The effect of nursery applied fungicides on the growth and mycorrhiza abundance of Scots pine seedlings

摘要

Seedling growth, and abundance of ectomycorrhizal fungi, was determined on container-grown Scots pine (Pinus sylvestris L.) seedlings following nursery treatment with the fungicides chlorothalonil and propiconazole. Seedlings were grown in paper containers filled with low-humified sphagnum peat according to normal forest nursery practice. There were three treatment groups sprayed with fungicides and a control group without fungicides with four, 40 X 60 cm~2, seedling containers per group. The seedlings were treated with (i) chlorothalonil (Bravo~R 500), (ii) propiconazole (Tilt~R 250 EC) or (iii) first with chlorothalonil and then with propiconazole. The amounts of chlorothalonil and propiconazole in each application were 2000 g/ha (a.i.) and 125g/ha (a.i.), respectively. Fungicides treatments did not affect mycorrhizal colonization of seedlings, measured either as a percentage of root-tips or as the ergosterol content of roots. Fungicide-induced changes in the free amino acid content of needleswere especially noteworthy. At the end of the first growing season the free amino acid assays showed (i) increases in the arginine and glutamine content in chlorothalonil-treated seedlings and (ii) an increase in gamma-aminobutyric acid and a decrease in glutamine content in propiconazole-treated seedlings. The results of this study indicate some type of stress-related growth reduction in chlorothalonil-treated container seedlings at the end of the first growing season.