Interactive Effects of IoT-Based Microclimatic Regulation and Nitrogen Supply on Growth, Yield, and Water Productivity of Hydroponically Grown Bokchoy Crop

IoT-powered climate intelligence is redefining protected hydroponics by delivering dynamic, real-time orchestration of temperature, humidity, and nutrient environments where even subtle micro-variations can decisively shape plant performance, yield potential, and system efficiency. This experiment, conducted in the Hi-Tech polyhouse at Lovely Professional University, Punjab, assessed the combined influence of IoT-regulated microclimate and nitrogen supply on hydroponic bokchoy (Brassica rapa var. chinensis). The experiment was conducted in a Split-Plot Design (SPD) with three replications, where three microclimatic regimes [MCC₁ (16–18°C; 80–85% RH), MCC₂ (21–23°C; 70–75% RH), and MCC₃ (26–28°C; 60–65% RH)] were assigned to the main plots, and three nitrogen levels [N₁ (100 ppm), N₂ (150 ppm), and N₃ (200 ppm)] were allocated to the sub-plots, resulting in nine treatment combinations. The IoT-based monitoring system demonstrated high precision (R² > 0.90), ensuring reliable environmental control. Growth, yield, and water productivity were significantly influenced by both factors and their interaction. A moderate regime of 21–23°C and 70–75% RH combined with 150 ppm nitrogen consistently delivered superior outcomes, including earlier maturity, enhanced vegetative growth, higher yield (370 g plant⁻¹), and improved water productivity (118 g L⁻¹). In contrast, suboptimal combinations reduced productivity by nearly half. The findings emphasize that synchronized climate automation and balanced nitrogen management are essential for maximizing efficiency and sustainability in smart hydroponic systems.