The Effect Of Field Temperature Increasing At The Late Winter For The Winter Wheat Grain Yield Formation

With the winter wheat cultivar named Shi Mai 18 and Heng Guan 35. The experiment was conducted in experimental field of dry farming institute of Hebei Academy of Agricultural Science from 2012-10 to 2014-6. The experiment was using plastic-film covering over the winter wheat at different time and different levels, and removing them at different time. By field survey and experiments in laboratory, thesis expatiated the effect on the physiology and ecology of the winter wheat of temperature improving at the early spring. The main results are as followed:2012-2013 the grain yield of the best treatment of Shi Mai 18 was higher than the conventional planting 37.5%, the same cultivar at 2013-2014 was 18.2%, at the same year Heng Guan 35 was 25.6%. The 1000-grain weight under the treatment of temperature increasing was higher than conventional planting 4.4%~12.5%, the reason was the suitable temperature for the grain filling rate of winter wheat under the treatments was longer than the conventional wheat planting. The grain yield under the treatment of the two years improved differently, the reason was that the enverienment of the the winter wheat growing was different. The biomass under the treatment of plastic-film covering over the winter wheat plant had improved significantly, the biomass of the treatment that plastic-film covering earliest and with three levels of Shi Mai 18 was higher than the conventional wheat planning 66.7% from covering the plastic-film to removing them, Heng Guan 35 was 66.9%,The earlier the plastic-film covering, the higher the biomass of the winter wheat at the mature stage, at the same time the grain yield improving. Taking the conventional winter planning as standard, the yield water consumption was diffrent under treatments, before removing the plastic-film it was lower under the treatments than the conventional planting, the earlier plastic-film covering the lower filed water consumption. After removing the plastic-film the yield water consumption increasing. The total water consumption was higher than conventional planting 3.1%~12.0%, and the water use efficiency was higher than conventional planting 2.3~4.4 kg/mm/hm~2, showing that yield increasing extent was higher than water consumption increasing extent.The plant morphology had changed under the treatment, the plant height, spike length, the top 1st length, and the first internode length were significantly higher than the conventional planting. Recovering to jointing, heading to harvest were the key period for the grain yield, plastic-film covering extend the two period, providing a favorable condition to grain yield increasing. The relationship between the three elements of yield components and development days, average daily temperature, accumulated temperature which was deciding the number of them, were significant correlation. In this experiment the plastic-film covering with three layers plastic-film at the earliest time of Shi Mai 18 and two layers plastic-film of Heng Guan 35 were the suitable treatments and the development days, average daily temperature, accumulated temperature were closed to the most suitable.The biomass accumulated after anthesis was proportional to the grain yield, the treatment of plastic-film covering had significantly increased the biomass, that was higher than conventional planting 4.3~6.3 percentage point, it provided a foundation for the grain yield. Because of the temperature under the treatment was promoted the winter wheat growth and development in advance, the anthesis time was 2~7 days earlier than the conventional planting, so the beginning time for grain filling in advance, extending the grain filling time, at the same time the grain weight increased. The photosynthesis was earlier than the conventional planting, because of the temperature rising fast at the later growing stage, the winter wheat plant dead. The time of photosynthesis under the treatment was longer than the conventional planting, providing the material source to the gain.Plastic-film covering had significantly improved the contribution rate of the dry matter to the grain, that was because the aging of the winter wheat and the dry matter accumulated after anthesis transported to the grain were synchronous with grain filling. The conventional planting was wither when they were green, the reason was the temperature rising fast in the later growing stage, that leading to the dry matter accumulated before anthesis could not be transported to grain, so the grain weight falling. Nitrogen was an important element, the treatment had significantly increased the contribution rate to grain, providing the nutrition foundation to the grain.The suitable harvest time for the winter wheat was wax ripeness, this time the water contented in the grain was 20%~22%.The harvest time of Plastic-film covering was earlier than conventional planting 2~5 days, so this treatment could save time for the corn sowing, improving the grain yield of winter wheat, at the same time improving the grain yield of corn.