The effects of chemical pesticide reduction on the occurrence of diseases, pests, weeds and rice yield

A split-field test was conducted to explore how chemical pesticide reduction affects rice yield. Two weed control methods (shallow rotary tillage with conventional herbicide amounts and deep tillage with 30% less herbicide; main factor), two disease and pest control methods (conventional insecticide and fungicide amounts and plant activator protein application with 30% less insecticide and fungicide; sub-plot factor), and two seedling treatment methods (transplanting with and without pesticides; split-split plot factor) were used to investigate rice diseases, pests, weeds, and dry matter production. The results showed that deep tillage significantly decreased the weed numbers and weight compared to the shallow rotary tillage, and the white panicle rate (caused by the borer) was also significantly lowered. Rice plant leaf blast was significantly reduced by using conventional shallow rotary tillage after transplantation with pesticides or the spraying of plant activator protein. Both the weed control methods and the disease and pest control methods had significant effects on the stem sheath dry matter accumulation, and stem sheath dry matter transformation. The interactions between the weed control methods, disease and pest control methods, and seedling treatment methods significantly affected the stem sheath exportation and dry matter transformation. After the plant activator protein application, the stem sheath dry matter increased by 4.0% to 19.4% at the full heading stage. When deep tillage was used, the stem sheath dry matter increased by an average of 7.1%. However, the stem sheath exportation and dry matter transformation decreased from the full heading to maturity stages. Correlation analysis showed that the rice yield was significantly negatively correlated with weeds (tillering and grain-filling stages) and leaf blast (tillering stage). No effect on the rice yield was observed when strategies such as deep tillage, transplantation with pesticides, or the spraying of plant activator protein were employed with 30% less pesticide. These results suggest that the chemical pesticide amount could be reduced during planting by using control methods such as deep tillage, transplantation with pesticides, or the spraying of plant activator protein, and that the rice yield would remain stable.