Crescimento micelial de Fusarium Solani f. sp. piperis e respostas de cultivares de pimenta-do-reino (piper Nigrum L.) ao estresse abiótico e biótico: biometria, fotossíntese, resistência e avaliação de produtos alternativos de controle da fusariose
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Data
2017-08-29
Autores
Pinheiro, Verônica D'Addazio
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Universidade Federal do Espírito Santo
Resumo
Brazil is the third largest black pepper (Piper nigrum L.) producer of the world and the Espírito Santo State is the first producer among the Brazilian states, with a production of 37 thousand tons of grain. Fusariosis, caused by Fusarium solani f. sp. piperis, is considered the major diseases affecting black pepper, characterized by root rot and branch drying. The objective of this study was to evaluate the resistance of black pepper cultivars (Kottanadan and Bragantina) to abiotic (water deficit) and biotic (Fusarium solani f. piperis) stress, in order to characterize the physiological behavior of the plants, the plantpathogen interaction and to evaluate the alternative products efficiency in controlling the fusariosis. Three experiments were performed: first - In vitro evaluation of mycelial growth of four isolates of F. solani f. sp. piperis, cultivated in different products, revealing that silicon and chitosan induced fungal growth, while phosphite inhibited 100%. It was observed a fungistatic and fungitoxic effect of the Carbendazim and the products were not dose dependent for the study conditions (Chapter 1). Second - carried out in greenhouse conditions, this experiment compared the physiological performance of two black pepper cultivars (Kottanadan and Bragantina) submitted to water deficit. At 12 days of water deficit, lower photochemical changes associated with 90% survival confer to Kottanadan black pepper cultivar increased tolerance to water deficit. Chronic photoinhibition observed in Bragantina cultivar sustains this result (Chapter 2). Third - carried out in plant nursery conditions, this experiment aimed to evaluate the epidemiological (Chapter 3), biometric (Chapter 4) and photosynthetic parameters (Chapter 5) of the pepper cultivars inoculated with F. solani f. sp. piperis as well as the effect of alternative products for controlling (silicon, phosphite and chitosan), applied preventively and curatively. Higher level of disease resistance was observed for Kottanadan pepper cultivar, considering a higher incubation period and lower rates of progression, infection index, and both incidence and severity of disease. In general, higher values of biometric parameters observed for Kottanadan show that this cultivar was less affected by the disease when compared to Bragantina cultivar. The negative correlation between biometric parameters and incidence and disease severity confirm these results. Independently of disease severity, plants inoculated with F. solani f. sp. piperis remained photosynthetically active after 180 days. However, the Kottanadan black pepper cultivar was more resistant to Fusarium, considering the higher values of the relative chlorophyll content, chlorophyll a fluorescence and gas exchange parameters analyzed. In both pepper cultivars, in spite of the similarity observed between application times of the alternative products, plants supplemented with silicon, phosphite and chitosan showed better behavior compared to infected and non-supplemented plants. Phosphite and Silicon are more efficient for both suppressivity of fusariosis and resistance induction, considering the lower incidence and disease severity, the invariability of the plant biomass production as well as the majority of photosynthetic parameters for the Kottanadan black pepper cultivar.
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Biometry , Biometria , Mycelial growth , Crescimento micelia , Water deficit , Déficit hídrico , Epidemiology , Epidemiologia , Chlorophyll a florescence , Fluorescência da clorofila a , Black pepper , Pimenta-do-reino
Citação
PINHEIRO, Verônica D'Addazio. Crescimento micelial de Fusarium Solani f. sp. piperis e respostas de cultivares de pimenta-do-reino (piper Nigrum L.) ao estresse abiótico e biótico: biometria, fotossíntese, resistência e avaliação de produtos alternativos de controle da fusariose. 2017. 223 f. Tese (Doutorado em Biologia Vegetal) - Universidade Federal do Espírito Santo, Centro de Ciências Humanas e Naturais, Vitória, 2017.