What is the role of mycorrhizal fungi in nutrient uptake on rangeland soils?

• A. They compete with plants for nutrients and suppress growth.
• B. They are pathogens that harm roots.
• C. They form symbiotic associations with plant roots, especially aiding phosphorus uptake and improving water and nutrient acquisition.
• D. They only affect nitrogen fixation.

Answer: (C)

Mycorrhizal fungi form mutualistic links with plant roots, extending the plant’s foraging network through their hyphae. This partnership is especially important for phosphorus and for accessing water and other nutrients that roots alone can’t reach. In rangeland soils, phosphorus is often limited and moves slowly through the soil, so the fungi’s hyphae explore a much larger volume of soil than roots can, effectively increasing phosphorus uptake for the plant. In return, the plant supplies the fungi with carbon from photosynthesis.

So the best description is that these fungi form symbiotic associations with plant roots, aiding phosphorus uptake and improving overall water and nutrient acquisition. They’re not pathogens, they don’t primarily compete with plants in a detrimental way, and they aren’t limited to nitrogen fixation.