PS 28-136
Arbuscular mycorrhizal responsiveness of Panicum virgatum across varying geographic locations
Switchgrass (Panicum virgatum) is a dominant native perennial grass in the tallgrass prairies of the Central Great Plains of North America. This grass has been shown to be drought tolerant, able to withstand increasing temperatures, and contributes to livestock forage and wildlife habitat. Previous research has shown switchgrass to be strongly associated with arbuscular mycorrhizal (AM) fungi. This symbiotic relationship increases biomass production through increased acquisition of nutrients and water. Increasing interest in biomass production of switchgrass for bioenergy feedstock and grassland restoration requires an increased understanding of how soil nutrient availability and genotypic origin influence the success of this key grassland species. Therefore, we evaluated the growth and AM responsiveness of 15 switchgrass populations, collected over a wide geographic range of switchgrass in North America, in marginal (long-term row crop agricultural) soil. In addition, we selected three lowland varieties and evaluated growth and AM responsiveness in marginal soils amended with four fertilizer treatments (Control, nitrogen, nitrogen and phosphorus, phosphorus). Switchgrass was grown for 16 weeks in native prairie soils (mycorrhizal) or native steam-pasteurized (nonmycorrhizal) soil.
Results/Conclusions
We see strong evidence of a strong genetic component for AM responsiveness and biomass production in switchgrass. On average, lowland populations showed higher AM responsiveness than upland populations. When soils were amended with P or N and P, the three lowland populations exhibited a profound shift in AM responsiveness, with fertilization consistently reducing responsiveness of these three switchgrass populations. These results reveal that genotypic variations of switchgrass populations may widely vary based on soil fertility. Therefore, our research shows the importance of understanding genetics and soil quality to maximize restoration success and bioenergy feedstock production, in that our ecosystems can benefit by having plant species that create biomass while maintaining belowground connections that assist in soil health.