Plant growth–promoting rhizobacteria (PGPR) can be used as biofertilizers to enhance crop growth for better yield and soil fertility restoration. PGPR possesses certain traits such as nutrient solubilization, phytohormone production, and production of key enzymes for improved crop growth. These traits are also important for inhibiting the growth of plant root pathogens, improving root development, and conferring stress tolerance. However, the mere presence of PGPR traits in isolated bacteria may not directly reflect an improvement in plant growth, warranting researchers to evaluate phenotypic and physiological changes upon inoculation. The current manuscript provides a detailed step-by-step procedure for inoculating the PGPR Staphylococcus sciuri into seeds and seedlings of rice and tomato plants for visualizing the enhancement of root and shoot growth. The surface-sterilized seeds of rice and tomato plants are inoculated overnight with an actively grown log-phase culture of S. sciuri, and differences in growth and biomass of seedlings that emerged from the inoculated and uninoculated seeds are analyzed 10 days after germination. Plants grown in pots with sterile soil are also treated with PGPR S. sciuri by soil drenching. A remarkable increase in root and shoot growth is observed in inoculated plants. We suggest that treating seeds with bacteria and enriching the soil with bacterial inoculum provides an adequate load of PGPR that facilitates growth improvement. This method can be a reliable choice for screening and evaluating plant growth promotion by either isolated bacteria or bacterial consortia with plant-beneficial traits.

Key features

• Inoculation of seeds and seedlings with an actively grown log-phase culture of S. sciuri can induce root and shoot growth in rice and tomato plants.

• The improvement of root and shoot growth due to inoculation with S. sciuri can be evaluated under laboratory conditions.

• The method can be used to screen bacteria with plant growth promotion ability under laboratory conditions.

• The method is robust and can be used for evaluating the plant growth–promoting ability of many bacteria and the inoculation of multiple plant species.

Plant growth–promoting rhizobacteria (植物生长促进根际菌)

Tomato (番茄)

Rice (水稻)

Seeds (种子)

Seedlings (幼苗)

Biofertilizers (生物肥料)

Root growth (根系生长)

Graphical overview

Graphical overview of inoculation of seeds and seedlings of rice plants with plant growth–promoting rhizobacteria (PGPR) for increased root and shoot growth