Interactive Effects of Arbuscular Mycorrhizal Fungi and Organic Amendments on Maize Growth under Salinity Stress

Khaled D Alotaibi^*

• King Saud University Department of Soil Science, Riyadh, Saudi Arabia

Soil salinity poses a serious threat to sustainable crop production, particularly in arid and semiarid regions. To mitigate its adverse effects, effective approaches, including the use of organic amendments and bio-inoculants have been sought as potential solutions. This study investigated the individual and combined effects of arbuscular mycorrhizal fungi (AMF), biochar (BC), and compost (CP) on the growth and morphological and physiological traits of maize (Zea mays L.) grown in saline and non-saline soils. Treatments included AMF, BC, CP, AMF+BC and AMF+CP in addition to unamended controls. Soil salinity significantly reduced maize growth, photosynthetic pigment content, and nutrient uptake, while increasing sodium accumulation and oxidative stress markers. Individual application of AMF, BC, and CP alleviated several salinity-induced constraints; however, their combined application showed higher and more consistent improvements. In particular, AMF combined with BC markedly enhanced root colonization, shoot and root biomass, chlorophyll content, and uptake of nitrogen, phosphorus, and potassium, while reducing sodium accumulation and improving the K:Na ratio under saline conditions. These improvements were associated with increased proline accumulation and activation of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase), leading to reduced levels of malondialdehyde and hydrogen peroxide. Principal component analysis further revealed strong positive associations between combined AMF–organic amendment treatments and growth, nutrient balance, and stress-defense traits under salinity. Overall, the results demonstrate that integrating AMF with organic amendments, particularly biochar, provides an effective strategy for enhancing maize tolerance to salinity through coordinated improvements in nutrient acquisition, ion homeostasis, and oxidative stress regulation. This study highlights the potential of AMF and organic amendment combinations as sustainable and cost-effective tools for managing salinity stress in maize production systems, especially in salt-affected arid environments. However, more research is necessary to validate these findings across different saline soils and crops in field conditions.