Synergistic Effects of the Application of Beneficial Bacteria, Compost and Mineral Fertilizer on Onion Productivity in Burkina Faso

Abstract

Onion is one of the main vegetable crops grown in Burkina Faso, but poor soil fertility often limits its productivity. This study aims to evaluate the effect of using beneficial rhizobacteria in soil as bio-fertilizer in order to improve onion growth and yield, either individually or in combination with compost and mineral fertilizers. The M16 strain, which belongs to the Lysinibacillus genus, was characterized for its performance as a biofertilizer. The tested strain was positive for producing indole-3-acetic acid (IAA), hydrogen cyanide (HCN), and ammonia (NH₃); however, it was unable to fix atmospheric nitrogen. The effects of different combined treatments (Inoculum, Compost, NPK) on plant growth were evaluated at 20, 45, and 60 days after transplanting under open-field conditions. At 20 days, plant height was significantly higher with sole compost (p<0.001) than those recorded with the Inoculum+NPK and Inoculum+Compost treatments. At 45 and 60 days, the best growth was recorded with the combined treatments Inoculum+Compost+NPK and Inoculum+NPK (p=0.001 and p<0.001), respectively. These treatments also significantly affected neck diameter and bulb yield (p<0.001) and performed markedly better than performance compared to single-input treatments. Treatments combining the inoculum with compost and/or NPK significantly (p< 0.001) improved vegetative growth and bulb yield, unlike the individuals (inoculum alone, compost alone, NPK alone, or control). These findings confirm that the growth-promoting effects of bacterial inoculum were more vigorous when combined with organic and/or mineral nutrients. Furthermore, this study demonstrated the involvement of Lysinibacillus sp. in promoting onion growth in Burkina Faso.