Genetic characterization and classification of germplasm are very important in that they are helpful in breeding as well as conservation of genetic resources. In this investigation, 120 genotypes of Iranian rice germplasm were classified through data obtained from seven isozyme loci using cluster analysis. Enzyme extract was obtained from 6-8 day seedlings. Horizontal starch gel electrophoresis (HSGE) and Glaszman et al. Protocol (1988), with some modifications was employed. Cluster analysis lead to the classification of the samples in seven groups. More than %16 were positioned within Japonica and %9 positioned into Indica group. About %68 in two major groups fell out of Indica and Japonica group (with more similarity to Japonica) and %4 were positioned in three intermediate groups between Indica and Japonica. Forty-three isozyme genotypes were detected, with an average of 2.9 samples for each genotype group. In many cases, accessions with the same name revealed different isozyme genotypes (e.g. in Gharib and Binam). Genotype diversity index was 3.43, which is high in comparison with other Asian rices. These results showed a high genetic variability in Iranian landrace rices introducing them as a valuable and very rich resource of natural diversity for rice improvement as well as breeding.
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