Rhizobacterial, Fusarium Complex, and Fungicide Seed Treatments Regulate Shoot and Root Traits of Soybean Plants

Purpose The effects of microbes and agrochemicals on crop plants are previously reported via seed treatments. We know little about the impacts of fungicides and microbial seed treatments on soybean shoot and root traits. Methods We investigated the effects of separate consortia of two plant growth-promoting rhizobacteria (PGPR) such as Bacillus simplex R180 and Burkholderia ambifaria C628, two Fusarium species (Fusarium oxysporum and Fusarium graminearum) (Fusarium), and Fungicides seed treatments on soybean traits. Results and Conclusions The PGPR and Fusarium increased and reduced the root and shoot dry mass of soybean plants, respectively. Fusarium infected plants had a relatively higher trichome leaf density followed by the PGPR, Control, Fungicide + PGPR, and Fungicides treatments. The PGPR increased P contents, while Fusarium reduced Mg and Mn contents of soybean shoot tissues. The nutrient contents of large and fine roots also varied across the seed treatments. Overall, fine roots showed higher mineral contents than large roots. Soybean roots showed relatively higher mineral contents such as Mg, Zn, Ca, Mn, Cu, B, Fe, and Mo in the fungicide + PGPR and fungicide treatments. Root K contents were substantially higher in the microbial than chemical treatments. The reduced and increased trichome density as well as tissue P contents in response to the Fungicides and microbial (PGPR, Fusarium) treatments, respectively, suggest the negative and positive effects of fungicides and microbes on soybean root and shoot traits. In conclusion, chemicals, pathogenic and beneficial microbes may influence plant shoot and root traits that are important for plant growth and development. Keywords Seed treatments · Probiotics · Fungicides · Rhizobacteria · Fusarium · Soybean · Root chemistry · Root system architecture