Duração mínima do molhamento foliar no desenvolvimento da ferrugem (Puccinia psidii) e efeito da doença nas respostas fisiológicas do eucalipto

• Ano de defesa: 2015
• Autor(a) principal: Fonseca, Mariana Duarte Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Ciências Florestais; Centro de Ciências Agrárias e Engenharias; UFES; Programa de Pós-Graduação em Ciências Florestais
• Palavras-chave em Português: Leaf disease; Gas exchange; Leaf pigments; Epidemiology; Eucalyptus disease; Myrtaceae; Doença foliar; Trocas gasosas; Pigmentos foliares; Ferrugem; Pigmentos cloroplastídicos; Severidade; Doença do eucalipto; Epidemiologia; Eucalipto – Doenças; Recursos Florestais e Engenharia Florestal; 630
• Link de acesso: http://repositorio.ufes.br/handle/10/5058

The rust caused by the fungus Puccinia psidii, is one of the most important diseases of Eucalyptus culture. The objective of this study was to determine the minimum leaf wetness duration (LWD) the infection of P. psidii and development of the disease, as well as the effect of the disease on the physiological responses of Eucalyptus seedlings. The experiment was conducted using a completely randomized design in a 7x2 factorial arrangement – seven time periods of LWD (0, 4, 8, 12, 16, 20, 24 hours) and two clones – using four replicates per treatment; each replication consisted of one inoculated seedling. For inoculation, a suspension containing 2x104 urediniospore mL-1 was prepared and afterwards sprayed on Eucalyptus seedlings by a hand sprayer. After inoculation, the seedlings were enveloped in humid plastic bags for maintain of leaf wetness, then placed under ideal weather conditions of pathogen infection and remained therein according to pre-established LWD time periods. Next, the seedlings were transferred to a climatized greenhouse. We evaluated the latent period, incubation period, incidence, severity, area under the disease progress curve, gas exchange, photosynthetic pigments content and leaf area. The minimum LWD to infection by P. psidii and breakthrough disease was 4 h, although resulting in lower disease severity. Greater severities were observed in treatments as from as from 8 h LWD. The infection of the pathogen and increased severity of the disease negatively affected the physiological responses of seedlings, which caused cutback in net CO2 assimilation rate, stomatal conductance and increased in intercellular CO2 concentration, furthermore, this resulted in the reduction of photosynthetic pigments content and leaf area total of the plant.