Meta-analysis of biofertilizer effects of Bacillus species on tomato yield

Beneficial bacteria, especially Bacillus species, are increasingly being utilized as biofertilizers to promote plant growth and development. However, the meta-analysis of Bacillus species that have a biofertilizing effect on tomato yield parameters is not well understood. The objective of the study is to use meta-analytical procedure to resolve uncertainty, identify knowledge gaps, and create new insights using the results of published studies on the biofertilizer effect of Bacillus spp. on yield characteristics of tomato A comprehensive search of Litmaps yielded 398 articles, of which 15 were used in the meta-analysis. All the analyses were carried out using OpenMEE software and a random-effects model was used. Standardised mean differences (SMD) between tomato yield with and without Bacillus biofertilizer were computed to determine the effect magnitude. The findings showed a significant effect of Bacillus spp. on fruit number (SMD = 1.914; 95% CI 1.432, 2.395; p < 0.001), fruit weight (SMD = 2.08; 95% CI 1.42, 2.73; p < 0.001), fruit length (SMD = 0.96; 95% CI 0.27, 1.64 p = 0.530) and fruit diameter (SMD = 1.39; 95% CI 0.29, 2.48; p = 0.025) with evidence of significant heterogeneity (I² = 0-80.60%). The results of the study also showed that the Bacillus strain, bacterial count, dosage, application mode, days after planting (DAP), temperature, and duration as moderators affected the results of the meta-analysis. Most of the sources of heterogeneity were explained by the examined moderators. These results show the potential of Bacillus spp. as a biofertilizer to improve tomato yield characteristics. The present meta-analysis also set the guidelines for standardized experimental designs on the use of Bacillus spp. to enhance yield characteristics of tomato in the future.