Effects Of Tillage And Nitrogen Application On Nitrogen Utilization And Rhizosphere AMF Community In Dryland Wheat

Scientific application of nitrogen and enhancement of the transport of soil nitrogen by mycorrhiza are of great significance for establishing the goal of soil fertility in dryland wheat,increasing wheat yield,and mitigating environmental and water pollution.In this paper,dryland wheat and rhizosphere soil were used as research objects.It is proposed to study the two-way adjustment mechanism and the relationship between nitrogen transport,soil nitrogen component residues and rhizosphere soil AMF(arbuscular mycorrhizal fungi)diversity changes under different tillage measures combined with nitrogen level conditions.Based on the platform of the Yellow Soil Plateau Dryland Wheat Positioning Experiment Station of Shanxi Agricultural University(1978-present,Shanxi Wenxi),and the annual experiment of different cultivation measures and nitrogen application gradient of dryland wheat,The effects of tillage and nitrogen application on nitrogen utilization and rhizosphere AMF community in dryland wheat was studied by measureing the soil nitrogen components in different growth stages of wheat and the nitrogen use efficiency and using the most advanced metagenomic sequencing technology to analyze the AMF diversity of rhizosphere soil.The main results are as follows:1.In the various growth stages of winter wheat,tillage measures combined with different nitrogen applications mainly affected the content of nitrate nitrogen in the soil,but ammonium nitrogen was influenced little.Under the same nitrogen application level,deep tillage increased the content of nitrate nitrogen and ammonium nitrogen in the 0-60 cm soil layer of wheat rhizosphere compared with no-tillage treatment,There were significant differences in nitrate nitrogen content between 0-60 cm soil layer and0-20 cm soil layer during wintering period;There are significant differences in the 0-60 cm soil layer in the wintering,jointing and flowering stages of wheat under the different tillage measures combined with nitrogen applications.With the advancement of wheat growth period,The nitrate nitrogen content decreased in all soil layers and reached a minimum at maturity.2.Tillage combined with nitrogen treatment affected nitrogen metabolism in dryland wheat plants.With no-tillage(NT)treatment,the dry matter quality,nitrogen accumulation,nitrogen uptake and yield of each stage increased gradually with the increase of nitrogen application rate;Under deep tillage(DT)56treatment,the indexes were changed like the single-peak curve trend of increasing and then decreasing withthe increase of nitrogen application rate,the level of medium nitrogen(90 kg·hm-2)was significantly higher than other treatments;Under the same nitrogen application level,deep tillage can significantly increase the above indicators and yield than no-tillage(NT)mold treatment.3.AMF species in the rhizosphere soil samples of different treatment was identified with 1Paraglomus,3 classes,4 orders,5 familys,5 genus,and 29 species,Glomus and Claroideoglomus are dominant genus,and sp._VTX00308 and_sp._VTX00193 are dominant species.4.The deep tillage treatment can increase the AMF diversity and abundance in the deep soil of dryland wheat,the structure of AMF flora in different soil layers is very different;Under no-tillage treatment,the AMF diversity gradually decreases with the increase of soil depth,and its abundance reaches the maximum at 20-60 cm,and the other composition of microbial structure was quite different compared with other two soil layers are in the.5.When the nitrogen application rate is 90 kg·hm-2,the diversity and abundance of AMF in the same soil layer are higher than other nitrogen treatments,and the diversity is significant,also the diversity and abundance is highest in the 20-60 cm soil layer which are different from other soil samples under nitrogen treatment.6.Under deep tillage(DT)treatment,excessive nitrogen application significantly reduces AMF diversity and abundance;Shannon index and diversity of AMF was highest under no-tillage(NT)treatment combined with the middle nitrogen treatment(N2),but the abundance of AMF is gradually increasing with the increase of nitrogen application rate.Beta diversity analysis shows that the similarity between NTN1 and NTN2 samples of AMF structure is higher,and the dominant flora of Paraglomus.Glomus and Claroideoglomus is relatively close.7.The correlation between nitrate nitrogen and AMF diversity in 0-100 cm soil layer under different treatments was higher.Nitrogen uptake and plant nitrogen accumulation were not significantly correlated with Shannon index,but were closely related to Chao1 index,and plant nitrogen accumulation was significantly positively correlated with Chao1 index at jointing stage;Under deep-turned(DT)treatment,the amount of nitrogen uptake was significantly correlated with the Chao1 index at the peak of jointing-flowering nitrogen uptake.In conclusion,with using the deep tillage techniques combined with nitrogen application rate of 90kg·hm-2 in dryland wheat,AMF community structure of wheat rhizosphere soil was rich,the abundance and diversity were relatively high,the nitrogen utilization rate in soil was improved,and the nitrogen metabolism of wheat plants was also improved.