Effects of subsurface irrigation types on root distribution, leaf photosynthetic characteristics, and yield of greenhouse tomato

•Soil water-heat-air environment of continuous irrigation was more stable than intermittent irrigation under similar irrigation amount.•SICE2 increased the RLD in 0–20 cm soil layer, but SDI had a higher percentage of roots in 40–60 cm.•The spatial distribution of tomato roots was more symmetrical in SICE2 than in SDI under similar irrigation conditions.•The photosynthetic characteristics of tomato leaves under SDI showed obvious changes with irrigation events.•High yield and quality were achieved by SICE2 in greenhouse tomato production systems. Optimizing field management practices, particularly irrigation, to balance root growth and leaf photosynthesis is crucial for regulating yield formation and improving greenhouse vegetable productivity. In this study, two-season greenhouse experiments were conducted to investigate the effects of different irrigation methods (continuous irrigation and intermittent irrigation) and different emitter discharges under continuous irrigation on root development, photosynthetic characteristics, and yield of greenhouse tomato. The experiment consisted of four treatments: intermittent irrigation employing the subsurface drip irrigation system (SDI), continuous irrigation employing the subsurface irrigation applying ceramic emitters system (SICE), and the continuous irrigation treatments were divided into SICE1, SICE2, and SICE3 with emitter discharges of 0.15 L h−1, 0.26 L h−1, and 0.3 L h−1, respectively. The results showed that SICE2 had a more stable soil water-heat-air environment than SDI. The root length and surface area of SICE2 were greater than those of SDI. SICE2 increased root length density (RLD) and root surface area (RSA) in the 0–20 cm layer, while SDI increased them in the 40–60 cm layer. Furthermore, the plant-spacing direction symmetry of SICE2 (1.22–1) was better than that of SDI (1.39–1). Continuous irrigation improved root symmetry by increasing the irrigation amount. Significant differences in photosynthetic characteristics were observed between SDI and SICE2, especially in Pn, Tr, and Gs. These parameters fluctuated only from 2.02 % to 10.67 % with SICE, while they fluctuated from 52.63 % to 301.56 % with SDI in the two days before and after irrigation. SICE3 achieved the highest yield and lower WPC in both seasons. Continuous irrigation using SICE2 (111.6 t hm−2 in autumn, 119.6 t hm−2 in spring) harvested higher yields than intermittent irrigation using SDI (100.1 t hm−2 in autumn, 111.0 t hm−2 in sp