Enhancing the performance of chilli (Capsicum annuum) through twin role of plant growth promotion and disease suppressionvia Bacillus subtilis-based bioformulation

Abstract

Considering the majority of studies confined in vitro evaluation of microbial bioagents against diseases, a study was carried out during 2018–21 at Assam Agricultural University, Jorhat, Assam, (in vivo and field studies) to assess bio-efficacy of B. subtilis (strain LB22)-based liquid bioformulation against bacterial wilt (Ralstonia solanacearum) and anthracnose (Colletotrichum gloeosporioides) diseases of chilli (Capsicum annuum L.). In vivo efficacy of B. subtilis formulation (inclusive treatment involving seed treatment, seedling dip, soil treatment and foliar spray) showed significant suppressiveness against both the diseases coupled with enhanced growth and yield attributes. Subsequently, the field evaluation of Bacillus subtilis formulation comparing standard chemicals also edged over the latter by 15.45% in terms of yield gains in 2-years of study. A significant reduction was found in disease severity during field evaluation of Bacillus subtilis formulation on account of induced resistance via upregulated synthesis of plant defense-enzymes (Polyphenol oxidase, peroxidase, phenylalanine ammonia-lyase, and β-1,3-glucanase) by 2.3–11.0 folds with their peaks mostly expressed within 24–72 h. These results put forward a conceptual framework for delivery mechanism of a microbial bioagent in a formulation mode, having the potential to be effective against a number of other diseases as well.