Subsurface Drip Irrigation Optimization: Strategic Calibration of Dripper Flow and Pipe Burial Depth to Maximize Tomato Physiological Performance, Yield and Fruit Quality in Greenhouse Cultivation

ABSTRACT To address water scarcity and improve tomato production quality, a 2‐year, two‐factor completely randomized experiment was conducted to evaluate the effects of subsurface drip irrigation (SSDI) flow rate (0.9, 1.6 and 2.0 L/h denoted as F0, F1 and F2) and burial depth (0, 15 and 25 cm denoted as D0, D15 and D25) on tomato growth. SSDI significantly reshaped the vertical distribution of soil moisture. The soil water content (SWC) in both the shallow (0–40 cm) and deep (60–100 cm) layers exhibited sensitivity to the dripper flow rate and burial depth. The SWC in the 0‐ to 20‐cm layer decreased by 16%–72% with increasing depth, whereas that in the 20‐ to 40‐cm layer increased by 14% with flow. Below 60 cm, SWC showed enrichment with increasing flow and depth, reaching 48%. This vertical heterogeneity governs plant physiological responses. The F2D15 optimized growth by aligning wetting zones with the root system, whereas deep burial partially suppressed fruit number. Regarding fruit quality, F0 increased soluble sugars through water stress, whereas D25 significantly reduced soluble acids, raising the sugar‐to‐acid ratio. Comprehensive evaluation revealed that F2D15 ranked first in both years of trials, making it a recommended parameter for SSDI in local greenhouse tomato production.