Effects Of Stepwise Phosphorus Application By Drip Irrigation On Growing Development And Yield Of High-Yield Spring Maize Under Dense Planting

In order to clarify the effect of phosphorus application rate on the growth and yield of high-yield spring maize under the condition of stepwise phosphorus application under drip irrigation,this paper was published in Qianjiadian Town,Horqin District,Tongliao Province,Inner Mongolia（43°37’N,122°43’E）in 2019-2022.Conducted at the experimental demonstration base of the Institute of Crop Science,Chinese Academy of Agricultural Sciences,using Dika 159 as the test variety,using the traditional disposable base phosphorus fertilizer as the control,and using the integrated drip irrigation method of water and fertilizer in stages.The responses of maize leaf area,photosynthetic characteristics,dry matter accumulation characteristics,yield and composition factors,plant phosphorus nutrient accumulation and utilization,root morphology and lodging resistance to different phosphorus application rates were studied under different planting densities.The main results are as follows:1.Under the same phosphorus application rate,the leaf area index,group photosynthetic potential,SPAD value,stomatal conductance,net photosynthetic rate,transpiration rate,dry matter accumulation per plant,and dry matter accumulation after group flowering were significantly higher than those of traditional disposable base application in stepwise application of water and fertilizer integrated phosphate fertilizer.Under the stepwise application of phosphorus under drip irrigation,the change trend of first increasing and then decreasing with the increase of phosphorus application rate showed a trend of first increasing and then decreasing,and the highest treatment was P₆₀ under the density of 6.0×10⁴ plants/hm²（D1）.The density of9.0×10⁴ plants/hm²（D2）was the highest under P₉₀ treatment.2.Under the same condition of phosphorus application amount,the number of ear grains and 1,000 grain weight of water-fertilizer integrated phosphorus fertilizer dropwise were significantly higher than those of traditional one-time base application,and the yield increased by 8.74%at D1（2021）and increased by 9.1%（2021）and 9.11%（2022）under D2,respectively.Under the stepwise application of phosphorus by drip irrigation,the number of maize ears,the weight of 1,000 grains and the grain yield showed a trend of first increasing and then decreasing with the increase of phosphorus application,and the grain number and grain yield showed a trend of first increasing and then decreasing at D1.At D1,the yield of P₆₀ was the highest,reaching 15.82t/hm²（2022）.the yield of P₉₀ treatment was the highest,which were 18.18 t/hm²（2021）and 18.16 t/hm²（2022）at D2,respectively.There was no significant difference in effective panicle number between treatments.3.Under the same condition of phosphorus application,the phosphorus accumulation,phosphate fertilizer partial productivity,and agronological utilization efficiency of phosphate fertilizer were significantly higher than those of traditional one-time base application.Under stepwise phosphorus application under drip irrigation,the agronomic use efficiency of phosphate fertilizer under D2 population density showed a parabolic trend with the increase of phosphorus application,and the P₉₀ treatment was significantly higher than that of other treatments in 2 years.The partial productivity of phosphate fertilizer and the agronomic utilization efficiency of phosphate fertilizer under D1 density gradually decreased with the increase of phosphorus application,and the P₉₀ treatment was significantly lower than that of P₆₀treatment and significantly higher than that of other treatments.4.Under the same condition of phosphorus application amount,the root weight density,root length density,root mass ratio and root crown ratio of phosphorus fertilizer dropwise application of spring maize were significantly higher than those of traditional disposable base treatment.Under the condition of stepwise phosphorus dense planting in drip irrigation,the trend of first increasing and then decreasing with the increase of phosphorus application rate showed a maximum of P₉₀ treatment.5.Under the condition of stepwise drip application of dense drip irrigation phosphate fertilizer,the resistance to breaking of stalks in the maize spinning stage first increased and then decreased with the increase of phosphorus application,and it was the maximum under P₁₂₀（120 kg/hm²）within 2 years.During the ripening period,with the increase of phosphorus application,the resistance to breaking of stems gradually increased.The P₁₂₀ treatment had higher panicle height,basal internode diameter,3rd internode puncture strength（RPS）and dry weight per unit length（DWUL）than other treatments.The correlation analysis showed that the stem breaking resistance was significantly positively correlated with RPS and DWUL between the third segment,and negatively correlated with the panicle coefficient.