Rhodopseudomonas palustris increase soybean photosynthesis and protein levels in grains

Rhodopseudomonas palustris, a photosynthetic bacterium with biostimulant properties, enhances agricultural productivity by increasing plant resistance to environmental stresses. To assess its impact on soybean cultivation, we conducted a field experiment employing a randomized complete block design comprising six treatments and five replicates. The treatments included the following: (1) control treatment (no application); (2) bacterial treatment in the sowing furrow; (3) bacterial treatment in the sowing furrow involving two foliar applications at the six-trifoliate stage and the beginning of flowering; (4) foliar treatment at the six-trifoliate stage; (5) two foliar treatments, one at the six-trifoliate stage and one at the beginning of flowering; and (6) three foliar treatments, one at the six-trifoliate stage, one at the beginning of flowering and the third during pod formation. Foliar application of Rhodopseudomonas palustris at the six-trifoliate stage significantly increased the photosynthetic rate and height of the soybean plants. The starch content in the soybean leaves exhibited a greater increase across all the R. palustris treatments. Notably, compared with those in the control plants, the protein levels in the leaves in the R. palustris-treated groups were elevated. Furthermore, the treatments involving foliar application at the six-trifoliate stage and three foliar applications showed a marked increase in protein content in the grains. This approach optimizes soybean plant growth and increases grain protein content, thereby improving the nutritional value of cereal plants. Innovative biotechnologies, such as the application of R. palustris, have the potential to enhance physiological and biochemical responses while increasing the commercial quality of soybean crops.