Evaluation of phenotypic diversity, transgressive segregation and agro- morphological trait relations in generated populations from cross-breeding of Iranian rice cultivars

In order to facilitate the selection of new genotypes, diversity evaluation and analysis of relationships of effective traits on grain yield of rice in F2 populations produced by crossing of Anbarbo cultivar as mother parent with semi dwarf and highly produced by Shafagh and Najafi as paternal parents, 450 F2genotypes with three control varieties (Anbarbo, Shafagh and Najafi) were evaluated and grain yield and 16 different agronomic traits were investigated. By comparing the descriptive statistics of the parental cultivars and the resulting F2 progenies, positive and negative transgressive segregation was observed for most traits such as yield, harvest index, peduncle length and number of fertile tillers. Dry weight of panicle, number of grains per plant, biological yield, number of fertile tillers and grain per panicle, harvest index, 100-grain weight, height, panicle length and peduncle length had positive and significant correlations with grain yield. To select grain yield justifying traits, stepwise regression analysis was performed and dry weight of panicle ,number of grain per plant, 100-grain weight, number of grains per panicle, first and second internode lengths were introduced into the model as the most effective traits on grain yield. Path coefficient analysis showed that the most direct and positive affecting traits were number of grains per plant (0.834), 100-grain weight (0.348) and dry weight of panicle (0.122), respectively. In this research, grain number per plant, 100-grain weight and dry weight of panicle were identified as selection indexes for improving grain yield in rice and recommended for use in rice modification projects. According to the phenotypic variation observed among F2 progenies for different traits (variation range and coefficient of variation) in this study and applying the desired segregation in breeding programs, it could be achieved new lines with the desired characteristics and increased yield in later generations.