Ramie (Boehmeria nivea L.) is one of the most important fiber crops and biomass materials. However, previous studies showed that ramie presented a very low nitrogen agronomy efficiency (NAE, 23.2%~27.8%) in traditiona...Ramie (Boehmeria nivea L.) is one of the most important fiber crops and biomass materials. However, previous studies showed that ramie presented a very low nitrogen agronomy efficiency (NAE, 23.2%~27.8%) in traditional farming, and the nitrogen fertilizer was applied excessively in ramie field. Plant osmotic adjustment (OA) responses to environmental stresses positively and exhibits improvements in plant tolerance. Whereas results varied due to the complexity of plant-environment interactions and lack of insights of specific species. In order to improve ramie production through osmoregulation, our current study investigated the role of nitrogen application and osmotic adjustment in improving the growth and yield in two varieties of ramie (H2000-03 and Ceheng Jiama) with contrasting nitrogen use efficiency (NUE) grown at 5 different N rates including N0, N6, N9, N12 and N15;0, 6, 9, 12 and 15 mmol/L N, respectively. The results showed that ramie adapted to different nitrogen rates through OA and significant differences of osmolyte content between varieties only presented at the particular growth stage. Obvious inflexion of yield, osmolyte content involving proline, soluble protein (SP), soluble sugar (SS) and malonaldehyde (MDA);nitrogen sensitive index (NSI) and comprehensive evaluation (D) in both varieties were observed. Our results recommended that the overall lifting of OA at a lower N level and at the proper growth stage would be a reasonable approach for improving ramie NUE.展开更多
Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen （N） deficiency symptoms. However, halophytes grow soundly under ...Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen （N） deficiency symptoms. However, halophytes grow soundly under saline conditions. In order to clarify the N nutrition of the halophyte Salicornia bigelovii, it was grown at several N levels （1, 2, 3, and 4 mmol L-1）, supplied in the form of NO3 or ammonium （NH4＋）, under high NaCl conditions （200 mmol L-l）. NH4^＋- fed plants showed better growth than NO3-fed plants at 1-3 mmol L-1N, and plants in both treatments showed the same growth at 4 mmol L-1 N. Nitrogen contents in NO3-fed plants increased with the N concentrations in solution; competitive inhibition of NO3- absorption by Cl- was observed under lower N conditions. In addition, shoot dry weight was significantly correlated only with shoot N content. Therefore, growth of NO3-fed plants was regulated by N absorption. In contrast, N contents of shoots in NH4＋-fed plants did not change with N concentration. Shoot Na content decreased with increasing N concentration, while K content increased. Dry weight was highly correlated only with K content in NH4＋-fed plants. These observations indicated that growth of NH4＋-fed plants was mainly regulated by K absorption.展开更多
The effects of changing salinity and nitrogen limitation on dimethylsulfoniopropionate(DMSP) and dimethylsulfide(DMS) concentrations were investigated in batch cultures of coastal diatom Skeletonema costatum,an ecolog...The effects of changing salinity and nitrogen limitation on dimethylsulfoniopropionate(DMSP) and dimethylsulfide(DMS) concentrations were investigated in batch cultures of coastal diatom Skeletonema costatum,an ecologically important species.Changes in salinity from 20-32 caused no measurable variation in cell growth or culture yield,but increased intracellular DMSP per cell by 30%.Nitrogen limitation caused up to a two-fold increase in total DMSP per cell and up to a three-fold increase in DMS per cell.These changes in DMSP and DMS per cell in the Skeletonema costatum cultures with nitrogen limitation and changing salinity were primarily attributed to the physiological functions of DMSP as an osmolyte and an antioxidant.The data obtained in this study indicated that nitrogen limitation and salinity may play an important role in climate feedback mechanisms involving biologically derived DMS.展开更多
An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physio-logical acclimation of Pacific white shrimp （Litopenaeus vannamei） reared in diluted seawater （salin...An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physio-logical acclimation of Pacific white shrimp （Litopenaeus vannamei） reared in diluted seawater （salinity 4）. Six semi-purified practical diets containing 0.59, 0.96, 1.26, 1.48, 1.74, and 2.17 g potassium K＋ per 100 g diet were formulated, respectively. The survival and feed conversion rate did not show significant difference among groups of shrimps given these diets （P〉0.05）. The shrimps fed the diets containing 0.96-1.48 g K＋ per 100g diet gained the highest weight, specific growth rate, and protein efficiency ratio. Their ammonium-N excretion rate as well as hemolymph concentration of Na＋ and C1- were significantly lower than those of the control （P〈0.05）, but a reverse trend was observed for their gill Na＋/K＋-ATPase. Moreover, the shrimps fed with 1.48 g K＋ per 100 g diet were the highest in hemolymph urea level, and the phenoloxidase and lysozyme activities were significantly higher than those of the control （P〈0.05）. The growth and physiological response of the test shrimps suggested that diet containing 1.48 g K＋ per 100 g diet improved the growth of L. vannamei in low-salinity seawater, and enhanced the physiological acclimation of the organism.展开更多
Based on reference review, this study investigated ecosystem services supported by 10 typical rice paddies in six rice planting regions of China. The services were primary production, gas regulation, nitrogen transfor...Based on reference review, this study investigated ecosystem services supported by 10 typical rice paddies in six rice planting regions of China. The services were primary production, gas regulation, nitrogen transformation, soil organic matter accumulation, and water regulation and flood control. The results indicated that grain production of the 10 rice paddies was between 4.71 and 12.18 t ha^-1 y^-1; straw production was 4.65 to 9.79 t ha^-1 y^-1; gas regulation was calculated to emit O2 ranging from 8.27 to 19.69 t ha^-1 y^-1 and to assimilate greenhouse gases ranging from -2.13 to 19.24 t ha^-1 y^-1 （in CO2 equivalent）; nitrogen transformation was estimated as nitrogen input ranging from 209.70 to 513.93 kg N ha^-1 y^-1 and nitrogen output of 112.87 to 332.69 kg N ha^-1 y^-1; soil organic matter accumulation was calculated to be between 0.69 and 4.88 t C ha^-1 y^-1; water regulation was estimated to consume water resources of 19875 m3 ha^-1 y^-1 and to support water resources of 6430 m3 ha^-1 y^-1; and flood control of several of the rice paddies was calculated to be 1500 m3 ha^-1 y^-1. The integrated economic value of ecosystem services of these rice paddies was estimated at USD 8605–21 405 ha^-1 y^-1, of which 74%–89% of the value can be ascribed to ecosystem services outside primary production. The results also indicated that the integrated economic value of the ecosystem services of the 10 rice paddies was higher when nitrogen fertilizer was applied in the range of 275 to 297 kg N ha^-1. Until now, the economic value of the rice paddy ecosystem has been underestimated as only the economic value of grain and straw production was previously calculated. As more and more forest land and grassland is lost to urban and industrial use, cropland and especially rice paddies, will become more ecologically important to society. The economic value of ecosystem services supplied by rice paddies, outside primary production, are worthy of increased research attention.展开更多
Pneumatic cryogenic control valves(PCCV)are designed to meet the special requirements for the large cryogenic helium refrigeration system.Polychlorotrifluoroethylene(PCTFE)is adopted as the flat seal material of the v...Pneumatic cryogenic control valves(PCCV)are designed to meet the special requirements for the large cryogenic helium refrigeration system.Polychlorotrifluoroethylene(PCTFE)is adopted as the flat seal material of the valve seat.The leakage rates and compressive strain of the PCTFE gasket with different sealing stress are tested at both room temperature(293 K)and liquid nitrogen temperature(77 K).After 300 open/close cycles,the experimental results show that the sealing properties of the PCTFE gasket are improved.The leakage rates are about 10-8(293 K)and 10-4(77 K)Pam3 s-1 respectively.Finally,the effects of working pressure on sealing characteristics are discussed.The working pressure has little effect on compressive strain but it has a great influence on leakage rate.The leakage rate is linear with the working pressure of inlet at room temperature,but at liquid nitrogen temperature the leakage rate is linear with the square of the working pressure.展开更多
文摘Ramie (Boehmeria nivea L.) is one of the most important fiber crops and biomass materials. However, previous studies showed that ramie presented a very low nitrogen agronomy efficiency (NAE, 23.2%~27.8%) in traditional farming, and the nitrogen fertilizer was applied excessively in ramie field. Plant osmotic adjustment (OA) responses to environmental stresses positively and exhibits improvements in plant tolerance. Whereas results varied due to the complexity of plant-environment interactions and lack of insights of specific species. In order to improve ramie production through osmoregulation, our current study investigated the role of nitrogen application and osmotic adjustment in improving the growth and yield in two varieties of ramie (H2000-03 and Ceheng Jiama) with contrasting nitrogen use efficiency (NUE) grown at 5 different N rates including N0, N6, N9, N12 and N15;0, 6, 9, 12 and 15 mmol/L N, respectively. The results showed that ramie adapted to different nitrogen rates through OA and significant differences of osmolyte content between varieties only presented at the particular growth stage. Obvious inflexion of yield, osmolyte content involving proline, soluble protein (SP), soluble sugar (SS) and malonaldehyde (MDA);nitrogen sensitive index (NSI) and comprehensive evaluation (D) in both varieties were observed. Our results recommended that the overall lifting of OA at a lower N level and at the proper growth stage would be a reasonable approach for improving ramie NUE.
基金Supported by the "Global Center of Excellence for Dryland Science",a project of the Ministry of Education,Science,Culture,Sports and Technology of Japan
文摘Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen （N） deficiency symptoms. However, halophytes grow soundly under saline conditions. In order to clarify the N nutrition of the halophyte Salicornia bigelovii, it was grown at several N levels （1, 2, 3, and 4 mmol L-1）, supplied in the form of NO3 or ammonium （NH4＋）, under high NaCl conditions （200 mmol L-l）. NH4^＋- fed plants showed better growth than NO3-fed plants at 1-3 mmol L-1N, and plants in both treatments showed the same growth at 4 mmol L-1 N. Nitrogen contents in NO3-fed plants increased with the N concentrations in solution; competitive inhibition of NO3- absorption by Cl- was observed under lower N conditions. In addition, shoot dry weight was significantly correlated only with shoot N content. Therefore, growth of NO3-fed plants was regulated by N absorption. In contrast, N contents of shoots in NH4＋-fed plants did not change with N concentration. Shoot Na content decreased with increasing N concentration, while K content increased. Dry weight was highly correlated only with K content in NH4＋-fed plants. These observations indicated that growth of NH4＋-fed plants was mainly regulated by K absorption.
基金Supported by the National Natural Science Foundation of China(Nos. 41030858 and 40525017)the Changjiang Scholars Program,Ministry of Education of China,the Science and Technology Key Project of Shandong Province (No. 2006GG2205024)the Taishan Scholars Program of Shandong Province
文摘The effects of changing salinity and nitrogen limitation on dimethylsulfoniopropionate(DMSP) and dimethylsulfide(DMS) concentrations were investigated in batch cultures of coastal diatom Skeletonema costatum,an ecologically important species.Changes in salinity from 20-32 caused no measurable variation in cell growth or culture yield,but increased intracellular DMSP per cell by 30%.Nitrogen limitation caused up to a two-fold increase in total DMSP per cell and up to a three-fold increase in DMS per cell.These changes in DMSP and DMS per cell in the Skeletonema costatum cultures with nitrogen limitation and changing salinity were primarily attributed to the physiological functions of DMSP as an osmolyte and an antioxidant.The data obtained in this study indicated that nitrogen limitation and salinity may play an important role in climate feedback mechanisms involving biologically derived DMS.
文摘An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physio-logical acclimation of Pacific white shrimp （Litopenaeus vannamei） reared in diluted seawater （salinity 4）. Six semi-purified practical diets containing 0.59, 0.96, 1.26, 1.48, 1.74, and 2.17 g potassium K＋ per 100 g diet were formulated, respectively. The survival and feed conversion rate did not show significant difference among groups of shrimps given these diets （P〉0.05）. The shrimps fed the diets containing 0.96-1.48 g K＋ per 100g diet gained the highest weight, specific growth rate, and protein efficiency ratio. Their ammonium-N excretion rate as well as hemolymph concentration of Na＋ and C1- were significantly lower than those of the control （P〈0.05）, but a reverse trend was observed for their gill Na＋/K＋-ATPase. Moreover, the shrimps fed with 1.48 g K＋ per 100 g diet were the highest in hemolymph urea level, and the phenoloxidase and lysozyme activities were significantly higher than those of the control （P〈0.05）. The growth and physiological response of the test shrimps suggested that diet containing 1.48 g K＋ per 100 g diet improved the growth of L. vannamei in low-salinity seawater, and enhanced the physiological acclimation of the organism.
基金Strategic Priority Research Program of the Chinese Academy of Sciences (XDA05050203)National Natural Science Foundation of China (31140048, 30770410 and 31070384)Innovation Project of Institute of Geographic Sciences and Natural Resources Research, CAS (200905010)
文摘Based on reference review, this study investigated ecosystem services supported by 10 typical rice paddies in six rice planting regions of China. The services were primary production, gas regulation, nitrogen transformation, soil organic matter accumulation, and water regulation and flood control. The results indicated that grain production of the 10 rice paddies was between 4.71 and 12.18 t ha^-1 y^-1; straw production was 4.65 to 9.79 t ha^-1 y^-1; gas regulation was calculated to emit O2 ranging from 8.27 to 19.69 t ha^-1 y^-1 and to assimilate greenhouse gases ranging from -2.13 to 19.24 t ha^-1 y^-1 （in CO2 equivalent）; nitrogen transformation was estimated as nitrogen input ranging from 209.70 to 513.93 kg N ha^-1 y^-1 and nitrogen output of 112.87 to 332.69 kg N ha^-1 y^-1; soil organic matter accumulation was calculated to be between 0.69 and 4.88 t C ha^-1 y^-1; water regulation was estimated to consume water resources of 19875 m3 ha^-1 y^-1 and to support water resources of 6430 m3 ha^-1 y^-1; and flood control of several of the rice paddies was calculated to be 1500 m3 ha^-1 y^-1. The integrated economic value of ecosystem services of these rice paddies was estimated at USD 8605–21 405 ha^-1 y^-1, of which 74%–89% of the value can be ascribed to ecosystem services outside primary production. The results also indicated that the integrated economic value of the ecosystem services of the 10 rice paddies was higher when nitrogen fertilizer was applied in the range of 275 to 297 kg N ha^-1. Until now, the economic value of the rice paddy ecosystem has been underestimated as only the economic value of grain and straw production was previously calculated. As more and more forest land and grassland is lost to urban and industrial use, cropland and especially rice paddies, will become more ecologically important to society. The economic value of ecosystem services supplied by rice paddies, outside primary production, are worthy of increased research attention.
基金supported by the fund of the State Key Laboratory of Technologies in Space Cryogenic Propellants (Grant No. SKLTSCP1210)
文摘Pneumatic cryogenic control valves(PCCV)are designed to meet the special requirements for the large cryogenic helium refrigeration system.Polychlorotrifluoroethylene(PCTFE)is adopted as the flat seal material of the valve seat.The leakage rates and compressive strain of the PCTFE gasket with different sealing stress are tested at both room temperature(293 K)and liquid nitrogen temperature(77 K).After 300 open/close cycles,the experimental results show that the sealing properties of the PCTFE gasket are improved.The leakage rates are about 10-8(293 K)and 10-4(77 K)Pam3 s-1 respectively.Finally,the effects of working pressure on sealing characteristics are discussed.The working pressure has little effect on compressive strain but it has a great influence on leakage rate.The leakage rate is linear with the working pressure of inlet at room temperature,but at liquid nitrogen temperature the leakage rate is linear with the square of the working pressure.
