Effect of mycorrhizae, Thiobacillus and sulfur nutrition on the chemical composition of soybean [Glycine max (L.)] Merr. seed

A field experiment carried out in a calcareous soil with a low available phosphorus to evaluate effectiveness of biofertilizers, mycorrhizae (Glomus intraradices) and Thiobacillus sp. inoculation individually or in combination on seed yield, oil, protein and some elements (P, Fe, Mn, Zn) concentration in two soybean Glycine max (L.) Merr.] cultivars. The applied treatments were different fertilizers with 6 levels (including: NP (control, 12 kg N ha(-1) as urea, 46 kg P2O5 ha(-1) as triple super phosphate); NPK (NP + 75 kg K2O ha(-1) as potassium sulphate); NPKS NPK+ S (100 kg S ha(-1))]; NPKST (NPKS + seed inoculation with Thiobacillus bacteria); NPKM (NPK + Seed inoculation with mycorrhizae fungi) and NPKSTM (NPKS + seed inoculation with Thiobacillus and mycorrhizae) and two cultivars (JK and 032). Before planting, soybean seeds were inoculated by Bradyrhizobium japonicum in all treatments. Results showed that combined inoculation of biofertilizers increased yield, however the highest yield was observed in treatment NPKST. Increasing oil content (percentage) was more pronounced in treatments NPKM, while most protein content (percentage) increasing was observed in NPKS and NPKM. Fe and Zn concentrations were unaffected significantly by fertilizer treatments, but NPKSTM showed significantly higher value of seed's Mn concentration compared to treatments NP and NPK. Although no significant difference was observed in terms ofP concentration of 032 line among fertilizer treatments, JK cultivar and NPKSTM caused a significant increasing in P concentration compared to NP, NPKS and NPKM. Present results suggested that applying biofertilizers i.e., mycorrhizae and Thiobacillus increased soybean yield compared to control (NP). Overall, this study demonstrated that soybean seed yield and its chemical composition could be affected by biofertilizer inoculation.