Synergistic effects of substrate inoculation with Pseudomonas strains on tomato phenology, yield, and selected human health‐related phytochemical compounds

Abstract

Abstract Plant growth‐promoting rhizobacteria enhances nutritional availability during root colonization. Pseudomonas is the most popular bioinoculant due to its synergistic effects on plant development. This study evaluated the impact of four Pseudomonas strain substrate inoculations on tomato phenology, yield, and selected phytochemical components relevant to human health. The bacterial isolates have been characterized morphologically, biochemically, physiologically, and phylogenetically. Tomato plants on cocopeat substrate were inoculated individually with a bacterial suspension (optical density [OD]600 2.0). Controls included nitrogen–phosphate–potassium (NPK) fertilizer and tap water. The greenhouse experiment was laid out in a completely randomized design with five replications. Data were taken 30, 60, 90, and 120 days after inoculation. All four bacterial isolates could fix nitrogen, solubilize phosphate, and potassium and synthesize indole acetic acid in vitro. The 16S rRNA of the strains BF1P2‐6, BF2P1‐2, BF2P5‐1, and BF4P2‐5 were identified as Pseudomonas putida Y22, Pseudomonas taiwanensis GDLB‐32, Pseudomonas monteilii Bil‐NOR3_15, and Pseudomonas fluorescens Y5, respectively. The strains grew best at pH 7, NaCl 0.0%, and 35°C. Inoculated tomato plants tested over a period of 4 months in a greenhouse showed a significant increase in growth, leaf variables, and yield attributes. Pseudomonas‐inoculated plants were the highest in tannins (46.96 mg/100 g), followed by lycopene (45.57 mg/100 g) and Carotenoids (31.87 mg/100 g). The antioxidant activity of tomato fruit extracts showed the potential for free radicals scavenging activity against 2, 2‐diphenyl‐1‐picrylhydrazyl. Conditions such as pH and electrical conductivity for the cocopeat substrate were within acceptable limits. Bacterial strains and NPK increased cocopeat nitrogen, phosphate, and potassium bioavailability. This study reveals that Pseudomonas strains improve plant growth, yield, and health‐related phytochemical substances in tomato fruits, which could broaden their application in fruit and vegetable crops.