Arbuscular mycorrhizal colonization and phosphorus acquisition of plants: effects of coexisting plant species

Arbuscular mycorrhizal (AM) fungi influence interactions among plant species through enhancing nutrient uptake and possibly facilitating nutrient transport among plants. However, the effects of one plant species on coexisting plant species with regard to mycorrhizal colonization are not well understood. We examined root mycorrhizal colonization and phosphorus (P) acquisition of plants in a highly P-limiting soil in Lanxi city, Zhejiang, China from the year 2000 to 2002. Three dominant native plant species with different mycorrhizal properties, Digitaria ciliaris (poorly mycorrhizal species), Ixeris denticulate (moderately mycorrhizal species) and Kummerowia striata (highly mycorrhizal species), were planted in experimental plots. In the monocultures, K. striata was found to have the highest infection and D. ciliaris the lowest mycorrhizal infection, but shoot P-concentration was higher in both I. denticulate and D. ciliaris than that in K. striata. In the mixtures, D. ciliaris and I. denticulate did not significantly affect the mycorrhizal colonization, spore production and shoot P-concentration of K. striata plants, but K. striata and I. denticulate significantly increased root mycorrhizal colonization and shoot P-concentration of D. ciliaris. K. striata enhanced but D. ciliaris reduced mycorrhizal infection and shoot P-concentration of I. denticulate. These results suggested that highly mycorrhizal plant species may positively impact coexisting species with respect to mycorrhizal colonization and P acquisition, but the effects on poorly mycorrhizal species are less predictable.