Scientific Papers Series B Horticulture

epresenting the fluorescence intensity of apopulation of nuclei. Their intensity (positionof the histogram) is proportional to the amountof nuclear DNA (Figure 1).Figure 1. Frequency distribution histograms of fluorescence intensity stained with propidium iodide (PI) (A, A. argutaR8P23; B, A. chinensis ‘Soreli’; C, A. arguta 108P10, D, A. deliciosa var. deliciosa cv. Hayward K; Log values offluorescence intensity% CV for nuclei are given on each histogram).The comparison between the position of thesample’s peak and the internal standard’s peakgive a ratio of relatives intensities. The ploidylevels are calculated by comparingexperimental values with the value obtainedfrom Pisum sativum sample having a knownploidy level.As a result, ploidy analysis in which the DNAcontents of Arguta sp. collection, nuclei werecompared to those from a specie having knownploidy (Pisum sativum 2n=2x).This comparison can be made either betweentwo analyses performed under identicalconditions, or, in our case, through mixing thetwo samples for simultaneous measurement.Counting chromosomes in Actinidia speciesand their hybrids is technically difficult due tothe high numbers of chromosomes involvedand their small size. Chromosome numbershave been reported for only a few species butthe data support a polyploid sequence 2n = 2x,2n = 4x, 2n = 6x with x= 29. To determineploidy, the number of basic chromosome sets in191