Mycoremediation Capacity of Arbuscular Mycorrhizal Inocula Under Cadmium Stress and Their Influence on the Early Growth of Oryza sativa

Abstract

Soil contamination by heavy metals represents a critical challenge for agricultural productivity and food security in tropical regions, where the intensive use of chemical inputs increases the accumulation of persistent elements such as cadmium (Cd). Arbuscular mycorrhizal fungi (AMF) have emerged as a strategy to enhance
plant growth and increase tolerance to heavy metal stress. The aim of this study was to evaluate the ef fect of three types of mycorrhizal inocula (liquid, solid, and soil-derived) on the initial growth of Oryza sativa L. exposed to dif ferent Cd concentrations under controlled nursery conditions. The experiment was conducted over a 25-day period using a factorial design and assessing aboveground and belowground biometric variables, as well as Cd extraction capacity. Data were analyzed using analysis of variance (ANOVA) and multiple comparison tests, while Cd extraction response was evaluated by linear regression. The results demonstrated a dif ferential response of O. sativa depending on the type of mycorrhizal inoculum. The solid inoculum maximized aboveground performance, producing 18.5 functional leaves and the highest fresh biomass (2.85 g) at 30 mg kg–¹ Cd (p < 0.05). In contrast, the soil-derived inoculum enhanced fresh root development, reaching values close to 6.0 g at the same Cd concentration, whereas the liquid inoculum promoted the greatest stem diameter (p < 0.05), although with lower biomass accumulation. Plant height did not show significant dif ferences among treatments (p > 0.05). Cadmium extraction showed a positive relationship with metal concentration, with the regression model explaining 58.4% of the observed variability (adjusted R² = 0.58; p = 0.010), and higher accumulation occurring in foliar tissues. Overall, the results indicate that AMF modulate the physiological response of rice under Cd stress.