Effect of cool season turfgrass mixtures and mycorrhizal inoculation at establishment to sequential acute droughts under field conditions

Abstract Turfgrass species mixtures are often recommended over the use of single species due to greater genetic diversity to meet broader landscape needs. However, the intended composition of the mixture can change over time due to rates, contrasting tolerance to environmental stresses, and management practices. Strategies used to increase tolerance to stresses, such as drought, include applications of beneficial microorganisms, which may favor some turfgrass species in a mixture. The application of mycorrhizal inoculant is popular, but mycorrhizae's impact on turfgrass mixture response to drought is unknown. To address both the need for more information about turfgrass mixtures and the use of microbial inoculants, field experiments were conducted in Minnesota using mixtures and monocultures of Kentucky bluegrass ( Poa pratensis L.), perennial ryegrass ( Lolium perenne L.), and hard fescue ( Festuca brevipila Tracey), each with and without inoculation with mycorrhizae. Plots were exposed to sequential drought and recovery periods lasting ∼30 days. Data were collected on turfgrass health and species cover. Results showed that the application of mycorrhizal inoculant during the establishment period did not impact species cover and had little effect on reducing symptoms of drought stress. Hard fescue performed the best during both drought and recovery even when mixed at a low proportion with the other species, especially when mixed with Kentucky bluegrass. Turfgrass species cover was consistent across drought and recovery periods, except for when species were replaced by bare soils or weeds.