XVI International Botanical Congess

95% of plant species belong to families that present vesicular-arbuscular (VA) mycorrhizas. However, there is a small number of families that are usually not colonised by these fungi, e.g. Caryophyllaceae, Chenopodiaceae, Cruciferae, Polygonaceae, Resedaceae. The compatibiity of these fungi with plants has been described largely in terms of their impacts on the vegetative growth and survival. Howver, some studies suggest that mycorrhizal colonisation play a key role inn reproduction this effect being shown to different extents in different species Since the impact of the VA mycelia upon stages of the plant-life cycle other than establishment might be of major ecological iportance, the aim of this work was to deterine the effect of VA mycelia upon the reproductive ability of Cardamine hirsuta L. and Stellaria media L. In special chambers the tota number of flowers and seeds, as well as the ones produced per plant in the presence (M) and absence (NM) of VA fungi were quantified. The weight and P content of the seeds, as well as their germination percentage were determined. The survival of the seedlings was recorded during the experiments.