Potential of Bacillus subtilis inoculated on Biorichar Amended Soil for Suppression of Fusarium Wilt, Biochemical Changes and Leaf Gas Exchange under Water Stress Condition of Banana (Musa acuminata) cv. Berangan

Biological control of pathogens continues to be developed with antagonistic rhizobacteria is a promising strategy for banana plant protection. This study aimed to assess the ability of Bacillus subtilis on suppression of Fusarium wilt, biochemical changes and leaf gas exchange under water stress condition on banana cultivar Berangan. Different water stress was given based on field capacity at [well watered (100% FC), mild stress (75% FC) and severe stress (50% FC) and inoculated with different volume of Bacillus subtilis (0, 20, 40, and 60 mL) at concentrations of 108 CFU mL-1. The plantlets were challenged inoculated with Fusarium oxysporum one week after Bacillus subtilis were applied. The treatments were assigned by split plot design in randomized complete block design arrangement. The plants were destructively sampled at 45 and 90 day after transplanting (DAT). Results showed that, applications of Bacillus subtilis at high rate (60 mL) reduced disease incidence by 35.28% and 45.09% at 45 and 90 DAT respectively. Disease severity decreased by 39.83% at 45 DAT and increased by 45.09% at 90 DAT and under well watered conditions. The malondialdehyde (MDA) content was high in control treatment than the plants inoculated with Bacillus subtilis. To summarize, inoculation with 60 mL of Bacillus subtilis in rhizosphere soil to fight against Fusarium wilt could be promoted the plant health under water stress condition.