Enhanced growth of ginger plants by an eco- friendly nitrogen-fixing Pseudomonas protegens inoculant in glasshouse fields

BACKGROUND Excessive nitrogen (N) fertilization in glasshouse fields greatly increases N loss and fossil-fuel energy consumption resulting in serious environmental risks. Microbial inoculants are strongly emerging as potential alternatives to agrochemicals and offer an eco-friendly fertilization strategy to reduce our dependence on synthetic chemical fertilizers. Effects of a N-fixing strain Pseudomonas protegens CHA0-Delta retS-nif on ginger plant growth, yield, and nutrient uptake, and on earthworm biomass and the microbial community were investigated in glasshouse fields in Shandong Province, northern China. RESULTS Application of CHA0-Delta retS-nif could promote ginger plant development, and significantly increased rhizome yields, by 12.93% and 7.09%, respectively, when compared to uninoculated plants and plants treated with the wild-type bacterial strain. Inoculation of CHA0-Delta retS-nif had little impact on plant phosphorus (P) acquisition, whereas it was associated with enhanced N and potassium (K) acquisition by ginger plants. Moreover, inoculation of CHA0-Delta retS-nif had positive effects on the bacteria population size and the number of earthworms in the rhizosphere. Similar enhanced performances were also found in CHA0-Delta retS-nif-inoculated ginger plants even when the N-fertilizer application rate was reduced by 15%. A chemical N input of 573.8 kg ha(-1) with a ginger rhizome yield of 1.31 x 10(5) kg ha(-1) was feasible. CONCLUSIONS The combined application of CHA0-Delta retS-nif and a reduced level of N-fertilizers can be employed in glasshouse ginger production for the purpose of achieving high yields while at the same time reducing the inorganic-N pollution from traditional farming practices. (c) 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.