This review article describes the research progresses on the control of ginseng gray mold, summarizes domestic and international related experimental re-sults and literature data using chemical fungicide, plant extrac...This review article describes the research progresses on the control of ginseng gray mold, summarizes domestic and international related experimental re-sults and literature data using chemical fungicide, plant extracts, microbial prepara-tion and antagonistic bacteria to control ginseng gray mold, and final y puts forward the existing problem and future research direction of the treatment and control of ginseng gray mold.展开更多
A total of 348 species belonging to 8 phyla and 125 genera were observed in seasonally sampled phytoplankton of tidal rivers from 13 sampling sites around Luoyuan Bay, and all field samplings were carried out in produ...A total of 348 species belonging to 8 phyla and 125 genera were observed in seasonally sampled phytoplankton of tidal rivers from 13 sampling sites around Luoyuan Bay, and all field samplings were carried out in productive period(March/June/August/December) at ebb tide. Bacillariophyta species were the most abundant species, followed by Chlorophyta, Cyanophytes, Euglenophyta, Cryptophyta, Dinophyta, Xanthophyta and Chrysophytas. Seasonal distribution index(SDI) value ranged from 0.63 to 0.86, which meant that species found at those sites in 4 seasons tended to be largely different. Phytoplankton individuals ranged from 5.939×10~4 ind L^(-1) in winter to 75.31×10~4 ind L^(-1) in autumn. Phytoplankton biomass ranged from 0.620 mg L^(-1) in summer to 2.373 mg L^(-1) in autumn. The grey correlation analysis(GCA) showed that the nutrient variables played an important role in the influence on phytoplankton community in every season. The canonical correspondence analysis(CCA) revealed impact of environmental variables on the different species, most of Bacillariophyta species were negative correlation with nutrients(TP and NH_3-N) in the four seasons, Chlorophyta species and Cyanophyta species did not show obvious correlation with environment variables in every season. The combination of GRA analysis and CCA analysis provided a method to quantitatively reveal the correlation between phytoplankton community and environmental variables in water body of tidal rivers at this region.展开更多
The capacities of two arbuscular mycorrhizal (AM) fungi, Glomusmosseae and Glomus versiforme, to mineralize added organic P werestudied in a sterilized clacareous soil. Mycorrhizal (inoculated witheither of the AM fun...The capacities of two arbuscular mycorrhizal (AM) fungi, Glomusmosseae and Glomus versiforme, to mineralize added organic P werestudied in a sterilized clacareous soil. Mycorrhizal (inoculated witheither of the AM fungi) and non-mycorrhizal red clover (Trifoliumpratense L.) plants were grown for eight weeks in pots with upperroot, central hyphal and lower soil compartments. The hyphal and soilcompartments received either organic P (as Na-phytte) or inorganic P(as KH_2PO_4) at the rate of 50 mg P kg^-1. No P was added to theroot compartments.展开更多
The formation constants of Co ̄(2+), Ni ̄(2+), Cu ̄(2+) and Zn ̄(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof...The formation constants of Co ̄(2+), Ni ̄(2+), Cu ̄(2+) and Zn ̄(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof composition of the complexation solutions were obtained by two graphical approaches respectively Theformation constants decreased with increasing concentration of metal in the solution. The results provideunambiguous evidence for the heterogeneity of the function groups of humic substances. The formationconstants of FA were much smaller than those of HA, and the formation constants of Cu ̄(2+) were muchgreater than those of Co ̄(2+) , Ni ̄(2+) and Zn ̄(2+) . The potentiometric titration method for determining formationconstants are also discussed in the article.展开更多
The pot experiment was carried out in this study to further explore the impact of plant nutrient, slaked lime, pokeberry root powder on cadmium (Cd) absorption by rice, and to screen practical agronomic measures whi...The pot experiment was carried out in this study to further explore the impact of plant nutrient, slaked lime, pokeberry root powder on cadmium (Cd) absorption by rice, and to screen practical agronomic measures which could reduce the accumulation of cadmium. In the control treatment nothing but water was sprayed into rice, while in other treatments, plant nutrient, slaked lime and pokeberry root powder were sprayed on rice at the tillering stage, the heading stage and the dough stage, respectively. The plant samples and soil samples were collected after the harvest and then analyzed on aimed indexes. The results showed that Cd contents in rice plants were significantly decreased, total Cd contents in brown rice were significantly (P〈0.05) decreased after rice was sprayed with plant nutrient, slaked lime and pokeberry root powder at different growing stages. However, while rice was sprayed with the three materials all at the tillering stage, the heading stage and the dough stage, the total Cd contents in brown rice were decreased by a maximum reduction that was 53.4% to 57.5% below that of the control, which was signifcantly (P〈0.05) lower than other treatments. Meanwhile, the biggest reduction of Cd inrice sprayed with the three materials at the tillering stage was 19.6% to 35.1% below that of the control, which was signifcantly (P〈0.05) lower than other treatments. In conclusion, spraying plant nutrient, slaked lime and pokeberry root powder on rice at different growing stages could not only reduce the absorption accumulation of Cd by root system, but also change the activities of rice and physical and chemical properties of soil, and then inhibit the absorption of Cd by the root system and the transfer of Cd in the rice plant. Therefore, the multiple factors may be the main causes of reducing Cd contents in the brown rice when the three materials are sprayed on rice at different growing stages.展开更多
In order to verify the possible use of ramie as feed for ruminants, a study was undertaken on the chemical and nutritional evaluation of different parts of this plant. Four stocks of samples picked up in two different...In order to verify the possible use of ramie as feed for ruminants, a study was undertaken on the chemical and nutritional evaluation of different parts of this plant. Four stocks of samples picked up in two different periods (summer and autumn) were analyzed. The standard chemical composition was determined on the whole plant and on its parts, the study was particularly focused on leaves and tops, not used in fibre production and available as livestock feed. Organic matter enzymic digestibility (OMD) was determined on all the samples by a double step method based on cellnlolytic andproteolytic enzymes. The chemical analysis showed good crude proteins content in leaves, tops and whole plant: 17.00 ~ 1.52%, 15.25 ~ 0.77% and 11.79 ~ 3.32% on dry matter (DM) basis respectively and good acid (ADF) and neutral (NDF) detergent fibre fractions. Lignin and ash resulted high in all plant parts and organic matter (OM) was consequently low, ash analysis showed high calcium concentration, especially in leaves, with values exceeding 4% of din, whereas the other micro (except the lead) and macroelements were in a normal range. OMD and energy values resulted poor in leaves, tops and in the whole plant and lower than the other forages commonly used as feed for runninants, thus the utilisation of ramie plant and its by-products requests further investigations.展开更多
A comparison of field performance of Acacia xanthophloea, Schinus molle, Casuarina equisetifolia and Gravellia robusta plant species was made in an exhausted limestone quarry, backfilled with limestone mine waste in a...A comparison of field performance of Acacia xanthophloea, Schinus molle, Casuarina equisetifolia and Gravellia robusta plant species was made in an exhausted limestone quarry, backfilled with limestone mine waste in a semi-arid area in Athi River, Kenya. The aim of the study was to determine if the tree species had an influence on the soil chemical properties. The soil had alkaline pH ranging from 8.0 to 8.98, low nitrogen content (〈 0.03%), moderate phosphorus concentrations ranging from 44.15 ppm to 21.33 ppm and high to moderate exchangeable cations (Na, Ca, Mg and K). All the tree species exerted a positive influence on soil properties necessary for plant growth. The pH values and total phosphorus were relatively lower in soils close to the trees (0.5 m) and increased with distance from the trees, while the soil values for total nitrogen and exchangeable cations were relatively higher close to the trees. C. equisetifolia had the best growth performance and a higher positive influence on the soil chemical properties necessary for plant growth followed by A. xanthophloea. It was concluded that trees should remain a feature of quarry rehabilitation because of their role in maintaining the biophysical environment.展开更多
A pot experiment was conducted with multi-metal (Pb, Cd, Cu, and Zn) contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes (fly ash and steel ...A pot experiment was conducted with multi-metal (Pb, Cd, Cu, and Zn) contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes (fly ash and steel slag). The efficiency of amendments- induced metal stabilization was evaluated by diffusive gradients in thin films (DGT), sequential extraction, and plant uptake. The stability of remediation was assessed by an acidification test and by chemical equilibrium modeling. Addition of fly ash (20 g kg-1) and steel slag (3 g kg-1) resulted in similar increase in soil pH. Both amendments significantly decreased the concentrations of metals measured with DGT (CDGT) and the metal uptake by Oryza sativa L. Significant correlations were found between CDGT and the concentration of a combination of metal fractions (exchangeable, bound to carbonates, and bound to Fe/Mn oxides), unraveling the labile species that participate in the flux of metal resupply. The capability of metal resupply, as reflected by the R (ratio of CDGT to pore water metal concentration) values, significantly decreased in the amended soils. The CDGT correlated well with the plant uptake, suggesting that DGT is a good indicator for bioavailability. Acidification raised the extractable metal concentration in amended soil but the concentration did not return to the pre-amendment level. Equilibrium modeling indicated that the soil amendments induced the precipitation of several Fe, A1 and Ca minerals, which may play a positive role in metal stabilization. Chemical stabilization with alkaline amendments could be an effective and stable soil remediation strategy for attenuating metal bioavailability and reducing plant metal uptake.展开更多
The toxicity of trace elements (TEs), such as copper (Cu), zinc (Zn), and cadmium (Cd), often restrict land application of sewage sludge (SS) and there was little information about soil-plant transfer of TEs...The toxicity of trace elements (TEs), such as copper (Cu), zinc (Zn), and cadmium (Cd), often restrict land application of sewage sludge (SS) and there was little information about soil-plant transfer of TEs in SS from field experiments in China. In this study pot and field experiments were carried out for 2 years to investigate the phytoavailability of TEs in calcareous soils amended with SS. The results of the pot experiment showed that the phytoavailability of Zn and Cu in the SS was equal to 53.4%-80.9% and 54.8%-91.1% of corresponding water-soluble metal salts, respectively. The results from the field experiment showed that the contents of total Zn, Cu, and Cd in the soils increased linearly with SS application rates. With increasing SS application rates, the contents of Zn and Cu in the wheat grains initially increased and then reached a plateau, while there was no significant change of Cd content in the maize grains. The bioconcentration factors of the metals in the grains of wheat and maize were found to he in the order of Zn 〉 Cu 〉 Cd, but for the straw the order was Cd 〉 Cu 〉 Zn. It was also found that wheat grains could accumulate more metals compared with maize grains. The results will be helpful in developing the critical loads of sewage sludge applied to calcareous soils.展开更多
Dicotyledons cope with ion(Fe) shortage by releasing low-molecular-weight organic compounds into the rhizosphere to mobilize Fe through reduction and complexation mechanisms. The effects induced by these root exudates...Dicotyledons cope with ion(Fe) shortage by releasing low-molecular-weight organic compounds into the rhizosphere to mobilize Fe through reduction and complexation mechanisms. The effects induced by these root exudates on soil mineralogy and the connections between Fe mobilization and mineral weathering processes have not been completely clarified. In a batch experiment, we tested two different kinds of organic compounds commonly exuded by Fe-deficient plants, i.e., three organic acids(citrate, malate, and oxalate)and three flavonoids(rutin, quercetin, and genistein), alone or in combination, for their ability to mobilize Fe from a calcareous soil and modify its mineralogy. The effect of root exudates on soil mineralogy was assessed in vivo by cultivating Fe-deficient and Fe-sufficient cucumber plants(Cucumis sativus L.) in a RHIZOtest device. Mineralogical analyses were performed by X-ray powder diffraction. The batch experiment showed that citrate and, particularly, rutin(alone or combined with organic acids or genistein)promoted Fe mobilization from the soil. The combinations of rutin and organic acids modified the soil mineralogy by dissolving the amorphous fractions and promoting the formation of illite. These mineralogical alterations were significantly correlated with the amount of Fe mobilized from the soil. The RHIZOtest experiment revealed a drastic dissolution of amorphous components in the rhizosphere soil of Fe-deficient plants, possibly caused by the intense release of phenolics, amino acids, and organic acids, but without any formation of illite. Both batch and RHIZOtest experiments proved that exudates released by cucumber under Fe deficiency concurred to the rapid modification(on a day-scale) of the mineralogy of a calcareous soil.展开更多
According to fixed-position data for 1992-2003 from 16 runoff plots of Caijiachuan watershed which lie in Jixian County, Shanxi Province, in the loess area, this paper studied the relationship between vegetation and r...According to fixed-position data for 1992-2003 from 16 runoff plots of Caijiachuan watershed which lie in Jixian County, Shanxi Province, in the loess area, this paper studied the relationship between vegetation and runoff and sedimentproduction on slope lands. The results showed as follows: 1) Runoffand sediment production in Robinia pseudoacacia forestand Pinus tabulaeformis forest had a high correlation with precipitation amount and rainfall intensity, but the correlation decreased gradually with the increase of canopy density; 2) The secondary forest had better function of soil and water conservation than artificial R. pseudoacacia forest, and runoff and sedimentproduction in the former in an individual rain event was 65%-82% and 23%-92% lower than thosein the latter, respectively;3) The difference ofrunoff and sediment production in several land uses was very distinct. Runoff and sediment production in Ostryopsisdavidiana forest and the secondary forest were the least; runoff and sediment production in artificial R. pseudoacacia forest and P. tabulaeformis forest were 5-fold as much as those in O. davidiana forest. Besides, runoff and sediment production in mixed stand of apple trees and cropswere 16.14-fold and 2.96-fold higher than that in O. davidiana forest, respectively, but theamount decreased obviously after high-standard soil preparation for theformer;4) Based on gray correlation analysis of variousfactorsaffecting runoffand sedimentproduction on slope lands, it can be seen that stand canopy density and herb and litter biomass werethe most significant ones, whosegray correlation valuesall exceeded 0.6. Therefore, mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation reconstruction of the loess area, which help to increase coverage and litter thicknessto cut down the runoffand sediment production dramatically on slope lands.展开更多
基金Supported by National Natural Science Fondation of China(31260067)Collegeenterprise Cooperation Project of Yanbian University[(2015)6]~~
文摘This review article describes the research progresses on the control of ginseng gray mold, summarizes domestic and international related experimental re-sults and literature data using chemical fungicide, plant extracts, microbial prepara-tion and antagonistic bacteria to control ginseng gray mold, and final y puts forward the existing problem and future research direction of the treatment and control of ginseng gray mold.
基金financially supported by China Shenhua Energy Company Limited
文摘A total of 348 species belonging to 8 phyla and 125 genera were observed in seasonally sampled phytoplankton of tidal rivers from 13 sampling sites around Luoyuan Bay, and all field samplings were carried out in productive period(March/June/August/December) at ebb tide. Bacillariophyta species were the most abundant species, followed by Chlorophyta, Cyanophytes, Euglenophyta, Cryptophyta, Dinophyta, Xanthophyta and Chrysophytas. Seasonal distribution index(SDI) value ranged from 0.63 to 0.86, which meant that species found at those sites in 4 seasons tended to be largely different. Phytoplankton individuals ranged from 5.939×10~4 ind L^(-1) in winter to 75.31×10~4 ind L^(-1) in autumn. Phytoplankton biomass ranged from 0.620 mg L^(-1) in summer to 2.373 mg L^(-1) in autumn. The grey correlation analysis(GCA) showed that the nutrient variables played an important role in the influence on phytoplankton community in every season. The canonical correspondence analysis(CCA) revealed impact of environmental variables on the different species, most of Bacillariophyta species were negative correlation with nutrients(TP and NH_3-N) in the four seasons, Chlorophyta species and Cyanophyta species did not show obvious correlation with environment variables in every season. The combination of GRA analysis and CCA analysis provided a method to quantitatively reveal the correlation between phytoplankton community and environmental variables in water body of tidal rivers at this region.
基金National Key Basic Research Support Foundation (NKBRSF) of China(No. G1999011807) the Joint Open Laboratory of Soil and Environment between the Institute of Soil Science of the Chinese Academy of Sciences and Hong Kong Baptist University.
文摘The capacities of two arbuscular mycorrhizal (AM) fungi, Glomusmosseae and Glomus versiforme, to mineralize added organic P werestudied in a sterilized clacareous soil. Mycorrhizal (inoculated witheither of the AM fungi) and non-mycorrhizal red clover (Trifoliumpratense L.) plants were grown for eight weeks in pots with upperroot, central hyphal and lower soil compartments. The hyphal and soilcompartments received either organic P (as Na-phytte) or inorganic P(as KH_2PO_4) at the rate of 50 mg P kg^-1. No P was added to theroot compartments.
文摘The formation constants of Co ̄(2+), Ni ̄(2+), Cu ̄(2+) and Zn ̄(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof composition of the complexation solutions were obtained by two graphical approaches respectively Theformation constants decreased with increasing concentration of metal in the solution. The results provideunambiguous evidence for the heterogeneity of the function groups of humic substances. The formationconstants of FA were much smaller than those of HA, and the formation constants of Cu ̄(2+) were muchgreater than those of Co ̄(2+) , Ni ̄(2+) and Zn ̄(2+) . The potentiometric titration method for determining formationconstants are also discussed in the article.
文摘The pot experiment was carried out in this study to further explore the impact of plant nutrient, slaked lime, pokeberry root powder on cadmium (Cd) absorption by rice, and to screen practical agronomic measures which could reduce the accumulation of cadmium. In the control treatment nothing but water was sprayed into rice, while in other treatments, plant nutrient, slaked lime and pokeberry root powder were sprayed on rice at the tillering stage, the heading stage and the dough stage, respectively. The plant samples and soil samples were collected after the harvest and then analyzed on aimed indexes. The results showed that Cd contents in rice plants were significantly decreased, total Cd contents in brown rice were significantly (P〈0.05) decreased after rice was sprayed with plant nutrient, slaked lime and pokeberry root powder at different growing stages. However, while rice was sprayed with the three materials all at the tillering stage, the heading stage and the dough stage, the total Cd contents in brown rice were decreased by a maximum reduction that was 53.4% to 57.5% below that of the control, which was signifcantly (P〈0.05) lower than other treatments. Meanwhile, the biggest reduction of Cd inrice sprayed with the three materials at the tillering stage was 19.6% to 35.1% below that of the control, which was signifcantly (P〈0.05) lower than other treatments. In conclusion, spraying plant nutrient, slaked lime and pokeberry root powder on rice at different growing stages could not only reduce the absorption accumulation of Cd by root system, but also change the activities of rice and physical and chemical properties of soil, and then inhibit the absorption of Cd by the root system and the transfer of Cd in the rice plant. Therefore, the multiple factors may be the main causes of reducing Cd contents in the brown rice when the three materials are sprayed on rice at different growing stages.
文摘In order to verify the possible use of ramie as feed for ruminants, a study was undertaken on the chemical and nutritional evaluation of different parts of this plant. Four stocks of samples picked up in two different periods (summer and autumn) were analyzed. The standard chemical composition was determined on the whole plant and on its parts, the study was particularly focused on leaves and tops, not used in fibre production and available as livestock feed. Organic matter enzymic digestibility (OMD) was determined on all the samples by a double step method based on cellnlolytic andproteolytic enzymes. The chemical analysis showed good crude proteins content in leaves, tops and whole plant: 17.00 ~ 1.52%, 15.25 ~ 0.77% and 11.79 ~ 3.32% on dry matter (DM) basis respectively and good acid (ADF) and neutral (NDF) detergent fibre fractions. Lignin and ash resulted high in all plant parts and organic matter (OM) was consequently low, ash analysis showed high calcium concentration, especially in leaves, with values exceeding 4% of din, whereas the other micro (except the lead) and macroelements were in a normal range. OMD and energy values resulted poor in leaves, tops and in the whole plant and lower than the other forages commonly used as feed for runninants, thus the utilisation of ramie plant and its by-products requests further investigations.
文摘A comparison of field performance of Acacia xanthophloea, Schinus molle, Casuarina equisetifolia and Gravellia robusta plant species was made in an exhausted limestone quarry, backfilled with limestone mine waste in a semi-arid area in Athi River, Kenya. The aim of the study was to determine if the tree species had an influence on the soil chemical properties. The soil had alkaline pH ranging from 8.0 to 8.98, low nitrogen content (〈 0.03%), moderate phosphorus concentrations ranging from 44.15 ppm to 21.33 ppm and high to moderate exchangeable cations (Na, Ca, Mg and K). All the tree species exerted a positive influence on soil properties necessary for plant growth. The pH values and total phosphorus were relatively lower in soils close to the trees (0.5 m) and increased with distance from the trees, while the soil values for total nitrogen and exchangeable cations were relatively higher close to the trees. C. equisetifolia had the best growth performance and a higher positive influence on the soil chemical properties necessary for plant growth followed by A. xanthophloea. It was concluded that trees should remain a feature of quarry rehabilitation because of their role in maintaining the biophysical environment.
基金Supported by the NSFC-Guangdong Joint Foundation of China(No.U0833004)the National Natural Science Foundation of China(No.41101483)the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2011),China
文摘A pot experiment was conducted with multi-metal (Pb, Cd, Cu, and Zn) contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes (fly ash and steel slag). The efficiency of amendments- induced metal stabilization was evaluated by diffusive gradients in thin films (DGT), sequential extraction, and plant uptake. The stability of remediation was assessed by an acidification test and by chemical equilibrium modeling. Addition of fly ash (20 g kg-1) and steel slag (3 g kg-1) resulted in similar increase in soil pH. Both amendments significantly decreased the concentrations of metals measured with DGT (CDGT) and the metal uptake by Oryza sativa L. Significant correlations were found between CDGT and the concentration of a combination of metal fractions (exchangeable, bound to carbonates, and bound to Fe/Mn oxides), unraveling the labile species that participate in the flux of metal resupply. The capability of metal resupply, as reflected by the R (ratio of CDGT to pore water metal concentration) values, significantly decreased in the amended soils. The CDGT correlated well with the plant uptake, suggesting that DGT is a good indicator for bioavailability. Acidification raised the extractable metal concentration in amended soil but the concentration did not return to the pre-amendment level. Equilibrium modeling indicated that the soil amendments induced the precipitation of several Fe, A1 and Ca minerals, which may play a positive role in metal stabilization. Chemical stabilization with alkaline amendments could be an effective and stable soil remediation strategy for attenuating metal bioavailability and reducing plant metal uptake.
基金Supported by the Beijing Drainage Group Co. Ltd. and the Special Fund for Agro-Scientific Research in the Public Interest of China (No. 200903015)
文摘The toxicity of trace elements (TEs), such as copper (Cu), zinc (Zn), and cadmium (Cd), often restrict land application of sewage sludge (SS) and there was little information about soil-plant transfer of TEs in SS from field experiments in China. In this study pot and field experiments were carried out for 2 years to investigate the phytoavailability of TEs in calcareous soils amended with SS. The results of the pot experiment showed that the phytoavailability of Zn and Cu in the SS was equal to 53.4%-80.9% and 54.8%-91.1% of corresponding water-soluble metal salts, respectively. The results from the field experiment showed that the contents of total Zn, Cu, and Cd in the soils increased linearly with SS application rates. With increasing SS application rates, the contents of Zn and Cu in the wheat grains initially increased and then reached a plateau, while there was no significant change of Cd content in the maize grains. The bioconcentration factors of the metals in the grains of wheat and maize were found to he in the order of Zn 〉 Cu 〉 Cd, but for the straw the order was Cd 〉 Cu 〉 Zn. It was also found that wheat grains could accumulate more metals compared with maize grains. The results will be helpful in developing the critical loads of sewage sludge applied to calcareous soils.
基金supported by grants from the Italian MIUR (FIRB-Programma Futuro in Ricerca) (No. RBFR127WJ9, RHIZOCROP)the Free University of Bolzano (No. TN5056), Italy
文摘Dicotyledons cope with ion(Fe) shortage by releasing low-molecular-weight organic compounds into the rhizosphere to mobilize Fe through reduction and complexation mechanisms. The effects induced by these root exudates on soil mineralogy and the connections between Fe mobilization and mineral weathering processes have not been completely clarified. In a batch experiment, we tested two different kinds of organic compounds commonly exuded by Fe-deficient plants, i.e., three organic acids(citrate, malate, and oxalate)and three flavonoids(rutin, quercetin, and genistein), alone or in combination, for their ability to mobilize Fe from a calcareous soil and modify its mineralogy. The effect of root exudates on soil mineralogy was assessed in vivo by cultivating Fe-deficient and Fe-sufficient cucumber plants(Cucumis sativus L.) in a RHIZOtest device. Mineralogical analyses were performed by X-ray powder diffraction. The batch experiment showed that citrate and, particularly, rutin(alone or combined with organic acids or genistein)promoted Fe mobilization from the soil. The combinations of rutin and organic acids modified the soil mineralogy by dissolving the amorphous fractions and promoting the formation of illite. These mineralogical alterations were significantly correlated with the amount of Fe mobilized from the soil. The RHIZOtest experiment revealed a drastic dissolution of amorphous components in the rhizosphere soil of Fe-deficient plants, possibly caused by the intense release of phenolics, amino acids, and organic acids, but without any formation of illite. Both batch and RHIZOtest experiments proved that exudates released by cucumber under Fe deficiency concurred to the rapid modification(on a day-scale) of the mineralogy of a calcareous soil.
基金Funded by National Science and Technology Research Program for the Tenth Five-Year (No. 2001BA510B01).
文摘According to fixed-position data for 1992-2003 from 16 runoff plots of Caijiachuan watershed which lie in Jixian County, Shanxi Province, in the loess area, this paper studied the relationship between vegetation and runoff and sedimentproduction on slope lands. The results showed as follows: 1) Runoffand sediment production in Robinia pseudoacacia forestand Pinus tabulaeformis forest had a high correlation with precipitation amount and rainfall intensity, but the correlation decreased gradually with the increase of canopy density; 2) The secondary forest had better function of soil and water conservation than artificial R. pseudoacacia forest, and runoff and sedimentproduction in the former in an individual rain event was 65%-82% and 23%-92% lower than thosein the latter, respectively;3) The difference ofrunoff and sediment production in several land uses was very distinct. Runoff and sediment production in Ostryopsisdavidiana forest and the secondary forest were the least; runoff and sediment production in artificial R. pseudoacacia forest and P. tabulaeformis forest were 5-fold as much as those in O. davidiana forest. Besides, runoff and sediment production in mixed stand of apple trees and cropswere 16.14-fold and 2.96-fold higher than that in O. davidiana forest, respectively, but theamount decreased obviously after high-standard soil preparation for theformer;4) Based on gray correlation analysis of variousfactorsaffecting runoffand sedimentproduction on slope lands, it can be seen that stand canopy density and herb and litter biomass werethe most significant ones, whosegray correlation valuesall exceeded 0.6. Therefore, mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation reconstruction of the loess area, which help to increase coverage and litter thicknessto cut down the runoffand sediment production dramatically on slope lands.