Effects Of Combination Of Different Density And Nitrogen Application On Nitrogen Distribution And Nitrogen Metabolism In Wheat After Flowering

Wheat is the main food crop in China.Its grain output is directly related to China's food security.At different planting densities,Reasonable application of nitrogen fertilizer,Not only can increase the wheat grain yield,improve nitrogen fertilizer utilization efficiency,but also can reduce the pollution to the surrounding environment.In this study,the main wheat variety,Xiaokang 58 in Huanghuai Haimai District was used as a test material.The effect of nitrogen application rate under different planting densities on plant growth physiology,nitrogen transport and absorption and post-anthesis nitrogen metabolism in winter wheat was studied,and a reasonable mode of nitrogen fertilizer application in this area was sought.1.During the entire fertility season of wheat,the effect of nitrogen fertilizer on population quality is achieved through the improvement of individual quality.And in the later period of birth,the density is compensated.The increase of nitrogen application rate can significantly increase the plant height,the number of populations and the content of chlorophyll in the flag leaf of wheat.With the advancement of wheat flowering,the net photosynthetic rate and stomatal conductance of wheat flag leaf showed a decreasing trend,and there were differences under different density treatments.The intercellular CO₂ concentration of wheat flag leaf showed a decrease and then increased.There was a significant difference in intercellular CO₂concentration between different planting densities in the non-fertilized area and the low-fertilized area.The difference in the middle-fertilizer area was smaller,and there was no difference in the high-fertilizer area.The transpiration rate of wheat flag leaf showed an overall increase and then a decrease trend.Under the treatment of medium and high fertilizers,the density did not differ greatly.2.At the flowering stage of wheat,dry matter in the population showed a trend of increasing first and then decreasing with the increase of nitrogen fertilizer application,and the N2 treatment had the highest performance.There was no significant difference between the density treatments;with the growing period,the population dry matter increased;At the flowering stage,the dry matter of the wheat ear population was the largest,followed by the stem section,then the leaf.Dry matter in the population from the first leaf to the remaining leaves showed a gradual decrease.From one to the other,the population of dry matter gradually decreased.At the maturity stage,the dry matter of the grain part of the population was the largest,and the trend of the rest parts and the flowering period were consistent.3.The accumulation and translocation of nitrogen in leaves and stems and sheaths during the flowering and maturing stages of wheat showed a decreasing trend with the decline of wheat canopy,and increased with the increase of nitrogen application rate.The contribution of wheat leaf and stem transport to the grain decreases as the canopy declines.The contribution rate of nitrogen transport to wheat grains in various parts of wheat plants ranged from 0.01%to32.57%.With the increase of nitrogen fertilizer application,the contribution rate of glumes and cobs to grain showed a decreasing trend,which was the highest under N0 treatment.Under N3treatment,the contribution rate of wheat plant parts reached the maximum.The contribution rate of wheat plant parts to grain was highest under N2 and N3 treatments,and highest under N1 treatment.4.Appropriate application of nitrogen fertilizer can promote the transfer of nitrogen to grain and post-anthesis nitrogen assimilation in vegetative organs of wheat.The nitrogen harvest index decreased with the increase of nitrogen application rate and was the lowest under N₃?360kg/hm²?treatment.Under N₀,N₁?0,120kg/hm²?treatment,the nitrogen fertilizer application amount can be significantly increased by increasing nitrogen fertilizer input.Nitrogen partial productivity,nitrogen agronomic efficiency,and nitrogen fertilization rate all decreased with the increase of nitrogen application rate and were highest under N₁M₃?120kg/hm²,525×10⁴ seedlings/hm²?treatment.The contribution rate of nitrogen fertilizer showed a trend of rising first and then decreasing,reaching the maximum under the treatment of N₂M₃?240kg/hm²,525×10⁴ seedlings/hm²?.5.Under the condition of nitrogen application,the grain yield increased by 4.31 to 7.79times compared with that under no nitrogen application.When the wheat grain yield was high,it appeared under the combined treatment of 360 kg/hm² nitrogen,375 x 10⁴ basic seedlings/hm²,and nitrogen application rates of 240 kg/hm² and 525 x 10⁴ basic seedlings/hm²,They were 11855 kg/hm² and 11827 kg/hm² respectively.6.With the advancement of the number of days after flowering at flowering stage,the GS activity,NR activity,and GOGAT activity of wheat flag leaf showed a decreasing trend.The highest GS activity during flowering,The enzyme activity of GS decreased slowly from 0 to 7days,and the GS activity decreased rapidly from 7 to 28 days.The enzyme activities of GS,NR,GOGAT and GPT increased with the increase of the amount of fertilizer,and the overall performance was N₃>N₂>N₁>N₀.The GS and GOGAT activity trends in wheat kernels are similar to those in flag leaves.The activity of NR in flag leaves of wheat was the highest after flowering,and it gradually decreased with the advance of wheat after flowering.With the advancement of the number of days after flowering,the nitrate reductase activity in wheat grain first increased and then decreased,and it had a maximum at 14 days,and then declined.With the increase of nitrogen fertilizer application,the activity of NR,GS,GOGAT and GPT in wheat flag leaf increased.This is consistent with the changes in nitrogen uptake after anthesis in wheat,indicating that an appropriate increase in nitrogen application can promote nitrogen uptake and assimilation after wheat flowering.