Key Technical Points of Wheat Moisture-resistant Strain Sowing and Management of Promoting Seedlings from Weak to Strong in Daiyue District

Juqing GE

Daiyue District Administrative Examination and Approval Service Bureau, Tai’an 271000, China

Abstract According to the meteorological conditions of sowing period and the characteristics of seedling in each key growth period, the measures of rushing drainage, rushing harvest stubble, rushing sow, implementing late sowing, strengthening field management before winter and in spring are taken in Daiyue District during the autumn planting period of wheat, which reduce the influence of natural disasters and increase the yield of wheat.

Key words Moisture-resistant strain; Late sowing technique; Field management; Promoting seedlings from weak to strong

1 Introduction

Since September 2021, continuous rainfall has led to soil moisture saturation in some plots and even water accumulation in farmland. Under the influence of continuous rainy and sparse sunlight weather, too late sowing time led to weak wheat seedling condition before winter and in early spring. The techniques of wheat sowing and management of promoting seedlings from weak to strong since autumn planting in 2021 are introduced as follows.

2 Scientific moisture-resistant strain and implementation of key technologies

2.1 Rush drainage, rush harvest stubble and rush sowing

During the wheat planting period in 2021, all forces should be mobilized to dig communication channels in the fields with waterlogged plots and to organize large machinery to pump water and drain water from the fields. For the plots with severely saturated soil moisture, ditches should be opened in the field for water seepage and dispersion of soil moisture, so as to speed up water evaporation and to create conditions for agricultural machinery to enter the land. For the corn plots that are not harvested in time due to rain and waterlogging, good weather should be seized to speed up the progress of machine harvesting and dry corn in time. The cooperatives and enterprises with drying equipment should be actively cooperate to provide grain drying services for large grain growers, so as to solve the difficulties of large grain storage and to reduce losses as much as possible. The plots with suitable soil moisture should speed up the sowing progress to the greatest extent and strive to expand the suitable sowing area.

2.2 Implement late sowing technologyEarly maturing varieties should be reasonably selected, and "post-rain wheat" seeds should be completely abandoned. Fine land preparation should be attached importance to improve the quality of land preparation effectively. According to the principle of "early and less sowing, late and more sowing", the sowing amount can be increased depending on the situation: for those sowing after October 20, the sowing amount is increased by 0.5 kg every 2 d delayed; for those sowing after November, the sowing amount is increased by 0.5 kg for each delayed day, ensuring that rational population can be established. The quality of sowing must be improved, and appropriate shallow sowing can be adopted, with the general sowing depth of 3-4 cm. Too deep sowing makes the first internode of tillering node not elongate under normal circumstances, and even the second internode elongate excessively, leading to too long underground stem which will excessively consume nutrients in the seeds, weak wheat seedling growth, less tillers, small population before winter, less nutrient accumulation and weak frost resistance, which is not conducive to survive the winter safely[1]. Sufficient base fertilizer should be applied and phosphate and potassium fertilizer should be appropriately increased when sowing, to promote strong seedlings and enhance wheat resilience; plots with long standing water should test soil for formulated fertilization to ensure sufficient nutrients for wheat growth; in plots with suitable moisture content, crop straw returning to the field and ripening are important measures to improve soil structure, enrich soil fertility and accumulate organic matter and mineral nutrients in the field[2]. Seed coating or seed dressing should be well done to reduce the risk of seedling diseases and insect pests due to high humidity in the field, to improve the quality of seed coating or seed dressing and to reduce the initial occurrence of diseases and insect pests at seedling stage of wheat, thereby laying a good foundation for wheat harvest.

3 Strengthening pre-winter management to ensure safe wintering of wheat

3.1 Do a good job in field management according to land and seedlingFirst, we must do a good job in filling the gaps with seedlings. The plots with deficient seedlings and ridges should be replanted as early as possible, and the seeds of the original variety are replanted to prevent varieties from being mixed. Second, scientific repression should be adopted. For wheat fields with extensive tillage, poor land preparation quality, many surface clods and loose soil after straw returning to the field, 2-3 times of repression should be carried out before winter in order to realize the purpose of crushing clods, stabilizing the soil, raising and keeping soil moisture. Repression adheres to the principle of "pressing dry rather than wet", "pressing soft rather than hard" and "pressing light rather than heavy". Third, topdressing is performed in time. For wheat fields with insufficient base fertilizer, especially those with large water flow, heavy leaching loss of nutrients and fertilizer deficiency symptoms, topdressing should be carried out combined with watering or borrowing soil moisture in late November and early December before winter, in order to promote the growth of root and tillering.

3.2 Timely remove weeds by chemical agents and prevent and control the damage of diseases and insect pestsWe must strengthen monitoring and early warning, implement prevention and control in a scientific way, and strive to lower the initial incidence of diseases and insect pests before winter to reduce the severity of damage in the winter.

3.2.1Timely remove weeds by chemical agents. The weed resistance before winter is poor, and the prevention and control of weed damage should follow the principle of early prevention and controlling small weeds. (i) Timely medication. Stems and leaves should be treated with chemical agents after 3 leaves and 1 heart of wheat when weeds are basically out before winter. Chemical agents are sprayed from 9:00 to 16:00 on a sunny and calm day with the lowest temperature above 4 ℃, while the spray is prohibited in cloudy and rainy days, or windy days. (ii) Scientific medication. Mesosulfuron and its compound preparation are strictly forbidden on high gluten wheat and high quality wheat to avoid chemical injury. Clodinafop-propargyl and pinoxaden should not be used together with hormone herbicides. (iii) Precise pesticide application. The spray equipments with good performance and fan-shaped sprinkler head should be selected to avoid liquid waste and local chemical injury caused by "running, bubbling, dripping and leaking" of spray equipment, and to ensure uniform spray, no re-spray and no leakage.

3.2.2Control the damage of diseases and insect pests. The plots with stem rot can be sprayed with difenoconazole, thifluzamide and fluxapyroxad on stem base. The occurrence of red spider, wheat aphid, wireworm, sheath blight and other diseases and insect pests must be closely monitored, and comprehensive prevention and control should be carried out.

3.2.3Actively organize and implement unified prevention and control. The technical and equipment advantages of specialized prevention and control organizations should be optimized, and specialized and unified prevention and control operations should be promptly organized and launched to improve the effect, efficiency and benefit of prevention and control.

3.3 Irrigate wintering water as appropriate to protect wintering from freezing damageDue to large late sowing area of wheat last year, some plots have small seedlings and shallow roots, and coupled with less plant nutrient accumulation, the ability to resist low temperature and freezing injury decreases, especially the hilly and dry land with insufficient moisture content is prone to freezing injury. Irrigating wintering water is an important measure to ensure safe wintering of wheat and to ensure retroposed fertilizer and water in early spring, which can also harden the soil and crush clods. In the fields with extensive cultivation, more clods and loose soil when straw is returned to the field, especially in the wheat fields with more suspended roots and seedlings, poor soil water retention and normal moisture content before winter, it is necessary to irrigate wintering water timely to ensure that wheat seedlings survive the winter safely. Wheat fields with higher quality of land preparation, better seedling emergence and sufficient soil moisture content do not need wintering water. Before wintering, emphasis should be placed on suppression measures to protect seedlings from freezing and to survive the winter safely.

4 Strengthening spring management of wheat to promote seedlings from weak to strong

4.1 Timely repression and hoeing, increasing soil moisture and temperature to promote early growthHoeing is performed as early as possible after reviving, and timely repression is developed according to soil moisture content and seedling conditions. Repression in early spring should be followed by hoeing, which will realize the condition of loose in upper layer and solid in lower layer, thus increasing temperature and conserving moisture, and promoting early growth of seedlings. The repression can crush clods, seal cracks, harden the soil, reduce water evaporation, improve ground temperature, closely connect soil and roots, and improve the drought and cold resistance of plants, which is conducive to the absorption of nutrients by the root system and promotes the early and steady growth of seedlings.

4.2 Classified management according to seedlings, and promoting transformation and upgrading of seedlings condition

The wheat fields with less than 6.75 million tillers per hectare before winter should not be watered prematurely as long as the soil moisture is suitable in early spring. If the soil moisture is suitable from reviving to double ridge stage, ditches are opened for topdressing. If the relative water content of the root layer soil is less than 60%, the first watering is done, and 120-150 kg of urea and appropriate amount of diammonium phosphate are topdressed per hectare. In the middle jointing stage, if the relative soil content of root layer is lower than 70%, the second watering is done, and 105-150 kg of urea is topdressed per hectare combined with watering. The management of wheat fields with 6.75 to 9 million tillers per hectare before winter should focus on consolidating tillers before winter, regulating tillers in spring and increasing tiller yield. If the soil fertility level is higher, topdressing and watering should be carried out at the early jointing stage. Postponing reviving and jointing to mid-late March is beneficial to polarization and the formation of large panicles[3]. In the wheat fields with 9 to 12 million tillers per hectare and high soil fertility level before winter, topdressing and watering should be done at middle and late jointing stage. The fields with insufficient phosphorus application in base fertilizer or phosphorus deficiency should be supplemented with phosphorus, and nitrogen and phosphorus compound fertilizer are topdressed; for the fields with insufficient potassium application in base fertilizer, nitrogen and potassium compound fertilizer is applied appropriately at reviving or jointing stage. Dryland wheat fields should suppress and hoe immediately after soil thawing in early spring to raise and conserve soil moisture. The wheat fields lack of fertilizer should apply nitrogen fertilizer after soil getting pulp, thus promoting early growth of seedlings. The general wheat fields with strong seedlings should topdress immediately after rainfall from double ridge stage to jointing stage, and 180-225 kg of urea should be applied per hectare.

4.3 Good prediction and forecast, green prevention and control of diseases, insect pests and weedsThe occurrence and development trend of major diseases, insect pests and weeds at reviving and jointing stage should be closely followed, and the drugs and instruments should be prepared as soon as possible. Scientific prediction and forecast is performed to ensure professional unified prevention and control. For the prevention and control of sheath blight and root rot, 450-600 mL of 250 g/L propiconazole EC, or 300-450 mL of 300 g/L difenoconazole·propicondzole EC, or 20 mL of 240 g/L thifluzamide SC can be diluted with water and sprayed on wheat stem base per hectare once every 10-15 d. For the prevention and control of wheat basal rot, 450-900 mL of 18.7% propiconazol·azoxystrobin SC, 150-180 g of 80% tebuconazole WDG, or 50-65 mL of 200 g/L pydiflumetofen SC should be sprayed on wheat stem base per hectare. For the prevention and control of wheat spider, 60-120 g of 5% abamectin SC or 450-750 mL of 4% bifenthrin ME can be sprayed per hectare. For dicotyledonous weeds and monocotyledonous weeds in wheat field, the control agents are selected scientifically by classification, and herbicides are sprayed strictly in accordance with the recommended doses and methods on pesticide labels, so as to avoid the chemical injury of wheat and its subsequent crops caused by random increase of doses.

4.4 Paying close attention to the weather and prevent freezing injury and chilling injury in early springEarly spring (chilling) and freezing injury (late spring coldness) are common disasters in early spring, so we should pay close attention to weather changes, do a good job of early warning and prevention, and strive to reduce disaster losses. To prevent early spring freezing injury, irrigation can be done before cooling down to adjust the microclimate near the ground layer and to reduce the influence of early spring freezing injury on wheat fields. If early spring freezing injury occurs, it is necessary to remedy in time. The first is topdressing fertilizer in time. For wheat fields suffering from freezing injury, quick-acting fertilizer is applied according to the degree of damage, which will promote the early growth of seedlings and improve the panicle bearing tiller rate of high tillers of grade 2-4. Generally, about 150 kg urea is applied per hectare. The second is timely appropriate watering, which will promote wheat absorption of nitrogen, balance the plant water status, make small tillers grow as soon as possible, increase the number of effective tillers, and make up for the loss of the main stem. The third is spraying plant growth regulator on leaf surface. Spraying plant growth regulator on wheat leaves in time after freezing can promote the rapid growth of middle and small tillers and the rapid development of latent buds, increase the number of mature panicle and 1 000-grain weight of wheat, and significantly increase the yield of wheat.