Comparative Study On Planting Mode Of Spring Maize In Northeast Of China

Maize is one of the important food crops in China.Increasing density is an important technical means to excavate corn yield per unit area under the condition of guaranteeing the existing cultivated land area in our country.It is one of the important measures to realize high yield and high efficiency of maize in China.It is also the most economical and effective measure that is easy for farmers to grasp and easy to popularize and apply.Under the condition of modern intensive agricultural production,the ventilation and light transmission in the system and the microclimate in the field all changed after the maize was planted intensively.The soil physical and chemical properties and microbial activities also changed after maize was planted closely.The problems of lodging,empty stalk,premature aging,aggravation of diseases and insect pests are easy to occur after maize cultivation under high density.To maintain high yields,the amount of fertilizers and pesticides increases,and they increase environmental risks.Therefore,the choice of planting pattern is particularly important under the condition of dense planting.Based on this,this study conducted field experiments for many years from 2012 to 2018 at the agricultural experimental base of Jilin University(43°54'N,125°16'E)in Lvyuan district,Changchun city,Jilin province.The present study mainly investigated as followed:(1)arrangement row spacing for maize;(2)wide-narrow row planting pattern for maize;(3)maize and soybean intercropping;(4)maize and soybean rotation.The effect of planting patterns on grain yeild and agronomic traits was investigated.Techniques of efficient nitrogen fertilization on maize were analyzed.These results are partly benefited for field resrarchers in optimizing planting mode.We hope the results can provide reference for the sustainable development of black soil agriculture in northeast China.The main results were as follows:(1)Angle of ear leaf,leaf area and LAI of system were influced signigicantly in flowering and filling stage.40 cm row spacing treatment was greater than 50 cm and60 cm row spacing treatment for LAI of system.Maximum LAI of XY335 in flowering period was 5.91 and maximum LAI of ZD958 was 6.12.There was a trend of decrease in LAD with the increase of trailing distance.Under the condition of small row spacing(40 cm),the utilization rate of group light energy was significantly higher than that of other treatments.The dry matter accumulation of the whole growth period showed an s-shaped trend of increasing gradually.There was a significant positive correlation between grain yield and photosynthetic potential by the correlation analysis of maize.(2)The yield increase was closely related to maize densification tolerance and plant type.Maize varieties with convergent plant type and strong density-tolerance were more likely to get high yield when planted in wide-narrow rows.With the increase of planting density,the weight of 100 grains decreased and the number of grains per ear decreased.The increase of yield depended on the increase of effective seeds number.Under wide-narrow planting method,N fertilizer deep application(15cm under planting)had better yield performance than N fertilizer shallow application(10cm under planting).The yield of basal fertilizer combined with topdressing nitrogen fertilizer was significantly better than that of basal fertilizer.Comparing to conventional urea,under the same density condition,larger leaf area,higher harvest index and lower root-crown ratio were obtained with slow-release urea,which was beneficial to the increase of yield.(3)In order to obtain intercropping advantages,the planting density of maize,the main crop,should be increased.When the planting density of maize,the main crop,was 9.2 ten thousand plants/hm~2,the yield was the highest,up to 14044 kg/hm~2,and the additional income of soybean was 947 kg/hm~2.The optimum nitrogen application rate was 255 kg/hm~2 in maize/soybean intercropping system.The LER calculated by biological yield was 1.02-1.17,and the LER calculated by grain yield was 1.06-1.16,both greater than 1,indicating that the intercropping system had intercropping advantages.(4)In the short-term continuous cropping of maize,the change of grain yield was not significant compared with the rotation of maize.Compared with the continuous cropping mazie,the grain yield of the rotation mazie increased.With the extension of crop rotation period,the grain yield increase trend of crop rotation was more obvious.Grain yield with rotation of mazie was significantly higher than that of continuous cropping of mazie(F=5.70,P=0.0245)with rotation after 5 years,increase rate of over 20%.The soil organic matter and pH value of maize decreased after continuous cropping for many years(continuous cropping for 7 years).The change of soil organic matter was not significant after 7 years of maize and soybean rotation.The soil available nitrogen,available phosphorus and available potassium fluctuated greatly between years without obvious regularity.Continuous cropping of maize changed the structure of soil bacterial community.The genera endemic to continuous cropping maize were Rhodanobacter and RB41,while the genera endemic to rotation maize were Bradyrhizobium and Candidatus_Solibacter.The structure of soil fungus community was changed after maize continuous cropping.The relative abundance of Ascomycetes and Toectomyces decreased by10.23%and 0.63%,respectively,after several years of continuous cropping.The relative abundance of Basidiomycetes increased by 12.03%.