Abstract: The study with pot experiment showed that after cutting partial roots at returning green stage, the growth of winter wheat was restrained at early growth stage, and the leaf area was decreased significantly from returning green to jointing stage but restored to the level of the control at flowering stage. Under high soil moisture condition, root cutting increased the values of chlorophyll fluorescence parameters ETR, Φ_{PS Ⅱ}, q_P and q_N at jointing stage significantly. The accumulated dry matter weight per stem after anthesis was significantly higher in root-cut wheat (0.81 g) than in the control (0.56 g), with the accumulation coefficient (AC) of root-cut wheat increased by 38.79%, but no significant difference was observed in root weight. Under low soil moisture condition, there were no significant differences in the values of chlorophyll fluorescence parameters and accumulated dry matter weight per stem after anthesis between root-cut wheat and the control, but the root weight of root-cut wheat decreased significantly. Soil moisture didn’t enhance the compensation effect of the aboveground biomass and grain yield of root-rut wheat. Root cutting reduced the water consumption of winter wheat significantly. Under high soil moisture condition, root-cut wheat saved 2 000 ml of water, and its water use efficiency (WUE) (1.97 g·kg^-1) was significantly higher than that of the control (1.70 g·kg^-1). Under low soil moisture condition, root-cut wheat saved 1 500 ml of water, but there was no significant difference in the WUE between root-cut wheat and the control.

Key words: Predacious ladybird, Biological control efficiency, Function assessment