Understanding trends and gaps in global research of crop evapotranspiration: a bibliometric and thematic review

Estimating crop evapotranspiration (ETc) is crucial for ensuring sustainable and efficient agricultural water management. Although this subject has garnered sig-nificant attention from the global scientific community, a comprehensive study encom-passing the diversity, trends, and dynamics of research themes is currently lacking. To address this knowledge gap, this review employed a combined bibliometric and the-matic approach to analyze bibliographic data from 1872 documents retrieved from the Web of Science" core collection, spanning the period 1987-2022. The main findings of this review are as follows: (1) the scientific landscape is predominantly shaped by institutions from the USA and China; (2) the journal Agricultural Water Manage-ment emerged as the most prolific, with the highest number of publications and total citations; (3) a broad range of topics within ETc research were identified, with a nota-ble emphasis on remote sensing-related subjects; (4) strategic coordination mapping revealed that ETc and reference evapotranspiration (ET) remains an underdeveloped area of study; (5) climate change and machine learning emerged as key topics of sig-nificant scientific concern. The results suggest a need for enhanced institutional collab-orations and expanded research investigations, particularly in regions grappling with agricultural water scarcity. Furthermore, research investigations should focus on ETc and ETo to fill existing knowledge gaps and advance both theoretical understanding and practical applications. Future studies should aim to contribute to the understand-ing of the impacts of climate change on ETc by leveraging machine learning techniques and enhancing our understanding of crop water requirements and their application in irrigation management, while also ensuring continuous updates to the existing body of knowledge to meet future challenges.