Response Mechanism Of Grain Filling Characteristics Of Maize Varieties In Different Eras To Deep Loosening And Densification

Grain filling is the key stage to achieve high grain yield,and the increase of planting density is one of the main ways to increase maize yield.Deep loosening can effectively alleviate the adverse effects of dense planting conditions on maize individual plant,and then regulate plant growth and development under high density conditions and promote dry matter accumulation of grain.In order to explore the response mechanism of maize grain filling characteristics to subsoiling and densification,Maize Single Cross which was widely used in production from 1970s to 2010s was selected as experimental materials.Conventional shallow rotation(RT)and subsoiling(SS)tillage methods and three planting densities of 45000 plants/hm~2,75000 plants/hm~2 and 105000 plants/hm~2 were set up.From the aspects of canopy photosynthetic performance,grain filling characteristics,yield and its components,and grain nutritional quality,this thesis systematically analyzed the variation rules and internal dependence of various indexes of Maize Varieties in different years with the increase of planting density under subsoiling and shallow rotation tillage,and further revealed the response mechanism of maize grain filling characteristics to subsoiling and densification.It provides a theoretical basis for breeding High-yield Maize Varieties in Inner Mongolia and Improving Maize Yield by increasing density and subsoiling.The main results are as follows:(1)The difference mechanism of grain filling characteristics of Maize Varieties in different ages is as follows:In the process of variety replacement,2010s improved the canopy photosynthetic performance,ensured the suitable photosynthetic green leaf area and photosynthetic duration after flowering.The main reason for the increase of grain weight in 2010s was the significant increase of grain filling duration and grain filling rate at fast and slow growth stages.The significant increase of effective panicle number and 100 grain weight ensured the high-yield demand of 2010s varieties.Meanwhile,the starch and crude protein content coordinated the dry matter accumulation process of Corn Varieties in the process of variety replacement.(2)The response mechanism of grain filling characteristics of Maize Varieties in different ages to planting density was as follows:The higher the planting density was,the faster the decreasing rate was.After grain densification,the significant decrease of grain filling rate in the gradual and rapid growth stage led to the significant decrease of average grain filling rate,and the variation of grain filling duration was different among varieties.The decrease of average grain filling rate in2010s was relatively smaller,and the increase of grain filling duration was relatively larger.The main reason for increasing yield of 2010s was to ensure the increase of effective panicle number and the decrease of grain weight,and the process of increasing density was not conducive to the accumulation of total starch and crude protein content.(3)Subsoiling regulation mechanism of grain filling characteristics of Maize Varieties in different ages:Subsoiling can effectively improve the soil environment,ensure the good growth and development of plants,alleviate the decline rate of canopy photosynthetic performance due to the advancement of growth process and the increase of planting density,prolong the canopy photosynthetic time,and the effect on 2010s varieties is more obvious.The increase of grain filling rate in rapid and slow growth stages was the main reason for the increase of average grain filling rate in subsoiling.The increase of grain filling rate in rapid and slow growth stages was the main reason for the increase of average grain filling rate in subsoiling.The response of dry matter accumulation to deep pine in 2010s varieties was significantly higher than that of other varieties in the other years due to the increase of the proportion of fast increasing and slow increasing periods in the filling process.Subsoiling increased the increase of effective panicle number and decreased the decrease of grain number per panicle and 100 grain weight.Subsoiling was also conducive to the increase of grain bulk density,total starch content and soluble sugar content at S1 and S2 stages.