| As a sort of grain and forage crop, wheat become more and more critical in grain security and agricultural production. Whether wheat could achieve high and stable yield is of momentous significance to grain production. Owing that weeds always exist in every period of wheat’s life, the growth of wheat is abidingly disturbed that the crop quality and yield declined obviously. Chemical weed control technology is widely used because of less herbicide, more species, lower cost, wider range of selection and safer technique, etc. Especially herbicides-phenoxy acids(hormone) could remove broadleaf weeds effectively and prevent the germination of all types of weeds sustainly. Jinnong 190 is an important winter wheat in Changzhi County, Shanxi Province. Currently More and more people begin to adopt chemical weed control technology to inhibit the injury of weeds since it related to the local farmers’ income directly. Accordingly, looking for a weed control method with appropriate timing and credible dose become extremely necessary to winter wheat’s yield and the local economy.To find out the most advantageous time and pesticide concentration, this experiment spraying on the winter wheat(Jinnong 190) with herbicide MCPA in different period and different concentration. Then a comparative study from such characters as main agronomic traits(plant height, leaf area and top second leaf’s width), part of physical properties(chlorophyll content and membrane lipid peroxidation) and yield of winter wheat(Jinnong 190) is repeatedly made.Several aspects of the research results are:(1) With the increasing of processing concentration of MCPA, the plant height of wheat(Jinnong 190) in growth period(elongation stage to maturation stage) become slightly higher than the controls, and the increasing amplitude is about 1.18-2.23%. Spraying on the winter wheat with MCPA at low concentration as 375 ml/hm2 before elongation stage, the plant height of wheat become higher than the control group in growth period but it has not significant difference.(2) Both leaf area and top second leaf’s width of winter wheat(Jinnong 190) grow as the type of "S" along with the birth process no matter spraying with MCPA on winter wheat before or after the elongation stage. In addition, the leaf width of wheat in growth period narrows down with the increase of spraying concentration, especially when the concentration surpass 500 ml/hm2.(3) Spraying with different concentrations of MCPA on winter wheat(Jinnong 190) affects the chlorophyll content consumingly in different period. The content of chlorophyll always get lower along with the increasing of spraying concentration in the same growth period. While spraying after the elongation stage, the degree of inhibition would be greater than other times significantly. Therefore, spraying with herbicide before the elongation stage will be beneficial to the photosynthesis of winter wheat.(4) If spraying before the elongation stage, the content of malondialdehyde(MDA) in each growth period would be elevated with the increasing of the herbicide’s concentration. And the changing trend of pesticide processing after the elongation stage is more intuitive that the growth trend of MDA is almost in a straight line. The activity of SOD(superoxide dismutase) and POD(peroxidase) will be raised with the increase of the concentration of MCPA. Furthermore, there will be a greater negative impact on winter wheat in that the influence of spraying on the Membrane lipid peroxide before the elongation stage is really greater than another situation.(5) Spraying with different concentrations of MCPA on winter wheat(Jinnong 190) has not significant difference on spike grain number per plant, panicle length and spike number per plant. On the whole, it usually presents such circumstances as high concentration to inhibit and low concentration to promote. Spraying after the elongation stage, yield per plant and yield per unit area of the winter wheat(Jinnong 190) are the highest at the concentration of MCPA as 375 ml/hm2. |
