| Jujube(Ziziphus jujuba)belongs to the genus Ziziphus in the family Rhamnaceae and is native to China,and is an important economic forest tree and characteristic fruit tree in China.Because of the existence of many homonyms and heteronyms of local varieties of fresh jujube germplasm resources in Beijing area.In this study,36 fresh dates germplasm resources collected by the Institute of Forestry and Fruit Tree Research,Beijing Academy of Agriculture and Forestry were used to analyze their phenological characteristics,observe 20 qualitative traits and 16 quantitative traits,and conduct genetic diversity analysis research on germplasm resources using genetic diversity index,correlation analysis,principal component analysis and cluster analysis,etc.On the basis of this study,36 fresh dates germplasm resources were The study provided theoretical references for understanding the diversity and variability of phenotypic traits of fresh jujube germplasm resources in Beijing and laid the foundation for selecting and breeding excellent jujube varieties.The main findings are as follows:(1)Phenological period observation and analysis In 2022,the earliest start of budding was on 3 April,and leaf development began within 3-5 days after budding,with flowering starting on 25 April,giving a total flowering period of 60 days.(2)Quality trait analysis The Shannon-wiener diversity index H′ for 20 quality traits,including fruit shape and peel colour,ranged from 0.055 to 0.852,with the highest diversity index for fruit shape at 0.852 and lower variation for surface smoothness and secondary branch morphology,both at 0.055,suggesting that date palm phenotypes are rich in diversity of quality traits.(3)Quantitative trait analysis The coefficients of variation of the 16 quantitative traits ranged from 53.81% to 1.82%,with a large range of variation overall and a rich diversity of resources.The clustering analysis showed that the 16 quantitative traits of fresh date germplasm resources were divided into three categories: category Ⅰ included11 quantitative traits,category Ⅱ included four traits such as longitudinal and transverse fruit diameter,leaf width and secondary branch length,and category Ⅲ was leaf length;the fresh date germplasm resources were divided into three categories by cluster analysis,category Ⅰ germplasm resources all had small fruits and sour taste,category Ⅱdate germplasm resources had greater leaf width,leaf length and edibility than other germplasm,and category Ⅲ included three germplasm resources.These germplasm resources have a larger cross-sectional diameter than the longitudinal diameter of the fruit,and a larger weight per fruit;the principal component analysis showed that the cumulative contribution of the first five principal components was 76.8%,and a total of eight representative indicators were selected including duplicate indicators,reflecting most of the information represented by the original factors.(4)Overall evaluation The overall score(F)ranged from 0.342 to 1.447,with a mean value of 0.836.The top five jujube germplasm had an overall score between 1.447 and 1.237,with Jingzao 60 and Jingzao 39 being the local characteristics of the Beijing area.The bottom five germplasm scores ranged from 0.342 to 0.499,with all germplasm characterised by small fruit size.(5)Joint analysis and evaluation The results of the correlation analysis between the composite score and the phenotypic quantitative traits showed that the composite score was significantly correlated with ten phenotypic quantitative traits,five of which were highly significantly positively correlated,with the highest correlation coefficient for longitudinal fruit diameter.four quantitative traits were significantly positively correlated,with kernel content being significantly negatively correlated. |
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