In the present experiment, wheat seedlings (Trticucum aestivum L.) were grown on a purple soil withvarious fertilizer treatments in order to investigate the responses of nitrogen and related eusyme activitiesin the rh...In the present experiment, wheat seedlings (Trticucum aestivum L.) were grown on a purple soil withvarious fertilizer treatments in order to investigate the responses of nitrogen and related eusyme activitiesin the rhizosphere. The results revealed the increments of both organic matter and total N in the soil withthe proximity to the growing roots, especially in the treatment of supplying pig manure in combination withchemical fertilizer, suggesting that they could come from root and microorganism exudation which could beintensified by inorganic-organic fertilization, being of benefit to improving the physical and biological envi-ronment in the rhizosphere of wheat. Much more inorganic N was observed in the fertilized soils surroundingwheat roots than in the CK treatment, indicating the improvement of crop N supply in the rhisosphere ofwheat by fertilization.The activities of invertase, urease and protease in the root zone were greatly enhanced as compared tothose in the other parts of soils except that the urease activities were similar in the rhizo8phere and nonrhi-zosphere of the CK and pig manure treatments, indicating that invertase and protease could be produced bygrowing roots and rhizosphere microorganisms, in contrast to urease which could be stimulated by urea. Also,significant increment of these three enzyme activities in the rhizosphere of wheat by fertilizatioll, especially byapplication of chemical fertilizer combined with pig manurel suggested that fertilization not only acceleratedthe renewal of organic matter but also enhanced bioavailability of organic N in that soil zone. This couldbe the reason why the total amount of inorganic N available for plants was increased more obviously in therhizosphere of wheat of the fertilization treatments than in that of the CK treatment.展开更多
Scopolamine is a pharmaceutically important tropane alkaloid extensively used as an anticholinergic agent.Here,we report the simultaneous introduction and overexpression of genes encoding the rate-limiting upstream en...Scopolamine is a pharmaceutically important tropane alkaloid extensively used as an anticholinergic agent.Here,we report the simultaneous introduction and overexpression of genes encoding the rate-limiting upstream enzyme pu-trescine N-methyltransferase(PMT)and the downstream enzyme hyoscyamine6β-hydroxylase(H6H)of scopolamine biosynthesis in transgenic henbane(Hyoscyamus niger)hairy root cultures.Transgenic hairy root lines expressing both pmt and h6h produced significantly higher(P<0.05)levels of scopolamine compared with the wild-type and transgenic lines har-boring a single gene(pmt or h6h).The best line(T 3 )produced411mg/liter scopolamine,which was over nine times more than that in the wild type(43mg/liter)and more than twice the amount in the highest scopolamine-producing h6h single-gene transgenic line H 11 (184mg/liter).To our knowledge,this is the highest scopolamine content achieved through genetic engi-neering of a plant.We conclude that transgenic plants harboring both pmt and h6h possessed an increased flux in the tropane alkaloid biosynthetic pathway that enhanced scopolamine yield,which was more efficient than plants harboring only one of the two genes.It seems that the pulling force of the downstream enzyme(the faucet enzyme)H6H plays a more important role in stimulating scopolamine accumulation in H.niger whereas the functioning of the upstream enzyme PMT is increased propor-tionally.This study provides an effective approach for large-scale commercial production of scopolamine by using hairy root culture systems as bioreactors.展开更多
A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and ...A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52μg m-2 under initial soil cadmium concentrations to 65μg m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.展开更多
Distribution characteristics of soil animals, microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jins...Distribution characteristics of soil animals, microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jinsha River, China. Results showed that Hymenoptera, Araneae and Collembola were the dominant groups of soil animals in the plots studied. The numbers of groups and individuals and density of soil animals in the dry red soil series were higher than those in the Vertisol series, and the numbers of individuals and density of soil animals decreased with the degree of soil degradation. Bacteria dominated microbiocoenosis not only in the dry red soils but also in the Vertisols. Microbial numbers of the dry red soil series were higher than those of Vertisol series, and decreased with the degree of soil degradation. The activities of catalase, invertase, urease and alkaline phosphatase declined with the degradation degree and showed a significant decline with depth in the profiles of both the dry red soils and the Vertisols, but activities of polyphenol oxidase and acid and neutral phosphatase showed the same tendencies only in the Vertisols. It was concluded that the characteristics of soil animals, microorganisms and enzymatic activity could be used as the bio-indicators to show the degradation degree of the dry red soils and Vertisols. Correlation among these soil bio-indicators was highly significant.展开更多
The terrestrial ecosystem may be either a source or a sink of CH_4 in rice paddies, depending, to a great extent, on the change of ecosystem types and land use patterns. CH_4 emission fluxes from paddy fields under 4 ...The terrestrial ecosystem may be either a source or a sink of CH_4 in rice paddies, depending, to a great extent, on the change of ecosystem types and land use patterns. CH_4 emission fluxes from paddy fields under 4 cultivation patterns (conventional plain culture of rice(T1), no-tillage and ridge culture of rice(T2), no-tillage and ridge culture of rice and wheat (T3), and rice-wheat rotation(T4)) were measured with the closed chamber technique in 1996 and 1998 in Chongqing, China. The results showed that differences existed in CH_4 emission from paddy fields under these land management practices. In 1996 and 1998, CH_4 emission was 71 48% and 78 82%(T2), 65 93% and 57 18%(T3), and 61 53% and 34 22%(T4) of that in T1 during the rice growing season. During the non-rice growing season, CH_4 emission from rice fields was 76 23% in T2 and 38 69% in T1 The accumulated annual CH_4 emission in T2, T3 and T4 in 1996 decreased by 33 53%, 63 30% and 65 73%, respectively, as compared with that in T1 In 1998, the accumulated annual CH_4 emission in T1, T2, T3 and T4 was 116 96 g/m^2, 68 44 g/m^2, 19 70 g/m^2 and 11 80 g/m^2, respectively. Changes in soil physical and chemical properties, in thermal and moisture conditions in the soil and in rice plant growth induced by different land use patterns were the dominant causes for the difference in CH_4 emission observed. The relative contribution of various influencing factors to CH_4 emission from paddy fields differed significantly under different land use patterns. However, the general trend was that chlorophyll content in rice leaves, air temperature and temperature at the 5 cm soil layer play a major role in CH_4 emission from paddy fields and the effects of illumination, relative humidity and water layer depth in the paddy field and CH_4 concentration in the crop canopy were relatively non-significant. Such conservative land use patterns as no-tillage and ridge culture of rice with or without rotation with wheat are thought to be beneficial to reducing CH_4 emission from paddy fields and are, therefore, recommended as a significant solution to the problems of global(climatic) change.展开更多
This paper, taking Beiwenquan Town of Beibei, Chongqing as an example, assessed the impacts of land use on ecological health by comprehensive index method, and discussed methodological system of sustainable land use p...This paper, taking Beiwenquan Town of Beibei, Chongqing as an example, assessed the impacts of land use on ecological health by comprehensive index method, and discussed methodological system of sustainable land use planning based on ecological health. Results indicated that: 1) From 1992 to 2002, land use changes focused on 12 patterns with the total conversion area of 92.11%, which were related to cultivated land, residential and industrial-mining area, and orchard land. Urbanization and economic reconstruction were the leading driving forces. 2) There was obvious difference of the areas of ecotypes driven by land use change in wide valley and mild slope between 1992 and 2002, while there were little or no difference in steep slope and very steep slope. 3) Both of the conditions of ecological health in 1992 and 2002 were sound, and the ecotypes focused on the types of health and sub-health. But, health ecosystem in 1992, with an area of 764.64ha, accounting for 38.51% of the total evaluation area, was better than that in 2002, with an area of 636.10ha, accounting for 34.19% of the total evaluation area. 4) The ecotypes involved into different ranges have already degenerated, due to humankind’s disturbance, while the conditions of ecological health in the same ranges in 1992, regardless of stability and reconstruction, were better than that in 2002. 5) The planning scenario based on ecological health was accorded with the practice condition of Beiwenquan Town: 388.29ha of cultivated land could meet the Beiwenquan demand of food and byproduct; 1045.26ha of forest land area, the Beiwenquan demand of ecological health; and 1004.73ha of the residential and industrial-mining area, the Beiwenquan building demand. 6) Sustainable land use planning based on ecological health had higher useful value, because it not only stood to ecological theory, but also satisfied the developmental demand of society and economy.展开更多
Experiments were carried out to study the transformation of mercury in soils. Results showed that Hg 2+ was immediately converted into other forms once it entered into soils. Bentonite, humus or CaCO 3 accelera...Experiments were carried out to study the transformation of mercury in soils. Results showed that Hg 2+ was immediately converted into other forms once it entered into soils. Bentonite, humus or CaCO 3 accelerated the transformation of Hg 2+ by various mechanisms. Bentonite could convert Hg 2+ into residual form eventually, and application of CaCO 3 enhanced the formation of inorganic Hg. Humus competed strongly with clay minerals for binding Hg 2+ , thus increase of soil humus content led to increased formation of organically bound Hg.展开更多
A systematic approach was adopted to investigate the nutrient limiting factors in gray-brown purple soils and yellow soils derived from limestone in Chongqing, China, to study balanced fertilization for corn, sweet po...A systematic approach was adopted to investigate the nutrient limiting factors in gray-brown purple soils and yellow soils derived from limestone in Chongqing, China, to study balanced fertilization for corn, sweet potato and wheat in rotation. The results showed that N, P and K were deficient in both soils, Cu, Mn, S andZn in the gray-brown purple soils and Ca, Mg, Mo and Zn for the yellow soils. Balanced fertilizer application increased yields of corn, sweet potato and wheat by 28.4%, 28.7% and 4.4%, respectively, as compared to the local farmers' practice. The systematic approach can be considered as one of the most efficient and reliable methods in fertility study.展开更多
Hg in acid soil could be activited by liming and become available to plant, if excessive or insufficient amount of lime was applied. The changes of Hg activity in acid soil with different rates of CaCO3 amendment Were...Hg in acid soil could be activited by liming and become available to plant, if excessive or insufficient amount of lime was applied. The changes of Hg activity in acid soil with different rates of CaCO3 amendment Were studied by a pot experiment. To predict the adequate amount of lime application, a simple method using the pH (EDTA) as an indicator was suggested. The suitable range of lime application was the amount of lime addition when the pH of soil-EDTA system was.raised to 4.0-4.3.展开更多
A pot experiment was conducted to study the effect of nitrogen fertilizer on nitrogen and potassium uptake by four rice cultivars. Results showed that the quadatic parabola relationship between biomass of rice and nit...A pot experiment was conducted to study the effect of nitrogen fertilizer on nitrogen and potassium uptake by four rice cultivars. Results showed that the quadatic parabola relationship between biomass of rice and nitrogen levels was observed, with the maximum biomass at the nitrogen level of 150 mg kg-1.The rates of nitrogen and potassium uptake by the four rice cultivars depended on growth stage and rice cultivar with the maximum rate of N in Shanyou-63 and maximum rate of K in Kaiyou-5 (hybrid rice),respedively. The kinetics of nitrogen and potasssium uptake by rice plant could be quantitstively described by the following equations: y = a + blogt, y = ab + t1/2 and y = ae-bt. The b value in the equations was correlated significantly to the rates of nitrogen and potassium uptake (NR and KR, r=0.901**～0.990**),suggesting that the b value could be used to distinguish the index of nitrogen and potassium uptake capacity of rice. The maximum values of nitrogen uptake by plant (b value) and apparent recovery of fertilizer nitrogen were observed in Shanyou-63, and the minimum value in Eryou-6078. However, the capacity of potassium uptake (b value) by Kaiyou-5 ranked first and that by Shanyou-63 second. There was a significant linear relationship between nitrogen level and nitrogen uptake by rice, but a quadratic parabola relationship was found between nitrogen level and patassium uptake by rice. The application of nitrogen fertilizer decreased the ratios of potassium to nitrogen uptake by rice plant. The greatest reduction in the ratio was observed at high nitrogen level, and the least reduction was found in Kaiyou-5 and Shanyou-63 due to their greater ability to absorb potassium.展开更多
Seasonal changes in enzyme activities and citrate concentration during the development of citrus fruits were investigated. The result showed that the organic acid concentrations reached a peak in the 100 -130 days aft...Seasonal changes in enzyme activities and citrate concentration during the development of citrus fruits were investigated. The result showed that the organic acid concentrations reached a peak in the 100 -130 days after anthesis and gradually declined during later stages of fruit maturation in most varieties of citrus, but declined only slightly thereafter in lemon [Citrus limon(L.)Burm]; there is no relation between the activity of citrate synthetase(CS)and the different acid concentration in different citrus fruits; the increase of the activity of the cytosolic aconitase in the late period of the development of citrus fruits accelerated the degradation of citric acid in citrus fruits; the higher the activity of phosphoenolpyruvate carboxylase(PEPC)and the ratio of NAD-dependent isocitrate hydrogenase(PEPC /NAD-IDH),the more the concentrations of organic acids in citrus fruit.展开更多
The effects of retarding resistance evolution of mixing and sequencing acaricides were studied based on the resistance selection of three acaricides to Tetranychus cinnabarinus in the laboratory. Tetrany-chus cinnabar...The effects of retarding resistance evolution of mixing and sequencing acaricides were studied based on the resistance selection of three acaricides to Tetranychus cinnabarinus in the laboratory. Tetrany-chus cinnabarinus was continuously selected with fenpropathrin, abamectin and pyridaban for 28, 30 and 31 generations, respectively, and resistance factor increased to 65.6, 7.2 and 1.2 time, accordingly. Results of cross-resistance determination suggested that there were no cross-resistance existed among the three acaricides. Analysis of resistance selection and estimation of realized heritability (h2) of resistance to three single and two mixed acaricides showed that a mixture of fenpropathrin+abamectin would slow resistance development compared with a sequence of fenpropathrin followed by abamectin while the mixture of pyridaben+abamectin and the sequence of pyridaben followed by abamectin would effectively retard resistance evolution.展开更多
A field experiment was carried out to study nutrient balance among N, P, K and Mg in potato cultivation on an acid purple soil in Chongqing, China. The experiment included 8 treatments with equal P rate of 120 kg P2O5...A field experiment was carried out to study nutrient balance among N, P, K and Mg in potato cultivation on an acid purple soil in Chongqing, China. The experiment included 8 treatments with equal P rate of 120 kg P2O5 hm-2: N0K2, N1K2, N2K2, N3K2, N2K0, N2K1, N2K1Mg and N2K3, where N0, N1, N2 and N3 stand for the N rates of 0, 75, 150 and 225 kg N hm-2, and K0, K1, K2 and K3 for the K rates of 0, 165, 330 and 495 kg K2O hm-2, respectively. Among the treatments designed, Thatment N2K2 with a nutrient supply ratio of N:P2O5:K2O:MgO = 1.25:1:2.75:0.28 gave the highest tuber yield and dry matter, highest starch and Zn and lowest NO3- contents in tuber, and high N, P and K use efficiency with an uptake ratio of N:P:K:Mg = 11.38:1:13.32:0.33 by tuber. Yield and starch and protein contents of tuber were the lowest in Treatment N0K2. Dry matter was the lowest but protein and NO3- contents were the highest in Treatment N2K0. Treatment N2K1Mg had the highest N, P and K utilization rates. Statistical analysis showed that yields of tuber and starch were in a positive linear correlation with the uptake amount of various nutrients and protein of the potato tuber was in a significantly positive linear correlation with tuber N cotent and in a significantly negative linear correlation with tuber K and Mg contents. Balanced application of N, P, K and Mg fertilizers (Treatmeat N2K2) was recommended for realization of high yield and good quality in potato cultivation.展开更多
The chemical composition, total flavonoids and antioxidant capacity of 50% ethanolic extracts from raw and cooked buckwheat flour from southwest of China were determined. The heat treatment used to gelatinize the flou...The chemical composition, total flavonoids and antioxidant capacity of 50% ethanolic extracts from raw and cooked buckwheat flour from southwest of China were determined. The heat treatment used to gelatinize the flour starch significantly reduced the total flavonoids in the extract from 83.52 to 67.36 mg 100 g 1 of dry matter in the raw and cooked flour, respectively. The antioxidant capacity of the extracts was evaluated using autooxidation in a β carotene linoleate model system (AA or AAC), DPPH radical scavenging assay (IP) and oxygen radical absorbance capacity (ORAC) assay. Values for raw buckwheat flour extract were 97.84, 874.31, 76.45 and 94.92% for AA, AAC, ORAC and IP, respectively, while values in cooked buckwheat flour were 86.14, 842.88, 63.93 and 94.74% for AA, AAC, ORAC and IP, respectively. Values before cooked and raw buckwheat flour extracts were significantly different ( P <0.05) for AA, AAC, and ORAC.展开更多
A study was carried out on the transfer of native and added Ni towards plant both in different soils and at different time by using ^63 Ni tracer technique.The transfer of added Ni in soil was greater than native Ni a...A study was carried out on the transfer of native and added Ni towards plant both in different soils and at different time by using ^63 Ni tracer technique.The transfer of added Ni in soil was greater than native Ni and declined as time increased.The mobility was greater for soluble plus exchangeable fraction of soil Ni but very smaller for residual and Fe/Mn oxide bound fractions.These indicated that Ni was more mobile and more harmful in soils with a low pH and /or low content of Fe/Mn oxides.展开更多
The kinetic characteristics of P adsorption and desorption by organo-mineral colloidal complexes (OMC)were studied using acid, calcareous and neutral purple paddy soils taken from Chongqing and Sichuan, China.The resu...The kinetic characteristics of P adsorption and desorption by organo-mineral colloidal complexes (OMC)were studied using acid, calcareous and neutral purple paddy soils taken from Chongqing and Sichuan, China.The results showed that the P adsorption capacity of the organo-mineral colloidal complexes differed with the soil types, being higher for the acid and calcareous purple soils than for the neutral purple soils. Partial removal of the organic matter increased the adsorption capacity of the colloidal complexes. A very significant positive correlation was found between the amounts of P desorbed from OMC and the P saturation degrees.The P adsorption reaction was quick at the early stage and slowed later. The raise of temperature increased P adsorption capacity and P adsorption rate of the colloidal complexes. The adsorption processes could be described by the Elovich equation.展开更多
The most general contact in mechanical transmission is the elliptical one. In particular, a toroidal continuously variable transmission (CVT) has an elliptical shape in the contact area under the elastohydrodynamic lu...The most general contact in mechanical transmission is the elliptical one. In particular, a toroidal continuously variable transmission (CVT) has an elliptical shape in the contact area under the elastohydrodynamic lubrication regime, where the shearing of the fluid subjects to high contact stress and transmits the power. Many parameters affect the contact service performance of the half toroidal CVT, which include the properties of the contacting material (Young抯 modulus), operating parameters (input torque and maximum traction coefficient) and geometrical parameters (aspect cavity ratio, curvature ratio and half cone angle of the power roller). In this paper, the contacts between the input disk, the power roller and the output disk are formulated using the classical Hertzian contact theory. Based on the formulated equations, different system parameters, which affect the maximum Hertzian stresses, are compared. The comparative results will provide some observations of the relations between the maximum Hertzian stresses and transmission ratios in the form of graphs. These graphs give useful information for designer to know the maximum Hertzian stress during operation in such systems.展开更多
Three pairs of near-isogenic lines with different genetic backgrounds of yellow-seededand black-seeded rape (Brassica napus L.) were used as experiment materials to study therelationship of color formation in the seed...Three pairs of near-isogenic lines with different genetic backgrounds of yellow-seededand black-seeded rape (Brassica napus L.) were used as experiment materials to study therelationship of color formation in the seedcoat with enzyme activity and protein contentin it. The results showed that with similar genetic backgrounds, phenylalanine ammonia-lyase (PAL) and polyphenol oxidase(PPO) activities in the black-seeded lines were muchhigher than in their yellow-seeded counterparts and maximum PAL activity in the seedcoatoccurred comparatively late while no significant difference was present in glutaminesynthetase (GS) between the two types of rape. The plants were treated with red light,blue light, p-hydroxybenzoic acid (a PAL inhibitor), polyvinylpyridoxal (a PPO inhibitor),urea (a protein synthesis promoter) or chloramphenicol (CM, a plastid protein synthesisinhibitor) during seed development. It is speculated that PAL may be primarily responsiblefor coloration in the yellow seed; PPO may be the main factor contributing to thedarkness of the testa of the black genotypes; and nitrogen assimilation is, probably, notdirectly related to the difference in protein content observed between yellow- andblack-seeded genotypes, which may be induced mainly by PAL.展开更多
Particle size, rheological and thermal properties of potato starch from Yunnan province of China was in-vestigated. The particle size ranges from 0.429-102.3 um determined by laser light-scatter. The major flow type o...Particle size, rheological and thermal properties of potato starch from Yunnan province of China was in-vestigated. The particle size ranges from 0.429-102.3 um determined by laser light-scatter. The major flow type of 6 w/v% potato starch was shear-thinning fluid even the shear rate up to 800·s-1, and the gel formed by 6 w/v% potato starch fell to weak gel for its little difference between G' and G'', high dependence on frequency and low value of G'(Pa). The hardness and cohesiveness of potato starch gel were 31.3 g and 131.9 g·s, respectively. The thermal properties of potato starch were also determined by DSC at the starch:water=3:1. The To, Tp, and ΔH of potato starch were 62.23℃,67.31℃, and 2.22 J·g-1.展开更多
The cross resistance of four resistant strains of Liposcelis bostrychophila Badonnel, an important stored-product insect pest, was investigated. These four strains included the HCO2-R (hypercarbia-resistant strain),...The cross resistance of four resistant strains of Liposcelis bostrychophila Badonnel, an important stored-product insect pest, was investigated. These four strains included the HCO2-R (hypercarbia-resistant strain), HCLO-R (hypoxia and hypercarbia resistant strain), DDVP-R (DDVP-resistant strain) and PH3-R (PH3-resistant strain). The results indicated that there were cross-resistances between CA and insecticides, and the quantities of the cross-resistance were different. The cross-resistance factor (RF) of HCO2-R to hypoxia and hypercarbia was 3.2458, whilst, that of HCLO-R to hypercarbia was 1.8280. The RF of DDVP-R to PH3 was 3.9614, whilst, that of PH3-R to DDVP was 2.7852. The RF values of DDVP- R and PH3-R to hypercarbia were 1.3550 and 1.1816, respectively. However, the RF of HCO2- R to DDVP was 2.1372. There also was a low cross-resistance between DDVP-R and HCO2-R. The RF of HCO2-R to PH3 was 3.3698. This suggested that the insects resistant to high CO2 concentration atmosphere would develop significant resistance to PH3. However, the insects resistant to PH3 remain sensitive to hypercarbia atmosphere. Both DDVP-R and PH3- R developed resistance to high CO2 treatment. There was a low cross-resistance between DDVP-R and HCLO-R. The insects resistant to hypoxia and hypercarbia were very sensitive to DDVP. There also was cross-resistance between HCLO-R and PH3-R, but the resistance of PH3-R to hypoxia and hypercarbia was lower than that of HCLO-R to PH3. The difference of the overlapping and separate values indicated that there were differences in the intercross-resistance of four resistant strains.展开更多
文摘In the present experiment, wheat seedlings (Trticucum aestivum L.) were grown on a purple soil withvarious fertilizer treatments in order to investigate the responses of nitrogen and related eusyme activitiesin the rhizosphere. The results revealed the increments of both organic matter and total N in the soil withthe proximity to the growing roots, especially in the treatment of supplying pig manure in combination withchemical fertilizer, suggesting that they could come from root and microorganism exudation which could beintensified by inorganic-organic fertilization, being of benefit to improving the physical and biological envi-ronment in the rhizosphere of wheat. Much more inorganic N was observed in the fertilized soils surroundingwheat roots than in the CK treatment, indicating the improvement of crop N supply in the rhisosphere ofwheat by fertilization.The activities of invertase, urease and protease in the root zone were greatly enhanced as compared tothose in the other parts of soils except that the urease activities were similar in the rhizo8phere and nonrhi-zosphere of the CK and pig manure treatments, indicating that invertase and protease could be produced bygrowing roots and rhizosphere microorganisms, in contrast to urease which could be stimulated by urea. Also,significant increment of these three enzyme activities in the rhizosphere of wheat by fertilizatioll, especially byapplication of chemical fertilizer combined with pig manurel suggested that fertilization not only acceleratedthe renewal of organic matter but also enhanced bioavailability of organic N in that soil zone. This couldbe the reason why the total amount of inorganic N available for plants was increased more obviously in therhizosphere of wheat of the fertilization treatments than in that of the CK treatment.
文摘Scopolamine is a pharmaceutically important tropane alkaloid extensively used as an anticholinergic agent.Here,we report the simultaneous introduction and overexpression of genes encoding the rate-limiting upstream enzyme pu-trescine N-methyltransferase(PMT)and the downstream enzyme hyoscyamine6β-hydroxylase(H6H)of scopolamine biosynthesis in transgenic henbane(Hyoscyamus niger)hairy root cultures.Transgenic hairy root lines expressing both pmt and h6h produced significantly higher(P<0.05)levels of scopolamine compared with the wild-type and transgenic lines har-boring a single gene(pmt or h6h).The best line(T 3 )produced411mg/liter scopolamine,which was over nine times more than that in the wild type(43mg/liter)and more than twice the amount in the highest scopolamine-producing h6h single-gene transgenic line H 11 (184mg/liter).To our knowledge,this is the highest scopolamine content achieved through genetic engi-neering of a plant.We conclude that transgenic plants harboring both pmt and h6h possessed an increased flux in the tropane alkaloid biosynthetic pathway that enhanced scopolamine yield,which was more efficient than plants harboring only one of the two genes.It seems that the pulling force of the downstream enzyme(the faucet enzyme)H6H plays a more important role in stimulating scopolamine accumulation in H.niger whereas the functioning of the upstream enzyme PMT is increased propor-tionally.This study provides an effective approach for large-scale commercial production of scopolamine by using hairy root culture systems as bioreactors.
基金Project supported by the Chinese Postdoctoral Foundation (No. 10129) and the Swedish Agricultural Science Research Foundation (N
文摘A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52μg m-2 under initial soil cadmium concentrations to 65μg m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.
基金Project supported by the Foundation for 100 Distinguished Young Scientists, the Chinese Academy of Sciences (No. B010108) the Foundation for the Cooperation Between the Chinese Academy of Sciences Yunnan Province.
文摘Distribution characteristics of soil animals, microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jinsha River, China. Results showed that Hymenoptera, Araneae and Collembola were the dominant groups of soil animals in the plots studied. The numbers of groups and individuals and density of soil animals in the dry red soil series were higher than those in the Vertisol series, and the numbers of individuals and density of soil animals decreased with the degree of soil degradation. Bacteria dominated microbiocoenosis not only in the dry red soils but also in the Vertisols. Microbial numbers of the dry red soil series were higher than those of Vertisol series, and decreased with the degree of soil degradation. The activities of catalase, invertase, urease and alkaline phosphatase declined with the degradation degree and showed a significant decline with depth in the profiles of both the dry red soils and the Vertisols, but activities of polyphenol oxidase and acid and neutral phosphatase showed the same tendencies only in the Vertisols. It was concluded that the characteristics of soil animals, microorganisms and enzymatic activity could be used as the bio-indicators to show the degradation degree of the dry red soils and Vertisols. Correlation among these soil bio-indicators was highly significant.
文摘The terrestrial ecosystem may be either a source or a sink of CH_4 in rice paddies, depending, to a great extent, on the change of ecosystem types and land use patterns. CH_4 emission fluxes from paddy fields under 4 cultivation patterns (conventional plain culture of rice(T1), no-tillage and ridge culture of rice(T2), no-tillage and ridge culture of rice and wheat (T3), and rice-wheat rotation(T4)) were measured with the closed chamber technique in 1996 and 1998 in Chongqing, China. The results showed that differences existed in CH_4 emission from paddy fields under these land management practices. In 1996 and 1998, CH_4 emission was 71 48% and 78 82%(T2), 65 93% and 57 18%(T3), and 61 53% and 34 22%(T4) of that in T1 during the rice growing season. During the non-rice growing season, CH_4 emission from rice fields was 76 23% in T2 and 38 69% in T1 The accumulated annual CH_4 emission in T2, T3 and T4 in 1996 decreased by 33 53%, 63 30% and 65 73%, respectively, as compared with that in T1 In 1998, the accumulated annual CH_4 emission in T1, T2, T3 and T4 was 116 96 g/m^2, 68 44 g/m^2, 19 70 g/m^2 and 11 80 g/m^2, respectively. Changes in soil physical and chemical properties, in thermal and moisture conditions in the soil and in rice plant growth induced by different land use patterns were the dominant causes for the difference in CH_4 emission observed. The relative contribution of various influencing factors to CH_4 emission from paddy fields differed significantly under different land use patterns. However, the general trend was that chlorophyll content in rice leaves, air temperature and temperature at the 5 cm soil layer play a major role in CH_4 emission from paddy fields and the effects of illumination, relative humidity and water layer depth in the paddy field and CH_4 concentration in the crop canopy were relatively non-significant. Such conservative land use patterns as no-tillage and ridge culture of rice with or without rotation with wheat are thought to be beneficial to reducing CH_4 emission from paddy fields and are, therefore, recommended as a significant solution to the problems of global(climatic) change.
基金Under the auspices of the Key Project of Science and Technology oftheMinistryofEducation(No .03111) and In-cubationFund ProjectofScienceand Technology Committee ofChongqing (No .017079)
文摘This paper, taking Beiwenquan Town of Beibei, Chongqing as an example, assessed the impacts of land use on ecological health by comprehensive index method, and discussed methodological system of sustainable land use planning based on ecological health. Results indicated that: 1) From 1992 to 2002, land use changes focused on 12 patterns with the total conversion area of 92.11%, which were related to cultivated land, residential and industrial-mining area, and orchard land. Urbanization and economic reconstruction were the leading driving forces. 2) There was obvious difference of the areas of ecotypes driven by land use change in wide valley and mild slope between 1992 and 2002, while there were little or no difference in steep slope and very steep slope. 3) Both of the conditions of ecological health in 1992 and 2002 were sound, and the ecotypes focused on the types of health and sub-health. But, health ecosystem in 1992, with an area of 764.64ha, accounting for 38.51% of the total evaluation area, was better than that in 2002, with an area of 636.10ha, accounting for 34.19% of the total evaluation area. 4) The ecotypes involved into different ranges have already degenerated, due to humankind’s disturbance, while the conditions of ecological health in the same ranges in 1992, regardless of stability and reconstruction, were better than that in 2002. 5) The planning scenario based on ecological health was accorded with the practice condition of Beiwenquan Town: 388.29ha of cultivated land could meet the Beiwenquan demand of food and byproduct; 1045.26ha of forest land area, the Beiwenquan demand of ecological health; and 1004.73ha of the residential and industrial-mining area, the Beiwenquan building demand. 6) Sustainable land use planning based on ecological health had higher useful value, because it not only stood to ecological theory, but also satisfied the developmental demand of society and economy.
文摘Experiments were carried out to study the transformation of mercury in soils. Results showed that Hg 2+ was immediately converted into other forms once it entered into soils. Bentonite, humus or CaCO 3 accelerated the transformation of Hg 2+ by various mechanisms. Bentonite could convert Hg 2+ into residual form eventually, and application of CaCO 3 enhanced the formation of inorganic Hg. Humus competed strongly with clay minerals for binding Hg 2+ , thus increase of soil humus content led to increased formation of organically bound Hg.
文摘A systematic approach was adopted to investigate the nutrient limiting factors in gray-brown purple soils and yellow soils derived from limestone in Chongqing, China, to study balanced fertilization for corn, sweet potato and wheat in rotation. The results showed that N, P and K were deficient in both soils, Cu, Mn, S andZn in the gray-brown purple soils and Ca, Mg, Mo and Zn for the yellow soils. Balanced fertilizer application increased yields of corn, sweet potato and wheat by 28.4%, 28.7% and 4.4%, respectively, as compared to the local farmers' practice. The systematic approach can be considered as one of the most efficient and reliable methods in fertility study.
文摘Hg in acid soil could be activited by liming and become available to plant, if excessive or insufficient amount of lime was applied. The changes of Hg activity in acid soil with different rates of CaCO3 amendment Were studied by a pot experiment. To predict the adequate amount of lime application, a simple method using the pH (EDTA) as an indicator was suggested. The suitable range of lime application was the amount of lime addition when the pH of soil-EDTA system was.raised to 4.0-4.3.
文摘A pot experiment was conducted to study the effect of nitrogen fertilizer on nitrogen and potassium uptake by four rice cultivars. Results showed that the quadatic parabola relationship between biomass of rice and nitrogen levels was observed, with the maximum biomass at the nitrogen level of 150 mg kg-1.The rates of nitrogen and potassium uptake by the four rice cultivars depended on growth stage and rice cultivar with the maximum rate of N in Shanyou-63 and maximum rate of K in Kaiyou-5 (hybrid rice),respedively. The kinetics of nitrogen and potasssium uptake by rice plant could be quantitstively described by the following equations: y = a + blogt, y = ab + t1/2 and y = ae-bt. The b value in the equations was correlated significantly to the rates of nitrogen and potassium uptake (NR and KR, r=0.901**～0.990**),suggesting that the b value could be used to distinguish the index of nitrogen and potassium uptake capacity of rice. The maximum values of nitrogen uptake by plant (b value) and apparent recovery of fertilizer nitrogen were observed in Shanyou-63, and the minimum value in Eryou-6078. However, the capacity of potassium uptake (b value) by Kaiyou-5 ranked first and that by Shanyou-63 second. There was a significant linear relationship between nitrogen level and nitrogen uptake by rice, but a quadratic parabola relationship was found between nitrogen level and patassium uptake by rice. The application of nitrogen fertilizer decreased the ratios of potassium to nitrogen uptake by rice plant. The greatest reduction in the ratio was observed at high nitrogen level, and the least reduction was found in Kaiyou-5 and Shanyou-63 due to their greater ability to absorb potassium.
文摘Seasonal changes in enzyme activities and citrate concentration during the development of citrus fruits were investigated. The result showed that the organic acid concentrations reached a peak in the 100 -130 days after anthesis and gradually declined during later stages of fruit maturation in most varieties of citrus, but declined only slightly thereafter in lemon [Citrus limon(L.)Burm]; there is no relation between the activity of citrate synthetase(CS)and the different acid concentration in different citrus fruits; the increase of the activity of the cytosolic aconitase in the late period of the development of citrus fruits accelerated the degradation of citric acid in citrus fruits; the higher the activity of phosphoenolpyruvate carboxylase(PEPC)and the ratio of NAD-dependent isocitrate hydrogenase(PEPC /NAD-IDH),the more the concentrations of organic acids in citrus fruit.
文摘The effects of retarding resistance evolution of mixing and sequencing acaricides were studied based on the resistance selection of three acaricides to Tetranychus cinnabarinus in the laboratory. Tetrany-chus cinnabarinus was continuously selected with fenpropathrin, abamectin and pyridaban for 28, 30 and 31 generations, respectively, and resistance factor increased to 65.6, 7.2 and 1.2 time, accordingly. Results of cross-resistance determination suggested that there were no cross-resistance existed among the three acaricides. Analysis of resistance selection and estimation of realized heritability (h2) of resistance to three single and two mixed acaricides showed that a mixture of fenpropathrin+abamectin would slow resistance development compared with a sequence of fenpropathrin followed by abamectin while the mixture of pyridaben+abamectin and the sequence of pyridaben followed by abamectin would effectively retard resistance evolution.
文摘A field experiment was carried out to study nutrient balance among N, P, K and Mg in potato cultivation on an acid purple soil in Chongqing, China. The experiment included 8 treatments with equal P rate of 120 kg P2O5 hm-2: N0K2, N1K2, N2K2, N3K2, N2K0, N2K1, N2K1Mg and N2K3, where N0, N1, N2 and N3 stand for the N rates of 0, 75, 150 and 225 kg N hm-2, and K0, K1, K2 and K3 for the K rates of 0, 165, 330 and 495 kg K2O hm-2, respectively. Among the treatments designed, Thatment N2K2 with a nutrient supply ratio of N:P2O5:K2O:MgO = 1.25:1:2.75:0.28 gave the highest tuber yield and dry matter, highest starch and Zn and lowest NO3- contents in tuber, and high N, P and K use efficiency with an uptake ratio of N:P:K:Mg = 11.38:1:13.32:0.33 by tuber. Yield and starch and protein contents of tuber were the lowest in Treatment N0K2. Dry matter was the lowest but protein and NO3- contents were the highest in Treatment N2K0. Treatment N2K1Mg had the highest N, P and K utilization rates. Statistical analysis showed that yields of tuber and starch were in a positive linear correlation with the uptake amount of various nutrients and protein of the potato tuber was in a significantly positive linear correlation with tuber N cotent and in a significantly negative linear correlation with tuber K and Mg contents. Balanced application of N, P, K and Mg fertilizers (Treatmeat N2K2) was recommended for realization of high yield and good quality in potato cultivation.
文摘The chemical composition, total flavonoids and antioxidant capacity of 50% ethanolic extracts from raw and cooked buckwheat flour from southwest of China were determined. The heat treatment used to gelatinize the flour starch significantly reduced the total flavonoids in the extract from 83.52 to 67.36 mg 100 g 1 of dry matter in the raw and cooked flour, respectively. The antioxidant capacity of the extracts was evaluated using autooxidation in a β carotene linoleate model system (AA or AAC), DPPH radical scavenging assay (IP) and oxygen radical absorbance capacity (ORAC) assay. Values for raw buckwheat flour extract were 97.84, 874.31, 76.45 and 94.92% for AA, AAC, ORAC and IP, respectively, while values in cooked buckwheat flour were 86.14, 842.88, 63.93 and 94.74% for AA, AAC, ORAC and IP, respectively. Values before cooked and raw buckwheat flour extracts were significantly different ( P <0.05) for AA, AAC, and ORAC.
文摘A study was carried out on the transfer of native and added Ni towards plant both in different soils and at different time by using ^63 Ni tracer technique.The transfer of added Ni in soil was greater than native Ni and declined as time increased.The mobility was greater for soluble plus exchangeable fraction of soil Ni but very smaller for residual and Fe/Mn oxide bound fractions.These indicated that Ni was more mobile and more harmful in soils with a low pH and /or low content of Fe/Mn oxides.
基金the Applied Science Foundation of the Science and Technology Commission of Chongqing,China.
文摘The kinetic characteristics of P adsorption and desorption by organo-mineral colloidal complexes (OMC)were studied using acid, calcareous and neutral purple paddy soils taken from Chongqing and Sichuan, China.The results showed that the P adsorption capacity of the organo-mineral colloidal complexes differed with the soil types, being higher for the acid and calcareous purple soils than for the neutral purple soils. Partial removal of the organic matter increased the adsorption capacity of the colloidal complexes. A very significant positive correlation was found between the amounts of P desorbed from OMC and the P saturation degrees.The P adsorption reaction was quick at the early stage and slowed later. The raise of temperature increased P adsorption capacity and P adsorption rate of the colloidal complexes. The adsorption processes could be described by the Elovich equation.
基金the Ford-NSFC Foundation of China (No. 50122151).
文摘The most general contact in mechanical transmission is the elliptical one. In particular, a toroidal continuously variable transmission (CVT) has an elliptical shape in the contact area under the elastohydrodynamic lubrication regime, where the shearing of the fluid subjects to high contact stress and transmits the power. Many parameters affect the contact service performance of the half toroidal CVT, which include the properties of the contacting material (Young抯 modulus), operating parameters (input torque and maximum traction coefficient) and geometrical parameters (aspect cavity ratio, curvature ratio and half cone angle of the power roller). In this paper, the contacts between the input disk, the power roller and the output disk are formulated using the classical Hertzian contact theory. Based on the formulated equations, different system parameters, which affect the maximum Hertzian stresses, are compared. The comparative results will provide some observations of the relations between the maximum Hertzian stresses and transmission ratios in the form of graphs. These graphs give useful information for designer to know the maximum Hertzian stress during operation in such systems.
基金The research is part of the 863 Program in the Ministry of Science and Technology(2002AA207009,2003AA207131)the Key Program in the National Natural Science Foundation of China(30330400)the Foundation Program in the Committee of Science and Technology of Chongqing,China(2002-7274).
文摘Three pairs of near-isogenic lines with different genetic backgrounds of yellow-seededand black-seeded rape (Brassica napus L.) were used as experiment materials to study therelationship of color formation in the seedcoat with enzyme activity and protein contentin it. The results showed that with similar genetic backgrounds, phenylalanine ammonia-lyase (PAL) and polyphenol oxidase(PPO) activities in the black-seeded lines were muchhigher than in their yellow-seeded counterparts and maximum PAL activity in the seedcoatoccurred comparatively late while no significant difference was present in glutaminesynthetase (GS) between the two types of rape. The plants were treated with red light,blue light, p-hydroxybenzoic acid (a PAL inhibitor), polyvinylpyridoxal (a PPO inhibitor),urea (a protein synthesis promoter) or chloramphenicol (CM, a plastid protein synthesisinhibitor) during seed development. It is speculated that PAL may be primarily responsiblefor coloration in the yellow seed; PPO may be the main factor contributing to thedarkness of the testa of the black genotypes; and nitrogen assimilation is, probably, notdirectly related to the difference in protein content observed between yellow- andblack-seeded genotypes, which may be induced mainly by PAL.
文摘Particle size, rheological and thermal properties of potato starch from Yunnan province of China was in-vestigated. The particle size ranges from 0.429-102.3 um determined by laser light-scatter. The major flow type of 6 w/v% potato starch was shear-thinning fluid even the shear rate up to 800·s-1, and the gel formed by 6 w/v% potato starch fell to weak gel for its little difference between G' and G'', high dependence on frequency and low value of G'(Pa). The hardness and cohesiveness of potato starch gel were 31.3 g and 131.9 g·s, respectively. The thermal properties of potato starch were also determined by DSC at the starch:water=3:1. The To, Tp, and ΔH of potato starch were 62.23℃,67.31℃, and 2.22 J·g-1.
基金funded in part by the Nationa1 Natura1 Science Foundation(38800017)of ChinaFok Ying-Tung Education Foundation(71022).
文摘The cross resistance of four resistant strains of Liposcelis bostrychophila Badonnel, an important stored-product insect pest, was investigated. These four strains included the HCO2-R (hypercarbia-resistant strain), HCLO-R (hypoxia and hypercarbia resistant strain), DDVP-R (DDVP-resistant strain) and PH3-R (PH3-resistant strain). The results indicated that there were cross-resistances between CA and insecticides, and the quantities of the cross-resistance were different. The cross-resistance factor (RF) of HCO2-R to hypoxia and hypercarbia was 3.2458, whilst, that of HCLO-R to hypercarbia was 1.8280. The RF of DDVP-R to PH3 was 3.9614, whilst, that of PH3-R to DDVP was 2.7852. The RF values of DDVP- R and PH3-R to hypercarbia were 1.3550 and 1.1816, respectively. However, the RF of HCO2- R to DDVP was 2.1372. There also was a low cross-resistance between DDVP-R and HCO2-R. The RF of HCO2-R to PH3 was 3.3698. This suggested that the insects resistant to high CO2 concentration atmosphere would develop significant resistance to PH3. However, the insects resistant to PH3 remain sensitive to hypercarbia atmosphere. Both DDVP-R and PH3- R developed resistance to high CO2 treatment. There was a low cross-resistance between DDVP-R and HCLO-R. The insects resistant to hypoxia and hypercarbia were very sensitive to DDVP. There also was cross-resistance between HCLO-R and PH3-R, but the resistance of PH3-R to hypoxia and hypercarbia was lower than that of HCLO-R to PH3. The difference of the overlapping and separate values indicated that there were differences in the intercross-resistance of four resistant strains.
