Seed treatment and pre-inoculation of soybean: effect of storage period and agrochemicals on the physiological quality of seed and yield

Industrial seed treatment of soybean [Glycine max (L.) Merr.] has increased over the last years. New technologies have been developed to allow the inoculation procedure, which is traditionally done at the day of sowing, to be performed with the industrial treatment days or even weeks before sowing. Since little is known about the compatibility of agrochemicals and pre-inoculation, the objective of this study was to determine whether the storage period and the combination of fungicides and insecticides could negatively affect the physiological quality and yield of soybean seeds that were pre-inoculated. Soybean seeds received fourteen seed treatments that consisted of different fungicides and insecticides and were pre-inoculated with Bradyrhizobium elkanii. The seeds were treated and stored for 51 days until it was sown in the field. Every 17 days the physiological quality of the seed was assessed. The results shown that pre-inoculation did not affect the physiological quality of seeds. However, some combinations of agrochemicals, as well as storage period reduced seed vigor and seed germination, while increased abnormal seedlings. The findings of this study indicated that some combinations of fungicides and insecticides can have adverse effect on the physiological quality of seed that is stored for up to 51 days before sowing, but none of them jeopardized the nodulation and soybean yield under field conditions. Key words: Biological nitrogen fixation, Bradyrhizobium, compatibility, fungicide, Glycine max, HiCoat, industrial seed treatment, insecticide, polymer.