Influence of endophytic bacteria on seed germination and initial growth of camu-camu tree

Abstract

Abstract: Camu-camu (Myrciaria dubia [Kunth.] McVaugh) is an Amazonian fruit species of high nutritional and economic value, mainly due to its high vitamin C content and bioactive compounds. However, its propagation presents limitations, including low rooting rates in cuttings, genetic variability from sexual propagation,and high contamination in micropropagation systems. In this context, endophytic bacteria emerge as a sustainable alternative to stimulate plant growth through direct mechanisms, such as phytohormone production and biological nitrogen fixation, and indirect mechanisms, including the suppression ofphytopathogens. This study aimed to evaluate the effect of endophytic bacteria on seed germination and early growth of M. dubia. Seeds were surface-sterilized and inoculated in bacterial suspensions prepared in saline solution and maintained at 28°C for 120 minutes, under a completely randomized design with five treatments: Bacillus safensis, Bacillus altitudinis, , Bacillus pumilus,Brevundimonas sp.,and a non-inoculated control. The variables evaluated were germination, plant height,stem diameter, number of leaves, root length, and germination speed index. No significant differences were observed for germination, height, diameter, and number of leaves. However, root length showed significant increase, with B. safensis outperforming B. pumilus and the other treatments. The germination speed index was also higher for B. safensis compared with B. pumilus. Theseresults indicate that Bacillus strains have potential to enhance root development and seedling vigor,contributing to sustainable strategies for camu-camu propagation.