JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2023, Vol. 47 ›› Issue (3): 87-96.doi: 10.12302/j.issn.1000-2006.202205037

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Nuts’ phenotypic diversity analysis and character evaluation of 109 high-yield walnut individual trees

ZHANG Yunqi1(), DONG Ningguang1, HAO Yanbin1, CHEN Yonghao1, ZHANG Junpei2,*(), HOU Zhixia3, SU Shuchai3, WU Jiaqing1, QI Jianxun1,*()   

  1. 1. Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Science, Key Laboratory of Urban Agriculture (North China), Ministry of Agriculture and Rural Affairs, Beijing 100097, China
    2. State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
    3. The Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China
  • Received:2022-05-21 Revised:2022-07-09 Online:2023-05-30 Published:2023-05-25
  • Contact: ZHANG Junpei,QI Jianxun E-mail:zhyq1985@bjfu.edu.cn;zhangjunpei@caf.ac.cn;qijx@263.net

Abstract:

【Objective】Phenotypic analyses are the bases for improving variety breeding. Therefore, we analyzed phenotypic diversity of walnuts, and the nut characteristics were comprehensively evaluated to screen excellent walnut lines. 【Method】In this study, 109 high-yield walnut trees in the selective nursery of the Beijing Academy of Agricultural and Forestry Sciences were selected as research subjects. Based on the phenotypic data of nuts, the variation coefficient, diversity index, correlation, principal component, and cluster analysis were analyzed, and the nut characteristics were comprehensively evaluated. 【Result】(1)The variation of 18 phenotypic characteristics of the nuts contributed toward the observed statistically significant differences observed in the nuts, and the variation coefficient and the genetic diversity index ranged from 4.70% to 25.00%, and 2.849 to 3.023, respectively. The indicators representing nut size and dry weight had a high degree of dispersion among individuals, whereas the variation in nut shape was slight. (2) The dry weight index of each part of the nut had a significant positive correlation with indices reflecting nut size. The nut shape indices were closely related to nut diameters. The seed shell thickness and seed shell weight significantly affected the kernel percentage. (3) Nut size, shape and quality indicators can reflect most information on nut phenotypic traits. The total contribution of these three principal components was 91.596%. Eight main nut traits were screened: geometric average diameter, nut volume, dry weight of a single nut and kernel, sphericity, shell thickness, kernel percentage, and volume kernel percentage. (4) The 109 walnut germplasm resources were clustered into four groups at a Euclidean distance of 9.0, which could be used as hybrid materials for specific breeding purposes. (5) According to the integrated score of nut phenotypic traits of various germplasm resources and the general characteristics of ideal nuts, the excellent lines XJ45, A068, E030, XJ59 and W27 were selected. 【Conclusion】Through the screening of key evaluation indicators, combined with principal component analysis and the membership function method, the evaluation criteria for walnut germplasm resources could be preliminarily constructed, which would provide a breeding basis for effectively creating new varieties with commercial value in this region.

Key words: Juglans regia, germplasm resources, phenotypic characters, membership function method, comprehensive evaluation

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