Study On The Interaction Effect And Physiological Mechanism Between Sowing Rate And Nitrogen Level Of Winter Wheat

The objective of this study is to study the effects of different nitrogen level and sowing rate on the yield,growth and development,and ecological field characteristics of winter wheat,to explore the relationships between the wheat population competitiveness and its yield based on the ecological field theory,and to find a balance between nitrogen level and sowing dates for high yield and high efficiency in winter wheat.Field experiments were established as a split-plot design of five nitrogen levels(0,90,180,270,and 360 kg·hm-2)and four sowing rates(135,180,225,and 270 kg·hm-2)from 2020 to 2022 at Wen County,Henan Province.The grain yield,nitrogen accumulation,growth and development indexes(i.e.,plant height,crown width,and tillering)were measured and calculated for the aforementioned treatments.Results showed that:1.Winter wheat yields increased by 8.0% to 44.5% under nitrogen application and by 0.7% to10.5% under increased sowing rate of 135-270 kg·hm-2.The highest yield was 9223.3 kg·hm-2 in2021 with 225 kg·hm-2 and 270 kg·hm-2 with 270 kg·hm-2.The highest yield was 9151.7 kg·hm-2with 225 kg·hm-2 and 180 kg·hm-2 with 180 kg·hm-2.Nitrogen application affected the number of ears and grains per ear,and sowing amount affected the number of ears to increase wheat yield.Through equation fitting,the average nitrogen application and seeding amount of winter wheat in two years were 239.8 kg·hm-2 and 228.7 kg·hm-2 respectively2.Suitable sowing amount and nitrogen application amount were beneficial to dry matter and nutrient accumulation and grain yield increase of winter wheat.Dry matter weight,nitrogen accumulation,phosphorus accumulation and potassium accumulation increased by 15.0%-37.8%,29.4%-93.0%,12.5%-40.5% and 24.6%-72.7% in the mature stage of nitrogen application.Increasing seeding rate in the range of 135-270 kg·hm-2 resulted in an increase in aboveground dry matter weight of 1.3%-12.6%,nitrogen accumulation of 2.1%-19.2%,phosphorus accumulation of0.8%-19.2%,and potassium accumulation of-4.2%-8.1%.The highest accumulation of dry matter,nitrogen,phosphorus and potassium in the two-year experiment was concentrated in sowing rate of225-270 kg·hm-2 and nitrogen application rate of 180-270 kg·hm-2.3.Increasing sowing amount decreased crown width and tillering per plant,but increased plant height and population tillering number of winter wheat.Plant height,crown width,SPAD value and tillering per plant of winter wheat increased with increasing nitrogen application rate.The population structure of winter wheat can be improved jointly by sowing amount and nitrogen application amount,while the growth and development of winter wheat will be worsened if the sowing amount and nitrogen application amount are too high.By adjusting the nitrogen and nitrogen application amount,the population structure of winter wheat can be optimized and developed jointly,which is of great significance for high yield.Comprehensive analysis showed that the population structure,agronomic characters and photosynthetic characteristics of wheat with seeding rate of 225kg·hm-2 and nitrogen application rate of 180 kg·hm-2 were the best in this experiment.4.The equation relationship between population ecological field area and yield of winter wheat in different periods had a high degree of fitting.The ecological field area increased with the increase of seeding amount and nitrogen application amount,which showed a quadratic function relationship with yield,and high intra-species competition intensity would lead to grain yield reduction.Reasonable sowing rate and nitrogen application rate can build ideal winter wheat population,play the effect of nitrogen promoting growth and increasing population yield,and avoid the intensification of above-ground spatial competition.In 2021,when the ecological field area was14.4,33.5 and 248.6 at overwintering stage,joining stage and flowering stage,wheat yield was the highest,and the highest was 9042,8989 and 9325 kg·hm-2,respectively.In 2022,the highest wheat yield was 8948,8651 and 8982 kg·hm-2 when the ecological field area was 14.7,17.9 and 193.3 at overwintering stage,jointing stage and flowering stage,respectively.5.The content of protein,wet gluten,water absorption of dough,formation time and stability time were significantly increased,while the grain bulk weight was significantly decreased.In the range of 135-270 kg·hm-2,grain bulk weight and water absorption of winter wheat dough were significantly increased,while grain protein content,wet gluten content,dough formation time and stable time were significantly decreased.Better grain quality was obtained when sowing rate was135 kg·hm-2 and nitrogen application rate was 180 kg·hm-2.The nitrogen density optimal combination of winter wheat with nitrogen application amount of 239.8 kg·hm-2 and sowing amount of 228.7 kg·hm-2 had suitable ecological field and ideal population with high yield,which could be popularized and applied in northern Henan.