Damage caused by different inoculum levels of Aspergillus ochraceus on the vigour of soybean seeds

Abstract

The incidence and severity of Aspergillus ochraceus can reduce seed quality. In this study, we aimed to study the physiological quality of soybean seeds naturally infected with A. ochraceus. Seeds of soybean cv. Conquest with different levels of inoculum of A. ochraceus were obtained by the technique of water and separated into three classes (N0, N1 and N2) according to the constraint surface area covered with fungal structures. The control samples were taken from the N0 treatment, two samples of 200 soybean seeds, the first being treated with fungicides carboxin + thiram and the second sample subjected to surface disinfestation by immersion in a solution of sodium hypochlorite. Next, we assessed the vigour of seeds through the emergency test in trays and the tetrazolium test. The length, seedling fresh and dry weight of shoot and root were evaluated at 21 days after sowing. There was a reduction in the rate of speed of emergence and seedling emergence in the seeds with levels of up to 50 % of inoculum compared to treatment with fungicide. The length of the seedlings (44 %), fresh weight of shoot and root (82 %), dry weight of shoots (81 %) and root dry mass (76 %) were also reduced . Soybean seeds with incidence above 50 % of A. ochraceus showed total loss of vigor and decay of tissues.