Transmissibilidade de patógenos em cultivares de soja, com diferentes tempos de exposição da semente com fungos

Abstract

The sanity of seeds is a determining factor in uniformity at the booth of plants in a plantation and consequently yield suitable agricultural year conditions. As part of the rural producers use seed saves and many multipliers they don't test seed health, it is important to assess the speed of infection when there is a pathogen and environment. Before that, the experiment aimed to evaluate the speed of infection of three of the main fungi which attack the culture of soybean (Glycine max) and cause great economic losses requiring monitoring and control. The cultivars used were Fundacep 61, TMG 7262, and BMX Tornado, from producers in the region (saved seed). Fungi Colletotrichum truncatum were evaluated, Macrophomina phaseolina, anthracnose causes, causing root rot and Sclerotinia Sclerotinea, which causes white mold. For the conduct of the experiment the fungus were peaked in Petri dishes and after the seeds were deposited in the colonies, during 3 days of exposure, being these 12 hours, 24 hours and 48 hours, with controlled osmotic potential to avoid the twinning process from seed still in the Petri dish. Subsequently the seeds were deposited in 500 ml cups with mixture of soil and substrate on 2/1 ratio under 5 mm irrigation a day over a period of 44 days. Disease severity was evaluated from the scale, where zero is highly resistant and susceptible to Macrophomina phaseolina five highly, from zero to nine for Colletotrichum truncatum, and the 50% 0 to Sclerotinea sclerotiorun, in addition to size and dry weight of shoot and radicle. The results showed that there is interference in accordance with the characteristic of each cultivar, about severity. Similarly, the contact times interfered in the expression of all diseases.