The hand-held soil plant analysis development （SPAD） chlorophyll meter nitrogen status of the potato and guiding fertilization recommendations N recommendation, it is critical to establish the threshold SPAD value h...The hand-held soil plant analysis development （SPAD） chlorophyll meter nitrogen status of the potato and guiding fertilization recommendations N recommendation, it is critical to establish the threshold SPAD value has proved to be a promising tool in evaluating the n the process of N evaluation of potato plants and （SPAD reading）, below which nitrogen supplement is required. And taking convenient using into account, the threshold needs to be dynamic throughout the potato growing season so that the users can test their potato plants and make fertilization decision at any growing time of potato. To complete this goal, field experiments with different nitrogen supply levels were conducted in different sites in northern China from 2009 to 2011. The results showed that threshold SPAD values decrease as the growing season progresses for all cultivars and planting sites. By statistical analysis, the threshold regression models were established respectively as： y=-0.003χ2-0.0507χ＋58.213 （y, threshold SPAD value; χ, days after emergence） for the potato cultivar Kexin 1, and y=-0.003χ2＋0.017χ＋52.489 （y, threshold SPAD value; χ, days after emergence） for the cultivar Shepody, from which, the threshold SPAD value at any day after emergence can be calculated.展开更多
Nitrogen （N） is one of the most important nutrients for oilseed rape （Brassica napus L . ） , but there is a lack of quick diagnosis and recommended fertilization. Three field experiments were con-ducted to see...Nitrogen （N） is one of the most important nutrients for oilseed rape （Brassica napus L . ） , but there is a lack of quick diagnosis and recommended fertilization. Three field experiments were con-ducted to seek the best diagnostic method and establish a fertilizer rate recommendation model. For ex-periment 1, six treatments as application N 0,90,180,240,300 and 400kg ha -1 were designed, and the general N nutrition diagnosis method as SPAD -502 chlorophyll meter, RQflex plus 10 nitrate reflectrom- eter and GreenSeeker - 505 spectrometer were used at eight leaf stage, tenth leaf stage and bolting stage of rape to determine the suitable nitrogen rapid diagnosis method and establish the model of yield forecast and N rate recommendation as topdressing. The experiment 2 was designed to validate the veracity of yield forecast model obtained from experiment 1. The experiment 3 was designed to test the accuracy of N rate recommendation model come from experiment 1. The results indicated that there is a preferable inter-relation between N application rates and rape yield for experiment 1 （ y = - 0. 0176x2 ＋ 11. 136x ＋797. 88 ,R2 =0. 9905 ＊ ＊ ） , which conform to the performance of yield variation with N application levels as shortage, appropriate and excessive rapeseed. For three diagnosis methods, nitrate reflectrometer could reflect rape N nutrition status to some extent, but which influenced by rapeseed physiological char-acteristics such as lower biomass at seedling stage and luxury absorption of N at bolting stage, and the re-liability and stability of diagnosis were inferior. Spectrometer is suitable for quick N nutrition diagnosis at bolting stage, but the stage of topdressing is too late to meet the demand of N support. SPAD meter could more suitable in quick N diagnosis of oilseed rapes since it could reflect rape N nutrition preferable, and it has some advantages such as the strong stability, easy measuring and lower cost in detection. By SPAD meter, model of yield forecast yforeCastyield =370. 517xSPAD value -13310.3 （x 〈42. 54） and recommended N rate yR_dedNrate =162.7-[（370.517xSPADTflliie- 13 10. 3 ）/10. 0617 - 76. 7398 ] （x〈42.54） were established. For experiment 2, the actual yield and forecast yield showed good correlation （y = 0. 5022 ＋2244. 3x, R2 =0. 7852 ＊ ） . For experiment 3 , the amount of topdressing N calculate from recommended N rate model were put forward, and the yield for different treatments had no significant difference. Total-ly ,SPAD chlorophyll meter could be used in quick N nutrition diagnosis, forecast yield and N recommen-dation of oilseed rape.展开更多
A number of optical sensing tools are now available and can potentially be used for refining need-based fertilizer nitrogen(N)topdressing decisions.Algorithms for estimating field-specific fertilizer N needs are based...A number of optical sensing tools are now available and can potentially be used for refining need-based fertilizer nitrogen(N)topdressing decisions.Algorithms for estimating field-specific fertilizer N needs are based on predictions of yield made while the crops are still growing in the field.The present study was conducted to establish and validate yield prediction models using spectral indices measured with proximal sensing using GreenSeeker canopy reflectance sensor,soil and plant analyzer development(SPAD)chlorophyll meter,and two different types of leaf color charts(LCCs)for five basmati rice genotypes across different growth stages.Regression analysis was performed using normalized difference vegetation index(NDVI)recorded with GreenSeeker sensor and leaf greenness indices measured with SPAD meter and LCCs developed by Punjab Agricultural University,Ludhiana(India)(PAU-LCC)and the International Rice Research Institute,Philippines(IRRI-LCC).The exponential relationship between NDVI and grain yield exhibited the highest coefficient of determination(R^(2))and minimum normalized root mean square error(NRMSE)at panicle initiation stage and explained 38.3%–76.4%variation in yield using genotype-specific models.Spectral indices pooled for different genotypes were closely related to grain yield at all growth stages and explained53.4%–57.2%variation in grain yield.Normalizing different spectral indices with cumulative growing degree days(CGDD)decreased the accuracy of yield prediction.Normalization with days after transplanting(DAT),however,did not reduce or improve the predictability of yield.The ability of each model to predict grain yield was validated with an independent dataset collected from two experiments conducted at different sites with a range of fertilizer N doses.The NDVI-based genotype-specific models exhibited a robust linear correlation(R^(2)=0.77,NRMSE=7.37%,n=180)between observed and predicted grain yields only at 35 DAT(i.e.,panicle initiation stage),while the SPAD,PAU-LCC,and IRRI-LCC consistently provided reliable predictions(with respective R^(2)of 0.63,0.60,and 0.53 and NRMSE of 10%,10%,and 13.6%)even with genotype invariant models with 900 data points obtained at different growth stages.The study revealed that unnormalized values of spectral indices,namely NDVI,SPAD,PAU-LCC,and IRRI-LCC,can be satisfactorily used for in-season estimation of grain yield for basmati rice.As LCCs are very economical compared with chlorophyll meters and canopy reflectance sensors,they can be preferably used by small farmers in developing countries.展开更多
基金supported by the National Nature Science Foundation of China (31360502)the Pre-973 Project of China (2012CB126307)the Inner Mongolia Nature Science Foundation, China (2013ZD04)
文摘The hand-held soil plant analysis development （SPAD） chlorophyll meter nitrogen status of the potato and guiding fertilization recommendations N recommendation, it is critical to establish the threshold SPAD value has proved to be a promising tool in evaluating the n the process of N evaluation of potato plants and （SPAD reading）, below which nitrogen supplement is required. And taking convenient using into account, the threshold needs to be dynamic throughout the potato growing season so that the users can test their potato plants and make fertilization decision at any growing time of potato. To complete this goal, field experiments with different nitrogen supply levels were conducted in different sites in northern China from 2009 to 2011. The results showed that threshold SPAD values decrease as the growing season progresses for all cultivars and planting sites. By statistical analysis, the threshold regression models were established respectively as： y=-0.003χ2-0.0507χ＋58.213 （y, threshold SPAD value; χ, days after emergence） for the potato cultivar Kexin 1, and y=-0.003χ2＋0.017χ＋52.489 （y, threshold SPAD value; χ, days after emergence） for the cultivar Shepody, from which, the threshold SPAD value at any day after emergence can be calculated.
文摘Nitrogen （N） is one of the most important nutrients for oilseed rape （Brassica napus L . ） , but there is a lack of quick diagnosis and recommended fertilization. Three field experiments were con-ducted to seek the best diagnostic method and establish a fertilizer rate recommendation model. For ex-periment 1, six treatments as application N 0,90,180,240,300 and 400kg ha -1 were designed, and the general N nutrition diagnosis method as SPAD -502 chlorophyll meter, RQflex plus 10 nitrate reflectrom- eter and GreenSeeker - 505 spectrometer were used at eight leaf stage, tenth leaf stage and bolting stage of rape to determine the suitable nitrogen rapid diagnosis method and establish the model of yield forecast and N rate recommendation as topdressing. The experiment 2 was designed to validate the veracity of yield forecast model obtained from experiment 1. The experiment 3 was designed to test the accuracy of N rate recommendation model come from experiment 1. The results indicated that there is a preferable inter-relation between N application rates and rape yield for experiment 1 （ y = - 0. 0176x2 ＋ 11. 136x ＋797. 88 ,R2 =0. 9905 ＊ ＊ ） , which conform to the performance of yield variation with N application levels as shortage, appropriate and excessive rapeseed. For three diagnosis methods, nitrate reflectrometer could reflect rape N nutrition status to some extent, but which influenced by rapeseed physiological char-acteristics such as lower biomass at seedling stage and luxury absorption of N at bolting stage, and the re-liability and stability of diagnosis were inferior. Spectrometer is suitable for quick N nutrition diagnosis at bolting stage, but the stage of topdressing is too late to meet the demand of N support. SPAD meter could more suitable in quick N diagnosis of oilseed rapes since it could reflect rape N nutrition preferable, and it has some advantages such as the strong stability, easy measuring and lower cost in detection. By SPAD meter, model of yield forecast yforeCastyield =370. 517xSPAD value -13310.3 （x 〈42. 54） and recommended N rate yR_dedNrate =162.7-[（370.517xSPADTflliie- 13 10. 3 ）/10. 0617 - 76. 7398 ] （x〈42.54） were established. For experiment 2, the actual yield and forecast yield showed good correlation （y = 0. 5022 ＋2244. 3x, R2 =0. 7852 ＊ ） . For experiment 3 , the amount of topdressing N calculate from recommended N rate model were put forward, and the yield for different treatments had no significant difference. Total-ly ,SPAD chlorophyll meter could be used in quick N nutrition diagnosis, forecast yield and N recommen-dation of oilseed rape.
基金funded by the Department of Biotechnology(DBT)Government of India(No.BT/IN/UKVNC/42/RG/2014-15)the Biotechnology and Biological Sciences Research Council(BBSRC)under the international multi-institutional collaborative research project entitled Cambridge-India Network for Translational Research in Nitrogen(CINTRIN)(No.BB/N013441/1)。
文摘A number of optical sensing tools are now available and can potentially be used for refining need-based fertilizer nitrogen(N)topdressing decisions.Algorithms for estimating field-specific fertilizer N needs are based on predictions of yield made while the crops are still growing in the field.The present study was conducted to establish and validate yield prediction models using spectral indices measured with proximal sensing using GreenSeeker canopy reflectance sensor,soil and plant analyzer development(SPAD)chlorophyll meter,and two different types of leaf color charts(LCCs)for five basmati rice genotypes across different growth stages.Regression analysis was performed using normalized difference vegetation index(NDVI)recorded with GreenSeeker sensor and leaf greenness indices measured with SPAD meter and LCCs developed by Punjab Agricultural University,Ludhiana(India)(PAU-LCC)and the International Rice Research Institute,Philippines(IRRI-LCC).The exponential relationship between NDVI and grain yield exhibited the highest coefficient of determination(R^(2))and minimum normalized root mean square error(NRMSE)at panicle initiation stage and explained 38.3%–76.4%variation in yield using genotype-specific models.Spectral indices pooled for different genotypes were closely related to grain yield at all growth stages and explained53.4%–57.2%variation in grain yield.Normalizing different spectral indices with cumulative growing degree days(CGDD)decreased the accuracy of yield prediction.Normalization with days after transplanting(DAT),however,did not reduce or improve the predictability of yield.The ability of each model to predict grain yield was validated with an independent dataset collected from two experiments conducted at different sites with a range of fertilizer N doses.The NDVI-based genotype-specific models exhibited a robust linear correlation(R^(2)=0.77,NRMSE=7.37%,n=180)between observed and predicted grain yields only at 35 DAT(i.e.,panicle initiation stage),while the SPAD,PAU-LCC,and IRRI-LCC consistently provided reliable predictions(with respective R^(2)of 0.63,0.60,and 0.53 and NRMSE of 10%,10%,and 13.6%)even with genotype invariant models with 900 data points obtained at different growth stages.The study revealed that unnormalized values of spectral indices,namely NDVI,SPAD,PAU-LCC,and IRRI-LCC,can be satisfactorily used for in-season estimation of grain yield for basmati rice.As LCCs are very economical compared with chlorophyll meters and canopy reflectance sensors,they can be preferably used by small farmers in developing countries.
