Patologia de sementes de angico-vermelho (Parapiptadenia rígida (Bentham) Brenan), potencial de óleos essenciais no controle de Rhizoctonia sp. in vitro e no tratamento de sementes

Abstract

The pathogenic fungi hinder the germination of seeds and development. Therefore, the use of alternative methods and products can be an efficient way for its control. The objective of this study was to evaluate the effect of essential oils to treat angico-red seeds (Parapiptadenia rigid) and in vitro control Rhizoctonia sp. through experiments conducted in the laboratories of Phytopathology and UTFPR Seed Analysis - Campus Dois Vizinhos. Two experiments were developed: In the first experiment evaluated the potential of essential oils in control of Rhizoctonia sp. under in vitro conditions. Initially to develop this experiment, there was the seed health testing, adopting the methodology with eight gerbox boxes with 25 seeds and Germitest role as substrate, moistened with 7 mL of distilled water, remaining the incubated seeds seven days at 23 + 2 ° C temperature. After the incubation process has been identified as Rhizoctonia sp., the fungus with a greater incidence in the seeds of angico-red. Then, the fungus was isolated to give pure colony. The oils were tested in the volatile manner to this, there were four petri dishes representing the repetitions for each treatment (guacatonga, melaleuca, cherry, creaky and witness), and on each plate was added will a hurry paper tape cover plates, 10 μL of each essential oil remaining exposed to the fungus presence of these oils. Diameter measurements were performed on cross-shape, obtaining an average value of two measurements (A and B) growth of the fungal colony. .The Tea tree oil proved the most effective in inhibiting the mycelial growth of this fungus, while other oils did not differ statistically from the witness. In the second experiment evaluated the potential of essential oils on the physiological parameters of seed germination. For this, the seeds were treated with 100 μL of each essential oil, fixing the lids of each crucible a strip of filter paper, where the oils were added, and the seeds remain exposed to oils for 24 hours. After the treatment the seeds was installed seed germination test. It was used for testing the paper substrate Germitest moistened with two and a half times its dry weight (BRAZIL, 2009), performing eight repetitions of 20 seeds, with 25 ° C. The essential oil of Melaleuca guacatonga and provide increased seed germination, while chia oil inhibited the germination of P. rigid seeds compared to control. Angico-red seedlings size range found in the aerial part size (hypocotyl) of 1.5 and 6.1 cm and the radicle of the 1,2 and 8.5 cm long. The average weight of fresh weight of seedlings was 0.0528 g. This work presented importance for obtaining information relating to the main fungi that attack the species by providing subsidies for the control of plant pathogens, as well as more knowledge on the use of alternative products less toxic to the environment and to humans.