No effect of seed treatment on the rhizosphere microbial diversity

Summary

Pesticides are widely used in agriculture as crop protective agents. However, the harmful impacts of pesticides on the ecosystem – including impacts on insects, human health, and water and air pollution- are increasingly reported. Soil microbial diversity is a key indicator of soil health, making it essential to understand how pesticides and alternative treatments influence these communities.
We report findings from the first two years of a seven-year project comparing synthetic seed-treatments to alternative methods. This research, conducted in collaboration with a network of 20 farmers who are committed to the reduction of pesticides (both organic and conventional), aims to assess the impact of different seed treatments on rhizosphere microbial biodiversity. Farmers included Thermoseed-treated (vapor-treated) seed and untreated seeds as controls. Rhizosphere and bulk soil were sampled a few weeks after germination, followed by DNA extraction and sequencing of ITS region and 16S rRNA gene to analyze fungal and bacterial communities.
Results from the first two years indicate no significant effect of seed treatments on the alpha diversity of the rhizosphere microbial communities. While seed treatment had not detectable effect on community composition, beta diversity was primarily influenced by soil properties.
This study is unique in its large-scale comparison of seed treatments across multiple fields. As this long-term study progresses, continued monitoring will be essential to better understand the complex interactions between seed treatments, soil microbial communities, and environmental factors.