Optimization and validation of solar greenhouse intelligent environmental control system driven by leaf vapor pressure deficit

To address issues such as strong hysteresis and significant parameter fluctuations in traditional greenhouse environmental control systems, an intelligent environmental control system based on leaf vapor pressure deficit（Leaf VPD）was proposed．A dynamic coupling model between Leaf VPD and greenhouse environmental parameters was established, integrating fuzzy control theory with IoT technology to transition from threshold-based environmental parameter control to crop physiological state optimization．An outdoor cumulative temperature four-stage model and a multi-device coordination strategy were adopted to improve regulation efficiency．Experimental results demonstrated system's outstanding performance in temperature and humidity control．Daytime temperature and humidity compliance rates reached 92% and 89%, respectively, with fluctuations controlled within ±1.2 °C and ±8 percentage points．Regarding crop growth, tomatoes achieved an average plant height of 158 cm, a fruit setting rate of 95%, and a disease incidence rate of only 3%, significantly outperforming traditional manually controlled greenhouses．This system effectively enhanced environmental stability and crop physiological performance, offering a reliable technical support for facility agriculture intelligent development．