Research progress and hotspots of smart orchard based on bibliometrics

In order to better promote the development of smart agriculture, this review aims to analyze the research trends, frontiers, and hotspots of the smart orchard at home and abroad using bibliometric analysis. The commonly-used tool (Citespace) of quantitative literature analysis was adopted as the bibliometric analysis in the fields of science and technology. Web of science was selected as the retrieval platform to analyze the temporal and spatial distribution of research publications, main research contents, and frontier hotspots of smart orchards published from January 2002 to August 2022. Keywords of crop mainly included the longan, citrus, lychee, and peach. In addition, the keyword "orchard" was added for spare. 579 documents were finally obtained after screening and preprocessing using the following retrieval items: " TI=(longan or citrus or litchi or peach or orchard) And AB=(growth or disease or growing or pest or insect or tree or fruit) And AK=(drone or UAV or AI or intelligent or detection or segmentation or precision or spray or unmanned or robot or sensor or "deep learning" or "machine learning" or "agricultural machinery") . The retrieved data was used to conduct the following steps: The data processing software (Excel) and the bibliometric analysis tool (CiteSpace) were selected to conduct the quantitative analysis. The annual publication from 2002 to 2022 were counted using Excel and the built-in Web of science database. The collinear knowledge map of core authors, institutions, regions, and keywords was then obtained using Citespace and Excel statistical analysis tools. The analysis was also performed on the institutional cooperation network, literature co-citation, high-frequency word clustering, keyword co-occurrence, and keyword emergence. The development history, research regions, institutions, and spatial information, research technologies, and application hotspots of smart orchards were sorted out and summarized over the past 20 years using knowledge graphs. The main conclusions were as follows: The research on smart orchards was on the right track since 2014. There was the rapid development under the promotion of artificial intelligence technology since 2018. Reports published from 2018 to 2021 accounted for 37.5% of the total. In general, there were a relatively close exchange and cooperation between the authors (Lan YB, Chen C, and Tang Y), institutions (South China Agricultural University, China Agricultural University, and Univ of Florida), and regions (China, the United States, and Spain). China and the United States were the major countries in the smart orchard research, accounting for 58.2% of the total. The current research topics were focused mainly on fruit tree growth monitoring, pest identification, and early warning, unmanned or intelligent agricultural machinery operation. The technologies were adopted, including artificial intelligence models/algorithms, sensing, Internet of Things, and Precision control, according to the subdivision of research purposes. The research of deep learning, UAV, and artificial intelligence was the frontier of smart orchard development. The development of smart orchards was deeply promoted by advanced technology, especially artificial intelligence. However, the current limiting steps were determined by the high complexity of the environment and the lack of standard planting in further development. The research directions of smart orchards can be expected as the star-sky-ground three-dimensional orchard perception, air-ground collaborative unmanned precision operation, fruit picking, and visual traceability of fruit products in the future.