High planting density is essential to increasing maize grain yield.However,single plants suffer from insufficient light under high planting density.Ammonium(NH_4^+)assimilation consumes less energy converted from radi...High planting density is essential to increasing maize grain yield.However,single plants suffer from insufficient light under high planting density.Ammonium(NH_4^+)assimilation consumes less energy converted from radiation than nitrateIt is hypothesized that a mixed NO_3~–/NH_4^+supply is more important to improving plant growth and population productivity under high vs.low planting density.Maize plants were grown under hydroponic conditions at two planting densities(low density:only).A significant interaction effect was found between planting density and N form on plant biomass.Compared to nitrate only,75/25NO_3~–/NH_4^+increased per-plant biomass by 44%under low density,but by 81%under high density.Treatment with 75/25NO_3~–/NH_4^+increased plant ATP,photosynthetic rate,and carbon amount per plant by 31,7,and 44%under low density,respectively,but by 51,23,and 95%under high density.Accordingly,carbon level per plant under 75/25NO_3~–/NH_4^+was improved,which increased leaf area,specific leaf weight and total root length,especially for high planting density,increased by 57,17 and 63%,respectively.Furthermore,under low density,75/25NO_3~–/NH_4^+increased nitrogen uptake rate,while under high density,75/25NO_3~–/NH_4^+increased nitrogen,phosphorus,copper and iron uptake rates.By increasing energy use efficiency,an optimum NO_3~–/NH_4^+ratio can improve plant growth and nutrient uptake efficiency,especially under high planting density.In summary,an appropriate supply of NH_4^+in addition to nitrate can greatly improve plant growth and promote population productivity of maize under high planting density,and therefore a mixed N form is recommended for high-yielding maize management in the field.展开更多
Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insuffic...Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insufficien atomic hydrogen(H^(*))supply.Herein,we propose CuO/NiO heterojunction with the assistance of a built-in electric field to enhance mass transfer and H^(*)provision.The built-in electric field in Cu O/Ni O is success fully formed as demonstrated by X-ray photoelectron spectroscopy and ultraviolet photoemission spec troscopy.The results reveal that Cu O/Ni O achieves high NO_(3)^(-)reduction activity(100%)and NH_(4)^(+)selec tivity(100%)under low NO_(3)^(-)concentration conditions(100 mg/L NO_(3)^(-),ca.22.6 mg/L NO_(3)^(-)-N),which i superior to that of many recently reported electrocatalysts.Density functional theory calculations furthe clarify that the built-in electric field triggers the enhanced adsorption of reactants on CuO/NiO hetero junction interface and strong d-p orbital hybridization between reactants and CuO/NiO.Besides,the free energy diagram of hydrogen evolution reaction of CuO/NiO confirms the realization of enhanced H^(*)pro vision.Moreover,coupling experiments and consecutive cycle tests demonstrate the potential of CuO/NiO in practical applications.This work may open up a new path and guide the development of efficien electrocatalysts for electrocatalytic reduction of NO_(3)^(-)at low concentrations to NH_(4)^(+).展开更多
基金supported by the National Basic Research Program of China(2015CB150402)the National Natural Science Foundation of China(31672221 and 31421092)
文摘High planting density is essential to increasing maize grain yield.However,single plants suffer from insufficient light under high planting density.Ammonium(NH_4^+)assimilation consumes less energy converted from radiation than nitrateIt is hypothesized that a mixed NO_3~–/NH_4^+supply is more important to improving plant growth and population productivity under high vs.low planting density.Maize plants were grown under hydroponic conditions at two planting densities(low density:only).A significant interaction effect was found between planting density and N form on plant biomass.Compared to nitrate only,75/25NO_3~–/NH_4^+increased per-plant biomass by 44%under low density,but by 81%under high density.Treatment with 75/25NO_3~–/NH_4^+increased plant ATP,photosynthetic rate,and carbon amount per plant by 31,7,and 44%under low density,respectively,but by 51,23,and 95%under high density.Accordingly,carbon level per plant under 75/25NO_3~–/NH_4^+was improved,which increased leaf area,specific leaf weight and total root length,especially for high planting density,increased by 57,17 and 63%,respectively.Furthermore,under low density,75/25NO_3~–/NH_4^+increased nitrogen uptake rate,while under high density,75/25NO_3~–/NH_4^+increased nitrogen,phosphorus,copper and iron uptake rates.By increasing energy use efficiency,an optimum NO_3~–/NH_4^+ratio can improve plant growth and nutrient uptake efficiency,especially under high planting density.In summary,an appropriate supply of NH_4^+in addition to nitrate can greatly improve plant growth and promote population productivity of maize under high planting density,and therefore a mixed N form is recommended for high-yielding maize management in the field.
基金support of the National Natural Science Foundation of China(Nos.52170082,51938007,21906076,and 52300081)the Natural Science Foundation of Jiangxi Province(No.20212ACB203008)。
文摘Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insufficien atomic hydrogen(H^(*))supply.Herein,we propose CuO/NiO heterojunction with the assistance of a built-in electric field to enhance mass transfer and H^(*)provision.The built-in electric field in Cu O/Ni O is success fully formed as demonstrated by X-ray photoelectron spectroscopy and ultraviolet photoemission spec troscopy.The results reveal that Cu O/Ni O achieves high NO_(3)^(-)reduction activity(100%)and NH_(4)^(+)selec tivity(100%)under low NO_(3)^(-)concentration conditions(100 mg/L NO_(3)^(-),ca.22.6 mg/L NO_(3)^(-)-N),which i superior to that of many recently reported electrocatalysts.Density functional theory calculations furthe clarify that the built-in electric field triggers the enhanced adsorption of reactants on CuO/NiO hetero junction interface and strong d-p orbital hybridization between reactants and CuO/NiO.Besides,the free energy diagram of hydrogen evolution reaction of CuO/NiO confirms the realization of enhanced H^(*)pro vision.Moreover,coupling experiments and consecutive cycle tests demonstrate the potential of CuO/NiO in practical applications.This work may open up a new path and guide the development of efficien electrocatalysts for electrocatalytic reduction of NO_(3)^(-)at low concentrations to NH_(4)^(+).
