Sugar metabolism and metabolite profiling of maize grains are largely improved by the combination of arbuscular mycorrhizal fungi and humic acid

The increased use of chemical fertilizers in agricultural production leads to numerous negative environmental consequences, in addition to having an impact on the quality of the final product. Thus, the increasing demand for sustainable agricultural practices calls for innovative approaches to enhance crop production while minimizing environmental impact. The present study investigated the effects of arbuscular mycorrhizal fungi (AMF) and humic acid (HA) on sugar metabolism and metabolite profiling in maize grains. The study was conducted at the Experimental Farm of Mansoura University, Egypt, over the consecutive 2021 and 2022 growing seasons to test the impact of bio-organic treatments and low doses of chemical fertilizers on maize as a test plant. Combining HA and AMF markedly enhanced the metabolic profile of maize grains, leading to significant increases in total sugars (+16.16 %), total amino acids (+40.94 %), and saturated fatty acids (+145.45 %), while unsaturated fatty acids experienced a slight decrease (-11.11 %). These shifts in primary metabolites, including essential amino acids and fatty acids, are critical for metabolic functions and human nutrition. Additionally, the treatments promoted secondary metabolites accumulation, including water-soluble and lipid-soluble antioxidants, which have an important function in enhancing the antioxidant capacity of maize grains. In addition, the combination of HA and AMF enhanced elemental content in maize grains such as P and K content. Our findings demonstrate that the synergistic use of AMF and HA significantly enhances maize's metabolic profile and nutritive value. This eco-friendly strategy offers a promising path to sustainable maize production, improving food security and environmental health by reducing reliance on synthetic fertilizers. More research on bio-organic fertilizers and plant-soil interactions is needed in various habitats and plants, as well as underlying physiological, biochemical, and molecular studies.