Inoculation and Co‐Inoculation With Plant Growth–Promoting Bacteria in Chickpea: Physiological Aspects and Plant Growth

The inoculation of plants with growth‐promoting and nitrogen‐fixing bacteria is considered an effective alternative to reduce the use of nitrogen fertilizers and promote plant growth. This study aimed to evaluate the effect of inoculation and co‐inoculation with growth‐promoting bacteria on the physiological traits and growth of chickpea plants. A randomized block design was used with four replications and eight treatments: inoculation with Bradyrhizobium japonicum (Brad), inoculation with a mixture of Bacillus megaterium and Bacillus subtilis (Bac), Azospirillum brasilense (Azos), inoculation with a mixture of Bradyrhizobium + Bacillus (Brad/Bac), Bradyrhizobium + co‐inoculation with Azospirillum (Brad/Azos), mixture of Bacillus + co‐inoculation with Azospirillum (Bac/Azos), mixture of Bradyrhizobium + Bacillus + co‐inoculation with Azospirillum (Brad/Bac/Azos), and a noninoculated control (NI), using the chickpea cultivar BRS Cristalino. At full flowering, physiological traits were evaluated, and plants were collected to assess dry mass and nitrogen accumulation in the shoots, roots, nodules, and total plant biomass. The inoculation/co‐inoculation treatments did not significantly affect physiological parameters such as internal carbon concentration, photosynthetic rate, and water use efficiency in chickpea plants. However, the Brad/Bac/Azos treatment increased the shoot dry mass by 62.2%, total dry mass by 62.6%, and chlorophyll A content by 17.9%. Inoculations with multiple bacterial strains promoted greater plant development compared to those with a single strain. According to our study, the combined use of Bradyrhizobium , Bacillus , and Azospirillum was the best combination to promote chickpea growth.