Chlorosis at leaf margins is a typical symptom of potassium(K) deficiency, but inappropriate application of K with other nutrients often masks symptoms of K deficiency. A two-year field experiment was conducted to mea...Chlorosis at leaf margins is a typical symptom of potassium(K) deficiency, but inappropriate application of K with other nutrients often masks symptoms of K deficiency. A two-year field experiment was conducted to measure the interactive effects of N and K on leaf photosynthesis and dry matter accumulation and the resulting growth dilution effect on K concentration and leaf K deficiency symptoms. N application aggravated the imbalance of N and K nutrients and further exacerbated K deficiency symptoms under K limitation. Synergistic effects of N and K promoted plant growth, amplified the growth dilution effect, and reduced the critical K concentration in leaves. Using 90% of the maximum shoot biomass as a threshold,the critical K concentration was 0.72% at the recommended N(N180) fertilization level. The critical K concentration increased by 62.5% owing to the reduced biomass under insufficient N(N;) supply. In contrast, high N(N;) reduced the critical K concentration(0.64%), accelerating chlorophyll decomposition and exacerbating K deficiency symptoms. The basis of changing the critical K concentration by magnifying growth dilution effect was the functional synergistic effect of N and K on photosynthetic characteristics. Under insufficient N, the low maximum carboxylation rate(V;) limited the net photosynthetic rate(An) and necessitated more K to maintain high CO;transmission capacity, to improve the total conductance g;/V;ratio. High N supply increased gtotand V;possibly mitigating the effect of K reduction on photosynthesis. In conclusion, it is unwise to judge K status of plants only by K concentration without accounting for crop mass(or dilution effect), critical K concentration and deficiency symptoms are affected by N fertilization, and the synergistic effect of N and K on leaf photosynthesis is the foundation of maximal growth of plants under diverse critical K concentrations.展开更多
An experiment was conducted to study the response of broiler to diet dilution during the finishing period. Sixty 29-day-old commercial Avian male broiler chicks were assigned to two groups randomly, with 30 broilers e...An experiment was conducted to study the response of broiler to diet dilution during the finishing period. Sixty 29-day-old commercial Avian male broiler chicks were assigned to two groups randomly, with 30 broilers each. Birds were offered a conventional finishing diet or with 10% dilution diet with ground rice hulls from 29 to 49 days of age. The result showed that there were no significant differences between the effects of diet dilution and the control on final body weight, growth rate and feed conversion efficiency. Diet dilution led to a reduction in abdominal fat weight, whereas carcass and breast muscle weight were not affected.展开更多
In this paper,the flow field characteristics of Oblique Detonation Waves(ODWs)induced by a finite wedge under argon dilution are studied by solving the Euler equations with a detailed chemical model of hydrogen and ai...In this paper,the flow field characteristics of Oblique Detonation Waves(ODWs)induced by a finite wedge under argon dilution are studied by solving the Euler equations with a detailed chemical model of hydrogen and air.First,the effects of the expansion waves,argon concentration,geometric parameters,and Mach number on the ODW are discussed.The results show that the changes of these parameters may make the oblique detonation not be initiated.Then,the ODW initiation criterion of the finite wedge is summarized,as the characteristic length of the induction zone LCand the characteristic length of the oblique wedge LWmeet the condition LC/LW<1,the initiation of the ODW occurs;otherwise,it does not occur.What’s more,the Constant Volume Combustion(CVC)theory is applied to study the characteristic length of induction zone.It is found that CVC theory is more suitable for the“smooth transition”type of ODW flow field,the theoretical and numerical characteristic length in induction regions are in good agreement.This work is of great significance for the design of oblique detonation engines for hypersonic vehicles.展开更多
The Changjiang River diluted water(CDW)spreads into the East China Sea(ECS)primarily in a plume pattern,although in some years,low-salinity water lenses(LSWLs)detach from the main body of the CDW.In-situ observations ...The Changjiang River diluted water(CDW)spreads into the East China Sea(ECS)primarily in a plume pattern,although in some years,low-salinity water lenses(LSWLs)detach from the main body of the CDW.In-situ observations indicate that in August 2006,a LSWL detached from the main body of the CDW near the river mouth.In this paper,the effects of winds,tides,baroclinity and upwelling on LSWLs are explored with a threedimensional model.The results show that:(1)winds play a crucial role in these detachment events because windinduced northerly Eulerian residual currents impose an uneven force on the CDW and cut it off,thus forming a LSWL;(2)upwelling carries high-salinity water from the lower layer to the upper layer,truncating the low-salinity water tongue vertically,which is conducive to the detachment and maintenance of LSWLs;and(3)upwelling during the evolution of a LSWL is caused by the combined effects of winds and tides.The influences of windinduced upwelling are mainly near the shore,whereas the upwelling along the 30 m isobath is predominantly affected by tides,with the effect increasing from neap tide to spring tide.展开更多
基金financially supported by the National Natural Science Foundation of China(31872173)the National Key Research and Development Program of China(2018YFD0200900)+1 种基金China Agriculture Research System(CARS-12)the Fundamental Research Funds for the Central Universities(2662018PY077)。
文摘Chlorosis at leaf margins is a typical symptom of potassium(K) deficiency, but inappropriate application of K with other nutrients often masks symptoms of K deficiency. A two-year field experiment was conducted to measure the interactive effects of N and K on leaf photosynthesis and dry matter accumulation and the resulting growth dilution effect on K concentration and leaf K deficiency symptoms. N application aggravated the imbalance of N and K nutrients and further exacerbated K deficiency symptoms under K limitation. Synergistic effects of N and K promoted plant growth, amplified the growth dilution effect, and reduced the critical K concentration in leaves. Using 90% of the maximum shoot biomass as a threshold,the critical K concentration was 0.72% at the recommended N(N180) fertilization level. The critical K concentration increased by 62.5% owing to the reduced biomass under insufficient N(N;) supply. In contrast, high N(N;) reduced the critical K concentration(0.64%), accelerating chlorophyll decomposition and exacerbating K deficiency symptoms. The basis of changing the critical K concentration by magnifying growth dilution effect was the functional synergistic effect of N and K on photosynthetic characteristics. Under insufficient N, the low maximum carboxylation rate(V;) limited the net photosynthetic rate(An) and necessitated more K to maintain high CO;transmission capacity, to improve the total conductance g;/V;ratio. High N supply increased gtotand V;possibly mitigating the effect of K reduction on photosynthesis. In conclusion, it is unwise to judge K status of plants only by K concentration without accounting for crop mass(or dilution effect), critical K concentration and deficiency symptoms are affected by N fertilization, and the synergistic effect of N and K on leaf photosynthesis is the foundation of maximal growth of plants under diverse critical K concentrations.
基金National Basic Research Program of China (2004CB11750-5)
文摘An experiment was conducted to study the response of broiler to diet dilution during the finishing period. Sixty 29-day-old commercial Avian male broiler chicks were assigned to two groups randomly, with 30 broilers each. Birds were offered a conventional finishing diet or with 10% dilution diet with ground rice hulls from 29 to 49 days of age. The result showed that there were no significant differences between the effects of diet dilution and the control on final body weight, growth rate and feed conversion efficiency. Diet dilution led to a reduction in abdominal fat weight, whereas carcass and breast muscle weight were not affected.
基金supported by the Fundamental Research Funds for the Central Universities of China(No.310201906zy009)the Basic Research Plan of Natural Science in Shanxi Province—General Project(Youth),China(No.2019JQ-132)。
文摘In this paper,the flow field characteristics of Oblique Detonation Waves(ODWs)induced by a finite wedge under argon dilution are studied by solving the Euler equations with a detailed chemical model of hydrogen and air.First,the effects of the expansion waves,argon concentration,geometric parameters,and Mach number on the ODW are discussed.The results show that the changes of these parameters may make the oblique detonation not be initiated.Then,the ODW initiation criterion of the finite wedge is summarized,as the characteristic length of the induction zone LCand the characteristic length of the oblique wedge LWmeet the condition LC/LW<1,the initiation of the ODW occurs;otherwise,it does not occur.What’s more,the Constant Volume Combustion(CVC)theory is applied to study the characteristic length of induction zone.It is found that CVC theory is more suitable for the“smooth transition”type of ODW flow field,the theoretical and numerical characteristic length in induction regions are in good agreement.This work is of great significance for the design of oblique detonation engines for hypersonic vehicles.
基金The National Natural Science Foundation of China under contract No.41376012.
文摘The Changjiang River diluted water(CDW)spreads into the East China Sea(ECS)primarily in a plume pattern,although in some years,low-salinity water lenses(LSWLs)detach from the main body of the CDW.In-situ observations indicate that in August 2006,a LSWL detached from the main body of the CDW near the river mouth.In this paper,the effects of winds,tides,baroclinity and upwelling on LSWLs are explored with a threedimensional model.The results show that:(1)winds play a crucial role in these detachment events because windinduced northerly Eulerian residual currents impose an uneven force on the CDW and cut it off,thus forming a LSWL;(2)upwelling carries high-salinity water from the lower layer to the upper layer,truncating the low-salinity water tongue vertically,which is conducive to the detachment and maintenance of LSWLs;and(3)upwelling during the evolution of a LSWL is caused by the combined effects of winds and tides.The influences of windinduced upwelling are mainly near the shore,whereas the upwelling along the 30 m isobath is predominantly affected by tides,with the effect increasing from neap tide to spring tide.
