1. Causes of death of wheat in winter and spring (1) Endogenous factors refer to the ability of wheat plants to resist cold and drought. Using varieties with poor resistance to cold, it is easy to cause dead seedlings, individual sowing is too early, and spikes in winter are differentiated to those in Erlang. Wheat seedlings, with reduced ability to withstand cold, often suffered severe chilling and dead seedlings, and some late weak seedlings, which have accumulated less sugar, and are often exposed to cold and drought, and are prone to dead seedlings.
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(2) External factors refer to various factors other than the wheat plant itself, such as unfavorable weather, soil conditions, and improper cultivation measures, which will cause dead seedlings. For example, if there is less rainfall in summer and autumn, there is insufficient soil moisture, and in winter and spring, there is little rain. Snow, multiple cold winds, increased soil drought, and wheat twigs in the cold and warm changing soil caused serious wheat seedlings to die and die. Salt in saline soil can also lead to physiological dehydration and death of wheat. The varieties with weak winter and shallow tillering festivals are selected, and they are vulnerable to the temperature and temperature difference. If the seed is sown, the growth and development of wheat plants is poor, and the sowing is too late, too deep, too dense and easy to form weak seedlings, which is not good for wheat security. Overwintering, in the absence of enough groundwater, freezing water is not poured, resulting in early cold and death.
2. Cultivation measures to reduce dead seedlings (1) The selection of cold-resistant varieties for winter use and good cold resistance are the most cost-effective measures for defense against freezing and dead seedlings. Localities should adjust measures to local conditions. When introducing varieties, it is necessary to understand the characteristics of the varieties. High yield, but also have a certain cold resistance, at least in most localities can safely winter, before planting.
(2) Irrigation at the seedling stage is insufficient for early cropping of wheat fields. It can be used to water the seedlings during the tillering stage. If the soil fertility is insufficient, a small amount of chemical fertilizers can be topdressed to reach the early stage of seedling growth, and the deep roots and leaves are large, which will facilitate safe wintering. Seedlings, the main contradiction is that the accumulated temperature is insufficient, management should be based on cultivating loose soil to increase the ground temperature and the preservation of lotus, seedlings should not be watered, otherwise it will affect the upgrade of wheat seedlings cooling.
(3) timely winter irrigation Winter irrigation can form a good soil moisture environment, adjust the soil nutrients in the plough layer, increase the heat capacity of the soil, winter irrigation so that the topsoil is sealed tightly, can promote rooting, grow, grow, grow seedlings, reduce winter cold, Dead seedlings caused by drought, frozen water is not only conducive to winter seedling maintenance, but also reduce the adverse effects of early spring cold, drought and severe changes in temperature, it is an important measure to prevent the dead seedlings in winter and spring. Pouring frozen water to an appropriate period, it is advisable to freeze the water at night at 4°C with freezing temperatures and freezing temperatures. When the climate is lower than 4°C, there is a risk of freezing cold in winter irrigation. The winter irrigation should be controlled flexibly according to soil quality, seedling condition and lyricism. The clay should be properly poured in early, to prevent the water from infiltrating and freezing before freezing. The sand land should be poured late, and part of the wetland, rice field, or bottom wheat field can be poured. However, for feed-rich wheat fields, frozen water must be poured to crush and pull the pests.
(4) In order to promote the development of the root system, the wheat can be broken by pressing the wheat in time, breaking the cracks, solidifying the soil, solidifying the wheat root and the soil and promoting the development of the root system;
(5) Appropriate coverage of sand-covered wheat and soil-covered wheat during the winter season can deepen the depth of tillering section and protect the leaves of the near-ground layer to reduce evaporation of soil moisture, improve water conditions at the tiller section, and play a role in insulation and freezing protection. Generally, the cover soil 1-2 Centimeter can play a better anti-freeze preservation seedling effect, to the spring time to clear the ridge in the temperature of 5 °C when the soil cleared out of the field, for poor cold resistance varieties, late wheat sowing shallow sensation poor wheat fields, should be promptly covered Soil, the winter filming period to cover, can be warmed and protected to effectively prevent frost damage, slow growth, to increase the number of tillers, the development of large scales, the formation of strong seedlings, improve the tillers into the ear, the temperature of 3 °C cover film, cover easy to grow early , cover late leaves frozen, for late sowing, can be filmed after sowing. 