Progresso da ferrugem (puccinia psidii) em monocultivo de Eucalyptus grandis x Eucalyptus urophylla e em plantios consorciados com Acacia mangium
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Data
2016-12-20
Autores
Pieri, Cristiane De
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Universidade Estadual Paulista (Unesp)
Resumo
A cultura do eucalipto é uma das mais importantes do Brasil, constituindo-se em fonte de energia renovável e madeira, além de importantes processos agroindustriais para produção de celulose, papel entre outros. O eucalipto é infectado por uma diversidade de patógenos, principalmente fungos, desde o viveiro até em plantios adultos. O modelo de produção predominante é o monocultivo, adensado e intensamente adubado (adubação de base e duas a três coberturas). Em espécies/clones de eucalipto suscetíveis à Puccinia psidii, a ocorrência de epidemias é observada em condições climáticas favoráveis. Dessa forma, espera-se que o plantio consorciado com uma ou mais espécies não hospedeiras, a intensidade desta doença deva ser menor, devido a barreira física criada e dificulte a disseminação das estruturas reprodutivas do referido patógeno, diluindo o inóculo. Da mesma forma, o aumento do espaçamento também pode dificultar o estabelecimento do patógeno e, um plantio consorciado com uma espécie arbórea leguminosa que permita a fixação biológica de nitrogênio pode levar a redução da aplicação de adubos na forma química devido a ciclagem de nutrientes no sistema. Diante do exposto, os objetivos deste estudo foram: comparar o monocultivo de um clone oriundo da hibridação entre Eucalyptus grandis x E. urophylla e o cultivo do mesmo consorciado com a leguminosa Acacia mangium, com e sem adubação, em dois espaçamentos, quanto a intensidade da ferrugem e, crescimento das plantas (altura, diâmetro a altura do peito, volume e biomassa). Dentre os fatores testados, o uso da adubação no plantio foi o de maior relevância, afetando a intensidade da doença, bem como as variáveis de crescimento avaliadas. Até os dois anos de idade as plantas de acácia ocupam o estrato inferior quando consorciadas com o eucalipto, com isso não estabeleceram uma barreira física eficiente para o patógeno. O mesmo efeito não foi observado com o aumento do espaçamento. Apesar da maior intensidade da doença nos arranjos adubados, as plantas tiveram maior incremento em altura, volume e biomassa. Quanto ao consórcio, a acácia não foi eficaz como barreira física ao agente causal da ferrugem.
The eucalypt cultivation is one of the most important in Brazil, constituting in source of renewable energy and wood, as well as important agro-industrial processes for the cellulose production, paper and others. The eucalypt is infected by a variety of pathogens, mainly fungus, from the plant nursery to adult cultivation. The predominant production model is the monoculture, densely one and intensively fertilized (basic fertilization and two to three coverages).In eucalypt species/clones susceptible to Puccinia psidii, the occurrence of epidemics is observed in favorable climate conditions. Thus, it is expected that the combined cultivation with one or more non-host species, the intensity of this disease should be lower, due to the physical barrier created not to facilitate the dissemination of the reproductive structures of this pathogen, diluting the inoculum. Similarly, the increased spacing cannot also facilitate the pathogen establishment and a combined cultivation with a leguminous arboreal species allowing the biological fixation of nitrogen can lead to the reduction of the fertilizer application in chemical form due to the cycling of nutrients in the system. Based on the above, the objectives of this study were: to compare the monoculture of a clone from the hybridization between Eucalyptus grandis x E. urophylla and the same combined cultivation with the leguminous Acacia mangium, with and without fertilization in two spacing, about the rust intensity and the plant growth ( height, diameter at breast height, volume and biomass). Among the factors tested, the use fertilization at the cultivation was the most relevant, affecting the disease intensity, as well as the variables of the evaluated growth. Up to the age of two, acacia plants are on the lower layer when combined with eucalypt, thus failing to establish an efficient physical barrier for the pathogen. The same effect was not observed with increasing spacing. Despite the greater intensity of the disease in the fertilized arrangements, the plants had a greater increase in height, volume and biomass. About the combined cultivation, acacia was not effective as a physical barrier to the causative agent of rust.
The eucalypt cultivation is one of the most important in Brazil, constituting in source of renewable energy and wood, as well as important agro-industrial processes for the cellulose production, paper and others. The eucalypt is infected by a variety of pathogens, mainly fungus, from the plant nursery to adult cultivation. The predominant production model is the monoculture, densely one and intensively fertilized (basic fertilization and two to three coverages).In eucalypt species/clones susceptible to Puccinia psidii, the occurrence of epidemics is observed in favorable climate conditions. Thus, it is expected that the combined cultivation with one or more non-host species, the intensity of this disease should be lower, due to the physical barrier created not to facilitate the dissemination of the reproductive structures of this pathogen, diluting the inoculum. Similarly, the increased spacing cannot also facilitate the pathogen establishment and a combined cultivation with a leguminous arboreal species allowing the biological fixation of nitrogen can lead to the reduction of the fertilizer application in chemical form due to the cycling of nutrients in the system. Based on the above, the objectives of this study were: to compare the monoculture of a clone from the hybridization between Eucalyptus grandis x E. urophylla and the same combined cultivation with the leguminous Acacia mangium, with and without fertilization in two spacing, about the rust intensity and the plant growth ( height, diameter at breast height, volume and biomass). Among the factors tested, the use fertilization at the cultivation was the most relevant, affecting the disease intensity, as well as the variables of the evaluated growth. Up to the age of two, acacia plants are on the lower layer when combined with eucalypt, thus failing to establish an efficient physical barrier for the pathogen. The same effect was not observed with increasing spacing. Despite the greater intensity of the disease in the fertilized arrangements, the plants had a greater increase in height, volume and biomass. About the combined cultivation, acacia was not effective as a physical barrier to the causative agent of rust.
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Eucalipto, Plantios mistos, Doenças, Ferrugem das mirtáceas, Rizóbio, Eucalypt, Combined cultivation, Disease, Rust of Myrtaceae, Rhizobium