Greenhouse and field studies

In studies that lasted 3 years, Scots pine was grown with E. hermaphroditum in the greenhouse and field in four treatments designed to separate allelopathy and belowground resource competition. In the experiments, 

Allelopathy was reduced by the application of activated carbon to the soil (which had previously been shown to detoxify aqueous leaf extracts). 

Untreated controls provided a measure of the combined effects of competition and allelopathy on pine growth. 

Results of these experiments were striking, and showed that the greatest inhibition occurred when pines were subject to both allelopathy and resource competition, while the effects of allelopathy and resource competition separately caused intermediate inhibition (Nilsson 1994). Other greenhouse experiments (Nilsson et al. 1993) established that aqueous extracts of E. hermaphroditum reduced N uptake by both mycorrhizal and nonmycorrhizal Scots pine seedlings, and reduced the spread of mycorrhizal infection. 

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