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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #335908
Title: Nutrients and environment influence arbuscular mycorrhizal colonization both independently and interactively in Schizachyrium scoparium

Author
item FRATER, PAUL - University Of Iceland
item BORER, ELIZABETH - University Of Minnesota
item Fay, Philip
item Jin, Virginia
item KNAEBLE, BRIAN - Westminster College
item SEABLOOM, ERIC - University Of Minnesota
item SULLIVAN, LAUREN - University Of Minnesota
item WEDIN, DAVE - University Of Nebraska
item HARPOLE, W - Martin Luther University

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2018
Publication Date: 4/1/2018
Citation: Frater, P.N., Borer, E., Fay, P.A., Jin, V.L., Knaeble, B., Seabloom, E., Sullivan, L., Wedin, D., Harpole, W.S. 2018. Nutrients and environment influence arbuscular mycorrhizal colonization both independently and interactively in Schizachyrium scoparium. Plant and Soil. 425:493-506. https://doi.org/10.1007/s11104-018-3597-6.
DOI: https://doi.org/10.1007/s11104-018-3597-6

Interpretive Summary: Grassland plant species often support fungi that maintain direct physiological connections with plant roots, enable the fungus to acquire carbon from the plant and enabling the plant to acquire soil nutrients from the fungus. In this way, both the fungus and the plant can benefit from this interaction. However, the extent to which plants may benefit from nutrients supplied by the fungus depends strongly on how limiting nutrients and soil water are in the soil. The more limiting a nutrient, the more likely is the plant to support abundant mycorrhizal populations, measured by the density of fungus/root colonization. This study measured the density of fungal colonization of the native warm season grass little bluestem in plots fertilized with nitrogen, phosphorus, and potassium, individually and in combination. Increased nitrogen availability in plots fertilized with nitrogen reduced fungal colonization of little bluestem roots across five sites from Minnesota to Texas, while increased phosphorus limitation was associated with increased colonization. Fungal colonization also increased with aridity. This research provides new fundamental information on the factors controlling colonization of grassland species by potentially beneficial fungi, and provides information on mechanisms affecting the performance of a widespread grassland species in nutrient and water limited environments. This can help predict the future abundance and distribution of this grass, which is widespread in native pastures.

Technical Abstract: Arbuscular mycorrhizal fungi (AMF) are an important group of organisms for plant nutrient and water acquisition. Much is known about how the plant-mycorrhizae relationship changes with nutrient addition as well as with changes in environment; however, little is known about how nutrient addition alters AMF symbioses under different climate or soil conditions or with nutrient by environment interactions. We measured the percentage of AMF colonization in little bluestem (Schizachyrium scoparium) in plants fertilized with nitrogen, phosphorus, or potassium plus micronutrients at five sites spanning X degrees of latitude and a range of soil texture. We assessed how AMF colonization changed with nutrient addition and also used change in plant biomass with nutrient addition to test for effects of nutrient limitation on AMF colonization. We then performed a ridge regression to determine which variables best predicted AMF colonization and if any nutrient by environment interactions existed. Nitrogen (N) addition decreased AMF colonization. Annual aridity index (AAI), mean annual temperature (MAT), soil percent clay (%clay), soil pH, and the change in plant biomass with addition of phosphorus (delta-biomass P) all positively predicted the percentage of AMF colonization while the change in plant biomass with N addition (delta-biomass N) negatively predicted AMF colonization. Additionally, we found significant nutrient by environment interaction terms between AMF and N x soil percent sand (%sand), N x pH, and K x (delta-biomass P). Our results show the importance of understanding environmental conditions on AMF as well as nutrient by environment interactions when assessing how AMF respond to nutrient addition. Additionally, we show that AMF are significantly predicted by variables that are likely to be altered due to global change.