Trifolium pretense is one of the most important plant as well for enriching soil in nitrogen as for animal nourishment. At the Center for Testing and Ratifying the Cultivars from Ulmi near Targoviste, Dambovita County, were set up some crops with four Romanian created cultivars belonging to Trifolium pretense: Select, Roxana, Dacia-Tetra and Flora, each of them cultivated both in pure culture as in mixed culture with Dactylis glomerata. Both type of cultures were fertilized with manure and synthetical fertilizers (NPK) after a schema, in the view to releave the capacity of these plants for accumulating biominerals, but also their afinity for absorbing heavy and rare metals in correlation with the type and quantity of fertilizer. This paper is about the determinations concerning heavy metal content of Trifolium pretense - Flora cultivar. All samples were analysed by PIXE (Particle Induced X-ray Emission) method, at the Nuclear Physics Research Institute Bucuresti. Principle of PIXE method consist in ionization of the levels near the atomic nucleus. This ionization is followed by a rearrangement of the electronic architecture with emission of characteristic X-ray. Detection of X radiation with Si(Li) or intrinsic Ge semiconductor detectors. Characteristics of the method: destructiveness, rapidity (15-30 minutes), easy preparation of the samples, multielementarity, determination of the most of elements with Z higher than 13, a good confidence, the sensibility of this method is 1ppm. 70 Biological samples consisted in whole plant harvested from each field experience, drying at 105ºC one hour, then reduced to dusty and put on a special ray beam target. It were determinated in highest quantity iron (Fe) between 57 and 112 ppm in Flora mixed culture with Dactylis glomerata, and between 65 and 125ppm in the pure one. The iron content modulation was in correlation with the quantity and quality of fertilizer. The content in manganese (Mn) and copper (Cu) in Flora plants were in very lower quantities (under 1ppm) in all cases, that means Flora has any affinity for accumulating manganese and copper in higher concentrations no matter the fertilisers. Only in six culture variants with Flora the plants had in content vanadium trace. As well in mixed culture as in pure culture Flora plants accumulated vanadium in the variants which were fertlised with reduced quantities of manure or synthetical fertilizers. In the cases when was applied a higher quantity of synthetical fertilizers or when the culture was not fertilized, Flora plants didn’t absorbing vanadium.