Cultivation architecture modulates root-zone moisture, photosynthetic performance and yield–quality trade-offs in soilless greenhouse strawberry

Cultivation architecture can improve space-use efficiency in soilless greenhouse strawberry production, but its effects are often evaluated mainly through yield or canopy light interception. This study examined how elevated cultivation positions altered canopy and root-zone microenvironments, and how these changes related to plant physiology, fruit quality, yield and economic performance. Strawberry plants were grown in a solar greenhouse at four positions: double-layer upper (DL-U), double-layer lower (DL-L), single-layer at 1.0 m (SL-100) and single-layer at 0.6 m (SL-60). DL-U and SL-100 had greater light availability, whereas DL-L had the lowest daily light integral and the highest substrate moisture. Root-zone temperature, EC and pH also differed among positions, showing that architectural effects were not restricted to canopy light. At the plant level, SL-100 showed the strongest performance, with the highest cumulative yield per plant, consistently high root activity and stronger reproductive-stage gas exchanges. On a ground-area basis, the combined double-layer system produced 10.65 kg m−2, compared with 6.47 kg m−2 for SL-100 and 5.25 kg m−2 for SL-60. It generated the highest estimated operating net return (157.36 CNY m−2) when frame construction cost was excluded, because DL-U and DL-L contributed jointly within the same greenhouse footprint. SL-100 had the highest operating benefit–cost ratio (4.10). Fruit quality responses differed between full-fruiting and late-fruiting harvests, indicating that productivity, quality and production scale did not follow a single ranking across architectures. Correlation analysis, redundancy analysis and exploratory PLS-SEM were consistent with an association network linking microenvironmental gradients with root traits, fluorescence responses and growth responses. These findings suggest that optimization of elevated soilless strawberry systems should consider both canopy light and root-zone conditions, especially in double-layer systems where lower-layer shading and moisture retention may constrain plant performance.