Name: Verônica D'Addazio Pinheiro
Type: PhD thesis
Publication date: 29/08/2017
Advisor:
Name |
Role |
|---|---|
| Antelmo Ralph Falqueto | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Andreia Barcelos Passos Lima Gontijo | External Alternate * |
| Antelmo Ralph Falqueto | Advisor * |
| Diolina Moura Silva | Internal Examiner * |
| Edilson Romais Schmildt | External Examiner * |
| Inorbert de Melo Lima | Internal Alternate * |
| Paulo Cezar Cavatte | Internal Examiner * |
| Rosana Sambugaro | External Examiner * |
Summary: 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 growing 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. 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. Third - carried out in plant nursery conditions, this experiment aimed to evaluate the epidemiological, biometric and photosynthetic parameters of the pepper cultivars inoculated with F. solani 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 remained photosynthetically active after 180 days. However, the Kottanadan black pepper cultivar was more resistant to F. solani, 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.
