| The selection and promotion of mechanical grain-harvested maize varieties pose new challenges to the full utilization of heat in northern spring maize regions.Under the background of climate warming,exploring the potential for advancing the sowing date of grain-harvesting maize can make full use of regional heat resources and improving grain-harvesting Corn strives for sufficient dehydration time to provide the basis.In this study,Zhengdan 958（ZD958）was used as the common control variety,and the selected suitable local grain-harvesting maize varieties were used as the test materials.Experiments were carried out in East region of Xing’an Mountain,South region of Xing’an Mountain,West Liao River Plain,North region of Yanshan Mountain,Tumote Plain,and Hetao Plain.The sowing date networking experiment systematically analyzed the effect of sowing date on the growth and development of spring maize population and the matching utilization of heat resources in various ecological regions.The main results are as follows:（1）In the spring maize area of Inner Mongolia,there is 6-8 days ahead of the optimal sowing date for grain harvesting,and the maize yield can be increased by 7.5%-18.4%under the optimal sowing date.With the increase of latitude,it gradually becomes“narrower”.For every 1°increase in latitude,the average window period is shortened by 1.8 days,and the average advance of the sowing date is reduced by 2.8 days.（2）The sowing date had no significant effect on the corn harvest index,and early sowing at the right time significantly increased the population biomass by 3.9%by increasing the pre-flowering LAI and prolonging the post-flowering leaf area duration（“increase source”）;by increasing the number of grains per ear and 1000-grain weight（“increase sink”）,increase the productivity per plant and increase the yield per plant by 8.6%.（3）Early sowing at the right time can lead to early emergence of harvested maize,the utilization rate of effective accumulated temperature in spring is increased by 1.5%,the post-flowering duration of growth is extended by 2 days on average,the distribution of post-flowering accumulated temperature is increased by 1.5%～3.1%,dry matter accumulation is increased by 3.9%.The dry matter accumulation rate was increased by 9.5%,the grain filling was promoted,and the number of grains number per ear and 1000-kernels weight were increased.（4）Diurnal temperature range（Tr）is the core calorific factor that affects the dry matter accumulation at grain-filling stage.Under suitable early sowing,the dry matter accumulation increases by 0.4 t hm-2 for every 1℃increase in Tr.The full matching and utilization of dry matter accumulation in the early harvest period can increase the annual accumulated temperature utilization rate by 1.1～2.8 percentage points under the premise of increasing the yield of grain harvested spring maize by 10.4%.The mature period of corn is 3 to 5 days earlier,so as to obtain a dehydration accumulated temperature of 43.7℃～130.9℃ for the later grain dehydration,and achieve high-quality grain direct harvest.（5）The simulation yield of Hybrid-Maize model and the actual yield in the field were verified that early sowing can increase maize yield.And the sowing date of spring maize in Inner Mongolia has the potential to advance.The simulation results are in good agreement with the field results and show that it has a benificial application in high yield cultivation of grain harvesting maize in Inner Mongolia. |
