the days and HR for flowering in 54 peach varieties of differing CRs. Scanning electron microscopy was used to observe the effects of CA on the phenology of floral organ development in a selected peach variety. Our results indicate that, in general, peaches exhibit a reduced HR and accelerated flowering as the CA increases, but that the strength and trend of the CA–HR relationship is influenced by the CR and the variety. Low-CR varieties showed less sensitivity to CA increments, requiring higher relative increases in CA to significantly lower the HR, whereas high-CR varieties appeared to be more sensitive, with even modest changes leading to substantial reductions in HR. However, variations from this generality exist, even within varieties displaying the same rCA (the ratio of CA to CR). Additionally, we provide a summary of the relationship between the rCA and drHR in peaches of differing CRs, and identify several varieties exhibiting a strong response in the CA–HR relationship. This study also highlights the impact of CA on flower bud development, revealing slower progression under lower CA levels and accelerated growth with an increased CA. In particular, we identified the critical period of the enlargement and initiation of green scales as indicative of successful pollen grain formation. Finally, we present a schematic of the CA–HR relationship for flowering in peaches.