Arbuscular Mycorrhiza Fungi Enhance the Growth, Yield, and Quality of Medicinal Mondo Grass (Ophiopogon japonicus (L.f.) Ker–Gawl.) under Rainfed Conditions

Applying the biological product of arbuscular mycorrhiza fungi (AMF) is considered an effective strategy to improve crop productivity to cope with climate change in current agricultural production. The experiment was conducted to evaluate the impact on growth, yield, and secondary metabolites of medicinal mondo grass under rainfed conditions. The split-plot design was used with the main factor of six various AMF doses (0, 100, 200, 300, 400, and 500 kg·ha-1 year-1) and the sub-factor of two mondo grass genotypes (G1 and G2). AMF supplement had positive effects on both genotypes in increasing canopy size, the number of leaves and tillers, root growth, leaf osmotic pressure and chlorophyll fluorescence, total biomass, yield components, uptake of macronutrients, contents of polysaccharide, saponin, flavonoid, and decreasing leaf water deficit and ion leakage. G2 a higher drought-tolerant genotype performed better than G1 for investigated characteristics (except canopy height and SPAD), but the effect of AMF was clearer in the G1 genotype. Supplement of 300 kg AMF ha-1 year-1 could be the optimum rate for growth and medicinal quality of mondo grass under rainfed conditions.