Effect of PGPB on leaf nutrient status and growth of Begonia semperflorens

Bacteria are increasingly used in agriculture as eco-friendly alternatives to promote plant growth through mechanisms such as nitrogen fixation, phosphate solubilization, hormone production, and improved nutrient uptake. This study aims to examine the effects of plant growth-promoting bacteria on the growth, quality, and nutrient content of Begonia semperflorens, a commercially valuable ornamental plant known for its long flowering period and vibrant blooms. In this study, one-month-old Begonia semperflorens seedlings were dipped into bacterial suspensions (10⁸ CFU ml⁻¹) of Pseudomonas chlororaphis MF-1, Bacillus megaterium M-3, and Agrobacterium radiobacter A-16 for 20 minutes prior to planting. After planting, the seedlings were irrigated with bacterial suspensions as watering solution at twice at 15-day intervals. At the end of one month, plant growth and quality parameters (plant height, number of leaves, leaf area, plant fresh weight, plant dry weight, stem diameter, flower stem, plant crown width, number of blooming flowers). were evaluated, along with macro- and microelement contents (total N, P, K, Ca, Mn, Mg, and Fe) in both plant leaves and the growing medium. All bacterial treatments significantly improved plant growth and quality compared to the control group, with M-3 exhibiting the most pronounced effects, increasing plant height by 40%, leaf number by 133%, leaf area by 348%, and flower number by 61%. A-16 enhanced crown width (45%) and flower stem length (26%), while MF-1 improved plant height (43%) and flower production (51%). Additionally, M-3 increased total nitrogen in leaves by 43%, while bacterial treatments enhanced various elements in plant leaves. The results show that these bacterial isolates improve begonia plant characteristics, providing high-quality plants and offering a sustainable alternative as microbial fertilizers in ornamental plant cultivation.