according to the central meteorological observatory, from april 28 to may 1, the temperature in most parts of the north will continue to rise, with the temperature in north china and huanghuai rising sharply, with the temperature rising to 6-10 ℃ and the local temperature reaching over 12 ℃; it is estimated that from may 30 to may 2, the highest temperature in the central and southern part of north china and the central and western part of huanghuai will reach 32-34 ℃ and the local temperature will reach 35-37 ℃. in most of the above areas, there are 4-6 gusts in the afternoon, among which some areas in inner mongolia, northeast and other places can reach about 7 levels.
from late april to late may, wheat is in the stage of grain formation and filling, which is the key period of wheat yield formation. the suitable temperature for this stage is 20-24 ℃. the results showed that the high temperature above 30 ℃ would cause the interruption of grain filling, accelerate the aging of wheat, shorten the filling period, reduce the yield, and also lead to the decrease of the filling rate, grain weight and yield. in addition, the local gale weather may also lead to wheat lodging, affecting the number and weight of grains. if the management measures are not taken in advance, the wheat may suffer a "double blow"!
in order to make wheat pass the customs smoothly, these management measures are indispensable:
1、 water in advance to reduce the threat of high temperature
the water consumption of wheat from flowering to maturity accounts for one quarter of the total water consumption of the whole growth period. if the field is dry at this stage, it will not only affect the grain weight, heading, flowering, but also affect the number of grains per ear, especially in the face of the threat of high temperature, it needs to be watered in advance, which can not only ensure the physiological water consumption of wheat, but also improve the field microclimate, delay the early failure of root system and enhance photosynthesis of leaves it can resist the harm of dry hot wind, improve the plumpness and increase the weight of grain. however, it should be noted that if the amount of water is too large, the soil water will be saturated for a long time, and the air is lack, the root respiration will be inhibited, and the absorption of water and nutrients will be temporarily blocked, resulting in a temporary water and nutrient supply slowdown. if the plant is watered under high temperature and sun exposure, the leaves and other organs will dehydrate rapidly under the strong transpiration of the plant, which will cause the phenomenon of green ears and yellow leaves. therefore, we must pay attention to this period of watering: first, try to use water-saving irrigation measures such as sprinkler irrigation to reduce the amount of single irrigation and shorten the absorption barrier period. flood irrigation should be carried out as soon as possible after the water reaches the ground, so as to reduce the time of flooding; secondly, it should avoid the high temperature period, when the temperature is low in the morning and evening, and avoid the windy weather, so as to prevent lodging; thirdly, in case of dehydration and dry symptoms, it is necessary to spray foliar fertilizer in time, and supplement water and nutrients through the foliar surface in combination with one spray and three preventions, so as to slow down the water loss rate of the leaves until the roots the respiratory system was restored to normal.
2. topdressing or spraying foliar fertilizer to enhance the resistance of wheat can only water but not topdressing for the wheat field with high soil fertility level and sufficient topdressing in the early stage; for the wheat field with the phenomenon of de fertilization, urea can be topdressing combined with watering. spraying foliar fertilizer in time: generally 100-1000g urea, 150-200g potassium dihydrogen phosphate and 50kg water are used per mu.
3. prevent the harm of dry hot air
in this high temperature process, the highest temperature in the central and western regions of the yellow and huaihe river reaches 32-34 ℃, the local temperature can reach 35-37 ℃, and the relative humidity of the air is small. in addition, the soil moisture deviation in some areas is easy to form a dry hot wind, which causes the decrease of the wheat filling rate, the drying of the wheat grain, the decrease of the grain weight, and the reduction of the yield.
in order to prevent the disaster of dry hot wind, it is necessary to water 3 to 5 days in advance, and spray 0.1% acetic acid or 1:800 acetic acid solution on the leaf surface at the early stage of wheat filling, so as to reduce the opening angle of stomata on the leaf, inhibit transpiration, and improve the ability of wheat plants to resist drought and dry hot wind.
in addition, the application of potassium dihydrogen phosphate or water-soluble fertilizer containing amino acid can accelerate the growth and development of wheat in the later stage, enhance the ability of wheat to resist dry hot wind, and reduce the harm of dry hot wind.
4. prevention of wheat lodging
improper cultivation measures, such as too much sowing or improper fertilization, such as only paying attention to nitrogen and phosphorus fertilizer, ignoring potassium fertilizer and micro fertilizer and other reasons will reduce the lodging resistance of wheat. however, this year, when the jointing and booting date of wheat is advanced, some wheat fields are prosperous and there is a greater risk of lodging. once encountering gusts or strong winds, it is easy to lodging.
after lodging, the transportation of water and nutrients of wheat is blocked, which will seriously affect wheat maturity, reduce 1000 grain weight and reduce yield. the earlier the lodging, the greater the impact on the yield. for example, the yield can be reduced by 30% - 50% at heading stage and about 20% at filling stage.
if lodging occurs, do not force artificial straightening, let it grow naturally, and spray potassium dihydrogen phosphate or water-soluble fertilizer containing amino acid to enhance wheat stress resistance, prolong grouting time and stabilize wheat grain weight.
5. timely control of diseases and insect pests
the filling period of wheat is the most important period of wheat diseases and insect pests, such as powdery mildew, stripe rust, sheath blight, scab, aphid and sucking midge. especially this year, wheat stripe rust in jianghuai river basin is the most serious year in the same period in recent years. this year, scab also shows an aggravating trend. wheat fields prone to lodging are also prone to stripe rust, powdery mildew and scab pandemic, so it is necessary to take timely control measures.
in recent years, the occurrence of disease and pest mixture tends to be normal, and the "package" of disease and pest control and nutrition regulation is accepted by more and more dealers and growers with the advantages of labor-saving and worry free, and gradually becomes the "protagonist" of "one spray and three preventions".
the first use period: returning to green and rising period, to prevent and control stem base rot, sheath blight, powdery mildew and rust, aphids and red spiders; the seedlings are strong, the stem is thick, the leaves are green, the chlorophyll content is high, the photosynthesis is strong, the tillering of wheat is increased, and then the number of ears per mu is increased!
the second use period: in the early stage of heading and flowering, control of scab, powdery mildew and rust, aphids and trematodes; stronger plant pollination capacity, more grains per ear; longer mature and filling period of living culm, full grains and increased 1000 grain weight!