Abstract:

[Significance] Graph neural networks (GNN) have emerged as a powerful tool in the realm of data analysis, particularly in knowledge graph construction. By capitalizing on the interaction and message passing among nodes in a graph, GNN can capture intricate relationships, making them widely applicable in various tasks, including knowledge representation, extraction, fusion, and inference. In the context of agricultural knowledge graph (AKG) development and knowledge service application, however, the agricultural domain presents unique challenges. These challenges encompass data with high multi-source heterogeneity, dynamic spatio-temporal changes in knowledge, complex relationships, and stringent requirements for interpretability. Given its strengths in graph structure data modeling, GNNs hold great promise in addressing these difficulties. For instance, in agricultural data, information from weather sensors, soil monitoring devices, and historical crop yield records varies significantly in format and type, and the ability of GNNs to handle such heterogeneity becomes crucial. [Progress] Firstly, this paper provides a comprehensive overview of the representation methods and fundamental concepts of GNNs was presented. The main structures, basic principles, characteristics, and application directions of five typical GNN models were discussed, including recursive graph neural networks (RGNN), convolutional graph neural networks (CGNN), graph auto-encoder networks (GAE), graph attention networks (GAT), and spatio-temporal graph neural networks(STGNN). Each of these models has distinct advantages in graph feature extraction, which are leveraged for tasks such as dynamic updates, knowledge completion, and complex relationship modeling in knowledge graphs. For example, STGNNs are particularly adept at handling the time-series and spatial data prevalent in agriculture, enabling more accurate prediction of crop growth patterns. Secondly, how GNN utilize graph structure information and message passing mechanisms to address issues in knowledge extraction related to multi-source heterogeneous data fusion and knowledge representation was elucidated. It can enhance the capabilities of entity recognition disambiguation and multi-modal data entity recognition. For example, when dealing with both textual descriptions of agricultural pests and corresponding image data, GNNs can effectively integrate these different modalities to accurately identify the pests. It also addresses the tasks of modeling complex dependencies and long-distance relationships or multi-modal relation extraction, achieving precise extraction of complex, missing information, or multi-modal events. Furthermore, GNNs possess unique characteristics, such as incorporating node or subgraph topology information, learning deep hidden associations between entities and relationships, generating low-dimensional representations encoding structure and semantics, and learning or fusing iterative non-linear neighborhood feature relationships on the graph structure, make it highly suitable for tasks like entity prediction, relation prediction, denoising, and anomaly information inference. These applications significantly enhance the construction quality of knowledge graphs. In an agricultural setting, this means more reliable predictions of disease outbreaks based on the relationships between environmental factors and crop health. Finally, in-depth analyses of typical cases of intelligent applications based on GNNs in agricultural knowledge question answering, recommendation systems, yield prediction, and pest monitoring and early warning are conducted. The potential of GNNs for constructing temporal agricultural knowledge models is explored, and its ability to adapt to the changing nature of agricultural data over time is highlighted. [Conclusions and Prospects] Research on constructing AKGs using GNNs is in its early stages. Future work should focus on key technologies like deep multi-source heterogeneous data fusion, knowledge graph evolution, scenario-based complex reasoning, and improving interpretability and generalization. GNN-based AKGs are expected to take on professional roles such as virtual field doctors and agricultural experts. Applications in pest control and planting decisions will be more precise, and intelligent tools like smart agricultural inputs and encyclopedia retrieval systems will be more comprehensive. By representing and predicting entities and relationships in agriculture, GNN-based AKGs can offer efficient knowledge services and intelligent solutions for sustainable agricultural development.

Key words: graph neural networks, knowledge graph, knowledge representation, knowledge reasoning, knowledge service, agriculture