Made available in DSpace on 2016-04-28T14:59:47Z (GMT). No. of bitstreams: 1 2009 - Elio Barbieri Junior.pdf: 7095685 bytes, checksum: 1bcdc77a8d686ebd516a400693c004ae (MD5) Previous issue date: 2009-02-20 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Among the biochemical properties related to the use of nitrogen (N) for the plants, chlorophyll pigments occupy a relevant position. For that reason, and given the importance of the N fertilization for pasture productivity, it has been developed methodologies that allow determining leaf chlorophyll contents for indirect and non destructive procedures. With the purpose of supplying subsidies for N fertilization management in in pastures of Cynodon spp. cv. Tifton 85 was installed an experiment with purpose of verifying the performance of a commercial chlorophyll meter. The experimental strategy consisted of the induction of three levels of soil N availability, through N fertilization. The working hypotheses were the following ones: i) different soil N availabilities result in differentiated leaf chlorophyll contents in leaves recently emerged and fully expanded; ii) readings obtained with a chlorophyll meter are related with foliar Total chlorophyll contents; iii) chlorophyll contents are related with foliar N concentrations; e iv) chlorophyll content indicators keep relationship with green dry matter production. This study was carried out on a Haplic Planosol at the Experimental Campus of the Rural Federal University of Rio de Janeiro, Serop?dica, RJ, during the period of July to December 2008. An entirely randomized block design was used, with four repetitions. Main treatments were allocated in plots (4x4 m) and consisted of three N fertilization levels (0; 75 and 150kg N-ur?ia). Four sampling dates designed as days from a standardization cut made 131days after planting were allocated in sub-plots. Three of the sampling dates (8, 16 and 24 days) were pre-fixed, while the last was accomplished when the sward interception level of photosynthetically active radiation reached a value of 95%. Structural dynamics was followed by monitoring the following canopy variables: sward height; tiller density, leaf area index, green cover index and green dry mass accumulation. Chlorophylls a, b and (a+b) were measured always in the first fully expanded leaves of sun tillers by the Arnon method with modifications, and indirectly, with the chlorophyll meter ClorofiLOG?. In the same type of leaves, total N content was determined by Kjeldhal routine procedures. Principal results showed that concentrations of chlorophylls a, b and (a + b) in Tifton leaf blades were affected by nitrogen fertilization and sampling dates reaching maximal differences at the 24th day after cut. Chlorophyll meter readings (Falker Chlorophyll Index, FCI) and foliar N contents also responsed very sensibly to N rates, reaching maximal values at the16th day after cut. In the same day, Total chlorophyll contents and Total N leaf contents were also significantly correlated with FCI values, with r2 coefficients of 0,93 and 0,89 respectively. Correlation coefficient between total green dry matter and FCI values was 0,867. Total green dry matter accumulation at the last sampling date and FCI readings at 16th day after cut also resulted significantly related (r2 = 0,72), a promising relation for purposes of forage yield estimation. In conclusion, the obtained results allow affirming that, in Tifton 85, total chlorophyll content present in the first leaf totally expanded is a sensitive marker of soil N availability and therefore of N fertilization needs. Total chlorophyll content through its relationship with leaf N contents may be also a valuable tool for foliar N diagnosis. Both attributes were discriminated properly by the chlorophyll meter under evaluation. This apparatus maximized its performance in the period were happened Among the biochemical properties related to the use of nitrogen (N) for the plants, chlorophyll pigments occupy a relevant position. For that reason, and given the importance of the N fertilization for pasture productivity, it has been developed methodologies that allow determining leaf chlorophyll contents for indirect and non destructive procedures. With the purpose of supplying subsidies for N fertilization management in in pastures of Cynodon spp. cv. Tifton 85 was installed an experiment with purpose of verifying the performance of a commercial chlorophyll meter. The experimental strategy consisted of the induction of three levels of soil N availability, through N fertilization. The working hypotheses were the following ones: i) different soil N availabilities result in differentiated leaf chlorophyll contents in leaves recently emerged and fully expanded; ii) readings obtained with a chlorophyll meter are related with foliar Total chlorophyll contents; iii) chlorophyll contents are related with foliar N concentrations; e iv) chlorophyll content indicators keep relationship with green dry matter production. This study was carried out on a Haplic Planosol at the Experimental Campus of the Rural Federal University of Rio de Janeiro, Serop?dica, RJ, during the period of July to December 2008. An entirely randomized block design was used, with four repetitions. Main treatments were allocated in plots (4x4 m) and consisted of three N fertilization levels (0; 75 and 150kg N-ur?ia). Four sampling dates designed as days from a standardization cut made 131days after planting were allocated in sub-plots. Three of the sampling dates (8, 16 and 24 days) were pre-fixed, while the last was accomplished when the sward interception level of photosynthetically active radiation reached a value of 95%. Structural dynamics was followed by monitoring the following canopy variables: sward height; tiller density, leaf area index, green cover index and green dry mass accumulation. Chlorophylls a, b and (a+b) were measured always in the first fully expanded leaves of sun tillers by the Arnon method with modifications, and indirectly, with the chlorophyll meter ClorofiLOG?. In the same type of leaves, total N content was determined by Kjeldhal routine procedures. Principal results showed that concentrations of chlorophylls a, b and (a + b) in Tifton leaf blades were affected by nitrogen fertilization and sampling dates reaching maximal differences at the 24th day after cut. Chlorophyll meter readings (Falker Chlorophyll Index, FCI) and foliar N contents also responsed very sensibly to N rates, reaching maximal values at the16th day after cut. In the same day, Total chlorophyll contents and Total N leaf contents were also significantly correlated with FCI values, with r2 coefficients of 0,93 and 0,89 respectively. Correlation coefficient between total green dry matter and FCI values was 0,867. Total green dry matter accumulation at the last sampling date and FCI readings at 16th day after cut also resulted significantly related (r2 = 0,72), a promising relation for purposes of forage yield estimation. In conclusion, the obtained results allow affirming that, in Tifton 85, total chlorophyll content present in the first leaf totally expanded is a sensitive marker of soil N availability and therefore of N fertilization needs. Total chlorophyll content through its relationship with leaf N contents may be also a valuable tool for foliar N diagnosis. Both attributes were discriminated properly by the chlorophyll meter under evaluation. This apparatus maximized its performance in the period were happenedAmong the biochemical properties related to the use of nitrogen (N) for the plants, chlorophyll pigments occupy a relevant position. For that reason, and given the importance of the N fertilization for pasture productivity, it has been developed methodologies that allow determining leaf chlorophyll contents for indirect and non destructive procedures. With the purpose of supplying subsidies for N fertilization management in in pastures of Cynodon spp. cv. Tifton 85 was installed an experiment with purpose of verifying the performance of a commercial chlorophyll meter. The experimental strategy consisted of the induction of three levels of soil N availability, through N fertilization. The working hypotheses were the following ones: i) different soil N availabilities result in differentiated leaf chlorophyll contents in leaves recently emerged and fully expanded; ii) readings obtained with a chlorophyll meter are related with foliar Total chlorophyll contents; iii) chlorophyll contents are related with foliar N concentrations; e iv) chlorophyll content indicators keep relationship with green dry matter production. This study was carried out on a Haplic Planosol at the Experimental Campus of the Rural Federal University of Rio de Janeiro, Serop?dica, RJ, during the period of July to December 2008. An entirely randomized block design was used, with four repetitions. Main treatments were allocated in plots (4x4 m) and consisted of three N fertilization levels (0; 75 and 150kg N-ur?ia). Four sampling dates designed as days from a standardization cut made 131days after planting were allocated in sub-plots. Three of the sampling dates (8, 16 and 24 days) were pre-fixed, while the last was accomplished when the sward interception level of photosynthetically active radiation reached a value of 95%. Structural dynamics was followed by monitoring the following canopy variables: sward height; tiller density, leaf area index, green cover index and green dry mass accumulation. Chlorophylls a, b and (a+b) were measured always in the first fully expanded leaves of sun tillers by the Arnon method with modifications, and indirectly, with the chlorophyll meter ClorofiLOG?. In the same type of leaves, total N content was determined by Kjeldhal routine procedures. Principal results showed that concentrations of chlorophylls a, b and (a + b) in Tifton leaf blades were affected by nitrogen fertilization and sampling dates reaching maximal differences at the 24th day after cut. Chlorophyll meter readings (Falker Chlorophyll Index, FCI) and foliar N contents also responsed very sensibly to N rates, reaching maximal values at the16th day after cut. In the same day, Total chlorophyll contents and Total N leaf contents were also significantly correlated with FCI values, with r2 coefficients of 0,93 and 0,89 respectively. Correlation coefficient between total green dry matter and FCI values was 0,867. Total green dry matter accumulation at the last sampling date and FCI readings at 16th day after cut also resulted significantly related (r2 = 0,72), a promising relation for purposes of forage yield estimation. In conclusion, the obtained results allow affirming that, in Tifton 85, total chlorophyll content present in the first leaf totally expanded is a sensitive marker of soil N availability and therefore of N fertilization needs. Total chlorophyll content through its relationship with leaf N contents may be also a valuable tool for foliar N diagnosis. Both attributes were discriminated properly by the chlorophyll meter under evaluation. This apparatus maximized its performance in the period were happened Among the biochemical properties related to the use of nitrogen (N) for the plants, chlorophyll pigments occupy a relevant position. For that reason, and given the importance of the N fertilization for pasture productivity, it has been developed methodologies that allow determining leaf chlorophyll contents for indirect and non destructive procedures. With the purpose of supplying subsidies for N fertilization management in in pastures of Cynodon spp. cv. Tifton 85 was installed an experiment with purpose of verifying the performance of a commercial chlorophyll meter. The experimental strategy consisted of the induction of three levels of soil N availability, through N fertilization. The working hypotheses were the following ones: i) different soil N availabilities result in differentiated leaf chlorophyll contents in leaves recently emerged and fully expanded; ii) readings obtained with a chlorophyll meter are related with foliar Total chlorophyll contents; iii) chlorophyll contents are related with foliar N concentrations; e iv) chlorophyll content indicators keep relationship with green dry matter production. This study was carried out on a Haplic Planosol at the Experimental Campus of the Rural Federal University of Rio de Janeiro, Serop?dica, RJ, during the period of July to December 2008. An entirely randomized block design was used, with four repetitions. Main treatments were allocated in plots (4x4 m) and consisted of three N fertilization levels (0; 75 and 150kg N-ur?ia). Four sampling dates designed as days from a standardization cut made 131days after planting were allocated in sub-plots. Three of the sampling dates (8, 16 and 24 days) were pre-fixed, while the last was accomplished when the sward interception level of photosynthetically active radiation reached a value of 95%. Structural dynamics was followed by monitoring the following canopy variables: sward height; tiller density, leaf area index, green cover index and green dry mass accumulation. Chlorophylls a, b and (a+b) were measured always in the first fully expanded leaves of sun tillers by the Arnon method with modifications, and indirectly, with the chlorophyll meter ClorofiLOG?. In the same type of leaves, total N content was determined by Kjeldhal routine procedures. Principal results showed that concentrations of chlorophylls a, b and (a + b) in Tifton leaf blades were affected by nitrogen fertilization and sampling dates reaching maximal differences at the 24th day after cut. Chlorophyll meter readings (Falker Chlorophyll Index, FCI) and foliar N contents also responsed very sensibly to N rates, reaching maximal values at the16th day after cut. In the same day, Total chlorophyll contents and Total N leaf contents were also significantly correlated with FCI values, with r2 coefficients of 0,93 and 0,89 respectively. Correlation coefficient between total green dry matter and FCI values was 0,867. Total green dry matter accumulation at the last sampling date and FCI readings at 16th day after cut also resulted significantly related (r2 = 0,72), a promising relation for purposes of forage yield estimation. In conclusion, the obtained results allow affirming that, in Tifton 85, total chlorophyll content present in the first leaf totally expanded is a sensitive marker of soil N availability and therefore of N fertilization needs. Total chlorophyll content through its relationship with leaf N contents may be also a valuable tool for foliar N diagnosis. Both attributes were discriminated properly by the chlorophyll meter under evaluation. This apparatus maximized its performance in the period were happened the highest leaf N content and linking directly with final green dry matter accumulation. / Dentre as propriedades bioqu?micas relacionadas ? utiliza??o do nitrog?nio (N) pelas plantas, os teores de clorofila ocupam posi??o de destaque. Por essa raz?o, e dada a import?ncia que a aduba??o nitrogenada tem na express?o da produtividade das pastagens, tem sido desenvolvidas metodologias que permitem a determina??o do teor de clorofila por procedimentos indiretos e n?o destrutivos. No intuito de fornecer subs?dios para a defini??o de estrat?gias de aduba??o nitrogenada em pastagens de Cynodon spp. cv. Tifton 85 foi instalado um experimento com o prop?sito primordial de verificar o desempenho de um clorofil?metro comercial. Foi utilizada uma estrat?gia experimental consistente na indu??o de tr?s n?veis de disponibilidade de N no solo, atrav?s de aduba??o nitrogenada. As hip?teses que guiaram o experimento foram as seguintes: i) n?veis diferenciados de N no solo, resultam em teores diferenciados de clorofila em folhas rec?m emergidas; ii) leituras obtidas com um clorofil?metro guardam rela??o com os teores foliares das clorofilas; iii) teores de clorofila total relacionam-se com os teores foliares de N; e iv) os indicadores ligados ? clorofila foliar guardam rela??o com a produ??o de mat?ria seca. O experimento foi desenvolvido sobre um Planossolo H?plico, no campo experimental da Universidade Federal Rural do Rio de Janeiro, munic?pio de Serop?dica, RJ, durante o per?odo de julho a dezembro de 2008. O experimento foi disposto segundo um desenho em blocos inteiramente casualizados, com quatro repeti??es. Os tratamentos, alocados nas parcelas (4x4m), consistiram de tr?s n?veis de N (0; 75 e 150kg N-ur?ia/ha), enquanto que nas sub-parcelas, foram alocadas quatro dias de coletas, contados a partir um corte de uniformiza??o, realizado 131 dias ap?s o plantio do capim. Tr?s das datas de amostragem foram pre-fixadas, aos 8, 16 e 24 dias, enquanto a ?ltima foi realizada quando a pastagem atingiu um n?vel de intercepta??o de 95% da radia??o fotossint?ticamente ativa incidente. A din?mica estrutural foi acompanhada atrav?s da mensura??o das seguintes vari?veis do dossel: altura; densidade populacional de perfilhos; ?ndice de ?rea foliar, ?ndice de cobertura verde, e ac?mulo de massa verde seca. As clorofilas a, b, e (a+b), foram quantificadas, sempre em primeiras folhas completamente expandidas de perfilhos de sol, pelo m?todo de Arnon modificado, e indiretamente, com um aparelho ClorofiLOG?. Os teores de N total foram determinados nas mesmas folhas, pelo m?todo de Kjeldhal. Os resultados mostraram que os teores de clorofila a, b e (a+b) diferiram entre doses de N, e dias de amostragem, atingindo diferen?as m?ximas entre as doses de N aos 24 dias ap?s corte. As leituras do clorofil?metro (?ndice de Clorofila Falker, ICF) e os teores de N foliar tamb?m responderam sensivelmente ?s doses de N, atinguindo valores m?ximos aos 16 dias. Nesse mesmo dia, a an?lise de regress?o linear entre os teores de clorofila total e de N total, contra os respectivos valores de ICF resultou em coeficientes de determina??o de 0,93 e 0,89 respectivamente. O coeficiente de correla??o entre a massa verde seca total e os valores de ICF foi de 0,867. O ac?mulo de mat?ria verde seca total aos 28 dias ap?s o corte relacionouse linearmente com as leituras do clorofil?metro feitas aos 16 dias (r2=0,72), um tipo de resultado promissor em termos de estimativas de disponibilidade de forragem. Como conclus?o, os resultados permitiram verificar que os teores de clorofila total presentes na primeira folha totalmente expandida, responderam ? aplica??o de doses diferenciadas de N e se relacionaram estreitamente com os teores de N foliar. Ambos os atributos foram discriminados de forma precisa pelo clorofil?metro sob avalia??o. Este aparelho maximizou o seu desempenho no per?odo onde ocorreram os m?ximos teores de N foliar, relacionando-se diretamente com a mat?ria seca acumulada no final do per?odo de rebrota.