Antimicrobial activity of some coumarin containing herbal plants growing in Finland.

Antimicrobial screening against selected Gram-positive and Gram-negative bacteria, yeasts, mold, as well as plant pathogenic fungi, with emphasis on method optimization was carried out on methanol extracts prepared from seven plants grown in Finland. Sensitivity to the extracts was found to vary considerably among the micro-organisms, the extract from Petroselinum crispum and Ruta graveolens showing the highest toxicity against Rhizoctonia solani. The growth of Heterobasidium annosum was inhibited, whereas that of Phytophtora (cactorum) was promoted by all the extracts. The antibacterial and antifungal activities of six natural coumarin compounds were weak, except for the inhibitory effect against Fusarium culmorum.

Shoot density of Carex rostrata Stokes in relation to internal carbon:nitrogen balance.

Initiation of new shoots originating from basal meristems of older shoots of Carex rostrata was studied in relation to the internal carbon/nitrogen balance. In a greenhouse experiment, individual shoots with a vigorous formation of a new shoot contained the highest concentrations of free amino acids (FAA) and the lowest concentrations of total nonstructural carbohydrates (TNC), resulting in a low TNC/FAA ratio. Thus shoots with high availability of nitrogenous compounds in relation to carbohydrates started growing a new shoot. The results suggest that TNC/FAA ratios could affect shoot densities. Field measurements supported this view: TNC/FAA ratios were lower in a mesotrophic site with a high density of shoots than in an oligotrophic site with a low density of shoots. Compared with roots, TNC/FAA ratios of shoots seemed to be more decisive both in the greenhouse experiment and in the field. In the greenhouse experiment, initiation of new shoots was measured in fragmented shoots of Carex having no intraclonal connections. Even if physiological integration was lacking due to fragmentation, shoot initiation was efficiently controlled in relation to the internal carbon/nitrogen balance.