Cultivar–Environment Interactions in Macadamia: From Physiological Mechanisms to Regional Zoning, with Evidence from China’s Major Production Regions

Macadamia cultivation has expanded rapidly across diverse agro-ecological zones, but knowledge of cultivar–environment matching remains fragmented across disciplines, hindering the development of evidence-based zoning and management strategies. This review aims to synthesize multidisciplinary evidence into a coherent framework for understanding and managing cultivar–environment (C × E) interactions. We integrate findings from reproductive physiology, ecophysiology, horticulture, and regional agronomy, drawing on evidence from China’s three major production regions (Yunnan, Guangxi, and Guizhou), which represent a broad climatic gradient from dry-season water deficits to warm humid conditions and low-temperature valley stress. Our synthesis yields four principles: (i) Temperature and water regulate reproductive development through stage-specific thresholds. (ii) Cultivars differ markedly in heat requirement, cold tolerance, drought response, and self-compatibility. (iii) Cross-regional comparisons show that yield and kernel quality of identical cultivars vary substantially across provinces. (iv) Adaptive management practices, including high-density planting, sod culture, fertigation, and trunk infusion, can compensate for specific C × E mismatches. These findings are synthesized into a conceptual model linking environmental drivers, phenological windows, physiological thresholds, and management interventions. We identify three research priorities, namely, molecular dissection of adaptive traits, phenological-stage-aware predictive modeling, and standardized multi-location evaluation networks, as essential for supporting climate-resilient cultivar zoning and orchard management.