Winter wheat has entered the jointing stage of turning green. What can be done to improve the header rate?
Wheat turning green means that more than half of the wheat seedlings in the wheat field have heart leaves, and the length is not less than 1 cm. The period from turning green to getting up is about 1 month, which belongs to the last period of wheat seedling. The greening period of wheat is related to the planting area of wheat and the weather situation of the year, and the greening time is mostly from mid-late February to mid-late March.
The growth in this period is mainly rooting, long leaves and tillering, which is the key period for the formation of the number of spikes per mu, so the management focus in the green-returning period is on how long and large spikes are to improve the yield.
Cutting grass and loosening soil in 65438+ wheat field can not only improve soil permeability, but also promote soil moisture conservation, raise soil temperature and promote root development. Cutting grass and loosening soil should be carried out for 2-3 times from wheat turning green to jointing stage, and the principle of loosening soil is "shallow first and then deep". Inhibition of vigorous wheat seedlings can also control vigorous growth and prevent wheat lodging.
2. Chemical weeding in wheat fields Chemical weeding in wheat fields should be carried out after turning green and before jointing. Chemical weeding is prohibited after jointing, and herbicides should be selected according to the types of weeds in the field. When the weather is fine and the temperature is above 10℃, it should be sprayed at 165438+ from 0: 00 am to 2: 00 pm to avoid re-spraying and missed spraying.
Herbicides such as isoproturon and methyl disulfonate are prone to freezing injury if there is low temperature frost in the later stage. In order to reduce the risk of "frostbite", it is generally required that extreme cold weather does not occur within 20 days after the use of isoproturon, and other drugs generally require that extreme cold weather does not occur within 1 week after the use of isoproturon.
3. Wheat field control In general, dwarf varieties and weak wheat fields do not need to be controlled. Wheat field flourishing control is to coordinate vegetative growth and reproductive growth. Wangfang is carried out between turning green and getting up, and spraying the product after the jointing stage of wheat will be ineffective. Reasonable growth control can prevent lodging in the later stage of wheat seedlings and avoid yield reduction. Measures to control vigorous growth include weeding, root cutting and spraying chemicals to control vigorous growth.
At present, chemical control with drugs can delay the growth process of tillers, reduce the distance between basal internodes, improve the lodging resistance, and at the same time delay the population growth process to a certain extent and reduce the risk of freezing injury. It is suggested that uniconazole and methylphenidate should be used to control growth, and tebuconazole and pyraclostrobin should be used to control sheath blight and powdery mildew.
4. The time for watering green water is generally from the end of February to the middle of March. Whether it is necessary to water green water depends on the temperature, soil moisture, soil fertility and seedlings. If freezing water is not poured before winter or it is poured too early, the 0 ~ 5 cm soil layer is seriously short of water when turning green, or the tillering node is just in the dry soil layer, the turning green water should be poured in time, but the amount of water must not be too large, because the soil has not been completely thawed when turning green, and flooding with large water is easy to cause retting, which will affect the development of wheat seedlings and even cause serious seedling death; Generally, if the soil humidity is suitable, do not water the greening water, so as to avoid soil hardening after watering, reduce the ground temperature and affect greening; Water is poured late in winter, and if there is no shortage of water in the wheat field when it turns green, it can be appropriately postponed to the rising period.
5. Topdressing should be reasonable according to the seedling condition during the green turning period. First of all, for wheat fields with weak seedling condition, poor soil fertility and poor fertilizer efficiency, soil moisture can be grabbed and topdressing can be carried out when the surface begins to thaw. Secondly, in wheat fields with good growth, measures should be taken to give priority to prevention and control and combine prevention and control. The main measures include controlling weeds and spraying chemical control agents. Thirdly, in the wheat field with many seedlings and good seedling condition, topdressing green manure can be postponed until the wheat seedlings get up (early March) to control ineffective tillering and improve tillering rate.
5. 1 Wheat is yellow due to lack of nitrogen.
In autumn, problems such as premature sowing, insufficient application of base fertilizer or low nitrogen content of base fertilizer lead to yellowing of wheat leaves. Top-dressing of urea is about 5 kg per mu during the green turning period of wheat, and top-dressing of urea 12 ~ 15 kg per mu during the jointing period.
5.2 Insufficient application of phosphate fertilizer in wheat base fertilizer or phosphorus deficiency in soil leads to yellowing of wheat due to phosphorus deficiency, less secondary roots, dark green leaves and yellowing of tip. When the wheat seedlings are short of phosphorus, apply diammonium phosphate 10 kg or 45-50 kg of calcium superphosphate per mu of ditch.
6. Pest control The temperature gradually warmed up in spring, and the wheat entered the green period. During this period, a variety of wheat diseases and insect pests also began to enter the multi-occurrence period. The main diseases are sheath blight, powdery mildew and leaf rust, and the main pests are red spider and wheat aphid, among which the key monitoring objects are sheath blight, powdery mildew and red spider.
If it rains continuously, remember to go to the wheat field for observation. If there is sheath blight, spray pesticides in time, such as benzoxazole, triadimefon, diniconazole, tebuconazole and difenoconazole, and use them alternately.
If there are wheat aphids in the field, it is suggested to add bifenthrin, avermectin, nitenpyram and pymetrozine; The red spider is treated with pyridaben and the like. If the wheat grows vigorously or the seedling condition is weak, it can also be sprayed together with growth regulators and foliar fertilizers, which can not only save costs, but also achieve the goal of multiple effects with one spray.
7. Prevention of late spring cold is mainly prevention, and the most effective measure is to pay close attention to weather changes. If there is late spring cold in early spring, measures such as watering in time, topdressing potassium dihydrogen phosphate and spraying brassinolide can be taken to remedy it.