Atividade antifúngica de óleos essenciais, hidrolatos e decoctos de plantas do cerrado no controle da pinta preta do tomateiro

Abstract

Agriculture has sought alternative methods of control, including the use of plant derivatives like as extracts, essential oils and hydrolates, among others, which may lead to the discovery of control agents with possible new mechanisms of action against phytopathogens. Tomato production is affected by black spot, caused by the fungus Alternaria linariae. Essential oils (EO), hydrolates (HT) and decoctions (DC) have antifungal activity and have potential in alternative control to chemical-synthetic fungicides for disease control. In this study, the antifungal activity of the essential oils, decoctions and hydrolates of Cochlospermum regium (savannah cotton), Piper aduncum (monkey pepper), Protium ovatum (cerrado rosin), Pterodon emarginatus (sucupira), Hymenaea courbaril (jatoba) was investigated. and Eugenia dysenterica (cagaita) on the in vitro and in vivo development of Alternaria linariae. The antifungal activities on mycelial growth, mycelial growth velocity index and germination of Alternaria linariae conidia in vitro and the area under the curve of disease progress in vivo were evaluated, in addition to verifying the action of essential oils, decoctions and hydrolates. using an ultrastructure approach through scanning electron microscopy. The essential oil of P. aduncum (2.5%) inhibited by 76.42%, the mycelial growth of A. linariae, the other essential oils tested showed a reduction percentage greater than 50%. C. regium hydrolate (5%) inhibited the mycelial growth of the fungus by 63.46%. The E. dysenterica decoction inhibited 88.98% of the pathogen's mycelial growth. The essential oil, hydrolate and decoction of P. aduncum showed the lowest percentage of germination of conidia of A. linariae, the other essential oils, decoctions and hydrolates tested showed a reduction percentage greater than 20%. In vivo assays demonstrated the potential of essential oils, decoctions and hydrolates of C. regium, P. aduncum and E. dysenterica. The area under the disease progress curve in the Santa Clara cultivar with foliar application of monkey pepper essential oil at a concentration of 5% was 0 significantly lower than the value observed in the control (458.33). In the San Marzano cultivar, the essential oils of macaque pepper and savannah cotton were the most efficient with an area under the disease progress curve of 6.18 and 8.25 at a concentration of 2.5%, while the control showed the value of 453.79. The spraying of the essential oils of monkey pepper and savannah cotton from the cerrado at a concentration of 5% reduced the area below the disease progress curve in the cherry tomato cultivar (8.43 and 7.21 respectively) compared to the control (476 ,11). The Super Marmande cultivar showed a value of 0.56 for the area under the disease progress curve when the plants were sprayed with monkey pepper essential oil at a concentration of 5%, a value significantly lower than the control (468.95) The ultrastructural analysis showed that the application of monkey pepper EO, savannah cotton HT and cagaita DC at a concentration of 5%, led to morphological deformations, cellular extravasation and inhibition of conidia germination. The essential oils, hydrolates and decoctions tested in this study can significantly inhibit A. linariae in vitro and in vivo and have potential as a promising natural product for the control of black spot in tomato plants.