Colonisation of arbuscular mycorrhiza fungi (AMF) was studied in a pot experiment with four grasses (Bromus inermis, Lolium perenne, Festuca rubra and Poa pratensis) in low quality, calcareous, slightly humic (1.5 %) sandy soil. A regular organic treatment, the propylene glycol (PG) was used to enhance the microbial activity of the soil, diluted in water at 12.500 mg/L ratio. Soil was amended with Mn sludge (500 mg/kg) from Úrkút, Hungary before the sowing. Plants were grown 8 weeks and sampled several times during the growing season. Dry matter production, element uptake and AMF colonization and total catabolic enzyme activity of microbial biomass, as fluorescent-diacetate analysis (FDA) were studied. Available element content of potassium (K2O) and phosphorous (P2O5) or the Fe and Mn microelements was assessed by ICP analysis from the propylene-glicol (PG)- and/or the Mn-mud-treated soil samples. Great differences were found among the grasses and mycorrhiza colonization. Total catabolic enzymatic activity (FDA) and colonization with arbuscular mycorrhizal fungi (AMF) responded positively to the organic treatment of fast-degradable propylene-glycol. A reduced biomass production was recorded at those hosts at both treatments during the plant growth. The fresh (and dry) shoot biomass production was decreasing with the plant age as a function also with the applied treatments. Especially high AMF colonization intensity (M%) and arbuscular richness (A%) could be found at the Poa pratensis. Organic PG amendment enhanced the mycorrhiza intensity and function at all grasses, as well as the total catabolic enzyme activities (FDA) of microbes. Both PG and Mn-treatments had increased the availability of potassium in soil on a same extent, but no changes appeared in soil P content was found. We consider that variability in interaction and plant-microbe respond can provide an appropriate tool for the plant-selection in PG- and Mn-affected soils.

Mn-Fe availability; propylene glycol; sandy soil; grasses; mycorrhiza; toxicity

Presentation: oral