The international scientific community recognizes that meeting the food demands of a rapidly expanding global population requires sustainable agricultural innovations that reduce dependence on synthetic chemical inputs. Microorganisms known as plant growth promoting bacteria offer a viable biological solution because they colonize the root zones of crops to naturally stimulate nutrient uptake, synthesize vital hormones, and suppress destructive soil pathogens. However, when free-living beneficial bacteria are introduced directly into complex natural soils, their field survival rates often plummet due to severe environmental competition and fluctuating moisture levels. To overcome this limitation, agricultural researchers are evaluating porous, stable materials that can serve as protective microscopic habitats to shield the bacteria and ensure their long-term operational viability in the field.

The comprehensive field evaluation conducted in Greece focused on testing six distinct bacterial strains across three delivery methods, consisting of a standard liquid application, an inorganic mineral carrier known as zeolite, and an organic biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More carrier known as biochar. The primary findings revealed that the agricultural outcomes were heavily dictated by the specific genetic strain of bacteria utilized rather than the type of carrier material alone. Strains belonging to the species Bacillus subtilis demonstrated the most robust field adaptation, generating substantial increases in vegetative mass and overall food production. This high performance under open field conditions is attributed to the ability of these specific bacteria to colonize the root zone effectively, form protective biological films, and solubilize locked nutrients in the soil.

The physiological data showed that treating tomato crops with these beneficial bacterial strains enhanced the overall photosynthetic rate of the plants by up to 33.7 percent compared to untreated control plots. Among the delivery mechanisms, the organic biochar carrier demonstrated a distinct capacity to boost this light-processing efficiency due to its highly porous physical structure, which naturally retains optimal moisture and creates a stable microenvironment around the root systems. Furthermore, complex biological interactions between the carriers and specific bacterial strains directly altered the nutritional profile of the harvested tomatoes. When a specific strain of Bacillus subtilis was paired with the inorganic zeolite carrier, the resulting synergistic relationship acted as a mild biological trigger that activated the internal defense mechanisms of the plant, resulting in a 42 percent increase in antioxidant capacity and a 48 percent increase in total phenolic content.

To make sense of the vast amounts of agronomic data collected throughout the growing season, the researchers implemented advanced machine learning models to map the relationships between mid-season plant health metrics and final harvest outcomes. After testing twelve separate computer algorithms across thousands of hyperparameter combinations, a linear regression-based framework known as the Ridge algorithm proved to be the most accurate and efficient tool for the dataset. The machine learning analysis revealed that a plant’s transpiration rate, or how much water it releases through its leaves during the late stages of growth, serves as a powerful positive predictor for both total fruit yield and the concentration of soluble sugars within the fruit. Ultimately, these findings demonstrate that matching precise bacterial strains with compatible protective carriers provides a reliable, data-driven foundation for sustainable commercial farming.

Source: Katsenios, N., Sparangis, P., Kyriakou, C., Kasimatis, C. N., Andreou, V., Giannoglou, M., Chanioti, S., Vitsa, S., Gasparatos, D., Djordjevic, N., Katsaros, G., & Efthimiadou, A. (2026). Biochar and zeolite as carriers of PGPB strains: impact on the physiology, productivity and quality characteristics of industrial tomato. Scientific Reports.