Growth and Metabolic Response of Glycine max to the Plant Growth-Promoting Enterobacter Delta PSK and Bradyrhizobium japonicum Under Salinity Stress

Abstract

AbstractThis study was designed to test the ability of some plant growth-promoting bacteria to adverse the effects of salinity on soybean growth. The effect ofBacillusMAP3 andEnterobacterDelta PSK, along withBradyrhizobium japonicumwas studied on soybean at two levels of NaCl salinization (50 and 100 mM). The physical growth parameters of bacterized soybean (21 days old), particularly plants co-inoculated withBradyrhizobium japonicum + EnterobacterDelta PSK, were significantly enhanced compared to control plants. The shoot length, leaf area, root length, and chlorophyll a content increased by 49.58%, 78.58%, 20.19%, and 57.35%, respectively, indicating the promoting activity of this bacterial combination. After 19 days following the onset of salinity stress, the retarded growth parameters in controls improved significantly due to bacterial treatments, especially byBradyrhizobium japonicum + EnterobacterDeltaPSK, which increased the values of all growth parameters significantly regardless of the salinity level. Additionally, electrolyte leakage, the amounts of malondialdehyde and hydrogen peroxide decreased considerably due to this combined bacterial treatment.Overall, the combination treatment ofEnterobacterDelta PSK and the original symbiontB. japonicumenhanced soybean growth under salt stress, indicating the ability ofEnterobacterDelta PSK to mitigate osmotic stress. The effect of this strain on soybean yield should be further evaluated to pave the way for its use as a biofertilizer along withB. japonicum,especially under salt stress.