The objective is to study whether the accumulation and utilization of plant N are controlled by Mo status in winter wheat cultivars. Mo-efficient cultivar 97003 （eft） and Mo-inefficient cultivar 97014 （ineff） were...The objective is to study whether the accumulation and utilization of plant N are controlled by Mo status in winter wheat cultivars. Mo-efficient cultivar 97003 （eft） and Mo-inefficient cultivar 97014 （ineff） were grown in severely Mo-deficient acidic soil （Tamm-reagent-extractable Mo 0.112 mg kg^-1） with （＋Mo） and without （-Mo） the application of 0.13 mg kg^-1 Mo. The accumulation and use efficiency of plant total N were significantly higher in ＋Mo than that in -Mo and in eft than that in ineff under Mo deficiency. N use efficiency was remarkably higher in maturity but it was forwarded to jointing stage after Mo supply, thus indicating that Mo supply promoted the N use efficiency besides N uptake and eff was efficient in N uptake and utilization. The overall activity of nitrate reductase （NR, EC 1.6.6.1） was significantly higher in ＋Mo than in -Mo and ratio of ＋Mo/-Mo was even to 14.8 at filleting stage for ineff. Activity of glutamine synthetase （GS, EC 6.3.1.2） was significantly lower in ＋Mo than in -Mo. Concentration of nitrate and glutamate were also significantly lower in ＋Mo than in -Mo, thus provided evidences for enhancing N use efficiency by Mo supply. Activities of NR and GS were significantly higher and concentrations of nitrate and glutamate were significantly lower in eff than ineff under Mo deficiency, thus indicated eff was more efficient in N reduction and utilization. It is therefore concluded that Mo could promote N accumulation and utilization in winter wheat which was directly related to NR and feedback regulated by GS. Higher Mo status also results in higher accumulation and utilization of plant N in eft.展开更多
The objective was to probe the site where the biosynthesis of chlorophyll was blocked under Mo deficiency at low temperature, which led to the decrease of chlorophyll in winter wheat cultivars. The intermediates of ch...The objective was to probe the site where the biosynthesis of chlorophyll was blocked under Mo deficiency at low temperature, which led to the decrease of chlorophyll in winter wheat cultivars. The intermediates of chlorophyll biosynthesis were analyzed in winter wheat cultivars in soil culture, miniblock culture, and solution culture to study the effects of Mo on chlorophyll biosynthesis without Mo addition （CK, soil available Mo 0.112 mg kg^-1） and Mo addition （＋ Mo, 0.13 mg kg^-1 Mo was added）. Laevulinic acid （LA）, the competitive analog of δ-aminolaevulinic acid （ALA） was also introduced in the experiment. The ratio of Chl a/Chl b was constant between CK and ＋ Mo treatment, whereas it increased at low temperature, which indicated that Mo deficiency did not inhibit the transformation of Chl a to Chl b at low temperature. Under Mo deficiency, the contents of protochlorophyll （Pchl）, Mg-protoporphyrin Ⅸ （Mg-Proto Ⅸ）, protoporphyrin Ⅸ （proto IX）, and uroporphyrinogen Ⅲ （Uro Ⅲ） decreased [Uro Ⅲ decreased significantly （P 〈0.01）], whereas ALA and glutamate increased significantly （P 〈 0.01） compared with that of Mo addition, which suggested that the transformation from ALA to Uro Ⅲ might be inhibited. The content of ALA reversed after addition of LA, it was significantly higher （P 〈 0.01） in Mo addition than in CK. The results indicated that the transformation from ALA to Uro Ⅲ was blocked under Mo deficiency, which resulted in the inhibition of the biosynthesis of chlorophyll and led to the decrease of chlorophyll in winter wheat cultivars.展开更多
Straw return is an effective management practice. It not only utilizes agricultural waste but also introduces dissolved organic matter(DOM) into the soil. Selenium(Se) is an essential trace element in the human diet a...Straw return is an effective management practice. It not only utilizes agricultural waste but also introduces dissolved organic matter(DOM) into the soil. Selenium(Se) is an essential trace element in the human diet and contributes to the popularity of Se-enriched agricultural products in the Chinese market. Moreover, there are still some Se-enriched agricultural products that have yet to be utilized. This study investigated whether Se addition in soil caused component changes in the DOM extracted from rape straw. DOM extracted from rape straw grown in soil with four Se levels(0, 0.1, 0.5 and 1.0 mg Se kg-1 soil) was characterized by UV-Visible spectroscopy, fluorescence spectroscopy and FTIR spectroscopy. The UVvisible spectra revealed that 0.1 mg Se kg-1 soil reduced the molecular weight of DOM and caused the presence of more irreplaceable aromatic structures in the substituent groups of the DOM, while 0.5 and 1.0 mg Se kg-1 soil only reduced the DOM molecular weight. Fluorescence spectroscopy indicated that Se improved the humification degree but reduced the aromaticity of DOM. FTIR spectra proved that Se altered the contents of carboxylic acids, amino acids, alcohols and aromatic heterocycles in DOM, which were maximized in the 0.5 and 1.0 mg Se kg-1 treatment groups. We concluded that Se application could change the composition of DOM extracted from rape straw, potentially impacting the nutrient bioavailability in soil. This study provides basic data on Se-enriched rape straw utilization for eco-agriculture.展开更多
Pollution in urban zoos arises from diffuse and small point sources. However, its control has received little attention in past decades. Online and ofttine modes of ecological engineering technology were designed to c...Pollution in urban zoos arises from diffuse and small point sources. However, its control has received little attention in past decades. Online and ofttine modes of ecological engineering technology were designed to control pollution from small point and diffuse sources in Wuhan City Zoo, China. Their characteristics and performances were investigated in sixteen runoff events from 2003 to 2005. The results showed that the two modes both improved runoff water quality and had high retention rates for water and pollutants. In the outflows, the event mean concentrations （EMCs） of total suspended solids （TSS）, chemical oxygen demand （COD）, total nitrogen （TN） and total phosphorus （TP） were reduced by 88%, 59%, 46% and 71% for the online mode, and those were 77%, 42%, 50% and 66% for the ofttine mode. The annual retention rates of pollutant loads for the online mode were 94.9%-98.5% in the three study years; those for the ofitine mode were 70.5%-86.4%. Based on calculation, the online mode was able to store the runoff of 66.7 mm rainfall completely, and the ofttine mode could store that of 31.3 mm rainfall. In addition, the online mode can provide an effective way for rainwater utilization and good habitats for aquatic wildlives, and has an excellent aesthetics value for recreationsal pastimes. The ofiline mode can save land resources and may be an effective and economical measure for diffuse pollution control in urban areas.展开更多
基金Financial supports by the National Natural Science Foun-dation of China (30070431)the Key Technologies R&D Program of China during the 9th Five-Year Plan period(95-Agric-18-04)+1 种基金the Doctoral Fund of Ministry of Edu-cation of China (200805041061)the Earmarked Fund for Modern Agro-Industry Technology Research System, China
文摘The objective is to study whether the accumulation and utilization of plant N are controlled by Mo status in winter wheat cultivars. Mo-efficient cultivar 97003 （eft） and Mo-inefficient cultivar 97014 （ineff） were grown in severely Mo-deficient acidic soil （Tamm-reagent-extractable Mo 0.112 mg kg^-1） with （＋Mo） and without （-Mo） the application of 0.13 mg kg^-1 Mo. The accumulation and use efficiency of plant total N were significantly higher in ＋Mo than that in -Mo and in eft than that in ineff under Mo deficiency. N use efficiency was remarkably higher in maturity but it was forwarded to jointing stage after Mo supply, thus indicating that Mo supply promoted the N use efficiency besides N uptake and eff was efficient in N uptake and utilization. The overall activity of nitrate reductase （NR, EC 1.6.6.1） was significantly higher in ＋Mo than in -Mo and ratio of ＋Mo/-Mo was even to 14.8 at filleting stage for ineff. Activity of glutamine synthetase （GS, EC 6.3.1.2） was significantly lower in ＋Mo than in -Mo. Concentration of nitrate and glutamate were also significantly lower in ＋Mo than in -Mo, thus provided evidences for enhancing N use efficiency by Mo supply. Activities of NR and GS were significantly higher and concentrations of nitrate and glutamate were significantly lower in eff than ineff under Mo deficiency, thus indicated eff was more efficient in N reduction and utilization. It is therefore concluded that Mo could promote N accumulation and utilization in winter wheat which was directly related to NR and feedback regulated by GS. Higher Mo status also results in higher accumulation and utilization of plant N in eft.
基金This study was financed by National Natural Science Foundation of China(NSFC,30070431 and 39770428)the Key Project under Nineth Five-Year Plan of China Agricultural Administration(Agriculture 95-18-04).
文摘The objective was to probe the site where the biosynthesis of chlorophyll was blocked under Mo deficiency at low temperature, which led to the decrease of chlorophyll in winter wheat cultivars. The intermediates of chlorophyll biosynthesis were analyzed in winter wheat cultivars in soil culture, miniblock culture, and solution culture to study the effects of Mo on chlorophyll biosynthesis without Mo addition （CK, soil available Mo 0.112 mg kg^-1） and Mo addition （＋ Mo, 0.13 mg kg^-1 Mo was added）. Laevulinic acid （LA）, the competitive analog of δ-aminolaevulinic acid （ALA） was also introduced in the experiment. The ratio of Chl a/Chl b was constant between CK and ＋ Mo treatment, whereas it increased at low temperature, which indicated that Mo deficiency did not inhibit the transformation of Chl a to Chl b at low temperature. Under Mo deficiency, the contents of protochlorophyll （Pchl）, Mg-protoporphyrin Ⅸ （Mg-Proto Ⅸ）, protoporphyrin Ⅸ （proto IX）, and uroporphyrinogen Ⅲ （Uro Ⅲ） decreased [Uro Ⅲ decreased significantly （P 〈0.01）], whereas ALA and glutamate increased significantly （P 〈 0.01） compared with that of Mo addition, which suggested that the transformation from ALA to Uro Ⅲ might be inhibited. The content of ALA reversed after addition of LA, it was significantly higher （P 〈 0.01） in Mo addition than in CK. The results indicated that the transformation from ALA to Uro Ⅲ was blocked under Mo deficiency, which resulted in the inhibition of the biosynthesis of chlorophyll and led to the decrease of chlorophyll in winter wheat cultivars.
基金This work was supported by the National Natural Science Foundation of China(41571321 and 31201501)the Fundamental Research Funds for the Central Universities of China(2662018JC057)the Opening Project of Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality,Ministry of Agriculture and Rural Affairs of China(NK201702).
文摘Straw return is an effective management practice. It not only utilizes agricultural waste but also introduces dissolved organic matter(DOM) into the soil. Selenium(Se) is an essential trace element in the human diet and contributes to the popularity of Se-enriched agricultural products in the Chinese market. Moreover, there are still some Se-enriched agricultural products that have yet to be utilized. This study investigated whether Se addition in soil caused component changes in the DOM extracted from rape straw. DOM extracted from rape straw grown in soil with four Se levels(0, 0.1, 0.5 and 1.0 mg Se kg-1 soil) was characterized by UV-Visible spectroscopy, fluorescence spectroscopy and FTIR spectroscopy. The UVvisible spectra revealed that 0.1 mg Se kg-1 soil reduced the molecular weight of DOM and caused the presence of more irreplaceable aromatic structures in the substituent groups of the DOM, while 0.5 and 1.0 mg Se kg-1 soil only reduced the DOM molecular weight. Fluorescence spectroscopy indicated that Se improved the humification degree but reduced the aromaticity of DOM. FTIR spectra proved that Se altered the contents of carboxylic acids, amino acids, alcohols and aromatic heterocycles in DOM, which were maximized in the 0.5 and 1.0 mg Se kg-1 treatment groups. We concluded that Se application could change the composition of DOM extracted from rape straw, potentially impacting the nutrient bioavailability in soil. This study provides basic data on Se-enriched rape straw utilization for eco-agriculture.
基金Project supported by the Hi-Tech Research and Development Program (863)of China(No. 2002AA601022)the Hi-Tech Research and Development Program of Tianjin(No. 06FZZDSH00900).
文摘Pollution in urban zoos arises from diffuse and small point sources. However, its control has received little attention in past decades. Online and ofttine modes of ecological engineering technology were designed to control pollution from small point and diffuse sources in Wuhan City Zoo, China. Their characteristics and performances were investigated in sixteen runoff events from 2003 to 2005. The results showed that the two modes both improved runoff water quality and had high retention rates for water and pollutants. In the outflows, the event mean concentrations （EMCs） of total suspended solids （TSS）, chemical oxygen demand （COD）, total nitrogen （TN） and total phosphorus （TP） were reduced by 88%, 59%, 46% and 71% for the online mode, and those were 77%, 42%, 50% and 66% for the ofttine mode. The annual retention rates of pollutant loads for the online mode were 94.9%-98.5% in the three study years; those for the ofitine mode were 70.5%-86.4%. Based on calculation, the online mode was able to store the runoff of 66.7 mm rainfall completely, and the ofttine mode could store that of 31.3 mm rainfall. In addition, the online mode can provide an effective way for rainwater utilization and good habitats for aquatic wildlives, and has an excellent aesthetics value for recreationsal pastimes. The ofiline mode can save land resources and may be an effective and economical measure for diffuse pollution control in urban areas.
