稗草对水稻生长和产量性状的影响及其防除经济阈值研究OA

This research aimed to clarify the quantitative relationship between barnyardgrass(Echinochloa crus-galli)density and Oryza sativa growth and yield loss,and establish an economic threshold model for its control.Pot and field experiments were conducted to systematically evaluate the competition effects of 0-25 plants·mn-2 barnyardgrass on rice growth traits(plant height,tiller number)and yield components(effective panicles number,filled grains number,1000-grain weight)in both direct-seeded and machine-transplanted rice systems.Regression models were used to analyze the barnyardgrass density-rice yield loss relationship,and a control threshold model was constructed based on crop parameters.Pot trials showed that at ≥7 plants·barrel-1,rice plant height and tiller number were suppressed by 25.15％and 80.82％,respectively,exhibiting significant density-dependent stress.Field data indicated that 25 plants·m-2 barnyardgrass reduced rice height by 15.27％in direct-seeded rice and 24.07％in machine-transplanted rice,and reducing effective panicles number by 70％—80％,filled grains number by 45.55％and 52.80％,respectively,and 1000-grain weight by 3.46％and 3.86％,resulting in 86.44％and 89.40％yield loss in seeded and machine-transplanted rice,respectively.Regression model analysis indicated a quadratic relationship for direct-seeded rice(y=1.0870 x2+1.1526 x-4.0842,R2=0.969)and a linear response in machine-transplanted rice(y=11.6774x-15.1928,R2=0.948).After calibration,the economic thresholds for weed control were determined to be 2.55(direct-seeding)and 1.63 plants·m-2(machine-transplanting).Barnyardgrass reduces rice yield primarily by inhibiting tillering(＞42％reduction rate)and subsequently affecting panicle development(＞70％reduction in effective panicle number).The dynamic threshold models established in this study provide a basis for the precise control of barnyardgrass under different rice cultivation modes.These results reveal differential responses of direct-seeded and machine-transplanted rice to varying barnyardgrass density stresses.This information holds significant practical value for constructing precision weed management systems.