The influence of shading on the yield and quality of southern sweet-grass (Hierochloë australis (Schrad.) Roem. & Schult.) raw material
Southern sweet-grass (Poaceae) rarely occurs in Polish coniferous or mixed forests. Leaves of this plant, rich in coumarin compounds, are mainly used as a flavouring raw material in alcohol, tobacco and cosmetic industry. The aim of the study was to investigate the influence of shading on the yield and quality of southern sweet-grass. The experiment was established at the certificated organic field of Department of Vegetable and Medicinal Plants. The sunlight was reduced up to 50 and 70% by using shading nets. The object of experiment was two-year-old plants grown on the alluvial soil. Leaves were harvested two times: in mid-May and in the last week of August (regrowth). The highest yield of leaves was observed at 50% of shading. The shaded plants were characterized by higher content of coumarin and 3,4-dihydrocoumarin and lower content of bergapten in comparison to non-shaded ones. In the leaves five phenolic acids and two flavonoids were identified.