Can soil nitrate: ammonium ratios influence plant carbon: nitrogen ratios of the early succession plant? Can plant carbon: nitrogen ratios limit the plant growth in early succession? To address these two question...Can soil nitrate: ammonium ratios influence plant carbon: nitrogen ratios of the early succession plant? Can plant carbon: nitrogen ratios limit the plant growth in early succession? To address these two questions, we performed a two-factor (soil nitrate: ammonium ratio and plant density) randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate: ammonium ratios, the carbon: nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate: ammonium ratios and plant density influenced the carbon: nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate: ammonium ratios, with the increase of soil nitrate: ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon: nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate: ammonium ratios affected the carbon: nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate: ammonium ratios influenced the carbon: nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate: ammonium ratios can be a limiting factor for the growth of the early succession plant.展开更多
The ratio of nitrogen/phosphorus (N/P) is known to affect cell proliferation of some marine micro algae. We evaluated the effect of N/P ratios on the proliferation and succession of phytoplankton using five marine mic...The ratio of nitrogen/phosphorus (N/P) is known to affect cell proliferation of some marine micro algae. We evaluated the effect of N/P ratios on the proliferation and succession of phytoplankton using five marine micro algae species. We used two sources of nitrogen, NH4Cl (N1) and urea (N2), and a single source of phosphorous, NaH2PO4(P). The optimal N/P ratio that differed among the five species was affected by the source of nitrogen, being as follows (N1/P, N2/P in order): Thalassiosira sp. (30/1, 20/1), Heterosigma akashiwo (30/1, 30/1), Chroomonas salina (20/1, 30/1), Chaetoceros gracilis (40/1, 60/1), and Alexandrium sp. (10/1, 30/1). Thus, the source of nitrogen must be considered when analyzing the N/P ratio. Our results provide insight for predicting phytoplankton succession in coastal waters and may be used to forecast the potential risk of harmful algal blooms.展开更多
The growth and interspecies competition of two red tide algal species Thalassiosira pseudonana Hasle et Heimdal and Gymnodinium sp. were studied under different concentration ratios of nitrogen to phosphorus, and the ...The growth and interspecies competition of two red tide algal species Thalassiosira pseudonana Hasle et Heimdal and Gymnodinium sp. were studied under different concentration ratios of nitrogen to phosphorus, and the algal hatch culture experiments were conducted. The physiological and biochemical indexes were measured periodically, including the maximum comparing growth rate, relative growth rate, average double time and chlorophyll a concentration. The results showed that when the concentration ratio of nitrogen to phosphorus was 16: 1, the maximum comparing growth rate, relative growth rate and chlorophyll a concentration of Thalassiosira pseudonana all reached the highest,and average double time was the shortest. This implied that the optimal concentration ratio of nitrogen to phosphorus of Thalassiosira pseudonana is 16: 1. When the concentration ratio of nitrogen to phosphorus was 6:1, the maximum comparing growth rate, relative growth rate and the chlorophyll a concentration of Gymnodinium sp. reached the highest, and average double time was the shortest, so the optimal concentration ratio of nitrogen to phosphorus of Gymnodinium sp. is 6: 1. From the growth curves as indicated both in the cell density and the chlorophyll a concentration, it is suggested that the influence of concentration ratio of nitrogen to phosphorus on the chlorophyll a concentration and the cell density are almost the same. Different concentration ratios of nitrogen to phosphorus had weak influence on community succession and the competition between the two algae. Gymnodinium sp. may use the phosphorus in vivo for growth, so it is important to pay attention to the concealment of phosphorus, in order to avoid the outbreak of red tide. On the basis of the importance of nitrogen and phosphorus and the ratio of their concentration, the possible outbreak mechanism of red tide of the two algae was also discussed.展开更多
Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen (COD/TN) ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work...Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen (COD/TN) ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work, a novel sequencing batch biofilm reactor (NSBBR) was developed to enhance the nitrogen removal from wastewater with low COD/ TN ratio. The NSBBR was divided into two units separated by a vertical clapboard. Alternate feeding and aeration was performed in the two units, which created an anoxie unit with rich substrate content and an aeration unit deficient in substrate simultaneously. Therefore, the utilization of the influent carbon source for denitrification was increased, leading to higher TN removal compared to conventional SBBR (CSBBR) operation. The results show that the CSBBR removed up to 76.8%, 44.5% and 10.4% of TN, respectively, at three tested COD/TN ratios (9.0, 4.8 and 2.5). In contrast, the TN removal of the NSBBR could reach 81.9%, 60.5% and 26.6%, respectively, at the corresponding COD/TN ratios. Therefore, better TN removal performance could be achieved in the NSBBR, especially at low CODfrN ratios (4.8 and 2.5). Furthermore, it is easy to upgrade a CSBBR into an NSBBR in practice.展开更多
The effects of varying nitrogen (N): phosphorus (P) ratios on the growth and N-uptake and assimilation of the harmful dinoflagellates Prorocentrum minimum and Prorocentrum donghaiense were examined in turbidistat cult...The effects of varying nitrogen (N): phosphorus (P) ratios on the growth and N-uptake and assimilation of the harmful dinoflagellates Prorocentrum minimum and Prorocentrum donghaiense were examined in turbidistat culture experiments. Algal cultures were supplied with media containing PO34? in various concentrations to obtain a wide range of N:P ratios. Experiments to determine rates of N uptake and assimilation of different N sources (NO3?, NH4+, urea and glycine by P. minimum and NO3?, NH4+ by P. donghaiense) were conducted using 15N tracer techniques at each N:P ratio. The growth rates suggested nutrient limitation at both high and low N:P ratios relative to the Redfield ratio. On a diel basis, the growth of both species was regulated by the light-dark cycle, which may be a result of regulation of both light- dependent growth and light-independent nutrient uptake. Maximum growth rates of both species always occurred at the beginning of light phase. In P-rich medium (low N:P ratio), both species had higher N assimilation rates, suggesting N limitation. Low assimilation coefficients at high N:P ratios suggested P limitation of N uptake and assimilation. NO3? and NH4+ contributed more than 90% of the total N uptake of P. minimum. Reduced N sources were more quickly assimilated than NO3?. Highest average daily growth rates were recorded near an N:P ratio of 12 for both species. The N uptake rates of cultures at N:P ratios near Redfield ratio were more balanced with growth rates. The linkage between growth rates and N uptake/assimilation rates were conceptually described by the variation of cell N quota. The N:P ratios affect the N uptake and growth of Prorocentrum spp., and may regulate their bloom progression in eutrophic ecosystems.展开更多
With the rapid development of economy and increase of population in the drainage areas,the nutrient loading has increased dramatically in the Changjiang estuary and adjacent coastal waters.To properly assess the impac...With the rapid development of economy and increase of population in the drainage areas,the nutrient loading has increased dramatically in the Changjiang estuary and adjacent coastal waters.To properly assess the impact of nutrient enrichment on phytoplankton community,seasonal microcosm experiments were conducted during August 2010 July 2011 in the coastal waters of Zhejiang Province.The results of the present study indicated that the chl a concentration,cell abundance,diversity indices,species composition and community succession of the phytoplankton varied significantly with different N/P ratios and seasons.Higher growth was observed in the 64:1(spring),32:1(summer),16:1(autumn)and 128:1,256:1(winter)treatments,respectively.The values of Shannon-Wiener index(H′)and Pielou evenness index(J)were lower in the 8:1 and 16:1 treatments in autumn test,while H'value was higher in the 128:1 and 8:1 treatments in winter test.A definite community succession order from diatoms to dinoflagellates was observed in the autumn and winter tests,while the diatoms dominated the community throughout the culture in the spring and summer tests.展开更多
Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sustainable production.In order to investigate the effect of various nitrogen to phosphorus ratios on c...Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sustainable production.In order to investigate the effect of various nitrogen to phosphorus ratios on cells growth,chlorophyll content and accumulation of lipids in Dunaliella tertiolecta,experiments were carried out in modified microalgal medium with inorganic nitrogen(nitrate-nitrogen) or organic nitrogen(urea-nitrogen) as the sole nitrogen source at initial N:P ratios ranging from 1:1 to 32:1.The favorable N:P of 16:1 in the nitrate-N or urea-N medium yielded the maximum cell density and specific growth rate.Decrease in chlorophyll content were observed at the N:P of 4:1 in both nitrate-N and urea-N cultures.It was also observed that the maximum lipids concentration was obtained at the N:P of 4:1 in both nitrate and urea nutrient medium.The lipid productivity and lipid content of cultures in the urea-N medium at the N:P of 4:1were markedly higher than those from cultures with other N:P ratios(p < 0.05).The results of this work illustrate the possibility that higher ratios of nitrogen to phosphorus have enhancing effect on cells growth of D.tertiolecta.Conversely,higher lipid accumulation is associated with a decrease in chlorophyll content under lower ratios of nitrogen to phosphorus.The results confirm the hypothesis of this study that a larger metabolic flux has been channeled to lipid accumulation in D.tertiolecta cells when the ratios of nitrogen to phosphorus drop below a critical level.展开更多
Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carb...Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carbon and nitrogen nutrition balance of soils. We studied the characteristics of soil organic carbon and total nitrogen by investigating a large number of apple orchards in major apple production areas in China. High apple orchard soil organic carbon content was observed in the provinces of Heilongjiang, Xinjiang, and Yunnan, whereas low content was found in the provinces of Shandong, Henan, Hebei, and Shaanxi, with the values ranging between 6.44 and 7.76 g·kg-1. Similar to soil organic carbon, soil total nitrogen content also exhibited obvious differences in the 12 major apple producing provinces. Shandong apple orchard soil had the highest total nitrogen content (1.26 g·kg-1), followed by Beijing (1.23 g·kg-1). No significant difference was noted between these two regions, but their total nitrogen content was significantly higher than the other nine provinces, excluding Yunnan. The soil total nitrogen content for Xinjiang, Heilongjiang, Hebei, Henan, and Gansu was between 0.87 and 1.03 g·kg-1, which was significantly lower than that in Shandong and Beijing, but significantly higher than that in Liaoning, Shanxi, and Shaanxi. Six provinces exhibited apple orchard soil C/N ratio higher than 10, including Heilongjiang (15.42), Xinjiang (13.38), Ningxia (14.45), Liaoning (12.24), Yunnan (11.03), and Gansu (10.63). The soil C/N ratio was below 10 in the remaining six provinces, in which the highest was found in Shaanxi (9.47), followed by Beijing (8.98), Henan (7.99), and Shanxi (7.62), and the lowest was found in Hebei (6.80) and Shandong (6.05). Therefore, the improvement of soil organic carbon should be given more attention to increase the steady growth of soil C/N ratio.展开更多
[ Objective] To investigate the effects of concentrate/roughage ratios and nitrogen levels on in-vitro rumen fermentation of urea-treating corn stalk. [ Method] The concentrate/roughage ratios were 7: 3, 5:5 and 3:...[ Objective] To investigate the effects of concentrate/roughage ratios and nitrogen levels on in-vitro rumen fermentation of urea-treating corn stalk. [ Method] The concentrate/roughage ratios were 7: 3, 5:5 and 3: 7. The crude protein levels were 11% and 14%. The in-vitro culture time was 2, 4, 6 and 48 h. [ Result] The pH value of broth decreased significantly with the decline in the proportion of roughage ( P 〈 0.01 ) and with the increase in the crude protein levels (P 〈 0.05). The ammonium nitrogen concentration and acetic acid/propionic acid ratio of the fermen- ted products decreased with the increase in the crude protein levels and proportion of concentrate in diet. The diet with concentrate/roughage ratio of 5:5 and crude protein level of 14% had significantly higher digestibility of dry matter and organic matter than other diets ( P 〈 0.05). The digesti- bility of organic matter increased gradually with the increasing proportion of concentrate and crude protein level. With the increase in the proportion of concentrate, the microbial protein levels increased remarkably, while the acetic acid/propionic acid ratio declined. [ Conclusion] The concentrate/ roughage ratios and nitrogen levels affect rumen fermentation and microbial growth during in-vitro culture. However, the best supplementary feeding results of urea-treatinq corn stalks can be obtained when the concentrate/rouahaae ratio is below 5:5 and the crude protein level is 14%.展开更多
Soil C /N ratio is an important influencing factor in soil nitrogen cycling. Two-year old apple trees( Borkh. cv. ‘Fuji'/Malus hupehensis) were used to understand the effect of soil C/N ratio [6. 52( CK),10,15,20...Soil C /N ratio is an important influencing factor in soil nitrogen cycling. Two-year old apple trees( Borkh. cv. ‘Fuji'/Malus hupehensis) were used to understand the effect of soil C/N ratio [6. 52( CK),10,15,20,25,30,35 and 40]on apple growth and nitrogen utilization and loss by using15N trace technique. The results showed that,with the increasing of soil C/N ratio,apple shoot length and fresh weight increased at first,and then decreased; the higher apple shoot length and fresh weight appeared in C/N = 15,20 and 25 treatments,and there were no significant differences among these three treatments,but significantly higher than the other treatments. Statistical analysis revealed that there was significant difference in nitrogen utilization rate between the different treatments,the highest N utilization rate was occurred in soil C/N = 25 treatment which value was 22. 87%,and there was no significant difference between soil C/N = 25 and C/N = 20 treatments,but both the two treatments were significantly higher than the other treatments; Soil C/N = 40 had the lowest N utilization rate which value was 15. 43%,and this value was less than CK( 16. 65%). The proportion of plant absorption nitrogen from fertilizer was much higher when the value of soil C/N ratio in the range of 15- 25,but the percentage of plant absorption nitrogen from soil was much higher when the soil C/N ratio was too low( < 15) or high( < 25). Amount of residual nitrogen in soil increased gradually with the soil C/N ratio increasing,the amount of residual nitrogen in C/N = 40 treatment was 1. 32 times than that in CK. With the increasing of soil C/N ratio,fertilizer nitrogen loss decreased at first,and then increased,fertilizer nitrogen loss was the minimum in C/N = 25 treatments( 49. 87%) and the maximum were occurred in CK( 61. 54%). Therefore,regarding the apple growth and nitrogen balance situation,the value of soil C/N ratio in the range of 15- 25 would be favorable for apple growth and could increase effectively nitrogen fixed by soil,reduce nitrogen loss,and improve the nitrogen utilization ratio.展开更多
In order to screen suitable high hybrid wheat seed production technology,the split-plot experiment design was adopted and study was carried out about the effects of the different row ratios of male and female parents ...In order to screen suitable high hybrid wheat seed production technology,the split-plot experiment design was adopted and study was carried out about the effects of the different row ratios of male and female parents and application amount of nitrogen fertilizer on hybrid wheat seed production and its component factors. The results showed that the seed production increased with the increase in the number of female parent row. When the row ratio of male and female parents was 2 ∶ 6,the seed production was 3 683. 8 kg/ha; when the application amount of nitrogen fertilization was 50 kg/ha,the seed production was 3 649. 4 kg/ha; the interaction between the row ratio of male and female parents and the application amount of nitrogen fertilizer indicated that when the row ratio of male and female parents was 2∶ 6 and the application amount of nitrogen fertilizer was 300 kg/ha,the seed production reached the highest( 4160. 6 kg/ha). The row ratio of male and female parents and application amount of nitrogen fertilizer had significant effect on the component factors of seed production,including the number of grains per spike,spike weight and setting percentage. When the row ratio of male and female parents was 2∶ 5,the number of grains per spike,spike weight and setting percentage were the highest at 26. 7 grains,1. 12 g,and 62. 6% respectively; when application amount of nitrogen fertilizer was 450 kg/ha,the number of grains per spike,spike weight and setting percentage were the highest at 26. 0 grains,1. 08 g,and59. 2% respectively; the interaction of row ratio of male and female parents and application amount of nitrogen fertilizer had significant effect on the number of grains per spike,spike weight and setting percentage; when the row ratio of male and female parents was 2∶ 5 and the application amount of nitrogen fertilizer was 300 kg/ha,the number of grains per spike,spike weight and setting percentage were the highest at 29. 6grains,1. 24 g,and 71. 6% respectively. The number of grains per spike is the largest component factor for seed production. Increasing the number of grains per spike can increase the seed production. According to the effects of row ratio of male and female parents and application amount of nitrogen fertilizer on the component factors of seed production,the optimal condition was 2∶ 5-2∶ 6 for row ratio of male and female parents and 300-450 kg/ha for application amount of nitrogen fertilizer.展开更多
[Objective]The aim was to provide a theoretical basis for the rational configuration of ratio of row spacing to intrarow spacing(RS/IS)of double-cropping rice.[Methods]With early rice‘Ganxin 203’and‘Zhongjiazao 17...[Objective]The aim was to provide a theoretical basis for the rational configuration of ratio of row spacing to intrarow spacing(RS/IS)of double-cropping rice.[Methods]With early rice‘Ganxin 203’and‘Zhongjiazao 17’and late rice‘Ganxin 688’and‘Wufengyou T025’as materials,the effects of RS/IS on yield,nitrogen accumulation and utilization were studied in the same planting density of31.20×104hills/hm2.[Results]The results showed that yield of early rice was higher in RS/IS2.8(30.0 cm×10.7 cm)and RS/IS2.0(25.0 cm×12.8 cm)treatment,and lower in RS/IS5.0(40.0 cm×8.0 cm)and RS/IS1.3(20.0 cm×16.0 cm)treatment,while late rice were higher in RS/IS5.0and RS/IS2.0treatment,and lower in RS/IS2.8and RS/IS1.3treatment.Total nitrogen accumulation and apparent utilization ratio of nitrogen of early rice were higher in RS/IS2.0treatment and lower in RS/IS5.0treatment,while,for late rice were higher in RS/IS2.8treatment and lower in RS/IS5.0treatment.Nitrogen requirement for 100 kg grain production of early rice was higher in RS/IS1.3treatment and lower in RS/IS2.0treatment,while,for late rice were higher in RS/IS2.8treatment,lower in RS/IS5.0treatment.[Conclusion]In sum,4 varieties of early and late rice obtained higher yield in 25.0 cm×12.8 cm and lower yield in 20.0 cm×16.0 cm,and total nitrogen accumulation,nitrogen requirement for 100 kg grain production and apparent utilization ratio of nitrogen were all lower in 40.0 cm×8.0 cm.展开更多
基金supported in part by the National Basic Research Program of China (2009CB421303)supported by National Natural Science Foundation of China (30970546)
文摘Can soil nitrate: ammonium ratios influence plant carbon: nitrogen ratios of the early succession plant? Can plant carbon: nitrogen ratios limit the plant growth in early succession? To address these two questions, we performed a two-factor (soil nitrate: ammonium ratio and plant density) randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate: ammonium ratios, the carbon: nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate: ammonium ratios and plant density influenced the carbon: nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate: ammonium ratios, with the increase of soil nitrate: ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon: nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate: ammonium ratios affected the carbon: nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate: ammonium ratios influenced the carbon: nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate: ammonium ratios can be a limiting factor for the growth of the early succession plant.
基金Supported by the Initial Fund for Introduced Talent from the Tianjin University of Science and Technology (No. 20090413) the National Key Technology R&D Program (No. 2010BAC68B04)
文摘The ratio of nitrogen/phosphorus (N/P) is known to affect cell proliferation of some marine micro algae. We evaluated the effect of N/P ratios on the proliferation and succession of phytoplankton using five marine micro algae species. We used two sources of nitrogen, NH4Cl (N1) and urea (N2), and a single source of phosphorous, NaH2PO4(P). The optimal N/P ratio that differed among the five species was affected by the source of nitrogen, being as follows (N1/P, N2/P in order): Thalassiosira sp. (30/1, 20/1), Heterosigma akashiwo (30/1, 30/1), Chroomonas salina (20/1, 30/1), Chaetoceros gracilis (40/1, 60/1), and Alexandrium sp. (10/1, 30/1). Thus, the source of nitrogen must be considered when analyzing the N/P ratio. Our results provide insight for predicting phytoplankton succession in coastal waters and may be used to forecast the potential risk of harmful algal blooms.
文摘The growth and interspecies competition of two red tide algal species Thalassiosira pseudonana Hasle et Heimdal and Gymnodinium sp. were studied under different concentration ratios of nitrogen to phosphorus, and the algal hatch culture experiments were conducted. The physiological and biochemical indexes were measured periodically, including the maximum comparing growth rate, relative growth rate, average double time and chlorophyll a concentration. The results showed that when the concentration ratio of nitrogen to phosphorus was 16: 1, the maximum comparing growth rate, relative growth rate and chlorophyll a concentration of Thalassiosira pseudonana all reached the highest,and average double time was the shortest. This implied that the optimal concentration ratio of nitrogen to phosphorus of Thalassiosira pseudonana is 16: 1. When the concentration ratio of nitrogen to phosphorus was 6:1, the maximum comparing growth rate, relative growth rate and the chlorophyll a concentration of Gymnodinium sp. reached the highest, and average double time was the shortest, so the optimal concentration ratio of nitrogen to phosphorus of Gymnodinium sp. is 6: 1. From the growth curves as indicated both in the cell density and the chlorophyll a concentration, it is suggested that the influence of concentration ratio of nitrogen to phosphorus on the chlorophyll a concentration and the cell density are almost the same. Different concentration ratios of nitrogen to phosphorus had weak influence on community succession and the competition between the two algae. Gymnodinium sp. may use the phosphorus in vivo for growth, so it is important to pay attention to the concealment of phosphorus, in order to avoid the outbreak of red tide. On the basis of the importance of nitrogen and phosphorus and the ratio of their concentration, the possible outbreak mechanism of red tide of the two algae was also discussed.
基金supported by the Project of Science and Technology of Zhejiangthe National Natural Science Foundation of China (No. 50878195)
文摘Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen (COD/TN) ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work, a novel sequencing batch biofilm reactor (NSBBR) was developed to enhance the nitrogen removal from wastewater with low COD/ TN ratio. The NSBBR was divided into two units separated by a vertical clapboard. Alternate feeding and aeration was performed in the two units, which created an anoxie unit with rich substrate content and an aeration unit deficient in substrate simultaneously. Therefore, the utilization of the influent carbon source for denitrification was increased, leading to higher TN removal compared to conventional SBBR (CSBBR) operation. The results show that the CSBBR removed up to 76.8%, 44.5% and 10.4% of TN, respectively, at three tested COD/TN ratios (9.0, 4.8 and 2.5). In contrast, the TN removal of the NSBBR could reach 81.9%, 60.5% and 26.6%, respectively, at the corresponding COD/TN ratios. Therefore, better TN removal performance could be achieved in the NSBBR, especially at low CODfrN ratios (4.8 and 2.5). Furthermore, it is easy to upgrade a CSBBR into an NSBBR in practice.
基金supported by the University of Maryland Center for Environmental Science (UMCES), Horn Point Laboratory. This is UMCES contribution number 4503
文摘The effects of varying nitrogen (N): phosphorus (P) ratios on the growth and N-uptake and assimilation of the harmful dinoflagellates Prorocentrum minimum and Prorocentrum donghaiense were examined in turbidistat culture experiments. Algal cultures were supplied with media containing PO34? in various concentrations to obtain a wide range of N:P ratios. Experiments to determine rates of N uptake and assimilation of different N sources (NO3?, NH4+, urea and glycine by P. minimum and NO3?, NH4+ by P. donghaiense) were conducted using 15N tracer techniques at each N:P ratio. The growth rates suggested nutrient limitation at both high and low N:P ratios relative to the Redfield ratio. On a diel basis, the growth of both species was regulated by the light-dark cycle, which may be a result of regulation of both light- dependent growth and light-independent nutrient uptake. Maximum growth rates of both species always occurred at the beginning of light phase. In P-rich medium (low N:P ratio), both species had higher N assimilation rates, suggesting N limitation. Low assimilation coefficients at high N:P ratios suggested P limitation of N uptake and assimilation. NO3? and NH4+ contributed more than 90% of the total N uptake of P. minimum. Reduced N sources were more quickly assimilated than NO3?. Highest average daily growth rates were recorded near an N:P ratio of 12 for both species. The N uptake rates of cultures at N:P ratios near Redfield ratio were more balanced with growth rates. The linkage between growth rates and N uptake/assimilation rates were conceptually described by the variation of cell N quota. The N:P ratios affect the N uptake and growth of Prorocentrum spp., and may regulate their bloom progression in eutrophic ecosystems.
基金supported by the Ministry of Science and Technology of P.R.China under grant contracts (No.2010CB428903)the National Natural Science Foundation of China (No.41306112)+3 种基金the National Marine Public Welfare Research Project of China (Nos.201305043,200805069)the Zhejiang Provincial Natural Science Foundation (Nos.LY13D060004,Y5110131)the Marine Science Foundation of State Oceanic Administration for Youth (Nos.2013140,2013144)the Basic Scientific Research Fund of SIO,China (Nos.JG1311,JG1221)
文摘With the rapid development of economy and increase of population in the drainage areas,the nutrient loading has increased dramatically in the Changjiang estuary and adjacent coastal waters.To properly assess the impact of nutrient enrichment on phytoplankton community,seasonal microcosm experiments were conducted during August 2010 July 2011 in the coastal waters of Zhejiang Province.The results of the present study indicated that the chl a concentration,cell abundance,diversity indices,species composition and community succession of the phytoplankton varied significantly with different N/P ratios and seasons.Higher growth was observed in the 64:1(spring),32:1(summer),16:1(autumn)and 128:1,256:1(winter)treatments,respectively.The values of Shannon-Wiener index(H′)and Pielou evenness index(J)were lower in the 8:1 and 16:1 treatments in autumn test,while H'value was higher in the 128:1 and 8:1 treatments in winter test.A definite community succession order from diatoms to dinoflagellates was observed in the autumn and winter tests,while the diatoms dominated the community throughout the culture in the spring and summer tests.
基金partially supported by Tianjin Marine Revitalization Plan of Science and Technology (No.KJXH2013-16) from Tianjin Oceanic Administration,China
文摘Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sustainable production.In order to investigate the effect of various nitrogen to phosphorus ratios on cells growth,chlorophyll content and accumulation of lipids in Dunaliella tertiolecta,experiments were carried out in modified microalgal medium with inorganic nitrogen(nitrate-nitrogen) or organic nitrogen(urea-nitrogen) as the sole nitrogen source at initial N:P ratios ranging from 1:1 to 32:1.The favorable N:P of 16:1 in the nitrate-N or urea-N medium yielded the maximum cell density and specific growth rate.Decrease in chlorophyll content were observed at the N:P of 4:1 in both nitrate-N and urea-N cultures.It was also observed that the maximum lipids concentration was obtained at the N:P of 4:1 in both nitrate and urea nutrient medium.The lipid productivity and lipid content of cultures in the urea-N medium at the N:P of 4:1were markedly higher than those from cultures with other N:P ratios(p < 0.05).The results of this work illustrate the possibility that higher ratios of nitrogen to phosphorus have enhancing effect on cells growth of D.tertiolecta.Conversely,higher lipid accumulation is associated with a decrease in chlorophyll content under lower ratios of nitrogen to phosphorus.The results confirm the hypothesis of this study that a larger metabolic flux has been channeled to lipid accumulation in D.tertiolecta cells when the ratios of nitrogen to phosphorus drop below a critical level.
文摘Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carbon and nitrogen nutrition balance of soils. We studied the characteristics of soil organic carbon and total nitrogen by investigating a large number of apple orchards in major apple production areas in China. High apple orchard soil organic carbon content was observed in the provinces of Heilongjiang, Xinjiang, and Yunnan, whereas low content was found in the provinces of Shandong, Henan, Hebei, and Shaanxi, with the values ranging between 6.44 and 7.76 g·kg-1. Similar to soil organic carbon, soil total nitrogen content also exhibited obvious differences in the 12 major apple producing provinces. Shandong apple orchard soil had the highest total nitrogen content (1.26 g·kg-1), followed by Beijing (1.23 g·kg-1). No significant difference was noted between these two regions, but their total nitrogen content was significantly higher than the other nine provinces, excluding Yunnan. The soil total nitrogen content for Xinjiang, Heilongjiang, Hebei, Henan, and Gansu was between 0.87 and 1.03 g·kg-1, which was significantly lower than that in Shandong and Beijing, but significantly higher than that in Liaoning, Shanxi, and Shaanxi. Six provinces exhibited apple orchard soil C/N ratio higher than 10, including Heilongjiang (15.42), Xinjiang (13.38), Ningxia (14.45), Liaoning (12.24), Yunnan (11.03), and Gansu (10.63). The soil C/N ratio was below 10 in the remaining six provinces, in which the highest was found in Shaanxi (9.47), followed by Beijing (8.98), Henan (7.99), and Shanxi (7.62), and the lowest was found in Hebei (6.80) and Shandong (6.05). Therefore, the improvement of soil organic carbon should be given more attention to increase the steady growth of soil C/N ratio.
基金funded by the Development and Reform Commission of Jilin Province (2010)
文摘[ Objective] To investigate the effects of concentrate/roughage ratios and nitrogen levels on in-vitro rumen fermentation of urea-treating corn stalk. [ Method] The concentrate/roughage ratios were 7: 3, 5:5 and 3: 7. The crude protein levels were 11% and 14%. The in-vitro culture time was 2, 4, 6 and 48 h. [ Result] The pH value of broth decreased significantly with the decline in the proportion of roughage ( P 〈 0.01 ) and with the increase in the crude protein levels (P 〈 0.05). The ammonium nitrogen concentration and acetic acid/propionic acid ratio of the fermen- ted products decreased with the increase in the crude protein levels and proportion of concentrate in diet. The diet with concentrate/roughage ratio of 5:5 and crude protein level of 14% had significantly higher digestibility of dry matter and organic matter than other diets ( P 〈 0.05). The digesti- bility of organic matter increased gradually with the increasing proportion of concentrate and crude protein level. With the increase in the proportion of concentrate, the microbial protein levels increased remarkably, while the acetic acid/propionic acid ratio declined. [ Conclusion] The concentrate/ roughage ratios and nitrogen levels affect rumen fermentation and microbial growth during in-vitro culture. However, the best supplementary feeding results of urea-treatinq corn stalks can be obtained when the concentrate/rouahaae ratio is below 5:5 and the crude protein level is 14%.
基金Special Fund for Agro-scientific Research in the Public Interest(201103003)the Earmarked Fund for China Agriculture ResearchSystem(CARS-28)
文摘Soil C /N ratio is an important influencing factor in soil nitrogen cycling. Two-year old apple trees( Borkh. cv. ‘Fuji'/Malus hupehensis) were used to understand the effect of soil C/N ratio [6. 52( CK),10,15,20,25,30,35 and 40]on apple growth and nitrogen utilization and loss by using15N trace technique. The results showed that,with the increasing of soil C/N ratio,apple shoot length and fresh weight increased at first,and then decreased; the higher apple shoot length and fresh weight appeared in C/N = 15,20 and 25 treatments,and there were no significant differences among these three treatments,but significantly higher than the other treatments. Statistical analysis revealed that there was significant difference in nitrogen utilization rate between the different treatments,the highest N utilization rate was occurred in soil C/N = 25 treatment which value was 22. 87%,and there was no significant difference between soil C/N = 25 and C/N = 20 treatments,but both the two treatments were significantly higher than the other treatments; Soil C/N = 40 had the lowest N utilization rate which value was 15. 43%,and this value was less than CK( 16. 65%). The proportion of plant absorption nitrogen from fertilizer was much higher when the value of soil C/N ratio in the range of 15- 25,but the percentage of plant absorption nitrogen from soil was much higher when the soil C/N ratio was too low( < 15) or high( < 25). Amount of residual nitrogen in soil increased gradually with the soil C/N ratio increasing,the amount of residual nitrogen in C/N = 40 treatment was 1. 32 times than that in CK. With the increasing of soil C/N ratio,fertilizer nitrogen loss decreased at first,and then increased,fertilizer nitrogen loss was the minimum in C/N = 25 treatments( 49. 87%) and the maximum were occurred in CK( 61. 54%). Therefore,regarding the apple growth and nitrogen balance situation,the value of soil C/N ratio in the range of 15- 25 would be favorable for apple growth and could increase effectively nitrogen fixed by soil,reduce nitrogen loss,and improve the nitrogen utilization ratio.
基金Supported by State Key Research and Development Program of Ministry of Science and Technology(2016YFD0101603)Fundamental Research Funds for the Central Universities in 2016(XDJK2016A020)
文摘In order to screen suitable high hybrid wheat seed production technology,the split-plot experiment design was adopted and study was carried out about the effects of the different row ratios of male and female parents and application amount of nitrogen fertilizer on hybrid wheat seed production and its component factors. The results showed that the seed production increased with the increase in the number of female parent row. When the row ratio of male and female parents was 2 ∶ 6,the seed production was 3 683. 8 kg/ha; when the application amount of nitrogen fertilization was 50 kg/ha,the seed production was 3 649. 4 kg/ha; the interaction between the row ratio of male and female parents and the application amount of nitrogen fertilizer indicated that when the row ratio of male and female parents was 2∶ 6 and the application amount of nitrogen fertilizer was 300 kg/ha,the seed production reached the highest( 4160. 6 kg/ha). The row ratio of male and female parents and application amount of nitrogen fertilizer had significant effect on the component factors of seed production,including the number of grains per spike,spike weight and setting percentage. When the row ratio of male and female parents was 2∶ 5,the number of grains per spike,spike weight and setting percentage were the highest at 26. 7 grains,1. 12 g,and 62. 6% respectively; when application amount of nitrogen fertilizer was 450 kg/ha,the number of grains per spike,spike weight and setting percentage were the highest at 26. 0 grains,1. 08 g,and59. 2% respectively; the interaction of row ratio of male and female parents and application amount of nitrogen fertilizer had significant effect on the number of grains per spike,spike weight and setting percentage; when the row ratio of male and female parents was 2∶ 5 and the application amount of nitrogen fertilizer was 300 kg/ha,the number of grains per spike,spike weight and setting percentage were the highest at 29. 6grains,1. 24 g,and 71. 6% respectively. The number of grains per spike is the largest component factor for seed production. Increasing the number of grains per spike can increase the seed production. According to the effects of row ratio of male and female parents and application amount of nitrogen fertilizer on the component factors of seed production,the optimal condition was 2∶ 5-2∶ 6 for row ratio of male and female parents and 300-450 kg/ha for application amount of nitrogen fertilizer.
基金Supported by the Project of "Demonstration and Integration of Agricultural Non-point Source Pollution Prevention and Control Technology in Rice Production Areas of Southern Plain of China"Belonging to National Science and Technology Program for"Twelfth Five-Year"Plan(2012BAD15B03)Youth Innovation Funds of Jiangxi Academy of Agricultural Sciences "Effects of Row-Spacing on Yield of Different Double Cropping Rice Varieties and Its Mechanism"(2010-CQN004)
文摘[Objective]The aim was to provide a theoretical basis for the rational configuration of ratio of row spacing to intrarow spacing(RS/IS)of double-cropping rice.[Methods]With early rice‘Ganxin 203’and‘Zhongjiazao 17’and late rice‘Ganxin 688’and‘Wufengyou T025’as materials,the effects of RS/IS on yield,nitrogen accumulation and utilization were studied in the same planting density of31.20×104hills/hm2.[Results]The results showed that yield of early rice was higher in RS/IS2.8(30.0 cm×10.7 cm)and RS/IS2.0(25.0 cm×12.8 cm)treatment,and lower in RS/IS5.0(40.0 cm×8.0 cm)and RS/IS1.3(20.0 cm×16.0 cm)treatment,while late rice were higher in RS/IS5.0and RS/IS2.0treatment,and lower in RS/IS2.8and RS/IS1.3treatment.Total nitrogen accumulation and apparent utilization ratio of nitrogen of early rice were higher in RS/IS2.0treatment and lower in RS/IS5.0treatment,while,for late rice were higher in RS/IS2.8treatment and lower in RS/IS5.0treatment.Nitrogen requirement for 100 kg grain production of early rice was higher in RS/IS1.3treatment and lower in RS/IS2.0treatment,while,for late rice were higher in RS/IS2.8treatment,lower in RS/IS5.0treatment.[Conclusion]In sum,4 varieties of early and late rice obtained higher yield in 25.0 cm×12.8 cm and lower yield in 20.0 cm×16.0 cm,and total nitrogen accumulation,nitrogen requirement for 100 kg grain production and apparent utilization ratio of nitrogen were all lower in 40.0 cm×8.0 cm.