Study on relationships between yield and its components in Iranian coriander genotypes

Coriander is mainly cultivated and widely distributed for the seeds. Therefore, development cultivar with high seed yield is important in coriander. On other hands, seed yield is a complex quantitative trait, considerably affected by environment and usually has a low heritability. Therefore, Study on relationships between yield and its components will improve the efficiency of a breeding program with appropriate selection criteria. The objectives of this research were to analyze the correlation between seed yield and related traits in coriander and by applyusing sequential path analysis and heritability estimates to identifying effective traits for which may be useful in breeding higher-yieldingimprove coriander genotypes. Plant materials including 36 genotypes of diallel crosses progenies of six coriander landrace and theirF1 and F2 generations were evaluated in randomized complete block design with three replications. The phonological, morphological characteristics and yield and its components including days to flowering, days to end of flowering, days to ripening, leaf number, branch number per plant, umbel number per plant, fertile umbel number per plant, seed number per plant, thousand seed weight, seed weight per plant (seed yield) and chlorophyll content were measured. Diallel analysis through Griffing method, correlation analysis, stepwise regression analysis and sequential path analysis was performed on the data. Results of genetic analysis of variance showed significant general and specific combining abilities for all traits that reveals the importance of both additive and non additive gene effect in controlling these traits. Also, results showed that the highest coefficient correlation was obtained between fertile umbel number per plant (r=0.67**) and thousand seed weight (r=0.66**) with seed yield. Sequential stepwise multiple regression analysis was performed to organize the predictor variables into first and second order paths based on their respective contributions to the total variation of yield and minimum collinearity. Based on the variance inflation factor and magnitude of direct effects, fertile umbel number per plant (r=0.45**), days to flowering (r=-0.46**), thousand seed weight (r=0.31**) and seed number per plant (r=0.30**) were considered as first order variables and accounted for 86 percent of total variation of yield. The t-test of significance, using standard error values, indicating that all direct effects were significant. Number of fertile umbels had the largest direct effect (0.45) on seed weight and also number of fertile umbels had the largest indirect effect (0.40) on seed weight through thousand seed weight. The results indicated that three traits including fertile umbel number per plant, thousand seed weight and seed number per plant considering the positive correlation and direct effect with seed yield and having additive genetic control and high narrow-sense heritability, can be used as a suitable criterion in selecting for increased seed yield in breeding programs of coriander in different generations of coriander under field conditions. Also, considering the negative correlation and direct effect of day to flowering with seed yield and having additive genetic control and high narrow-sense heritability, early maturity can be considered as an independent selection index for breeding of different varieties of coriander