It is very important to master the rainfall utilization efficiency and spatial-temporal distribution characteristics in order to improve the agricultural water resource utilization efficiency. In this study, an adaptability index (AI) was constructed to reflect the relationship between rainfall and crop water demand. Spatial analysis and clustering analysis were used to study the spatial distribution characteristics and evolution rules of the adaptability between water demand and rainfall in the growing period of summer maize in Henan Province of China. The results showed that there were significant spatial differences in the adaptability of different regions, and such differences change with time, indicating that AI has certain uncertainties in the region and growth season. In general, the AI of the whole growth period of summer maize is mainly determined by the AI of tasseling period-milky period, while the multi-year change rate of AI is mainly determined by the emergence period-jointing period, tasseling period-milky period, and milky period-maturity period The adaptability of summer maize to rainfall in the study area can be divided into three categories, among which the one with increased adaptability occupies the main part, and the one with sharply decreased adaptability were also distributed in the study area. The above studies indicate that it is important to pay attention to the adaptability of rainfall to agricultural water management. The complexity division of crop water demand by rainfall adaptability index can guide the establishment of reasonable and accurate irrigation system.
Keywords: Adaptability; Agricultural water management; Crop water requirement; Rainfall; Summer maize; Temporal and spatial distribution.