Chemical treatment and inoculation with beneficial bacteria in maize seed germination

Abstract

Maize (Zea mays L.) is one of the most widely cultivated cereals globally and the second most produced grain in Brazil. To increase crop grain yield, the application of plant growth-promoting bacteria (PGPB) as inoculants has gained prominence. This study evaluated the effects of inoculation with Azospirillum brasilense, Bacillus subtilis, Bacillus amyloliquefaciens, and Priestia aryabhattai, with and without chemical seed treatment, on maize seed germination and early seedling development. The experiment was conducted in two settings: laboratory (germination test using Germitest paper) and greenhouse (sand bed). A completely randomized design (CRD) was used, arranged in a 2 × 5 factorial scheme (with and without chemical treatment × five inoculants), with four replications. Results indicated that A. brasilense showed the best performance across both environments, promoting higher germination rates, root length, and root dry mass, especially in seeds without chemical treatment. P. aryabhattai also showed positive effects, though to a lesser extent. In contrast, B. amyloliquefaciens negatively impacted germination, with a higher percentage of dead seeds and lower seedling vigor. Chemical seed treatment with fungicides and insecticides negatively influenced some growth parameters and reduced the effectiveness of certain inoculants, likely by affecting bacterial viability. A significant interaction was observed between inoculant type and seed treatment for root dry mass. It is concluded that inoculation with A. brasilense, particularly in untreated seeds, is a promising strategy to enhance maize seed germination and early growth, highlighting its potential as a sustainable alternative to improve crop establishment and initial development.