Evaluation of rice germplasmes in hybridization block and producing of F1 generation

This study was carried out with 105 genotypes of rice in Rice Research Institute of IRAN(RASHT) in 2003.The objectives of this experiment were to maintain and classification of the rice genotypes , to improve new rice varieties through hybridization. All genotypes were sown in nursery 3 times with 15 days interval for flowering synchronization. The experimental design was augmented in Randomized Complet Block Design with five blocks and five replications. Each treatment was planted on six rows of four-meter length. In addition, 69 F1 generations were sowed in nursery. The genotypes and F1 generation were planted as one seedling per hill in the paddy field. The seedling space was 25cm ×25cm .One hundred twenty-one crosses were done between local and foreign parents and the result was showed that enough seeds were obtained for each hybrid. The single plant of each parent was harvested for maintaining of purity. The grain yield of each F1 was harvested as bulk after removing of the off types. In this study 16 quantitative and qualitative traits were measured on 10 random plants from each plot. Analysis of variance showed a highly significant difference among genotypes for all traits except milling recovery. That proved the existence of genetic variation among genotypes. The difference between blocks was not significant. Therefore the data of the unreplicated varieties were not adjusted and the average data of genotypes were analyzed after making standard based on Z distribution. Cluster analysis with ward’s method classified all of the genotypes into three clusters. Genotypes of second and third clusters including 64 genotypes were known as high yielding, semi dwarf varieties with high number of tiller and fill grain per panicle. Therefore the crosses between genotypes of these two clusters and the genotypes of first cluster with 41 traditional varieties as low yielding but excelent grain quality are suggested to improve the high yielding and good grain quality rice varieties. Key word : Rice, genetic variability, hybridization, and cluster analysis