Bacterial Isolates from Avocado Orchards with Different Agronomic Management with Potential for Promoting Plant Growth and Phytopathogens Control

The bacterial diversity of soils cultivated with avocado (Persea americana M.) is influenced by various factors, perhaps the most determining being the type of agronomic manage-ment used by farmers. In conventional agronomic management (CM), high doses of agro-chemicals such as fungicides and bactericides are applied, which alter the biological fer-tility of the soil, including the bacterial populations present in the rhizosphere. In contrast, in organic agronomic management (OM), the use of agrochemicals is avoided, and organ-ic amendments are applied instead. These amendments contain a large quantity and di-versity of bacteria that may be beneficial for soil remediation and crop nutrition. This re-search aimed to isolate and morphologically characterize rhizospheric bacteria from avo-cado trees under different agronomic management practices (CM and OM). The bacterial isolates were tested for their in vitro plant growth promoting capacity through biochemi-cal assays for phosphorus and calcium solubilization and nitrogen fixation. Additionally, their in vivo effect on the growth of tomato (S. lycopersicum) was evaluated, and their an-tagonistic capacity against Fusarium sp. was assessed. The results showed differences in the quantity, diversity, and morphologies of bacterial isolates depending on the type of agronomic management. Greater diversity was found in OM (Shannon diversity index of 2.44) compared to CM (1.75). Regarding plant growth promotion both in vitro and in vivo, OM isolates showed higher activity and promoted greater tomato growth; these same iso-lates also exhibited antagonistic activity against Fusarium sp. This indicates that OM plots of P. americana presented a greater diversity of bacterial isolates with plant growth-promoting effects and antagonistic activity compared to CM plots, highlighting the impact of agronomic management on soil bacterial populations.