assessment of genetic diversity through morphologic characteristics in rice genotypes

background and objectives: rice (oryza sativa) is one of the most important cereal crops and is the staple food source for over fifty percent of the world’s population. the population of rice-consuming countries is multiplying daily, and it is estimated that rice production must be increased in the coming years and an incensement in production will be the main goal of plant breeders. this has to be achieved by the development of high yielding rice varieties with improved nutritional quality and tolerance to biotic and abiotic stresses. studies on genetic diversity and genetic structure of natural populations are important in order to define strategies for plant breeding.materials and methods: 100 diverse rice accessions including global genotypes from different countries and international breeding lines were chosen to assess genetic relationships between traits. the experiment was carried out in an incomplete block design (lattice) with three replications. this collection was used to measure important agronomic traits such as: yield and yield component, grain shape characteristics, flag leaf characters and flowering time.results: the anova revealed significant (p < 0.01) variation for all the traits. orthogonal comparisons for three categories of iranian genotypes, foreign varieties and inbred lines, revealed iranian genotypes were defined as a rich source for grain quality genes, while foreign varieties despite the lack of grain quality had appropriate grain yield, whereas breeding lines had suitable potential in yield components. ward’s clustering method classified genotypes in three main groups with different characteristics. principal components analysis explained 84.8% of variation with five first components.conclusion: the present study, evaluate important agronomic traits to find out status of iranian germplasm against foreign inbred lines and varieties, results determine that foreign germplasm with appropriate characteristics could be a complementary material beside iranian germplasm in rice breeding projects. evaluated population has an appropriate variation for all traits. according to the results of the orthogonal comparison, each of the iranian genotypes, foreign genotypes and breeding lines had unique characteristics. however, iranian genotypes could be considered appropriate in terms of grain quality traits but against foreign varieties had high yield but not suitable in grain quality. though, breeding lines sounds a good source for yield component traits. hence, the population could be a rich and diverse collection of important agronomic traits. in present study cluster analysis and principal component analysis separate the rice genotypes based on morphological characters, and individuals with similar characteristics were classified in similar group.