The common pea (Pisum sativum L.) is widely cultivated due to its nutritional value and adaptability, though climate change and increasing food demand require improved agricultural strategies. The genus Metarhizium, an entomopathogenic fungus, has shown potential to enhance plant growth and physiology. This study aims to evaluate the effect of naturalized Metarhizium spp. isolates on agronomic parameters and root architecture of Pisum sativum seedlings under greenhouse conditions. Fungi were isolated from rhizosphere soils using Tenebrio molitor larvae. Six Metarhizium strains and a control (sterile distilled water) were tested, with eight replicates per treatment. After 36 days, growth parameters and chlorophyll content were measured at ambient temperatures between 12.1 ± 1.5 and 42.4 ± 2.4 °C. Significant differences were analyzed using Tukey’s HSD post hoc test (p < 0.05). Significant increases in shoot length were observed in strains MM23B and MM26B (13.2 ± 0.6 and 13.0 ± 1.1 cm). Stem diameter was higher in MM23B, G9C, and MM30D (3.1–3.2 mm). Chlorophyll content increased moderately, with MM29C reaching 296.7 ± 35.9 compared to 242.5 ± 22.8 µmol m⁻² in the control. Shoot biomass was highest in G9C, MM23B, and MM26B (0.27–0.29 g) with higher shoot/root ratios in MM23B and MM26B (2.41 and 2.58). Root biomass showed no significant differences. However, root system architecture was modified, particularly in MM26B, which significantly increased root length (239.08 ± 34.22 cm) and area (20.70 ± 2.13 cm²), without changes in volume or diameter. Finally, naturalized Metarhizium spp. isolates demonstrated potential as plant growth-promoting fungi, improving physiological and morphological parameters in early P. sativum development.

Modern agriculture, heavily influenced by the Green Revolution, has increased productivity through the intensive use of external inputs and agrochemicals, but at the cost of growing environmental degradation, loss of biodiversity, pest resistance, and risks to human health. This production model has proven to be environmentally unsustainable in the face of current challenges, such as climate change, the increase in the world’s population, and the depletion of natural resources. In this context, agroecology emerges as an integrative scientific approach that promotes the transition from conventional agricultural systems to diversified, resilient, and functionally balanced agroecosystems, based on ecological principles and the progressive reduction of synthetic inputs. This review addresses the role of fungal microorganisms, with an emphasis on entomopathogenic fungi and fungi associated with the plant microbiome, as key tools in the sustainable management of biotic agricultural challenges. This paper addresses the biology and multifunctionality of entomopathogenic fungi, not only as biological control agents but also as crop growth promoters and phytopathogen suppressors. Taken together, the background information presented reinforces the potential of entomopathogenic fungi as strategic components in agroecological transition processes, contributing to productive sustainability, reduced agrochemical use, and the restoration of the ecological functionality of agroecosystems.