Índice relativo de clorofila e o estado nutricional em nitrogênio durante o ciclo do cafeeiro fertirrigado
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Data
2008-02-01
Autores
Godoy, Leandro José Grava de [UNESP]
Santos, Thiago da Silva [UNESP]
Villas Boas, Roberto Lyra [UNESP]
Leite Júnior, João Batista [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ciência do Solo
Resumo
O clorofilômetro (SPAD-502, Minolta) é um aparelho portátil que permite obtenção do índice relativo de clorofila (IRC) de modo simples, rápido e não destrutivo no próprio campo, o qual se correlaciona com a concentração de N em várias culturas, e que pode tornar mais rápida a correção de deficiência, otimizando a utilização da fertirrigação. Objetivou-se com este trabalho verificar se o IRC pode ser indicativo do estado nutricional em N, podendo auxiliar no ajuste da fertirrigação nitrogenada durante o ciclo do cafeeiro. O experimento foi desenvolvido em Botucatu, SP, em área com cafeeiros do cultivar Catuaí Vermelho, com dois anos, no espaçamento de 2,5 x 0,8 m e irrigado por gotejamento. O delineamento experimental utilizado foi em blocos casualizados, com quatro repetições, aplicando-se um tratamento sem adubação, mas com irrigação, e mais quatro tratamentos utilizando fertirrigação com 33, 66, 100 e 133 % da dose de N recomendada, parcelada semanalmente (52,8; 105,6; 160,0; e 212,7 kg ha-1, respectivamente). O IRC aumentou linearmente com as doses de N, e a produtividade correlacionou-se significativamente com o IRC, do florescimento até a colheita, porém não com a concentração de N foliar. Os IRCs nos cafeeiros com maior produtividade foram de 81,5 a 83,2 (florescimento e início de expansão dos frutos), de 76,2 a 78,3 (expansão dos frutos), de 68,3 a 69,8 (início da granação), de 64,0 a 65,9 (na granação) e de 61,7 a 62,7 unidades SPAD (na maturação). O clorofilômetro pode ser utilizado para definir a probabilidade de resposta ao N no decorrer do ciclo do cafeeiro.
The chlorophyll meter (SPAD-502, Minolta) is a portable device that measures the relative chlorophyll index (RCI) in a simple, fast and non-destructive way in the field. This index is correlated with leaf N concentration in several crops, and allows the correction of N deficiency, optimizing fertigation. The objective of this study was to test RCI as an indicator of the nitrogen status in coffee trees to adjust fertigation during the development cycle. The experiment was carried out in Botucatu, state of São Paulo, Brazil, in an area with two-year old coffee plants of cultivar Red Catuaí, spaced at 2.5 x 0.8 m, under drip irrigation. The experiment had a randomized block design with four replications and five treatments: control treatment under irrigation and without fertilization, and four N rates using fertigation with 33, 66, 100, and 133 % of the recommended annual N rate (52.8; 105.6; 160.0 and 212.7 kg ha-1, respectively). The fertilizer treatments were split in weakly applications. The RCI increased linearly with the N rates and the yield was significantly correlated with RCI, from flowering to harvest. However, there was no correlation between beans yield with the leaf N concentration. The RCIs of high yielding coffee plants were 81.5-83.2 (flowering and beginning of fruit filling), 76.2-78.3 (fruit expansion) 68.3 - 69.8 (beginning of grain formation), 64.0-65.9 (during grain formation) and 61.7-62.7 SPAD units (grain maturation). The chlorophyll meter can be used throughout the coffee development cycle to define the likelihood of N response in coffee trees.
The chlorophyll meter (SPAD-502, Minolta) is a portable device that measures the relative chlorophyll index (RCI) in a simple, fast and non-destructive way in the field. This index is correlated with leaf N concentration in several crops, and allows the correction of N deficiency, optimizing fertigation. The objective of this study was to test RCI as an indicator of the nitrogen status in coffee trees to adjust fertigation during the development cycle. The experiment was carried out in Botucatu, state of São Paulo, Brazil, in an area with two-year old coffee plants of cultivar Red Catuaí, spaced at 2.5 x 0.8 m, under drip irrigation. The experiment had a randomized block design with four replications and five treatments: control treatment under irrigation and without fertilization, and four N rates using fertigation with 33, 66, 100, and 133 % of the recommended annual N rate (52.8; 105.6; 160.0 and 212.7 kg ha-1, respectively). The fertilizer treatments were split in weakly applications. The RCI increased linearly with the N rates and the yield was significantly correlated with RCI, from flowering to harvest. However, there was no correlation between beans yield with the leaf N concentration. The RCIs of high yielding coffee plants were 81.5-83.2 (flowering and beginning of fruit filling), 76.2-78.3 (fruit expansion) 68.3 - 69.8 (beginning of grain formation), 64.0-65.9 (during grain formation) and 61.7-62.7 SPAD units (grain maturation). The chlorophyll meter can be used throughout the coffee development cycle to define the likelihood of N response in coffee trees.
Descrição
Palavras-chave
Coffea arabica L., clorofilômetro, SPAD, fertirrigação e nitrogênio, chlorophyll meter, Coffea arabica L., fertigation, nitrogen, SPAD
Como citar
Revista Brasileira de Ciência do Solo. Sociedade Brasileira de Ciência do Solo, v. 32, n. 1, p. 217-226, 2008.