Morfofisiologia de plantas jovens de café arábica submetidas a níveis de sombreamento artificial e doses de paclobutrazol
Data
2018-02-20
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual do Sudoeste da Bahia
Resumo
Os benefícios proporcionados pelo sombreamento, associados às modulações morfológicas resultantes da utilização de paclobutrazol, podem ser uma importante estratégia para o cultivo do cafeeiro, principalmente em regiões onde são mais acentuados a restrição hídrica, os altos índices de radiação solar e a elevação da temperatura atmosférica. Objetivou-se com este trabalho avaliar o desempenho morfofisiológico de cafeeiros jovens submetidos a doses de paclobutrazol, em ambientes com restrição artificial de luz. Os ensaios foram realizados em ambientes sombreados artificialmente com malhas de polietileno de cor preta, nos níveis de 20%, 40%, 60% e 80% de restrição luminosa, e um ambiente a pleno sol, na Universidade Estadual do Sudoeste da Bahia, em Vitória da Conquista. Em cada um desses ambientes, foi conduzido um experimento, constituído de cinco tratamentos, definidos pela aplicação via substrato de diferentes doses de paclobutrazol (0; 10; 20; 30 e 40 mg de ingrediente ativo por planta). Utilizou-se delineamento inteiramente casualizado, com quatro repetições, e cada unidade experimental foi constituída por um vaso com uma planta de café. As trocas gasosas foliares foram analisadas em blocos, com quatro repetições, devido às variações ocorridas ao longo do período de avaliação. Aos 100 dias após a aplicação do paclobutrazol, foram avaliados altura da planta, diâmetro do caule, número de folhas e de ramos plagiotrópicos, índice de ramificação, massa seca da parte aérea, das raízes e total, área foliar total, individual e específica, razão de área foliar, índice SPAD, potencial hídrico e teor relativo de água foliar, pigmentos fotossintéticos, teor de prolina nas folhas e extravasamento de eletrólitos. As trocas gasosas foliares foram avaliadas aos 99 dias após a aplicação do paclobutrazol. Procedeu-se a análise conjunta de experimentos e análise de variância da regressão para o estudo das doses de paclobutrazol e dos níveis de sombreamento. Os modelos de regressão foram definidos com base na significância, maior valor do coeficiente de determinação, e na resposta biológica para cada característica estudada. Para realização das análises estatísticas e plotagem dos gráficos, foi utilizado o programa Sistema de Análises Estatísticas e Genéticas, versão 9.1, e o Excel 2013. O sombreamento foi favorável às plantas jovens de café arábica, promovendo maior crescimento e melhor desempenho fisiológico, em comparação aos cafeeiros conduzidos a pleno sol. A morfofisiologia de cafeeiros arábica ‘Catuaí Vermelho IAC 144’, submetidos ao sombreamento artificial durante o crescimento vegetativo inicial, é mais vigorosa quando comparada à de plantas conduzidas a pleno sol. A aplicação de paclobutrazol via solo, nas dosagens determinadas neste estudo, é pouco efetiva em promover alterações morfofisiológicas em plantas jovens de café. As alterações morfológicas induzidas pela restrição de luz e consideradas como desfavoráveis ao crescimento vegetativo inicial dos cafeeiros arábica não são restringidas ou atenuadas pela aplicação das dosagens de paclobutraol via solo determinadas neste estudo. A ampla variação dos níveis de restrição de luz, associada à restrita amplitude das doses de paclobutrazol em estudo, torna incipiente a interação entre os fatores para cafeeiros arábica jovens.
The benefits provided by shading, associated with morphological modulations of the use of paclobutrazol, can be an important strategy for coffee cultivation, especially in regions where water restriction, high solar radiation, and atmospheric temperature rise are most pronounced. The objective of this study was to evaluate the morphophysiological performance of young coffee plants submitted to paclobutrazol doses in environments with different levels of artificial light restriction. The tests were performed in environments with artificial shading, with levels of 20%, 40%, 60% and 80% of light restriction, and a full-sun environment at the Universidade Estadual do Sudoeste da Bahia, in Vitória da Conquista. In each of these environments, an experiment wasc arried out, consisting of five treatments, defined by substrate application of different doses of paclobutrazol (0, 10, 20, 30 and 40 mg of active ingredient per plant). A completely randomized design with four replications was used, and each experimental unit consisted of a pot with a coffee plant. Leaf gas exchanges were analyzed in blocks, with four replications, due to the variations that occurred during the evaluation period. At 100 days after application of paclobutrazol, plant height, stem diameter, number of leaves and plagiotropic branches, branching index, dry mass of shoot, roots, and total mass, individual, specific, and total leaf area, leaf area ratio, SPAD index, water potential and relative leaf water content, photosynthetic pigments, leaf proline content, and electrolyte extravasation were evaluated. Leaf gas exchange was evaluated at 99 days after application of paclobutrazol. Joint analysis of experiments and regression analysis of variance for the study of doses of paclobutrazol and levels of shading were performed. Regression models were defined based on the significance, higher value of coefficient of determination, and on biological response for each studied characteristic. Statistical analysis and plotting of the graphs were performed using the software Statistical and Genetic Analysis System (SAEG), version 9.1, and Excel 2013. Shading was favorable to young arabica coffee plants, promoting greater growth and better physiological performance, in comparison to coffee plants in full sun. Morphophysiology of 'Catuaí Vermelho IAC 144' arabica coffee trees, submitted to artificial shading during initial vegetative growth, is more vigorous when compared to plants grown in full sun. The application of paclobutrazol via soil at the dosages determined in this study is not very effective in promoting morphophysiological changes in young coffee plants. The morphological changes induced by light restriction, considered unfavorable to the initial vegetative growth of arabica coffee plants, are not restricted or attenuated by the application of paclobutrazol dosages via soil determined in this study. The wide range of light restriction levels, coupled with the limited range of paclobutrazol doses under study, makes incipient the interaction between factors for young Arabica coffee.
The benefits provided by shading, associated with morphological modulations of the use of paclobutrazol, can be an important strategy for coffee cultivation, especially in regions where water restriction, high solar radiation, and atmospheric temperature rise are most pronounced. The objective of this study was to evaluate the morphophysiological performance of young coffee plants submitted to paclobutrazol doses in environments with different levels of artificial light restriction. The tests were performed in environments with artificial shading, with levels of 20%, 40%, 60% and 80% of light restriction, and a full-sun environment at the Universidade Estadual do Sudoeste da Bahia, in Vitória da Conquista. In each of these environments, an experiment wasc arried out, consisting of five treatments, defined by substrate application of different doses of paclobutrazol (0, 10, 20, 30 and 40 mg of active ingredient per plant). A completely randomized design with four replications was used, and each experimental unit consisted of a pot with a coffee plant. Leaf gas exchanges were analyzed in blocks, with four replications, due to the variations that occurred during the evaluation period. At 100 days after application of paclobutrazol, plant height, stem diameter, number of leaves and plagiotropic branches, branching index, dry mass of shoot, roots, and total mass, individual, specific, and total leaf area, leaf area ratio, SPAD index, water potential and relative leaf water content, photosynthetic pigments, leaf proline content, and electrolyte extravasation were evaluated. Leaf gas exchange was evaluated at 99 days after application of paclobutrazol. Joint analysis of experiments and regression analysis of variance for the study of doses of paclobutrazol and levels of shading were performed. Regression models were defined based on the significance, higher value of coefficient of determination, and on biological response for each studied characteristic. Statistical analysis and plotting of the graphs were performed using the software Statistical and Genetic Analysis System (SAEG), version 9.1, and Excel 2013. Shading was favorable to young arabica coffee plants, promoting greater growth and better physiological performance, in comparison to coffee plants in full sun. Morphophysiology of 'Catuaí Vermelho IAC 144' arabica coffee trees, submitted to artificial shading during initial vegetative growth, is more vigorous when compared to plants grown in full sun. The application of paclobutrazol via soil at the dosages determined in this study is not very effective in promoting morphophysiological changes in young coffee plants. The morphological changes induced by light restriction, considered unfavorable to the initial vegetative growth of arabica coffee plants, are not restricted or attenuated by the application of paclobutrazol dosages via soil determined in this study. The wide range of light restriction levels, coupled with the limited range of paclobutrazol doses under study, makes incipient the interaction between factors for young Arabica coffee.
Descrição
Dissertação de mestrado defendida na Universidade Estadual do Sudoeste da Bahia.
Palavras-chave
Cultivo, Desempenho fisiológico, Sombreamento em cafeeiro
Citação
RIBEIRO, A. F. F. Morfofisiologia de plantas jovens de café arábica submetidas a níveis de sombreamento artificial e doses de paclobutrazol. 2018. 104 f. Dissertação (Mestrado em Fitotecnia) - Universidade Estadual do Sudoeste da Bahia, Vitória da Conquista. 2018.