Prevention and control of winter wheat dead seedlings in winter

1. Causes of wheat winter and spring dead seedlings (1) Internal factors. Using varieties with poor cold resistance, it is easy to cause dead seedlings, individual sowing is too early, and the young ears are differentiated in the two-edge stage of wheat seedlings, the cold tolerance is weakened, and the dead seedlings are often severely damaged by freezing, some late weak seedlings, and their own accumulated sugar. Less, in case of cold and drought, it is also prone to dead seedlings.
(2) External causes. Unfavorable weather, soil conditions and inappropriate cultivation measures will cause dead seedlings. For example, if there is less rainfall in summer and autumn, soil bottom is insufficient, winter and spring are less rain and snow, more cold winds, and soil drought, so that wheat is divided into sections. In the soil layer of sudden change in temperature and temperature, the wheat is seriously dead and dead; the salt in the saline-alkaline soil can also cause the physiological dehydration of wheat to die, and then the wheat is weaker and the branching is shallower. Suffering from the danger of large temperature difference between the ground and the temperature; the planting of the wheat plant is poor, and the planting is too late, too deep and too dense, and it is easy to form weak seedlings, which is not conducive to the safe wintering of wheat. In the case of insufficient bottom soil, no water is frozen. , leading to early cold and dead seedlings.
2. Reducing the cultivation measures of dead seedlings (1) Selecting cold-resistant varieties to use winter strong and cold-resistant varieties is the most cost-effective measure to prevent freezing and killing of dead seedlings. Sex, but also have a certain degree of cold resistance, at least in most years of the country can safely overwinter before planting.
(2) Irrigation at the seedling stage. For early-sown wheat fields with insufficient bottom stalks, the seedling stage water can be poured in the tillering stage. If the soil fertility is insufficient, a small amount of chemical fertilizer can be properly applied to achieve early growth of the seedlings, and the deep roots are large, which is conducive to safe wintering. For late sowing seedlings, the main contradiction is the lack of accumulated, management should improve Row crop cultivators to moderate soil moisture based.
(3) timely winter irrigation. Winter irrigation soil moisture can form a good environment, regulate soil nutrients in the topsoil, can promote tillering and rooting, grew tiller, sterile seedlings, reduce winter cold, dead seedling early caused by pouring cold water is not only beneficial to seedling winter, but also to reduce early spring cold, drought and bring the temperature varies strongly adverse effects, and therefore is an important measure winter Simiao defense.
Pouring cold water for a suitable period, in order to eliminate day night cold water temperatures preferably at 4 ℃, climate permanently flooded lower than the risk occurs when there is frost 4 ℃; should be considered permanently flooded soil, growth of the seedlings, moisture and flexibility, clay It should be properly poured early to avoid frozen water before infiltration occurs not all Ling frozen. The sand land should be poured late, and some of the wet fields, rice fields or bottom wheat fields can be poured.
(4) Pressing wheat in time. Compressed wheat can break up the pull, break the cracks, practise the soil, make the wheat roots and the soil tightly combined, and promote the development of the root system; the wheat has the effect of lifting and protecting the roots.
(5) Appropriate coverage. In winter, the cover wheat and the broken soil cover wheat can deepen the depth of the tiller and reduce the evaporation of soil moisture, improve the water condition at the tiller joint, and play the role of heat preservation and antifreeze. Generally, the soil can be covered by 1~2 cm. In the spring, it is necessary to clear the ridges in time, and when the temperature is 5 °C, the soil will be cleared out of the field. For the varieties with poor cold resistance, the wheat fields with poor sorghum should be covered in the wheat field in time, and the mulch cover should be covered during the wintering period to increase the temperature. Effectively prevent freezing damage, increase the tillering, and increase the effect of tillering into ears. When the temperature is 3 °C, the film is covered, the cover is easy to grow, and the cover is frozen after the cover. For the late sowing wheat, the film can be covered after sowing.

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