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

BACKGROUND Excessive nitrogen (N) fertilization in greenhouse 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 nitrogen-fixing strain Pseudomonas protegens CHA0-ΔretS-nif on ginger plant growth, yield, and nutrient uptake, and on earthworm biomass and the microbial community were investigated in greenhouse fields in Shandong Province, northern China. RESULTS Application of CHA0-ΔretS-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-ΔretS-nif had little impact on plant P acquisition, whereas it was associated with enhanced N and K acquisition by ginger plants. Moreover, inoculation of CHA0-ΔretS-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-ΔretS-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 × 105 kg ha-1 was feasible. CONCLUSIONS The combined application of CHA0-ΔretS-nif and a reduced level of N-fertilizers can be employed in greenhouse ginger production for the purpose of achieving high yields while at the same time reducing the inorganic-N pollution from traditional farming practices. This article is protected by copyright. All rights reserved.