Spatiotemporal Variation in Precipitation-Water Requirement Matching of Maize and Its Response to Planting Strategy Optimization in Northeast China

Rainfed spring maize production in semi-arid to semi-humid transition regions is constrained by spatial and temporal mismatches between precipitation supply and crop water demand, yet whether planting strategies optimized for high and stable yield can also improve water supply–demand matching remains unclear. This study aimed to characterize long-term water supply–demand patterns, identify suitable planting strategies under drought at different growth stages, and evaluate their potential benefits for precipitation–crop water demand matching. An APSIM-Maize model, calibrated and validated using observed maize phenology and grain yield, was applied to Liaohe Plain, Northeast China, under historical climate conditions from 1951 to 2020. A total of 125 combinations of cultivar (C), sowing date (S), and planting density (D) were evaluated in each climatic region using the high-stability coefficient, abbreviated as HSC, followed by an assessment of their effects on the water supply–demand ratio, abbreviated as WSDR. Long-term simulations showed that the mean effective precipitation of 515.84 mm was lower than the crop water requirement of 548.54 mm, with precipitation insufficient to meet crop water demand in 64.3% of the years. Water supply–demand matching was particularly weak during the early growing season and in semi-arid regions. Among the 125 tested planting combinations, C4-S5-D1 (middle–late cultivar, late sowing, low planting density) consistently achieved the highest HSC across both climatic regions and drought periods. Compared with conventional management, delaying sowing by 10 days and reducing planting density by 1.0 plant m−2 increased HSC by 9.40–11.87% in the semi-arid region and 4.02–5.00% in the semi-humid region. The subsequent WSDR assessment showed calculated relative increases of 6.44–8.52% and 9.54–12.95% in the semi-arid and semi-humid regions, respectively, across all 22 stations. Notably, the relative increases in HSC were greater in the semi-arid region, whereas those in WSDR were greater in the semi-humid region, highlighting distinct regional responses in drought-condition yield performance and water supply–demand matching to planting-strategy optimization. By linking long-term crop simulations with yield stability assessment and water supply–demand evaluation, this study provides a framework for identifying promising planting combinations within predefined management ranges that may contribute to stable crop production and improved precipitation–crop water demand matching in rainfed agricultural systems.