The study aimed to investigate the fast and nondestructive method for detecting carbon and nitrogen content in citrus canopy.The multispectral imagery of Tarocco blood orange(Citrus sinensis L.Osbeck)plant canopy was ...The study aimed to investigate the fast and nondestructive method for detecting carbon and nitrogen content in citrus canopy.The multispectral imagery of Tarocco blood orange(Citrus sinensis L.Osbeck)plant canopy was obtained by a multispectral camera array mounted at an eight-rotor unmanned aerial vehicle(UAV)flying at an altitude of 100 m above the canopy in Wanzhou District of Chongqing Municipality,China.Average spectral reflectance data of the whole canopy,mature leaf areas and young leaves areas were extracted from the imagery.Two spectral pre-processing methods,multiplicative scatter correction(MSC)and standard normal variable(SNV),and two modeling methods,the partial least squares(PLS)and the least squares support vector machine(LS-SVM),were adopted and compared for their prediction accuracy of total content of nitrogen,soluble sugar and starch in the leaves.The results showed that,based on the spectral data extracted from the mature leaves in the multispectral imagery,the PLS model based on the original spectrum obtained a Rp(correlation coefficient)of 0.6469 and RMSEP(root mean squares error of prediction)of 0.1296,suggested that it was the best for the prediction of total nitrogen content;the PLS model based on MSC(multiplicative scatter correction)spectrum pre-processing was the best for predicting total soluble sugar content(Rp=0.6398 and RMSEP=8.8891);and the LS-SVM model based on MSC was the best for the starch content prediction(Rp=0.6822 and RMSEP=14.9303).The prediction accuracy for carbon and nitrogen contents based on the spectral data extracted from the whole canopy and the young leaves were lower than that from the mature leaves.The results indicate that it is feasible to estimate the carbon and nitrogen contents by low-altitude airborne multispectral images.展开更多
The need to accurately estimate gaseous nitrogen losses from soils is required to have a better understanding of the processes involved as well as soil and environmental conditions, and management practices contributi...The need to accurately estimate gaseous nitrogen losses from soils is required to have a better understanding of the processes involved as well as soil and environmental conditions, and management practices contributing to these emissions. The objective was to quantify the denitrification rate using undisturbed cores with acetylene, as related to nitrogen (N) fertilization rate in a spring wheat crop (Triticum aestivum L.) under conventional tillage. Soil denitrification losses remained low throughout most of the growing season, when water-filled pore space (WFPS) was below 60%, ranging from 0.79 to 447.3 g N2O-N ha-1•day-1 in the fertilized plot and was less than 47.3 g N2O-N ha-1•day-1 in the control. Denitrification rates were the highest when N fertilizer was applied after frequent and intensive rain. A good correlation was found between the logarithm of the daily denitrification rate and WFPS (r = 0.67, n = 90);however the NO3-N concentration was not a good indicator (r = 0.21, n = 90). Cumulative N2O-N losses by denitrification averaged 3.5 and 0.9 kg N2O-N ha-1 in the fertilized and unfertilized treatment, respectively, during a period of 4 months this difference was not significant. Most N2O-N losses occurred early in the spring;therefore sampling schedules need to focus on this period.展开更多
森林生态系统作为生物圈的重要组成部分,维持着全球植被碳库的86%和土壤碳库的40%（Houghton et al.,2001;胡会峰等,2006）。因此,森林在调节全球气候、维持全球碳平衡方面起着非常重要的作用（Fang et al.,2001;Woodbury et al.,2007;H...森林生态系统作为生物圈的重要组成部分,维持着全球植被碳库的86%和土壤碳库的40%（Houghton et al.,2001;胡会峰等,2006）。因此,森林在调节全球气候、维持全球碳平衡方面起着非常重要的作用（Fang et al.,2001;Woodbury et al.,2007;Hu et al.,2008）。然而,展开更多
利用农田开放式空气CO2浓度增高(free air CO2 enrichment,FACE)系统,CO2浓度设正常CO2(ambient,AMB)和高CO2(FACE,AMB+200μmol/mol)2个水平,施N量设低氮(LN,15g/m2,以纯氮计)、中氮(NN,25g/m2)和高氮(HN,35g/m2)3个水平,对水稻品种武...利用农田开放式空气CO2浓度增高(free air CO2 enrichment,FACE)系统,CO2浓度设正常CO2(ambient,AMB)和高CO2(FACE,AMB+200μmol/mol)2个水平,施N量设低氮(LN,15g/m2,以纯氮计)、中氮(NN,25g/m2)和高氮(HN,35g/m2)3个水平,对水稻品种武香粳14结实期剑叶和倒2叶的内肽酶活力变化情况进行了研究。结果表明:1)同AMB相比,FACE处理使剑叶抽穗后10d、20d以及倒2叶抽穗到抽穗后20 d内肽酶活力明显提高,但使剑叶成熟期内肽酶活力明显下降;使剑叶抽穗后10d、20d和成熟期以及倒2叶抽穗到成熟期内肽酶比活力明显提高;FACE对抽穗后10d、20d叶片内肽酶活力和比活力影响较大,而对抽穗期和成熟期的影响较小。同LN相比,HN使灌浆前期叶片内肽酶活力明显降低,灌浆中后期则呈增加趋势;HN降低了叶片各期内肽酶比活力,灌浆前期降幅大于后期。2)同AMB相比,FACE使叶片抽穗后10d至成熟期可溶性蛋白含量明显降低;同LN相比,HN明显减缓FACE处理对抽穗后10d至成熟期功能叶片可溶性蛋白含量的影响。3)除成熟期叶片可溶性蛋白含量与内肽酶活力呈正相关外,结实期剑叶及倒2叶可溶性蛋白含量与对应时期内肽酶活力呈显著负相关。上述结果说明,FACE处理下水稻剑叶及倒2叶结实中后期可溶性蛋白含量明显下降与结实期叶片内肽酶活力的变化关系密切。展开更多
基金the International Science&Technology Cooperation Program of China(2013DFA11470)National Science&Technology Pillar Program(2014BAD16B0103)+2 种基金Chongqing Science&Technology support demonstration project(cstc2014fazktpt80015)Jiangxi Province 2011 Collaborative Innovation Special Funds“Co-Innovation Center of the South China Mountain Orchard Intelligent Management Technology and Equipment”(Jiangxi Finance Refers to[2014]NO 156)Chongqing Key Laboratory of Citrus(CKLC201302).
文摘The study aimed to investigate the fast and nondestructive method for detecting carbon and nitrogen content in citrus canopy.The multispectral imagery of Tarocco blood orange(Citrus sinensis L.Osbeck)plant canopy was obtained by a multispectral camera array mounted at an eight-rotor unmanned aerial vehicle(UAV)flying at an altitude of 100 m above the canopy in Wanzhou District of Chongqing Municipality,China.Average spectral reflectance data of the whole canopy,mature leaf areas and young leaves areas were extracted from the imagery.Two spectral pre-processing methods,multiplicative scatter correction(MSC)and standard normal variable(SNV),and two modeling methods,the partial least squares(PLS)and the least squares support vector machine(LS-SVM),were adopted and compared for their prediction accuracy of total content of nitrogen,soluble sugar and starch in the leaves.The results showed that,based on the spectral data extracted from the mature leaves in the multispectral imagery,the PLS model based on the original spectrum obtained a Rp(correlation coefficient)of 0.6469 and RMSEP(root mean squares error of prediction)of 0.1296,suggested that it was the best for the prediction of total nitrogen content;the PLS model based on MSC(multiplicative scatter correction)spectrum pre-processing was the best for predicting total soluble sugar content(Rp=0.6398 and RMSEP=8.8891);and the LS-SVM model based on MSC was the best for the starch content prediction(Rp=0.6822 and RMSEP=14.9303).The prediction accuracy for carbon and nitrogen contents based on the spectral data extracted from the whole canopy and the young leaves were lower than that from the mature leaves.The results indicate that it is feasible to estimate the carbon and nitrogen contents by low-altitude airborne multispectral images.
文摘The need to accurately estimate gaseous nitrogen losses from soils is required to have a better understanding of the processes involved as well as soil and environmental conditions, and management practices contributing to these emissions. The objective was to quantify the denitrification rate using undisturbed cores with acetylene, as related to nitrogen (N) fertilization rate in a spring wheat crop (Triticum aestivum L.) under conventional tillage. Soil denitrification losses remained low throughout most of the growing season, when water-filled pore space (WFPS) was below 60%, ranging from 0.79 to 447.3 g N2O-N ha-1•day-1 in the fertilized plot and was less than 47.3 g N2O-N ha-1•day-1 in the control. Denitrification rates were the highest when N fertilizer was applied after frequent and intensive rain. A good correlation was found between the logarithm of the daily denitrification rate and WFPS (r = 0.67, n = 90);however the NO3-N concentration was not a good indicator (r = 0.21, n = 90). Cumulative N2O-N losses by denitrification averaged 3.5 and 0.9 kg N2O-N ha-1 in the fertilized and unfertilized treatment, respectively, during a period of 4 months this difference was not significant. Most N2O-N losses occurred early in the spring;therefore sampling schedules need to focus on this period.
文摘森林生态系统作为生物圈的重要组成部分,维持着全球植被碳库的86%和土壤碳库的40%（Houghton et al.,2001;胡会峰等,2006）。因此,森林在调节全球气候、维持全球碳平衡方面起着非常重要的作用（Fang et al.,2001;Woodbury et al.,2007;Hu et al.,2008）。然而,
文摘利用农田开放式空气CO2浓度增高(free air CO2 enrichment,FACE)系统,CO2浓度设正常CO2(ambient,AMB)和高CO2(FACE,AMB+200μmol/mol)2个水平,施N量设低氮(LN,15g/m2,以纯氮计)、中氮(NN,25g/m2)和高氮(HN,35g/m2)3个水平,对水稻品种武香粳14结实期剑叶和倒2叶的内肽酶活力变化情况进行了研究。结果表明:1)同AMB相比,FACE处理使剑叶抽穗后10d、20d以及倒2叶抽穗到抽穗后20 d内肽酶活力明显提高,但使剑叶成熟期内肽酶活力明显下降;使剑叶抽穗后10d、20d和成熟期以及倒2叶抽穗到成熟期内肽酶比活力明显提高;FACE对抽穗后10d、20d叶片内肽酶活力和比活力影响较大,而对抽穗期和成熟期的影响较小。同LN相比,HN使灌浆前期叶片内肽酶活力明显降低,灌浆中后期则呈增加趋势;HN降低了叶片各期内肽酶比活力,灌浆前期降幅大于后期。2)同AMB相比,FACE使叶片抽穗后10d至成熟期可溶性蛋白含量明显降低;同LN相比,HN明显减缓FACE处理对抽穗后10d至成熟期功能叶片可溶性蛋白含量的影响。3)除成熟期叶片可溶性蛋白含量与内肽酶活力呈正相关外,结实期剑叶及倒2叶可溶性蛋白含量与对应时期内肽酶活力呈显著负相关。上述结果说明,FACE处理下水稻剑叶及倒2叶结实中后期可溶性蛋白含量明显下降与结实期叶片内肽酶活力的变化关系密切。
