Óleos essenciais como alternativa de controle de patógenos em sementes de ipê amarelo (Handroanthus chrysotrichus Mart. Ex A. DC.Mattos)

Abstract

The use of fungicides to control plant pathogens has caused some problems related to resistance to active ingredients, in addition to serious damage to the environment and to humans. In this sense, research on alternative methods of plant pathogens control has great relevance. The objective was to evaluate the effect of essential oils of Surinam cherry (Eugenia uniflora), thyme (Thymus vulgaris), clove (Syzygium aromaticum) and eucalyptus (Eucalyptus sp) in control of plant pathogens present in seed yellow ipê and Fusarium sp. in vitro. The work was developed in plant pathology laboratories and in the UTFPR seeds during 2014. Prior to the implementation of the experiments the seeds of yellow ipê were collected UTFPR – Dois Vizinhos, selected and isolated Fusarium sp. thereof. Two experiments were conducted, the first in vitro, evaluating the effect of the oils on the fungus Fusarium sp .. For these experience a 3mm disc containing Fusarium sp. was disposed in the center of petri dishes containing PDA (Potato Dextrose Agar), essences and oils were applied on filter paper and fixed in this upper cover plate. The samples were sealed and placed in BOD (26°C and photoperiod of 12 hours), and evaluated for 7 days mycelial growth of the pathogen. In the second experiment, we assessed the effect of the oils in the treatment of ipê seeds. The seeds were treated by volatilization with the same oils in vitro experiment, and for that the same were prepared in batches of 100 seeds, placed in a stainless steel crucible containers, and the essential oil applied on filter paper (oil by 20microlitros paper / cup), then the crucibles sealed by a 24-hour period, and for control using distilled water. After the treatments, the seeds were evaluated for germination test, considering the percentage of sprouted plants, incidence of pathogens and size of seedlings. Furthermore, the plant material was collected for determination of biochemical analysis of total proteins, enzyme activity phenylalanine ammonia-lyase, chitinase and β-1-3glucanses. For both experiments the experimental design was completely randomized, with four repetitions. Clove oils from India, thyme and eucalyptus have fungicide, while the Surinam cherry has fungistatic action in the control of Fusarium sp. under in vitro conditions. Thyme oil did not cause damage to seedlings, and reduced the incidence of pathogens. No observed effect of the oils on the process of induction of resistance in plants.