The experiment was carried out in Shijiawangzi Village,Xiaomeng Town,Yanzhou District,Jining City,Shandong Province from 2020 to 2021.The test variety was Yannong1212,a high-yield wheat variety.In the experiment,wheat fields with three yield levels were selected,and the annual yield levels were 10 500 kg ha-1,9 000 kg ha-1and 7 500 kg ha-1,respectively,denoted by S,H and M,and different yield levels were studied.Differences in soil physicochemical properties and nitrogen utilization in wheat fields.1 Differences in soil physicochemical properties and nitrogen supply capacity in wheat fields at different yield levelsBefore sowing stage of the soil bulk density of 0~40 cm soil layers in S wheat field is significantly lower than that in H wheat field,and the soil porosity is significantly higher than that in H wheat field.The contents of total nitrogen,organic matter,available phosphorus,available potassium and alkaline nitrogen in 0~40 cm soil layers in S wheat field were significantly higher than those in H wheat field,and the lowest in M wheat field.The activities of soil urease,invertase,alkaline phosphatase,catalase and protease in 0~20 cm soil layer in S wheat field were significantly higher than those in H wheat field,and the lowest in M wheat field.The results show that S wheat field has good physical and chemical properties and sufficient nutrients,which can meet the nutrients required for wheat growth and development,promote nitrogen transformation and improve yield.The contents of ammonium nitrogen and nitrate nitrogen in 0~100 cm soil layers of S wheat field were significantly higher than those in H wheat field,and the lowest in M wheat field and the contents of soluble organic nitrogen and soil microbial biomass nitrogen in 0~60cm soil layers were the highest.The results show that S wheat field has high soil nitrogen supply capacity,which is conducive to the absorption and utilization of nitrogen by wheat and improve the efficiency of nitrogen utilization.2 Difference of dry matter production and yield in wheat field at different yield levelsThe leaf area index and photosynthetically active radiation capture ratio of S wheat field after anthesis were significantly higher than those in H wheat field,and the lowest in M wheat field,after anthesis,the PAR use efficiency and PAR conversion efficiency were significantly higher than those in H wheat field,and the lowest in M wheat field.The results showed that S wheat field had higher photosynthetically active radiation capture ratio and leaf area index at the filling stage,which could intercept more light energy and improve the light energy utilization ability of wheat.The net photosynthetic rate of flag leaves in S wheat field was 14.74%and 37.17%higher than that in H and M wheat fields,45.05%and 102.99%higher than that in 28 days after anthesis,respectively;the transpiration rate and stomatal conductance of flag leaves at14,21,28 and 35 days after anthesis were significantly higher than those in H wheat field,and the lowest in M wheat field.The specific leaf nitrogen content per area between S wheat field and H wheat field at anthesis stage and 20 days after anthesis,which was significantly higher than M wheat field.The results showed that S wheat field had high photosynthetic capacity in the middle and late filling stage,which was conducive to the accumulation of wheat dry matter.The dry matter accumulation of wheat in S wheat field from pre-winter to mature stage was significantly higher than those in H wheat field,and the lowest in M wheat field,and the dry matter accumulation in mature stage was 21.19%and 62.67%higher than that in H and M wheat fields,respectively,the distribution of dry matter in grains,the allocation amount after anthesis and their contribution to grains in mature stage were significantly higher than those in H wheat field,and the lowest in M wheat field,and the grain filling rate 7~35 days after anthesis was significantly higher than those in H wheat field,and the lowest in M wheat field The results showed that S wheat field was conducive to the distribution of dry matter to grains,improve grain weight and obtain high yield.Compared with M wheat field,H wheat field increased the yield by increasing spike mumber and kernel number,spike mumber increased by 33.43%and kernel number increased by 9.11%.Compared with H wheat field,S wheat field achieved high yield by increasing spike mumber and 1000-graim weight,spike mumber by 13.61%,1000-grain weight by11.26%.Compared with H and M wheat fields,the yield of S wheat field increased by27.91%and 80.87%respectively.The results showed that S wheat field better coordinated the three factors of yield composition,and increased grain yield by increasing spike mumber and1000-grain weight.3 Differences in soil nitrogen accumulation,transport and nitrogen use efficiency in wheat fields at different yield levelsThe nitrogen accumulation of plants from pre-winter to maturity and the distribution of nitrogen in grains at maturity in S wheat field were significantly higher than those in H wheat field,and the lowest in M wheat field,the nitrogen uptake efficiency was 5.51%and 14.26%higher than that in H and M wheat fields,the nitrogen use efficiency was 10.54%and 17.38%higher,the nitrogen utilization efficiency was 16.60%and 34.16%higher,the nitrogen partial factor productivity was 13.70%and 40.68%higher,and the nitrogen harvest index was 5.56%and 10.15%higher,respectively.The activities of nitrate reductase,glutamine synthetase and endopeptidase in flag leaves in S wheat field were significantly higher than those in H wheat field,and the lowest in M wheat field at 21 and 28 days after anthesis,the contents of soluble protein and free amino acid in flag leaves after anthesis were significantly higher than those in H wheat field,and the lowest in M wheat field.The results showed that the accumulation of plant nitrogen and the transfer of nitrogen to grain in S wheat field were higher,which was conducive to the improvement of wheat nitrogen use efficiency. |