Seed coating with plant growth-promoting rhizobacteria enhances potato (Solanum tuberosum L.) growth and yield

Utilizing beneficial plant growth-promoting rhizobacteria (PGPR) offers an effective approach for achieving sustainable crop production. However, research on the application and mechanisms of PGPR seed coating in potato ( Solanum tuberosum L.) remains limited. Therefore, we conducted a two-year field experiment involving five seed-coating treatments: untreated (CK), chemical coating (CB), Bacillus velezensis coating (SM), and two composite formulations, CM1 ( Bacillus subtilis + Paenibacillus mucilaginosus ) and CM2 ( Bacillus subtilis + Bacillus licheniformis ). The results showed that PGPR markedly improved soil NO₃ − -N and available P contents by stimulating carbon (C), nitrogen (N), and phosphorus (P) cycling enzymes. During potato flowering stages, soil NO₃ − -N and available P increased by 16.29 and 17.29%, respectively. PGPR also increased plant height and stem diameter by 10.89 and 34.46% relative to CB, and elevated SPAD values and net photosynthetic rate ( P n ) at flowering by 20.22 and 32.22%, respectively. At maturity, potato aboveground, root, and tuber dry matter under PGPR increasing by 31.27, 44.21, and 41.88% compared with CB. Enhanced root biomass and nutrient acquisition promoted nutrient redistribution in potato, increasing N and P translocation to tubers by 17.13 and 50.48%, respectively. CM2 exhibited the highest tuber N and P accumulation, increasing by 66.74 and 55.25%, and achieved a 38.9% higher yield compared with the other treatments. Overall, PGPR enhanced soil nutrient availability, plant photosynthetic performance, nutrient acquisition, and nutrient translocation, thereby supporting greater biomass accumulation and promoting sustainable potato production. The PGPR seed coating represents an effective and scalable strategy for achieving resource-efficient and sustainable potato production.