| In this study,field experiments were conducted in Xuchang city,Henan Province for two consecutive years from 2019 to 2021.Bainong 207 was used as the experimental material and a single-factor randomized trial was conducted to analyze the effects of different nitrogen application levels on post-anthesis nitrogen transport utilization and yield of wheat.The main results are as follows:The total tiller number of wheat plants increased at each growth stage.However,the proportion of ear and ear decreased,and the proportion of tiller ear was opposite.The total tiller number of N180,N240 and N300 treatments had little difference,and was significantly higher than that of N0 treatment.With the advance of wheat growth period,dry matter of wheat population increased.At anthesis,the residual dry matter was the largest,followed by ear and then leaf.The dry matter at the mature stage was the largest.With the increase of nitrogen application rate,dry matter accumulation in different organs increased first and then decreased at maturity.Stem + leaf sheath and grain dry matter were the highest under N240 treatment.The effects of different nitrogen treatments on dry matter accumulation at flowering and maturity stage were significant.The flag leaf SPAD value of wheat increased from anthesis stage and reached the maximum value 15 days after anthesis.The net photosynthetic rate and stomatal conductance of wheat increased firstly and then decreased with the advance of grain filling,and reached the maximum value at 10 d after anthesis.The intercellular CO2 concentration showed a single-peak decreasing trend.The trends of FLAG leaf SPAD,net photosynthetic rate,stomatal conductance and intercellular CO2 concentration decreased with the increase of nitrogen application rate.From anthesis stage to maturity stage,the content of total soluble sugar and total nitrogen in plant vegetative organs decreased continuously,and remained at a low level in maturity stage.The total nitrogen content of wheat grains from 10 d after anthracing to maturity stage was the highest under N240 treatment.The total nitrogen content of grains at 15 d and 25 d after anthesis reached the maximum value under N300 treatment.The soluble total sugar content of wheat at maturity stage did not increase significantly with the increase of nitrogen application rate,and the soluble sugar content of wheat under N240 treatment was the highest except for 10 and 15 days after flowering.The change rule of leaf,stem + leaf sheath was not obvious.With the advance of filling stage,the nitrogen accumulation in aboveground of wheat plants increased significantly among different nitrogen treatments,and the nitrogen accumulation in plants under N0 treatment was significantly lower than that under N application,and the maximum nitrogen accumulation in leaves,stems and leaf sheaths reached at 5 days after flowering,and the maximum nitrogen accumulation in grains at maturity stage.The nitrogen accumulation in various organs of wheat increased gradually with increasing n fertilizer application,and the grain value in N240 treatment was the highest.The increase of nitrogen application rate increased the nitrogen transport efficiency of wheat nutrient organs,and the difference was significant and reached the maximum in N240 treatment.Nitrogen partial productivity and agronomic use efficiency decreased with the increase of nitrogen application rate.The 1000-grain weight and grain yield of wheat were significantly affected by nitrogen application rate,both of which showed an increasing trend with the increase of nitrogen application rate.The spike number per unit area of wheat also showed an increasing trend,and the spike number and grain number per spike of wheat increased with the increase of nitrogen application rate.There was no significant difference between nitrogen treatments,and the spike number was the highest under N240 treatment.Based on the above data analysis results,the optimal nitrogen application rate was 240 kg·hm-2,which could maintain higher SPAD value and improve photosynthetic capacity of wheat leaves,promote the accumulation of photosynthetic products,significantly increase soluble sugar content and total nitrogen content in wheat grains,and promote nitrogen transfer to grains.The number of spike,grain number per spike and 1000-grain weight of wheat were also higher,leading to higher yield.In this study,field experiments were conducted in Xuchang country,Henan Province for two consecutive years from 2019 to 2021.Bainong 207 was used as the experimental material and a single-factor randomized trial was conducted to analyze the effects of different nitrogen application levels on post-anthesis nitrogen transport utilization and yield of wheat.The main results are as follows:With the increase of nitrogen application rate,the total tiller number of wheat plants increased.However,the proportion of total ear and main stem ear decreased,while the proportion of tiller ear was opposite.The total tiller number of N180,N240 and N300 treatments had little difference,but was significantly higher than that of N0 treatment.With the advance of wheat growth period,dry matter of wheat population increased.With the increase of nitrogen application rate,dry matter accumulation in different organs of wheat increased firstly and then decreased.At maturity stage,dry matter accumulation and yield of stem and leaf sheath were the highest in N240 treatment,and the yield was significantly higher than other nitrogen treatments.The effects of different nitrogen treatments on dry matter accumulation at flowering and maturity stage were significant.The trends of SPAD value,net photosynthetic rate,stomatal conductance and intercellular CO2 concentration in flag leaf of wheat increased with the increase of nitrogen application rate,and there were differences in specific performance.During wheat grain-filling process,the transpiration rate,chlorophyll content,stomatal conductance and intercellular CO2 concentration of flag leaves were the highest under N240 level,but there was no significant difference among individual nitrogen treatments.The transpiration rate of wheat decreased with the advance of grain filling process,and reached the maximum value at 10 days after anthesis.From anthesis stage to maturity stage,the content of total soluble sugar and total nitrogen in plant vegetative organs decreased continuously,and the content of total soluble sugar and total nitrogen in plant vegetative organs was at a low level in maturity stage.From 10 d after anthesis to maturity stage,total nitrogen content in wheat grains was the highest in N240.The total nitrogen content of grains at 15 d and25 d after anthesis reached the maximum value under N300 treatment.The total soluble sugar content of wheat at maturity stage did not increase significantly with the increase of nitrogen application rate,and the soluble sugar content of wheat under N240 treatment was the highest except for 10 and 15 days after flowering.The change rule of leaf,stem + leaf sheath was not obvious.The thousand grain weight and grain yield of wheat were significantly affected by nitrogen application rate.With the increase of nitrogen application rate,both of them showed an increasing trend,and the spike number per unit area of wheat also showed an increasing trend.The spike number and grain number per spike of wheat increased with the increase of nitrogen application rate,which was the highest under N240 treatment,and there was no significant difference between nitrogen treatments.Based on the above data analysis results,the optimal nitrogen application level was 240 kg·hm-2,which could maintain higher SPAD value and improve photosynthetic capacity of wheat leaves,promote the accumulation of photosynthetic products,and significantly increase soluble sugar content and total nitrogen content in wheat grains.It is beneficial to improve grain filling level,not only promote nitrogen transfer to grain,but also higher spike number,grain number per spike and 1000-grain weight,so as to obtain higher yield. |
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