Regulatory Mechanism Of Synergistic Optimization Of Maize Topsoil Struture And Canopy On Premature Senescence Caused,by Close Planting And The Derived Cultivation Pattern Construction

Constructing a reasonable population to maintain canopy function at late growth stage,and improving soil properties,andand eliminatinging soil obstaclebarrier factors to supporting fullfill the nutrition needings of abovegroundmaize growth and development are effective measures to fully tap mining canopy productivity and plough layer supplying capacity.Also it is a breakthrough to achieve maize high yield synergy with yield stability and procuting efficiency.In this study,we focused on innovating key cultivation the innovative technology technologies to synergistic optimize maize canopy and topsoil structure.The maize variety Zhongdan 909 was selected.Different soil tillage methods(subsoiling and no tilliage)and nitrogen fertilizer(0,180,360 kg ha-1)application were set for the optimization of tillage layers.and different planting methods(Small double row dislocation planting technology,wide and narrow rows planting technology and equal spacing planting technology)were set for canopy optimization.By analyzing soil bulk density,weight,distribution and vitality of root,three-dimensional distribution of light,dry matter accumulation,photosynthetic performance,we studied for the effect and regulation of key technologies on maize premature senescence under high density planting.Morover,we established a method to evaluate density-tolerance of maize variety and constructed a inovative cultivating pattern characterized by strip deep tillage,stubble cleaning on ridge,seed staggered sowing in two closed rows.This new cultivating model had been applyed for maize production in the Northeast and Huang-Huai-Hai regions of China for sever years.T and demonstrated benefit increasing production and efficiency,decreasing costs.The main results were as follows:(1)Subsoiling significantly increased the yield of maize,and the average yield at the three densities reached by 4.80%,7.20%,and 8.92%.The positive regulation effect of subsoiling on yield was mainly due to more number of grains per ear and 1000-grain weight,under the subsoiling treatment,the dry matter mass of the population increased by 13.12%averagely.The subsoiling can maintain a high g7reen area after flowering,which is 13.34%,13.88%and 15.45%higher than the control treatment.At the same time,the Pn values in the deep-smoothing conditions increased by 9.14%,15.93%,and 25.60%,respectively,and the soil bulk density can be effectively reduced by subsoiling measures.The bulk density of the 0-30cm soil layer decreased by 5.87%,averagely.It can increase the distribution of roots in deep soils.Under 10-50cm deep rooting layer,he dry weight of roots were increased t at this layer,which was increased by 40.68%,32.17%and 20.15%at three planting densities,respectively.Deeply,the root bleeding at post-anthesis increased by an average of 17.41%,15.82%,and 28.90%.(2)Nitrogen application can promote the development of root system,increase the root volume per plant,promote the distribution of root system,increase the root volume of 0-40cm soil layer.The results showed that root length density and root surface area was higher under high nitrogen level.It was beneficial to absorb more nutrients in the soil and maintain the growth of the root system.Nitrogen fertilizer treatment enhances the vitality of the root system and maintains the root absorption support function.The N1 and N2 levels of the root system are higher by 37.90%and 72.10%than that of N0.The higher root vigor effectively delayed the senescence of late plants.Under high nitrogen levels,the plant senescence slowed,maintaining higher root vigor function and stronger photosynthetic capacity of shoots above the ground,which in tumly favored the accumulation of dry matter and promoted the formation of grain yield.(3)Continuous planting density mode can effectively study the relationship between y:ield and density under a wide range of density conditions.We established the Horel model of yield-density(y=abxxc,R2=0.6656**)accurately quantified population canopy productivity.Through small-scale planting experiment,a small double-row planting patterns(T1)was selected.Compared with the control,the T1 planting method:increased yield by 14.3%the averagely.The canopy layer capacity increased by about 500 plants,and the population dry matter accumulation increased by 12.25%.It can effectively improve the lower canopy light transmittance.(4)The maize topsoil-canopysynergistic optimization technology model can effectively solve the maize production problems such as large amount of front ash,serioius burning of straw,poor sowing quality,poor uniformity,and low population density,etc.The ridges,strips,deep loosening and fertilization,dense planting and double rows of precision seeding techniques are highly integrated,and it is a simplified,low-energy-consuming and safe corn planting model with high yield and high efficiency.