Subsurface irrigation with ceramic emitters improves greenhouse tomato yield and resource utilization efficiency by stabilizing soil hydrothermal status

Maintaining a stable and suitable soil hydrothermal status is crucial for promoting the high quality and yield of greenhouse vegetables throughout the year. Irrigation by regulating soil moisture changes to soil heat capacity is an effective measure to alleviate the fluctuation of soil hydrothermal environment caused by interannual solar radiation. To investigate the soil hydrothermal status of greenhouse tomatoes under subsurface irrigation with ceramic emitters (SICE) and its impact on tomato growth and yield, we conducted a two-season greenhouse experiment with subsurface drip irrigation (SDI) as a control. The results showed that soil hydrothermal changes under SICE fluctuated less with time in the autumn and spring experiment than SDI; SICE could increase soil temperature in the tomato root zone profile in winter and decrease the profile temperature in summer. This indicates that SICE could reduce the direct effect of air temperature on soil temperature and maintain a stable and suitable soil hydrothermal condition. Furthermore, the underground and vegetative biomass of SICE stopped increasing with the rapid growth of water and heat resources to the inflection point. They shifted to the accumulation of reproductive biomass. However, the vegetative biomass of SDI continued to increase in the late stage of water and heat resources. Therefore, under similar total biomass conditions, SICE obtained more output. SICE increased tomato yields by 11.60 in autumn and 8.36 t hm -2 in spring compared to SDI. The regulation mechanism also improved the hydrothermal resource utilization efficiency under SICE, with SICE increasing water and heat resource use efficiency by 24.04 % and 3.73 % (in autumn) and 9.80 % and 6.00 % (in spring), respectively, compared to SDI. We conclude that SICE is an effective and promising irrigation method for greenhouse tomato cultivation for stabilizing the soil water and heat environment, promoting yield, and improving the utilization rate of solar radiation.