Effect of H2S and rhizobia on the number of soybean nodules, endogenous H2S content and nitrogenase activity under water deficiency condition
Soybean nodules numbers were prominently enhanced by Q8 and Q8+NaHS treatments under MW condition compared with NW and SW conditions, whereas no significant difference was observed between Q8 and Q8+NaHS treatments under MW and SW condition (Fig. 2A, B). Interestingly, the increase in the nodules number did not lead to enhance the root nodule biomass. On the contrary, under MW condition plant treated with Q8 exhibited a 49.9% loss of nodules biomass compared with the NW condition, and the MW condition plant treated with Q8+NaHS exhibited a 44.2% loss of nodules biomass compared with the NW condition (Fig. 2C). In addition, the endogenous H2S content of the nodule was reduced by Q8 and NaHS+Q8 treatments with the decrease of water content. Under SW condition, the endogenous H2S content of the nodule was observably higher by Q8+NaHS treatment than Q8 treatment, but it was no apparent difference between the NW and MW conditions (Fig. 2D). Additionally, the nitrogenase activities were reduced by Q8 and Q8+NaHS treatments with the decrease of water content, similar to the changes of nodule endogenous H2S (Fig. 2E), but there was a slight enhancement of the nitrogenase activity by Q8+NaHS treatment under the three water conditions compared with Q8 treatment.