Estudos das relações de Septoria glycines com sementes de soja (Glycine max)

Abstract

Septoria brown spot disease, caused by Septoria glycines, has been a serious concern for soybean producers in Brazil due to the increasing occurrence in most regions that produce this crop in the country. The disease has been known in Brazil since the 70s, however has only been considered a serious problem to soybean production in recent years. In the literature, the causal agent of this disease is transmitted by soybean seeds, however there are no reports of this type of relationship in Brazilian conditions. In this work the aim was to investigate the transmissibility and effects of the pathogen from soybean plants to their seeds and from seeds to plants in the controlled conditions. Evaluation tests were carried out in laboratory and greenhouse, having as reference points two types of inoculation from plants and from seeds, different inoculum levels and cultivation temperatures. Methodologies already known and described in the literature for other pathosystems with the same purposes of this work were followed. The results showed that Septoria glycines was able to be transmitted from plant to seed and from seed to plant, in variable levels depending on the variables used for this study. The transmission rates and effects of the pathogen from the seeds occurred in the function of temperature and inoculum level, but the intensity of these effects was lower compared with other pathogens in soybean such as Colletotrichum truncatum, Sclerotinia sclerotiorum, Phomopsis sojae, Rhizoctonia solani, Fusrium pallidoroseum. Based on the results of this study, it is also evidenced will be necessary to improve the soybean seed health test for the detection of Septoria glycines in seed used for cultivation.