In this paper, wheat in Zhumadian, Henan Province was used as a sample. By using a cumulative temperature instrument to detect the temperature change in winter and the wheat yield in the following year, the optimum temperature for wheat production in winter was discussed. The detected results are now analyzed as follows: 1 Increased winter wheat and increased density The average number of tillers per winter wheat after winter 1981 was averaged over a five-year period, and the change trend was basically consistent with the temperature change. In the 1980s, there was no significant change in the average number of tillers before the winter; after the 1990s, there was a steady increase in the increasing trend of 0.3 per plant. Except in the cold winter and late sowing years, the number of tillers in other years was generally high. In the 80's. The number of effective panicles in wheat depends mainly on the number of tillers before winter, so the increase in the number of tillers on the one hand is very beneficial to increase the number of effective panicles in wheat, but on the other hand it is easy to cause too large groups before the winter, affecting the strong seedlings. . According to statistics, after the 1990s, the average density during the wintering period is the same as the number of tillers, and there is a tendency of increasing. The average value is 222 plants/hm2 more than in the 1980s, of which 2319 plants were produced in 1995-1996 and 1999-2000 respectively. /hm2 and 1545 strains/hm2, a record. This pre-winter temperature rise and density increase trend is unfavorable for safe wintering of wheat. One is prone to wheat prolongation, and the other is to weaken the cold-resistance of wheat. Once strong cold air passes through, the growth of wheat is easy. Was frozen to death, resulting in reduced wheat production. 2 When the sowing time is appropriate, the accumulated temperature before winter is too high Zhumadian accumulated temperature before the winter is generally about 650e#d is appropriate, high is prone to prosperous. In the 1980s, the pre-winter accumulated temperature was more suitable. In addition to the individual years, the pre-winter accumulated temperature was between 500~700e#d; after the 1990s, only 3 years accumulated temperature was relatively normal, and 7 years were above 700e#d, 1997 In 1998 and 1998 and 1999 and even more than 800e#d, the accumulated temperature before winter was far more than enough. From the sowing time point of view, the 1980s and 1990s were almost the same, all in the early fall of October to mid-October after the autumn harvest, is an appropriate sowing. According to the traditional concept, sowing late, due to low temperatures, is not conducive to wheat delivery, so that small but small before winter, thus affecting yield. However, in recent years, with the increase of temperature, especially in autumn and winter, the phenomenon of continuous warming is becoming more and more intensified. Appropriate late planting not only does not affect production, but it is more favorable to yield. For example, in 2001-2002, due to drought caused by late sowing for more than half a month, so that the accumulated temperature before winter in the 400e # d below, the small and small tiller, when the autumn and winter warmth is very serious phenomenon, the winter before the seedlings are weak but to avoid The winter season is prosperous. The rapid temperature rise in the spring and the polarization of wheat is shortened. However, due to the low density in the early period, the density of wheat at the jointing stage has become more reasonable, which is one of the main reasons why wheat production hit record highs. Therefore, with the gradual warming of the climate, especially the increasingly prominent phenomenon of warm autumn and winter, whether it is necessary to break the traditional concept of planting, appropriate late broadcast, this is a question worth pondering. 3 The growth rate of wheat is accelerated and the development period is significantly advanced The table of average interval days for various development periods of winter wheat (Annex Table) clearly reflects changes in the wheat breeding process since the 1990s. From the time of planting to harvesting in the 1990s, except for jointing to heading and flowering to milk ripening due to the influence of spring cold and low temperature and continuous rain, the growth period has been extended. In other periods, especially before the jointing stage, the tillering period has been prolonged. The other development periods are relatively shortened, marking the acceleration of the wheat breeding process and the extension of the wheat's pre-winter growth period. At the same time, it also shows that the development period is obviously ahead of schedule, especially the jointing to flowering period from 2001 to 2002. The development period is actually half a month earlier, which is rare in the past years. This phenomenon of severe developmental stages disturbs the normal growth order of wheat: wheat usually completes young panicle differentiation a year ago, but winter temperatures are high. Wheat spike differentiation has been completed before winter and even jointing, making wheat resistant The cold ability weakened; the spring temperature was higher, so that the differentiation of flower spikes was earlier and the differentiation period was shortened, which was very unfavorable for the formation of large spikes and multiple spikes in wheat. These adverse factors can have different degrees of impact on wheat yield. 4 The phenomenon of overwintering becomes increasingly inconspicuous Usually, the last day of the first 5-day average temperature is less than 0e, which is defined as the beginning of overwintering; or the region where the winter temperature is oscillated around 0e per year, depending on the height of the wheat plant. Through statistical analysis of daily average temperature over the years in Zhumadian City, it was found that before the 1980s, the average temperature on the 5th day in most of the rooms from late December to February was below 0e or oscillated around 0e. After the 1990s, the temperature has changed significantly. In December and the end of February, the average temperature <0e days is basically eliminated. From January to February, only in the individual days of individual years, the average temperature of 5 days is <0e. They are all above 0e; from the height of growth, the plants did not stop growing during the wintering period, but there was a slight increase. Therefore, in recent years, it has been difficult to determine the beginning of overwintering in this area. According to crop observations, the wintering dates in the 1980s averaged on January 2 and the overwintering dates after the 1990s averaged on January 8. The overwintering period lags behind, especially in 2001-2002. From the schedule, it can also be seen that after the 90s, the delivery period has been prolonged, and the returning green period has been advanced and the wintering period has been relatively shortened. All indications indicate that with the gradual warming of the climate, winter wheat in this area has no apparent wintering period. 5 Thoughts In view of the high temperature accumulation before winter and the high fertility characteristics of wheat tiller, appropriate late sowing should be conducted, or the sowing amount should be reduced when sowing in order to reduce the occurrence of pre-winter prolonged growth, late lodging, wheat pests and diseases and spring freeze injury. In the future, in terms of variety improvement, selection of new varieties, etc., in addition to taking into account the varieties of disaster resistance, lodging resistance and other conditions, we must consider the current temperature conditions as the main factors affecting the quality and high yield of wheat. With the gradual warming of the climate, crop diseases, pests, and weeds have become increasingly serious. Therefore, it is necessary to increase the intensity of field management and actively prevent and control diseases, insects and weeds. In addition, the advancement of the development period also reminds people to change the traditional cultivation methods, establish a sense of advanced field management, carry out advanced management of crops, ensure timely management of the fields, and take appropriate measures to promote the healthy growth of crops.
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