Morpho-Physiological and Biochemical Responses of Two Turfgrass Species to Arbuscular Mycorrhizal Fungi and Humic Acid Under Water Stress Condition

Given the anticipation of water supply becoming increasingly scarce in the future and costlier, water conservation in turfgrass management has become extremely important. The application of mycorrhizal fungi in water scarcity has been considered as one of the most promising methods to improve turfgrass management. Accordingly, the present study evaluates the potential role of arbuscular mycorrhizal fungi (AMF) inoculation in the growth of two turfgrass species under water stress conditions. Two turfgrass species (Kentucky bluegrass [Poa pratensis] and perennial ryegrass [Lolium perenne L.]) were subjected to two watering regimes (well-watered [watering 100% field capacity] and water deficit [watering 50% field capacity]) in the presence of AMF (a mixture of Funneliformis mosseae and Rhizophagus irregularis, or non-inoculated plants [non-AMF] as control) and humic acid spray treatments (0 mg/L and 500 mg/L). Not surprisingly, lack of water resulted in diminished morphological traits, mineral nutrient concentrations, chlorophyll and carotenoid contents, relative water content, and enzyme activities, and increased proline content, malondialdehyde, and hydrogen peroxide concentrations in both turfgrass species. On the other hand, AMF-inoculated plants grown under well-watered conditions showed increased plant biomass, phosphorous concentration, and relative water content compared to non-AMF plants. Further, nitrogen and potassium concentrations and catalase activity were improved by humic acid. There was no significant difference in water stress tolerance between P. pratensis and L. perenne. In conclusion, the two turfgrass species showed a good response to AMF inoculation under water stress conditions, where humic acid was found to be less effective.