Foliar nitrogen(N)application is an effective strategy to improve protein content and quality in wheat kernels,but the specific effects of N forms remain unclear.In a two-year field study,foliar application of various...Foliar nitrogen(N)application is an effective strategy to improve protein content and quality in wheat kernels,but the specific effects of N forms remain unclear.In a two-year field study,foliar application of various N forms(NO_(3)^(-),urea,NH_(4)^(+))at anthesis was performed to measure their effects on wheat grain protein accumulation,quality formation,and the underlying mechanisms.Foliar application of three N forms showed varying effects in improving grain gluten proteins and quality traits.Under NH_(4)^(+) application,there was more post-anthesis N uptake for grain filling,with relatively strong increase in enzyme activities and gene expression associated with N metabolism in flag leaves at 8–20 days after anthesis(DAA),whereas its promotion of grain N metabolism became weaker after 20 DAA than those under NO_(3)^(-) and urea treatments.More N was remobilized from source organs to grain under treatment with foliar NO_(3)^(-) and urea.Genes controlling the synthesis of gluten protein and disulfide bonds were upregulated by NO_(3)^(-) and urea at 20–28 DAA,contributing to increased grain protein content and quality.Overall,foliar applications of NO_(3)^(-) and urea were more effective than those of NH_(4)^(+) in increasing grain N filling.These findings show that manipulating the source–sink relationship by reinforcing grain N metabolism and N remobilization is critical for optimizing grain protein accumulation and quality formation.展开更多
Straw return can effectively improve farmland soil microenvironment and fertility.However,excessive straw in the topsoil adversely affects seed germination and crop growth.At present,the characteristics and key drivin...Straw return can effectively improve farmland soil microenvironment and fertility.However,excessive straw in the topsoil adversely affects seed germination and crop growth.At present,the characteristics and key driving factors of straw decomposition in dry farmlands are unclear.Based on the interactions between tillage practices including zero tillage(ZT),chisel tillage(CT),and plow tillage(PT)and nitrogen(N)fertilization,i.e.,low N(N1,180 kg ha^(-1)),normal N(N2,240 kg ha^(-1)),and high N(N3,300 kg ha^(-1)),quantitative polymerase chain reaction technology and an enzymatic detection kit were used to investigate the effects of key straw C-degrading enzyme activities and microbial abundance in soil on maize straw decomposition during the growth period of winter wheat in the winter wheat/summer maize double cropping system in a dry farmland of the Loess Plateau,China.Between 2018 and 2020,ZT and CT significantly increased winter wheat yield(by 10.94%and 12.79%,respectively)and straw decomposition velocity(by 20%and 26.67%,respectively),compared with PT.Compared to N1 and N3,N2 significantly increased wheat yield(by 4.65%and 5.31%,respectively)and straw decomposition velocity(by 26.33%and 13.21%,respectively).The partial least squares pathway modelling showed significant positive direct effects of soil moisture,NO3-,NH4+,total N,bacteria,and cellulase,laccase,and xylanase activities on straw decomposition,while soil pH,fungi,and Actinomycetes had significant negative direct effects.Overall,conservation tillage(ZT and CT)combined with N2 was beneficial for straw decomposition in the drylands of the Loess Plateau and improved straw resource utilization and basic soil fertility.The results of the study clarified the key drivers of straw decomposition in dry farmlands and provided new ideas for developing updated soil management practices and adaptive N application strategies to promote the resource utilization of straw and achieve the goals of carbon peaking and carbon neutrality.展开更多
Southeastern Tibet is one of the most glaciated regions on the Tibetan Plateau both at present and during the Quaternary. Numerical dating of glacial deposits has allowed the establishment of a provisional chronology ...Southeastern Tibet is one of the most glaciated regions on the Tibetan Plateau both at present and during the Quaternary. Numerical dating of glacial deposits has allowed the establishment of a provisional chronology of Quaternary glacial fluctuations in this region, with the oldest glaciation(Guxiang Glaciation) occurring in marine oxygen isotope stage 6(MIS-6).During our recent field investigations, a morphostratigraphically older lateral moraine than that of the Guxiang Glaciation has been first identified, which is ~500–600 m above the Guxiang Glaciation moraine and discontinuously preserved on valley shoulders in the Bodui Zangbo River valley, eastern Nyainqêntanglha Range in southeastern Tibet. Considering the moraine is best preserved at Nitong Village, here we name the glacier advance which deposited the moraine as "Nitong Glaciation". Using electron spin resonance(ESR) technique, we dated the Nitong Glaciation moraine to 506.3±60.4 ka. Taking into account the age error and climatic conditions, we consider it most likely that the Nitong Glaciation occurred during MIS-12, although it might had happened sometime earlier.展开更多
基金supported by the National Natural Science Foundation of China(31971860).
文摘Foliar nitrogen(N)application is an effective strategy to improve protein content and quality in wheat kernels,but the specific effects of N forms remain unclear.In a two-year field study,foliar application of various N forms(NO_(3)^(-),urea,NH_(4)^(+))at anthesis was performed to measure their effects on wheat grain protein accumulation,quality formation,and the underlying mechanisms.Foliar application of three N forms showed varying effects in improving grain gluten proteins and quality traits.Under NH_(4)^(+) application,there was more post-anthesis N uptake for grain filling,with relatively strong increase in enzyme activities and gene expression associated with N metabolism in flag leaves at 8–20 days after anthesis(DAA),whereas its promotion of grain N metabolism became weaker after 20 DAA than those under NO_(3)^(-) and urea treatments.More N was remobilized from source organs to grain under treatment with foliar NO_(3)^(-) and urea.Genes controlling the synthesis of gluten protein and disulfide bonds were upregulated by NO_(3)^(-) and urea at 20–28 DAA,contributing to increased grain protein content and quality.Overall,foliar applications of NO_(3)^(-) and urea were more effective than those of NH_(4)^(+) in increasing grain N filling.These findings show that manipulating the source–sink relationship by reinforcing grain N metabolism and N remobilization is critical for optimizing grain protein accumulation and quality formation.
基金supported by the National Natural Science Foundation of China(No.31971860).
文摘Straw return can effectively improve farmland soil microenvironment and fertility.However,excessive straw in the topsoil adversely affects seed germination and crop growth.At present,the characteristics and key driving factors of straw decomposition in dry farmlands are unclear.Based on the interactions between tillage practices including zero tillage(ZT),chisel tillage(CT),and plow tillage(PT)and nitrogen(N)fertilization,i.e.,low N(N1,180 kg ha^(-1)),normal N(N2,240 kg ha^(-1)),and high N(N3,300 kg ha^(-1)),quantitative polymerase chain reaction technology and an enzymatic detection kit were used to investigate the effects of key straw C-degrading enzyme activities and microbial abundance in soil on maize straw decomposition during the growth period of winter wheat in the winter wheat/summer maize double cropping system in a dry farmland of the Loess Plateau,China.Between 2018 and 2020,ZT and CT significantly increased winter wheat yield(by 10.94%and 12.79%,respectively)and straw decomposition velocity(by 20%and 26.67%,respectively),compared with PT.Compared to N1 and N3,N2 significantly increased wheat yield(by 4.65%and 5.31%,respectively)and straw decomposition velocity(by 26.33%and 13.21%,respectively).The partial least squares pathway modelling showed significant positive direct effects of soil moisture,NO3-,NH4+,total N,bacteria,and cellulase,laccase,and xylanase activities on straw decomposition,while soil pH,fungi,and Actinomycetes had significant negative direct effects.Overall,conservation tillage(ZT and CT)combined with N2 was beneficial for straw decomposition in the drylands of the Loess Plateau and improved straw resource utilization and basic soil fertility.The results of the study clarified the key drivers of straw decomposition in dry farmlands and provided new ideas for developing updated soil management practices and adaptive N application strategies to promote the resource utilization of straw and achieve the goals of carbon peaking and carbon neutrality.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41771065, 42071088, 41271077 and 41371080)。
文摘Southeastern Tibet is one of the most glaciated regions on the Tibetan Plateau both at present and during the Quaternary. Numerical dating of glacial deposits has allowed the establishment of a provisional chronology of Quaternary glacial fluctuations in this region, with the oldest glaciation(Guxiang Glaciation) occurring in marine oxygen isotope stage 6(MIS-6).During our recent field investigations, a morphostratigraphically older lateral moraine than that of the Guxiang Glaciation has been first identified, which is ~500–600 m above the Guxiang Glaciation moraine and discontinuously preserved on valley shoulders in the Bodui Zangbo River valley, eastern Nyainqêntanglha Range in southeastern Tibet. Considering the moraine is best preserved at Nitong Village, here we name the glacier advance which deposited the moraine as "Nitong Glaciation". Using electron spin resonance(ESR) technique, we dated the Nitong Glaciation moraine to 506.3±60.4 ka. Taking into account the age error and climatic conditions, we consider it most likely that the Nitong Glaciation occurred during MIS-12, although it might had happened sometime earlier.
