The reuse of treated wastewater in agricultural systems could partially help alleviate water resource shortages in developing countries. Treated wastewater differs from fresh water in that it has higher concentrations...The reuse of treated wastewater in agricultural systems could partially help alleviate water resource shortages in developing countries. Treated wastewater differs from fresh water in that it has higher concentrations of salts, Escherichia coli and presence of dissolved organic matter, and inorganic N after secondary treatment, among others. Its application could thus cause environmental consequences such as soil salinization, ammonia volatilization, and greenhouse gas emissions. In an incubation experiment, we evaluated the characteristics and effects of water-filled pore space （WFPS） and N input on the emissions of nitrous oxide （N2O） and carbon dioxide （CO2） from silt loam soil receiving treated wastewater. Irrigation with treated wastewater （vs. distilled water） significantly increased cumulative N2O emission in soil （117.97 μg N kg-1）. Cumulative N2O emissions showed an exponentially increase with the increasing WFPS in unamended soil, but the maximum occurred in the added urea soil incubated at 60% WFPS. N2O emissions caused by irrigation with treated wastewater combined with urea-N fertilization did not simply add linearly, but significant interaction （P〈0.05） caused lower emissions than the production of N2O from the cumulative effects of treated wastewater and fertilizer N. Moreover, a significant impact on cumulative CO2 emission was measured in soil irrigated with treated wastewater. When treated wastewater was applied, there was significant interaction between WFPS and N input on N2O emission. Hence, our results indicated that irrigation with treated wastewater should cause great concern for increasing global warming potential due to enhanced emission of N2O and CO2.展开更多
To reveal the period and after-effect of soil water stress on winter wheat, the article employs the experiment results carried out in the greenhouse. The results showed that the root-restricted weights varied with str...To reveal the period and after-effect of soil water stress on winter wheat, the article employs the experiment results carried out in the greenhouse. The results showed that the root-restricted weights varied with stress degrees and stress times during and after water stressing. In the course of stress, the chief reason resticting the weight of root was the stress intensity at this time, and that of severe stress treatment was larger than that of mild stress treatment. After water stress was relieved, the results of the after-effect of soil water stress on root growth were that, the stress intensity of short-time and mild stress was larger than that of long-time and severe stress. Comparing two-stage stress intensities, root-restricted weight resulted from after-effect intensity of stress under all of the short-time treatment, and the mild and the long-time stress treatments, while that resulted from the period stress intensity under the severe and the long-time stress treatments. In general, the effects of water stress on root were attributed to the three factors, a formed basis in the previous stage, the after-effect of water condition before this stage and influence of water in this stage, which lead to the characters of root in the whole growth stage.展开更多
Glasshouse and laboratory tests were carried out in 1996 - 1998 using winter wheat cultivars Beinong 6 as materials. The growth dynamics of the whole-wheat plant were analysed under constant and fluctuated soil water ...Glasshouse and laboratory tests were carried out in 1996 - 1998 using winter wheat cultivars Beinong 6 as materials. The growth dynamics of the whole-wheat plant were analysed under constant and fluctuated soil water condition. The results revealed that water stress made the starting time of crop greatest growth phase(STCGGP) in advance, prolonged crop greatest growth phase(CGGP), decreased the rate of crop greatest growth (CGGR or CGRm), and as a result, the rate of dry matter accumulation was reduced and the growth of the crop was slowed down. Rewatering delayed STCGGP, shortened CGGP, increased CGGR, thus, the rate of dry matter accumulation had been boosted and the growth of the crop was accelerated. The growth rate, dry matter weight and grains yield of winter wheat were almost equal to the well-watered controls if they were rewatered under the condition of moderate water stress during the jointing stage.展开更多
The equilibrium between root, shoot and growth stability under different soil water conditions were investigated in a tube experiment of winter wheat. The water supplying treatments included： sufficient irrigation at...The equilibrium between root, shoot and growth stability under different soil water conditions were investigated in a tube experiment of winter wheat. The water supplying treatments included： sufficient irrigation at whole growth phase, moderate deficiency irrigation at whole growth phase, serious deficiency irrigation at whole growth phase, sufficient irrigation at jointing stage, tillering stage, flowering stage, and fillering respectively, after moderate and serious water deficit during their previous growth stage. Root and shoot biomass were measured. On the basis of the cooperative root-shoot interactions model, the equilibrium and growth stability were studied on the strength of the kinetics system theory. There was only one varying equilibrium point between the root and shoot over the life time of the winter wheat plant. Water stress prolonged the duration of stable growth, the more serious the water deficit, the longer the period of stable growth. The duration of stable growth was shortened and that of unstable growth was prolonged after water recovery. The growth behavior of the plants exposed to moderate water deficit shifted from stable to unstable until the end of the growth, after rewatering at flowering. In the life-time of the crop, the root and shoot had been adjusting themselves in structure and function so as to maintain an equilibrium, but could not achieve the equilibrium state for long. They were always in an unbalanced state from the beginning to the end of growth. This was the essence of root-shoot equilibrium. Water stress inhibited the function of root and shoot, reduced root shoot interactions, and as a result, the plant growth gradually tended to stabilize. Rewatering enhanced root shoot interactions, prolonged duration of instable growth. Rewatering at flowering could upset the inherent relativity during the long time of stable growth from flowering to filling stage, thus leading to unstable growth and enhanced dry matter accumulating rate in the whole plant.展开更多
After water stress at various levels and durations at different growth stages, rewatering could greatly stimulate the leaf area development of winter wheat. The results showed that the stimulation effect changed with ...After water stress at various levels and durations at different growth stages, rewatering could greatly stimulate the leaf area development of winter wheat. The results showed that the stimulation effect changed with water stress time, degree and duration. Rewatering under earlier stress had greater stimulation effect on leaf area than that under later stress. Higher stimulation effect was observed under severe water stress than that under moderate stress. Longer duration of stress resulted in low stimulation effect. In spite of the greater stimulation effect under severe and longer stress, the final leaf area in these situations was lower than that under moderate stress and shorter duration. Whenever the stress occurred, the stimulating effect was due to the increase of the leaf area of the tillers. Once the leaf on the main stem emerged during stress period, rewatering had no effect on its size, and consequently its leaf area. The stimulation of rewateirng on leaf area contributed to the final grain yield by 45% under moderate stress, and 67% under severe stress. Although the stimulation partly compensated for the loss during stress, the final leaf area and the grain yield could not reach the level without water stress.展开更多
As the third paper in the multiple-part series,we report the statistical properties of radio bursts detected from the repeating fast radio burst(FRB)source FRB 20201124A with the Five-hundred-meter Aperture Spherical ...As the third paper in the multiple-part series,we report the statistical properties of radio bursts detected from the repeating fast radio burst(FRB)source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope during an extremely active episode between the 25th and 28th of September 2021(UT).We focus on the polarization properties of536 bright bursts with S/N>50.We found that the Faraday rotation measures(RMs)monotonically dropped from-579to-605 rad m^(-2)in the 4 day window.The RM values were compatible with the values(-300 to-900 rad m^(-2))reported 4 months ago.However,the RM evolution rate in the current observation window was at least an order of magnitude smaller than the one(~500 rad m^(-2)day^(-1))previously reported during the rapid RM-variation phase,but is still higher than the one(≤1 rad m^(-2)day^(-1))during the later RM no-evolution phase.The bursts of FRB 20201124A were highly polarized with the total degree of polarization(circular plus linear)greater than 90%for more than 90%of all bursts.The distribution of linear polarization position angles(PAs),degree of linear polarization(L/I)and degree of circular polarization(V/I)can be characterized with unimodal distribution functions.During the observation window,the distributions became wider with time,i.e.,with larger scatter,but the centroids of the distribution functions remained nearly constant.For individual bursts,significant PA variations(confidence level 5σ)were observed in 33%of all bursts.The polarization of single pulses seems to follow certain complex trajectories on the Poincarésphere,which may shed light on the radiation mechanism at the source or the plasma properties along the path of FRB propagation.展开更多
基金funded by the National Natural Science Foundation of China (50979107)
文摘The reuse of treated wastewater in agricultural systems could partially help alleviate water resource shortages in developing countries. Treated wastewater differs from fresh water in that it has higher concentrations of salts, Escherichia coli and presence of dissolved organic matter, and inorganic N after secondary treatment, among others. Its application could thus cause environmental consequences such as soil salinization, ammonia volatilization, and greenhouse gas emissions. In an incubation experiment, we evaluated the characteristics and effects of water-filled pore space （WFPS） and N input on the emissions of nitrous oxide （N2O） and carbon dioxide （CO2） from silt loam soil receiving treated wastewater. Irrigation with treated wastewater （vs. distilled water） significantly increased cumulative N2O emission in soil （117.97 μg N kg-1）. Cumulative N2O emissions showed an exponentially increase with the increasing WFPS in unamended soil, but the maximum occurred in the added urea soil incubated at 60% WFPS. N2O emissions caused by irrigation with treated wastewater combined with urea-N fertilization did not simply add linearly, but significant interaction （P〈0.05） caused lower emissions than the production of N2O from the cumulative effects of treated wastewater and fertilizer N. Moreover, a significant impact on cumulative CO2 emission was measured in soil irrigated with treated wastewater. When treated wastewater was applied, there was significant interaction between WFPS and N input on N2O emission. Hence, our results indicated that irrigation with treated wastewater should cause great concern for increasing global warming potential due to enhanced emission of N2O and CO2.
基金the Ministry of Science and Technology of China （1999011700） the National Natural Science Foundation of China （49971042）.
文摘To reveal the period and after-effect of soil water stress on winter wheat, the article employs the experiment results carried out in the greenhouse. The results showed that the root-restricted weights varied with stress degrees and stress times during and after water stressing. In the course of stress, the chief reason resticting the weight of root was the stress intensity at this time, and that of severe stress treatment was larger than that of mild stress treatment. After water stress was relieved, the results of the after-effect of soil water stress on root growth were that, the stress intensity of short-time and mild stress was larger than that of long-time and severe stress. Comparing two-stage stress intensities, root-restricted weight resulted from after-effect intensity of stress under all of the short-time treatment, and the mild and the long-time stress treatments, while that resulted from the period stress intensity under the severe and the long-time stress treatments. In general, the effects of water stress on root were attributed to the three factors, a formed basis in the previous stage, the after-effect of water condition before this stage and influence of water in this stage, which lead to the characters of root in the whole growth stage.
基金the National Nature Science Foundation of China(No.49971042).
文摘Glasshouse and laboratory tests were carried out in 1996 - 1998 using winter wheat cultivars Beinong 6 as materials. The growth dynamics of the whole-wheat plant were analysed under constant and fluctuated soil water condition. The results revealed that water stress made the starting time of crop greatest growth phase(STCGGP) in advance, prolonged crop greatest growth phase(CGGP), decreased the rate of crop greatest growth (CGGR or CGRm), and as a result, the rate of dry matter accumulation was reduced and the growth of the crop was slowed down. Rewatering delayed STCGGP, shortened CGGP, increased CGGR, thus, the rate of dry matter accumulation had been boosted and the growth of the crop was accelerated. The growth rate, dry matter weight and grains yield of winter wheat were almost equal to the well-watered controls if they were rewatered under the condition of moderate water stress during the jointing stage.
基金supported by the National Basic Research Program of China(973 Program,G1999011709)the Natural Science Foundation of Guangdong Province,China(33135).
文摘The equilibrium between root, shoot and growth stability under different soil water conditions were investigated in a tube experiment of winter wheat. The water supplying treatments included： sufficient irrigation at whole growth phase, moderate deficiency irrigation at whole growth phase, serious deficiency irrigation at whole growth phase, sufficient irrigation at jointing stage, tillering stage, flowering stage, and fillering respectively, after moderate and serious water deficit during their previous growth stage. Root and shoot biomass were measured. On the basis of the cooperative root-shoot interactions model, the equilibrium and growth stability were studied on the strength of the kinetics system theory. There was only one varying equilibrium point between the root and shoot over the life time of the winter wheat plant. Water stress prolonged the duration of stable growth, the more serious the water deficit, the longer the period of stable growth. The duration of stable growth was shortened and that of unstable growth was prolonged after water recovery. The growth behavior of the plants exposed to moderate water deficit shifted from stable to unstable until the end of the growth, after rewatering at flowering. In the life-time of the crop, the root and shoot had been adjusting themselves in structure and function so as to maintain an equilibrium, but could not achieve the equilibrium state for long. They were always in an unbalanced state from the beginning to the end of growth. This was the essence of root-shoot equilibrium. Water stress inhibited the function of root and shoot, reduced root shoot interactions, and as a result, the plant growth gradually tended to stabilize. Rewatering enhanced root shoot interactions, prolonged duration of instable growth. Rewatering at flowering could upset the inherent relativity during the long time of stable growth from flowering to filling stage, thus leading to unstable growth and enhanced dry matter accumulating rate in the whole plant.
基金National Fundamental Research and Development (No. G1999011709 ) the National Natural Science Foundation (No.49971042).
文摘After water stress at various levels and durations at different growth stages, rewatering could greatly stimulate the leaf area development of winter wheat. The results showed that the stimulation effect changed with water stress time, degree and duration. Rewatering under earlier stress had greater stimulation effect on leaf area than that under later stress. Higher stimulation effect was observed under severe water stress than that under moderate stress. Longer duration of stress resulted in low stimulation effect. In spite of the greater stimulation effect under severe and longer stress, the final leaf area in these situations was lower than that under moderate stress and shorter duration. Whenever the stress occurred, the stimulating effect was due to the increase of the leaf area of the tillers. Once the leaf on the main stem emerged during stress period, rewatering had no effect on its size, and consequently its leaf area. The stimulation of rewateirng on leaf area contributed to the final grain yield by 45% under moderate stress, and 67% under severe stress. Although the stimulation partly compensated for the loss during stress, the final leaf area and the grain yield could not reach the level without water stress.
基金supported by the National SKA Program of China(2020SKA0120100,2020SKA0120200)the National Key R&D Program of China(2017YFA0402602)+7 种基金the National Natural Science Foundation of China(NSFC,Grant No.12041303)the CAS-MPG LEGACY project and funding from the Max-Planck Partner Groupsupported by the National Natural Science Foundation of China(NSFC,Grant Nos.11988101 and 11833009)the Key Research Program of the Chinese Academy of Sciences(Grant No.QYZDJ-SSW-SLH021supported by the Cultivation Project for the FAST scientific Payoff and Research Achievement of CAMS-CASsupported by the Key Research Project of Zhejiang Lab no.2021PE0AC0supported by National Natural Science Foundation of China(Grant No.12003028)the China Manned Spaced Project(CMS-CSST-2021-B11)。
文摘As the third paper in the multiple-part series,we report the statistical properties of radio bursts detected from the repeating fast radio burst(FRB)source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope during an extremely active episode between the 25th and 28th of September 2021(UT).We focus on the polarization properties of536 bright bursts with S/N>50.We found that the Faraday rotation measures(RMs)monotonically dropped from-579to-605 rad m^(-2)in the 4 day window.The RM values were compatible with the values(-300 to-900 rad m^(-2))reported 4 months ago.However,the RM evolution rate in the current observation window was at least an order of magnitude smaller than the one(~500 rad m^(-2)day^(-1))previously reported during the rapid RM-variation phase,but is still higher than the one(≤1 rad m^(-2)day^(-1))during the later RM no-evolution phase.The bursts of FRB 20201124A were highly polarized with the total degree of polarization(circular plus linear)greater than 90%for more than 90%of all bursts.The distribution of linear polarization position angles(PAs),degree of linear polarization(L/I)and degree of circular polarization(V/I)can be characterized with unimodal distribution functions.During the observation window,the distributions became wider with time,i.e.,with larger scatter,but the centroids of the distribution functions remained nearly constant.For individual bursts,significant PA variations(confidence level 5σ)were observed in 33%of all bursts.The polarization of single pulses seems to follow certain complex trajectories on the Poincarésphere,which may shed light on the radiation mechanism at the source or the plasma properties along the path of FRB propagation.
