Pseudomonas sp. JP1-10 Promotes Peanut Growth and Root Branching Across Greenhouse Salinity Conditions

Microbial inoculation may support crop growth under salinity, but general growth promotion must be distinguished from salinity-dependent responses. Pseudomonas sp. JP1-10 was evaluated in greenhouse-grown peanut at 0, 2.5, and 5 g NaCl kg−1 dry soil. Growth, antioxidant responses, and rhizosphere properties were assessed at 30 and 60 days; root architecture and tissue ions were assessed at 60 days, and reproductive fresh weights were assessed at maturity. Inoculation was associated with greater shoot and root fresh weights and longer primary roots across the salinity gradient. Root tip number increased by 57.49–86.52% and lateral root number by 95.33–107.23%, with salinity-dependent branching responses. Recorded shoot and root ion values suggested lower Na and higher K and K/Na mass ratios under salinity, although their conversion to absolute tissue concentrations requires validation. Antioxidant responses varied with tissue and sampling time. In saline treatments, rhizosphere available K and Fe were higher and electrical conductivity was lower with inoculation. Pod fresh weight increased overall by 1.07 g plant−1, without a salinity × inoculation interaction. Hundred-pod and hundred-kernel fresh weights were higher with inoculation at all three salinities, with salinity × inoculation interactions. These exploratory findings support general growth promotion and identify root branching and pod fresh weight as prominent responses associated with inoculation.