Table 2.

A list of studies reporting the legacy effect of microbial inoculants.

Crop species	Cropping system	PGPR Strains	Inoculation stage	Persistence duration	Production system	Effects on plants	References
Pepper	Monoculture	Bacillus velezensis NJAU-Z9	Pre-inoculation of seedlings	Two season trial legacy throughout growth stages	Field experiment	Higher rhizosphere bacterial richness which resulted in plant growth promotion and steady yield enhancement	139
Faba bean and potato	Rotation	Rhizobium gallicum 8a3 and/ or Ensifer meliloti 4H41	Pre-inoculation of faba bean seedlings at two leaf stage	March-June 2009 for faba bean September-December 2009 for potato grown in rotation	Field experiment	Rhizobial strains stimulated faba bean growth and enhanced its rotational effect in potato cropping systems by providing fixed N, increasing microbial diversity which all enhance its growth and resistance to diseases	131
Faba bean	Monoculture	Agrobacterium sp. 10C2	Sowing seeds in soils previously inoculated for 15 days	80 days post-soil inoculation	Greenhouse experiment	Inoculation increased nodule number, plant biomass, as well as grains’ P, polyphenols, flavonoids and total antioxidant capacity. richness and structure of potential bacterial phyla were positively induced.	145
Oat and alfalfa	Rotation	Sinorhizobium meliloti and/ or Azotobacter spp., Pseudomonas sp., Enterobacter sp., Bacillus megaterium	–	–	Greenhouse experiment	Promoted alfalfa growth, yield and N-accumulation through the inoculation of a preceding oat crop	146
Ryegrass and alfalfa	Rotation	Sinorhizobium meliloti L3Si	Inoculation of sown reygrass seeds	6 weeks for reygrass in 2009 6 weeks for alfalfa in 2010	Greenhouse experiment	Inoculation enhanced growth of both plants and increased rhizobial abundance, nodulation, and total N-uptake of subsequent alfalfa planst	147
Maize and wheat	Monoculture	Bacillus sp	Maize seed coated with the PSB	Between 5 June to 10 September 2016 for maize and fall of 2016–2017 for wheat	Field experiment	Inoculation improved grain yield, soil properties, RP solubility and P-uptake in both plants	93
Alfalfa - wild rye	Intercropping	Sinorhizobium meliloti	Inoculation of sown seeds	Two years experiment from 2006 to 2008	Field experiment	Inoculation induced remarkable shifts of the rhizosphere bacterial communities, and enzyme activities after and enhanced yield parameters	142