Benefits of using vermiculite in the soybean seed germination testing

The incidence of abnormalities in germination tests using rolled paper substrate (RP) is common when evaluating seeds treated with insecticide, especially neonicotinoid molecules, probably due to the high concentration and absorption of the products in this type of substrate. It is, therefore, necessary to adjust methodologies so that the results represent these treated seeds, one of which is using vermiculite between the rolled paper (RP + V). This study evaluated the benefits of RP + V and the effect of neonicotinoid insecticides on soybean seed germination. It was carried out on NS 8080 soybean seeds and divided into two experiments. In the first experiment, RP and RP + V were compared with treated with fungicide and insecticide and untreated seeds regarding imbibition time, primary root length and total seedling length. In the second experiment, all the seeds were treated with fungicide and polymer. This experiment used a 4 × 2 design, with four seed treatments, three with neonicotinoid insecticides, and control, and two substrates (RP and RP + V). Evaluations included the percentage of normal seedlings in the first count at 5 days and in the final count at 7 days for RP + V and 8 days for RP. The RP + V substrate has several benefits for the germination test of soybean seeds, including increased speed of soaking and seedling growth; greater precision in expressing the quality of the batch, regardless of seed treatment and cultivar; mitigation of the phytotoxic effects of neonicotinoid insecticides; and the possibility of carrying out the final count of normal seedlings at 7 days.