Development of a novel bio-organic fertilizer for plant growth promotion and suppression of rhizome rot in ginger

Rhizome rot of ginger caused by Fusarium oxysporum f. sp. zingiberi (Foz) is a soil-borne disease that adversely affects the seed rhizomes and crop production. Bacillus amyloliquefaciens NJPRHSDAQ-1 (NP-1), which has a substantial inhibitory effect on Foz in vitro, was isolated from the ginger rhizosphere. A pot experiment indicated that a bio-organic fertilizer made from NP-1 (BIO2) or other universal biocontrol agents (BIO1), the suspension of NP-1 (NP-1), and its cell-free fermentation broth (NP-1fb), all effectively reduced the disease incidence of rhizome rot, stimulated plant growth, and improved the microbial community compared to the control. The best control effect (78.3%) and the most significant suppression of Foz abundance (75.8% compared to control) were all observed in the BIO2 treatment. Two field experiments further indicated that BIO2 amendment can significantly increase ginger yield by 8.0-11.5% and can decrease the Foz population by 30.8-51.0% compared to control plants receiving only chemical fertilizer. Application of BIO2 also increased the growth and nutrient quality of ginger and soil enzyme activity. Pearson correlation analysis indicated a significant negative relationship between the abundance of culturable bacteria and Foz, while a negative correlation between culturable actinomycetes/fungi population and invertase/urease activity was observed. This study highlights the application prospect of a novel bio-organic fertilizer in ginger production for both disease suppression and growth promotion.