Field management techniques of winter rape in the later stage

At present, rape field growth enters the late stage, vegetative growth and reproductive growth are very exuberant, which is an important period to improve seed setting rate, oil content and grain weight, and is very important for yield formation. The main techniques of field management in the later stage of winter rape are as follows: first, apply flower and grain fertilizer skillfully according to local conditions. Rape can not mature until about 60 days after the first flowering, and a lot of nutrition is still needed during this period. Topdressing flower fertilizer is an important measure to increase rape yield in the later stage. The application of flower fertilizer should be determined according to seedling condition, soil fertility and other conditions. For the fields with sufficient fertilization in the early stage and vigorous growth of rape, 0.2 jin of potassium dihydrogen phosphate per mu can be used to fertilize 100 jin of water and spray evenly, which can not only prevent premature senescence, but also promote the synthesis and transformation of fat in seeds and increase the oil content of seeds. For the fields with little fertilization in the early stage and poor growth of rape, 3-4 jin of urea per mu can be applied before the rain at the first flowering stage to supplement nitrogen fertilizer. For the fields with premature senescence, light leaves and early final flowering, urea can be applied 2 jin per mu at the end of flowering, or 0.1 jin of urea and 0.2 jin of potassium dihydrogen phosphate per mu can be evenly sprayed on 100 jin of water. Attention should be paid to prevent excessive application of nitrogen fertilizer in the middle and later stages, resulting in greasy plants, an increase in shrunken seeds and a decrease in fat content. Second, resist drought and waterlogging, and prevent lodging. Drought is often encountered in the middle and later stage of winter rape area in northern China, so it is necessary to irrigation in time to resist drought and maintain a certain field humidity. There are more Rain Water in the middle and later stage of the southern winter rape area, so it is necessary to clear the ditch and reduce humidity in time, control the groundwater level, keep the three ditches unblocked, and prevent the occurrence of waterlogging damage and diseases. In the middle and later stage of rape, the relative water content in the field is generally 60% and 70%. During the period from the final flowering to the basic setting of the pod, rape is easy to lodge and break, especially in the fields with prosperous plant growth, excessive density, shallow transplanting, insufficient soil cultivation, poor drainage and Sclerotinia sclerotiorum, or lodging most easily in heavy rain and strong wind. Lodging causes rape stalk breaking, nutrients can not be transported normally, lower pod photosynthesis is weakened, poor ventilation and light permeability in the field, susceptible to disease and mildew, seriously affecting the yield and quality of rape. In the middle and later stages of rape growth, it is necessary to keep the three ditches unblocked and cultivate the soil and roots in time. The vigorous growing fields should be prepared in advance to be supported by bamboo poles. Third, remove the old yellow leaves and control Sclerotinia sclerotiorum. Sclerotinia sclerotiorum is the most important disease in rape production, which can cause 1-30% yield loss or even higher, especially in flowering stage and pod development stage. The old yellow leaves in the middle and lower parts of the plant should be removed in time and taken out of the field in a sunny day to improve the ventilation and light transmission conditions in the field and prevent the occurrence of diseases. The fields with good growth, early onset and serious disease should be picked early, and those with poor growth and mild disease should be picked late or not. When the leaf incidence of the plant in the field reaches 10%, and the stem incidence reaches 1%, it is necessary to clear up and spray in time. 50% carbendazim wettable powder 0.2-0.3 jin or 40% sclerotia 0.2-0.3 jin per mu can be evenly sprayed on 100 jin of water, focusing on the middle and lower stems and leaves of the plant and the ground. For the over-growing fields, the pesticide should be sprayed again after an interval of 7-10 days to improve the control effect. Fourth, promote early maturity and harvest at the right time. For rapeseed with delayed maturity and affecting the connection of stubble, 3000-4000ppm ethephon solution per mu could be sprayed about 20 days after final flowering to promote early maturity and alleviate the contradiction of stubble. In the whole field, the pods of 2thumb 3 are yellowish green, and the pods in the middle of the main axis are loquat color. The suitable harvest time for rape is when the pods are green, generally about 25-30 days after the final flowering of rape. Rapeseed is suitable for a short harvest period, so it is necessary to grasp the opportunity to harvest with dew in the sunny morning to prevent pods from falling. Cut rape should be shipped out of the field in time, put on the wrong pile and covered with straw or film. When stacking, pods should be placed in a stack to facilitate post-ripening. Generally stacked for 4-6 days, seize the sunny morning in time to pile, spread, threshing, drying, Yang net.