In order to study the effects of shallow wet–dry irrigation at tillering stage on effective tiller numbers, photosynthetic activity, yield and water use efficiency (WUE) of rice in black soil region, a pot experiment was conducted at Qingan National Irrigation Test Station of Heilongjiang Province from May to September in 2019. Four irrigation treatments were set up at tillering stage, namely light shallow wet–dry irrigation (T1), moderate shallow wet–dry irrigation (T2), severe shallow wet–dry irrigation (T3) and shallow water irrigation (CK). The results showed that under water controlled conditions at tillering stage, the ineffective tiller numbers were reduced and earing rate was increased as compared to CK. The photosynthetic (Pn), stomatal conductance (gs) and transpiration rate (Tr) were decreased with the decrease in soil water potential while SPAD and intercellular CO2 concentration (Ci) were opposite. The Pn, gs, Tr and Ci in T1 and T2 treatments reached the normal level after re-watering at heading and milk-ripening stages. The yield (Y) and WUE in T1 treatment were higher than that of the other treatments, significantly (P < 0.05). Therefore, the study can provide the theoretical basis and reference for water-saving and high yield of rice in black soil region.
