种植密度和灌水追氮时期对小麦群体结构和产量的影响OA

Establishing a rational population structure serves as the basis for achieving water-saving and high-yield wheat under limited irrigation,while optimizing planting density and the timing of spring water and nitrogen application are key techniques for building such a structure.To investigate the effects of irrigation and nitrogen topdressing period and planting density under limited irrigation conditions on the population structure and yield of winter wheat.During the wheat growing seasons in 2022-2024,this experiment set three planting densities,150× 104 plants/hm2(D150),300× 104 plants/hm2(D300),and 450×104 plants/hm2(D450).For each density,three irrigation and nitrogen topdressing periods were set at the appearance of the 4th spring leaf(T4),5th spring leaf(T5),and 6th spring leaf(T6).The study systemically analyzed the effects of different irrigation and nitrogen topdressing periods and planting densities on the population structure,canopy photosynthetic characteristics,and grain yield of winter wheat.The results suggested that postponing spring irrigation and nitrogen topdressing period significantly decreased spike number and the area of the top two leaves,while increased the light interception rate in the middle and lower canopy layers.It mitigated the decline of LAI and SPAD in the middle and lower leaves during the early and mid-filling stage,and in the upper leaves during the late filling stage,but both the population photosynthetic rate and grain yield showed a decreasing trend during the grain-filling period.Increasing the planting density compensated for the loss of spike number caused by delayed irrigation and nitrogen topdressing,enhanced canopy light interception rate and canopy apparent photosynthetic rate,and demonstrated a yield-stabilizing effect under unfavorable climatic conditions.In conclusion,under the condition of spring irrigation limited to a single application,medium and high density(D300 and D450)combined with irrigation and nitrogen topdressing in spring at the 4th leaves stage(T4)were proved to be the optimal treatment in this experimental setting.