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This research was conducted in International Biochemistry and Biophysics Center of Tehran University. Five Iranian onion cultivars namely, Azarshar Tabriz, Dourcheh Isfahan, Tarum Zanjari, Ghermez Riy, Sefid Kashan which have the highest total yield and area of production in Iran were selected from their respective areas of production.
Mitotic cell division was studied in root tips of all cultivars, using feulgen staining method.
The results showed that 2n= 16 in all cultivars, comprising one pair of acrocentric chromosome with satellite (sixth pair), three pairs of metacentric (first, fifth, seventh) and four pairs of submetaceritric (second, third, fourth, eighth) chromosomes. The presence of satellite in Azarshahr Tabriz and Tarum Zanjan cultivars was quite visihlie(macro satellite) , but in the other three cultivars (Dourcheh Isfahan, Ghermez Ray and Sefid Kashan) it was very small (micro satellite).