Arbuscular mycorrhizal fungi (AMF) have been found to increase plant resistance to drought stress, although this is somewhat inconsistent across studies. Since different AMF species individually and in combination can impact plant growth, nutrient uptake and response to stress differently, we hypothesized that a diversity of AMF species may increase corn resistance to drought stress more effectively than single AMF species. We also examined differences among individual AMF species to see if some species were more effective than others in enhancing corn resistance to drought. In an 8 week pot experiment , corn plants were inoculated with either 5 single AMF cultures (Glomus intraradices, Acaulospora spinosa, Gigaspora rosea, Glomus clarum, Glomus etunicatum), a combination of 3 AMF species (Glomus intraradices, Gigaspora rosea, and Acaulospora spinosa), a combination of all 5 AMF species, or as a control with sterilized AMF inoculum. All AMF species were derived from agricultural soils and each treatment was replicated 6 times. After 4 weeks of well watered growth, a drought treatment (50% field capacity) was initiated in half the pots of all treatments and lasted 4 weeks. Response variables measured included plant dry weights (shoot and roots) at harvest, plant heights, shoot nutrients at harvest, photosynthesis at 8 weeks, and percent AMF colonization.
Results/Conclusions
Differences were found between the drought and non-drought plants across all response variables. Within drought treatments, AMF plants and control plants had similar shoot dry weights . In well watered treatments, most AMF plants had a lower shoot biomass than controls, but Glomus intraradices plants were similar to the control plants and Acaulospora spinosa plants were greater than the control plants. All AMF plants had lower root dry weights than control plants. Under well watered conditions, all AMF plants had lower photosynthesis than controls. However, under drought conditions, Glomus etunicatum, Glomus clarum, and the 3 AMF plants had similar or greater photosynthesis than control plants. Furthermore, in both the 3 AMF and Glomus etunicatum treatments, the drought photosynthesis rate was not significantly lower than the well watered photosynthesis. We will discuss the implications for AMF diversity on the full range of responses measured in our presentation. Our results suggest that AMF diversity can play a role in plant response to drought and are also important considerations for sustainable crop management under future global climate conditions. .