An-Najah Staff

One hundred and forty seven isolates belonging to forty one species of Pythium were used in this study. Pythium isolates were recovered from soil from the Palestinian West Bank and Gaza using the VP3 selective medium and the surface-soil-dilution plating technique. The isolates were used to test the robustness of the biometric approach and to examine the taxonomic value of biometric characters. Morphological characteristics including oogonium and oospore diameters, oospore wall thickness and derived indices (oospore wall index and aplerotic index) were used. The biometric parameter set which consists of oogonium and oospore diameters and oospore wall thickness were all of taxonomic value for the separation of species. This was clearly shown from canonical variate plots and cluster analysis. By using multivariate analysis of variance in this study inter and intra specific variations among Pythium species were demonstrated. However, according to dendrogram and canonical variate plots some of Pythium species were separated. Despite intra-specific variation, good species separation was obtained. Multivariate analysis of variance is shown in this study to be a useful technique of taxonomic value for the separation of Pythium species.