Abstract
Plant Growth Promoting Bacteria (PGPB) are emerging as a key solution for enhancing agricultural productivity in response to the growing global food demand. While PGPB enhance crop productivity, low bacterial survival in soil environments often reduces their field effectiveness. This study evaluated the impact of six PGPB strains, applied through three different carriers (liquid, zeolite and biochar) on the physiology, growth, yield and quality of industrial tomato, cultivated under Mediterranean field conditions. Results showed that, in comparison to the control, Bacillus subtilis strains 548, 557 and Z3 significantly increased the dry weight of tomato plants by up to 32.93% and yield by up to 23.8%. Photosynthetic rate was enhanced by up to 33.7% by the use of PGPB treatments and among carriers, biochar presented increased values compared to liquid and zeolite. Due to Carrier-PGPB interaction, certain combinations improved quality parameters, such as antioxidant capacity (up to 42% higher with B. subtilis 557 and zeolite) and total phenolic content (48% increase with B. subtilis 557 and Zeolite as a carrier). Overall, these findings highlight that optimizing the interaction between PGPB strains and suitable carriers is key to enhancing both yield and quality of industrial tomato, providing a mechanistic basis for the development of more efficient and sustainable biostimulant strategies.