Correlation and sequential path analysis in Ajowan (Carum copticum L.)

Study on the relationships between yield and its components will improve the efficiency of breeding programs by determining appropriate selection criteria. An investigation was carried out on 10 populations of Ajowan to investigate the association among yield components and their direct and indirect effects on the seed yield of Ajowan. Populations were collected from different regions of Iran including, Hamadan, Rafsanjan, Ardabil, Khorasan, Isfahan and Alamoot-e-Ghazvin. The experiment was conducted in completely randomized design with 8 to 10 replications in greenhouse conditions. Correlation coefficients were calculated among 16 studied traits. Positive and significant correlations were detected between single plant yield and most of the studied traits while the correlation between single plant yield and ripening period lenght was negative and significant (r = -0.41). A sequential path analysis was used to order the various variables based on their maximum direct effect and minimal colinearity. Based on sequential path analysis, plant height and number of umbels can be used as selection criteria for improving seed yield in Ajowan breeding programs.   Key words: Colinearity, landrace, medicinal plant, direct effect, indirect selection, predictor variables, sequential path analysis.