Dynamic analysis of walnut research based on bibliometrics

【Objective】Walnut (Juglans regia L.) , as one of the most important nut trees in the world, plays an important role in modern agricultural economy. The research direction of walnut in China is still not clear. This article trys to analyze the trends of walnut reseach in the world based on biblimetrics to offer the information to domestic researchers【Methods】The analysis was made according to summarizing the citation analysis of the issued volume, country, institution, author, published articles and main research contents of walnut research from 1998 to 2018 based on the databases on Web of Science and CNKI.【Results】In the database of Web of Science, there were 2 177 papers related to walnut research, from 63 countries, 902 institutions, 483 publications, and 3 021 authors, respectively. The top five countries of publishing contributors in the world were the United States of America, the P. R, of China, Spain, Turkey, and Iran. The Department of Agriculture of ths United States, University of California System, United States Forest Service, University of Tehran, Purdue University system and French National Institute for Agricultural Research have played important role in walnut research. A large number of articles were published by the institutions of the United States. Vahdati K, Sabate J, Leslie C A were the three top persons with regard to the number of articles published on walnut research in the world.Ros E resently published an article in title of“A walnut diet improves endothelial function in hypercho-lesterolemic subjects-A randomized crossover trial”in Circulation. Zambon D published a paper in title of“Substituting walnuts for monounsaturated fat improves the serum lipid profile of hypercholesterolemic men and women-A randomized crossover trial”in Annals of Internal Medicinewhose. Among the12 most influential authors, 7 authors came from the United States. FASEB Journal, Phytopathology and Hortscience have published the most impotant articles about the research of walnut in relations to human health, polyphenols, antioxidant activities, genetics and breeding in the world. The most comprehensive research has been accomplished by the researchers in the United States. Northwest University of Agriculture and Forestry and Chinese Academy of Sciences are the top two institutions which have published the more papers about walnut research in China. In the CNKI database, 17 044 research articles on walnuts have been retrieved, among them, the top three institutions with regard to the number of articles published are Northwest Agriculture and Forestry University, Agricultural University of Hebei and Xinjiang Agricultural University, the top three authors with regard to the number of articles published Pei Dong, Zhai Meizhi and Chen Chaoyin in China. Journal of Fruit Science, Acta Horticulturae Sinica, Transactions of the Chinese Society of Agricultural Engineering, Scientia Silvae Sinicae have published a large number of higher quality articles【Conclusion】The walnut research at home and abroad are multi-disciplinary and comprehensive. Through analysis, the research aspects of walnuts are concentrated relatively in following areas: First, the relationship between human health and antioxidant activity of polyphenols; Second, the development and utilization of walnut genetic resources, mainly focused on resource classification, genetic improvement, molecular biology research and the mechanism of disease resistance; Third, the deep processing of walnut kernels and the development and utilization of the green skin, husks, leaves, flowers and branches.