Bacillus sp. strain D5 based bioformulation enhances growth, yield and quality of Allium sativum L. under field conditions

Bacillus sp. strain D5 (Bar D5), a well-characterized plant growth promoting bacterium (PGPB) previously demonstrated to improve quality and yield of Crocus sativus L. (saffron), was evaluated for its efficacy in Allium sativum L. (garlic). Two independent field trials were carried out in the R.S. Pura region of Jammu district, J&K, India during November 2021-April 2022 (trial-1) and November 2023-April 2024 (trial-2). Application of a Bar D5 based bioformulation significantly enhanced multiple growth and yield parameters in garlic. The positively affected parameters were plant height, root length and number, leaf length and number, clove number and weight, and allicin content. The yield improvement was 80.8% in trial-1 and 77.9% in trial-2. Additionally, Bar D5 treatment resulted in a significant increase in soil nitrogen, phosphorus and potassium concentrations. The association of Bar D5 was confirmed at the time of harvest, demonstrating its successful establishment and persistence under field conditions. The highest Bar D5 load was detected in the rhizosphere, followed by bulk soil and clove skin. This distribution pattern indicates that, despite initial clove priming, the rhizosphere is the primary and preferred site of colonization and action of Bar D5. It can be hypothesized that Bar D5 migrates from cloves to the developing root system, where it proliferates in the rhizosphere. These findings highlight the potential of Bar D5 for sustainable, organic garlic production and support its further evaluation across diverse agro-ecological conditions.