| Fertilizer application is the basic guarantee of contemporary grain production and the material basis of promoting sustainable agricultural development.However,in recent years,excessive and unreasonable fertilization methods not only reduce crop yield and soil quality,but also pose a serious threat to the environment.Traditional fertilization methods are no longer in line with the current sustainable development model.In order to better guide the actual fertilization of wheat and improve the utilization rate of soil nutrient,this research uses the hydroponic experiment,field experiment and laboratory in Wan Mai 52 varieties as experimental material.The effects of nitrogen and phosphorus reduction on the growth and development of wheat seedlings,and the dynamic changes of soil total nitrogen,nitrate nitrogen,ammonium nitrogen,total phosphorus and available phosphorus were studied.Molecular biology was used to explore the molecular response of wheat seedling in low nitrogen and low phosphorus environment.The main results of this study are as follows:(1)The growth of shoots and roots of wheat seedlings in all treatments was farmers’habitual fertilization treatment(CF)>nitrogen fertilizer reduction treatment(CFN)>phosphorus fertilizer reduction treatment(CFP)>optimized nitrogen and phosphorus fertilizer reduction treatment(CFNP)>non-fertilization treatment(CK),and the performance of non-fertilization(CK)treatment was the worst,which significantly inhibited the growth of wheat.The plant height,leaf area and stem and leaf dry weight showed significant reduction in wheat seedlings under reduced application of nitrogen fertilizer(CFN),reduced application of phosphorus fertilizer(CFP),and the optimized reduction of nitrogen and phosphorus fertilizer(CFNP)compared with farmers’habitual fertilization(CF).The total root number,total root length,root activity and root dry weight were decreased significantly in wheat seedlings under reduced application of nitrogen fertilizer(CFN),reduced application of phosphorus fertilizer(CFP),and the optimized reduction of nitrogen and phosphorus fertilizer(CFNP)compared with farmers’habitual fertilization(CF).Our results show that no fertilization can significantly inhibit the growth of wheat seedlings,and the reduction of nitrogen and phosphorus fertilizer will also have an impact on the growth of seedlings.(2)In terms of soil nitrogen and phosphorus uptake by wheat seedlings under different treatments,the order of total nitrogen content from high to low was CF>CFP>CFN>CFNP>CK,and the order of total phosphorus content from high to low was CF>CFN>CFP>CFNP>CK.The non-fertilization treatment not only limited the growth of wheat seedlings,but also significantly reduced their ability to absorb soil nutrients.In addition,the total nitrogen content of wheat seedlings under the reduction of nitrogen fertilizer and the optimized reduction of nitrogen and phosphorus fertilizer was significantly lower than that under the farmers’habitual fertilization,and the total phosphorus content of wheat seedlings under the reduction of phosphorus fertilizer and the optimized reduction of nitrogen and phosphorus fertilizer was also significantly lower than that under the farmers’habitual fertilization.It can be seen that the absorption of nitrogen and phosphorus nutrients was also affected by the reduced fertilization in wheat seedlings.(3)In terms of the molecular response of wheat seedlings to low nitrogen and phosphorus,a large number of differentially expressed genes responding to low nitrogen and phosphorus environment were found in wheat seedlings.In low nitrogen environment,2083 differentially expressed genes were detected in wheat leaves,505 were up-regulated and 1578 were down-regulated;2265 differentially expressed genes were detected in roots,1688 were up-regulated and 577 were down-regulated.In low phosphorus environment,2318 differentially expressed genes were detected in wheat leaves,1646 were up-regulated and 672 were down-regulated;2018 differentially expressed genes were monitored in roots,1310 were up-regulated and 708 were down-regulated.Through functional enrichment of differentially expressed genes,it was found that these genes participate in various metabolic processes and regulate various enzymes activities,and participate in photosynthesis,carbon metabolism,signal transduction and material synthesis in metabolic pathways.(4)In terms of soil nutrient content,soil nitrogen in the tillage layer of each fertilization treatment showed a trend of decreasing first,then increasing and then decreasing gradually,and soil phosphorus overall showed a trend of decreasing gradually in the whole wheat growing season.Taking farmers’habitual fertilization as a reference,CFN and CFNP significantly reduced the total nitrogen content,NO3--N content and NH4+-N content in the topsoil,while the CFP had no significant effect on soil nitrogen content.CFP and CFNP also significantly reduced the total phosphorus and available phosphorus content in the topsoil,and reduced the application of nitrogen fertilizer has no significant impact on soil phosphorus content. |
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