Abstract

Pre-inoculation of soybean seeds with Bradyrhizobium spp. associated with polymers could be an alternative to the conventional inoculation performed at the day of sowing.  The objectives of this study were i) to determine whether the HiCoat® technology (peat inoculant + liquid inoculant + polymer) allows the survival of B. elkanii after storage of the inoculated seeds, and ii) to evaluate whether the pre-inoculation and seed treatment reduces the physiological quality of seed and soybean yield. Soybean seeds were treated with different fungicides and insecticides associated with pre-inoculation using HiCoat® and the seeds were stored at room temperature. The survival of B. elkanii was reduced over time with standard inoculation, however there was above 2 x 106 colony-forming units of B. elkanii per seed at 60 days after inoculation with HiCoat®. Seed germination, number of nodules per plant, mass of nodules, yield, number of grains per plant and number of pods per plants were not significantly affected by the pre-inoculation and seed treatments. Our findings indicated that the fungicide and insecticide associated with HiCoat® can be used to treat and to pre-inoculate seeds that can be stored for up to 71 days without compromising the nodulation of plants and soybean yield.

Key words: Industrial seed treatment, biological nitrogen fixation, storage period, fungicide, insecticide, polymer, HiCoat, Glycine max.