A study was carried out on contribution of iron pbosphate to phosphorus nutrition of rice plant nnderwaterlogged and moist conditions, respectively, by use of synthetic Fe￣(32) PO_4 . nH_2O, tagging directly the iron...A study was carried out on contribution of iron pbosphate to phosphorus nutrition of rice plant nnderwaterlogged and moist conditions, respectively, by use of synthetic Fe￣(32) PO_4 . nH_2O, tagging directly the ironphophate in calcareous paddy soils.Results showed that under waterlogged condition, similar to iron phosphate in acidic paddy soils, that incalcareous paddy soils was an important source of phosphorus to rice plant, and the amount of phosphorusoriginated from it generally constituted 30-65% of the total phosphorus absorbed by rice plant.展开更多
Based on the strong chelating property of bathophenanthroline disulfonic acid (BPDS) with root chelate reductase activity is usually measured with a spectrophotometer using MES (2-morpholinoethanesulfonic acid) or HEP...Based on the strong chelating property of bathophenanthroline disulfonic acid (BPDS) with root chelate reductase activity is usually measured with a spectrophotometer using MES (2-morpholinoethanesulfonic acid) or HEPES (2-(4-(2-Hydroxyethyl)-1-piperazinyl) ethanesulfonic acid) buffer in the dark because of high autoreduction rate of in the presence of light. However, the exclusion of light is inconvenient, especially when analyzing a large number of samples. The objective of this study was to develop a new method for determination of root reductase activity under normal laboratory conditions using a suitable buffer composition and concentration to eliminate the autoreduction of A modified method using a Tris (2-amino-2-hydroxymethyl-1,3-propanediol) buffer at pH 7.5 instead of MES or HEPES buffer and a decreased FeEDTA (Fe ethylene diamine tetraacetic acid) concentration of 50 μmol L-1 was developed. The autoreduction of using the Tris buffer was undetectable for temperatures at 4 and 28 °C and was also much lower than that using the other buffers even with sunlight during measurement of reduction. Furthermore, the differences in reductase activity among 5 plant species and 14 red clover cultivars (Trifolium pratense L.) could be easily detected with the modified method. The method developed in this study to measure root Fe chelate reductase activity was not only effective and reliable but also easily managed under normal laboratory light conditions.展开更多
This paper deals with the determination of available Si content in calcareous soils with Mo blue colorimetric analysis method.The experimental results showed that two acid reagents of sodium acetate buffering solution...This paper deals with the determination of available Si content in calcareous soils with Mo blue colorimetric analysis method.The experimental results showed that two acid reagents of sodium acetate buffering solution (pH 4) and 0.025 mol/L citric acid generally had a strong ability of extracting soil available Si,and theri soil filtrates were colorless,On the contrary,two alkaline extractants of 20 mg/mL sodium carbonate and 0.5 mol/L sodium bicarbonate only got a relevantly lower soil avaiable Si and theri extracts appeared deep color of organic and other pigments,which could be decolorized by adding certain amounts of P-free activated charcoal (about 0.1g/g soil),Int the procedure of Mo blue colorimetry,adding proper amount of oxalic acid and K(SbO)C4H4O6 could eliminate the interference of P to Si and Si to P,respectively.The concentration of acids was not the major factor suppressing the interferences between P and Si in the colorimetric analysis.In the medium of 0.2-0.8mole H×＋／L sulfuric acid,the intensity of the silicomolybdate blue color did not vary with acidity,no matter whether(NH4)2 Fe(SO4)2 or ascorbic acid was used as reductive reagent.About 10 minutes was needed to from a fully blue complex at 20-25°C，After 30 minutes,the blue color would slowly change into light one,and hence,the colorimetric process should be finished within a short time.展开更多
文摘A study was carried out on contribution of iron pbosphate to phosphorus nutrition of rice plant nnderwaterlogged and moist conditions, respectively, by use of synthetic Fe￣(32) PO_4 . nH_2O, tagging directly the ironphophate in calcareous paddy soils.Results showed that under waterlogged condition, similar to iron phosphate in acidic paddy soils, that incalcareous paddy soils was an important source of phosphorus to rice plant, and the amount of phosphorusoriginated from it generally constituted 30-65% of the total phosphorus absorbed by rice plant.
基金1 Project supported by the National Natural Science Foundation of China (No. 40271065) and the Science and TechnologyAgency of Japan for Postdoctoral Fellows.
文摘Based on the strong chelating property of bathophenanthroline disulfonic acid (BPDS) with root chelate reductase activity is usually measured with a spectrophotometer using MES (2-morpholinoethanesulfonic acid) or HEPES (2-(4-(2-Hydroxyethyl)-1-piperazinyl) ethanesulfonic acid) buffer in the dark because of high autoreduction rate of in the presence of light. However, the exclusion of light is inconvenient, especially when analyzing a large number of samples. The objective of this study was to develop a new method for determination of root reductase activity under normal laboratory conditions using a suitable buffer composition and concentration to eliminate the autoreduction of A modified method using a Tris (2-amino-2-hydroxymethyl-1,3-propanediol) buffer at pH 7.5 instead of MES or HEPES buffer and a decreased FeEDTA (Fe ethylene diamine tetraacetic acid) concentration of 50 μmol L-1 was developed. The autoreduction of using the Tris buffer was undetectable for temperatures at 4 and 28 °C and was also much lower than that using the other buffers even with sunlight during measurement of reduction. Furthermore, the differences in reductase activity among 5 plant species and 14 red clover cultivars (Trifolium pratense L.) could be easily detected with the modified method. The method developed in this study to measure root Fe chelate reductase activity was not only effective and reliable but also easily managed under normal laboratory light conditions.
文摘This paper deals with the determination of available Si content in calcareous soils with Mo blue colorimetric analysis method.The experimental results showed that two acid reagents of sodium acetate buffering solution (pH 4) and 0.025 mol/L citric acid generally had a strong ability of extracting soil available Si,and theri soil filtrates were colorless,On the contrary,two alkaline extractants of 20 mg/mL sodium carbonate and 0.5 mol/L sodium bicarbonate only got a relevantly lower soil avaiable Si and theri extracts appeared deep color of organic and other pigments,which could be decolorized by adding certain amounts of P-free activated charcoal (about 0.1g/g soil),Int the procedure of Mo blue colorimetry,adding proper amount of oxalic acid and K(SbO)C4H4O6 could eliminate the interference of P to Si and Si to P,respectively.The concentration of acids was not the major factor suppressing the interferences between P and Si in the colorimetric analysis.In the medium of 0.2-0.8mole H×＋／L sulfuric acid,the intensity of the silicomolybdate blue color did not vary with acidity,no matter whether(NH4)2 Fe(SO4)2 or ascorbic acid was used as reductive reagent.About 10 minutes was needed to from a fully blue complex at 20-25°C，After 30 minutes,the blue color would slowly change into light one,and hence,the colorimetric process should be finished within a short time.
