What question did this study set out to answer?

The study aims to evaluate the synergistic effect of native rhizobacteria and a specific bacterium on tomato growth under reduced fertilizer use.

March 12, 2026Applied Microbiology0 citationsOpen Access

Integrated Use of Plant Growth-Promoting Rhizobacteria and Chemical Fertilizers Improves the Growth and Yield of the Tomato Plant

BGBaby Lyn T. De Guzman MMMaria Luisa T. Mason PPariyanuj

Key Points

The study aims to evaluate the synergistic effect of native rhizobacteria and a specific bacterium on tomato growth under reduced fertilizer use.
Isolation of native rhizobacteria compatible with Bradyrhizobium diazoefficiens NE1-65.
Screening eighteen isolates on nitrogen-free media and assessing phosphorus and potassium solubilization.
Conducting a 90-day growth trial with varying fertilizer application rates and bacterial consortia.
Co-inoculation with RM-17 and B. diazoefficiens NE1-65 outperformed 100% fertilizer alone.
Increased plant height by 11.57% and fruit diameter by 9.23%.
Significantly higher fruit number (53.90%) and fruit weight (16.15%) with the combined approach at 75% fertilizer rate.

Abstract

Microbial biofertilizers offer a sustainable alternative to reduce inorganic fertilizer inputs in intensive vegetable production. While rhizobia are traditionally associated with legumes, their co-inoculation with native rhizobacteria for non-leguminous crops like tomatoes remains under-explored. This study aimed to isolate native rhizobacteria compatible with Bradyrhizobium diazoefficiens NE1-65 and evaluate their combined effect on the tomato plant (var. max F1) under reduced inorganic fertilizer rates. From the initial eighteen isolates screened on nitrogen-free media, and solubilization assays of phosphorus and potassium, three isolates (RM-8, RM-17, RM-18) were found compatible with B. diazoefficiens NE1-65. Isolate RM-17 (tentatively identified as Aureimonas sp. based on 16S rRNA gene sequence) was selected for its high K-solubilizing capacity (KSI = 8.60). Then, a 90-day growth trial compared various fertilizer application rates (0, 25, 50, 75, and 100%) with and without the bacterial consortia. The 75% fertilizer rate plus the consortia significantly outperformed the 100% fertilizer rate alone. Specifically, it increased plant height (11.57%), fruit diameter (9.23%), fruit number (53.90%), and fruit weight (16.15%). These findings demonstrate that the RM-17 and B. diazoefficiens NE1-65 consortia can partially substitute inorganic fertilizers while significantly enhancing tomato growth and yield, highlighting its potential application for sustainable tomato production systems.

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