Beneficial Microbes and Basal Fertilization in Antagonism of Banana Fusarium Wilt

Abstract

Fusarium Wilt Tropical Race 4 (TR4) is spreading rapidly all over the world and threatens banana production, especially the Cavendish variety, which is the main commercial cultivar in Asia. This work aims to use beneficial microbes and fertilizers to control TR4. Both Bacillus mycoides NP02 (BM) and Bacillus amyloliquefaciens BaPD1 (BA) antagonized TR4 growth in plate tests. In addition, basal nutrients (BN) in combination with BM and BA were used to treat 1-month-old banana seedlings infected by Fusarium Wilt; plant growth and nutrients of leaves were investigated after 6-month cultivation in the field. The seedling survival rates for uninfected and infected controls without the microbes were 89.4 ± 14.8% and 50 ± 10.7%, respectively. In contrast, the corresponding rates for 2BM, 5BM, 1BA, F1 (5BM + 4BN + 1BA) and G1 (1BM + 4BN + 1BA) in the infected plants were 80 ± 9.4%, 83 ± 4.3%, 85 ± 14.2%, 96.7 ± 1.9% and 96.7 ± 3.3%, respectively. The 2BM treatment promoted the growth of both uninfected and infected banana plants and the 5BA treatment significantly reduced the severity index by 1.45-fold. Plants infected with TR4 showed significantly reduced contents of nitrogen and potassium, but the contents of iron, copper and zinc were higher than those of healthy plants. Additionally, 1BM treatment stimulated the accumulation of nitrogen and zinc ions in the leaves of uninfected plants. Both the 1BA and 2BN treatments increased the iron (Fe) and nickel (Ni) metal ion levels of TR4 infected plants. The F2 (5BM + 2BN + 1BA) treatment significantly maintained the growth of banana plants under TR4 stress with increased contents of nickel and zinc in banana leaves, suggesting that these ions may play a key role in stimulating the growth of banana plants under the threat of TR4. This work shows the potential of applying BM, BN and BA in the control of Fusarium wilt in field conditions.