Path Analysis for Grain Yield on Populations of Fennel (Foeniculum vulgare M.) under Normal and Water Deficit Stress Conditions

Since the global approach to herbal medicine and chemical away from drugs, more attention to medicinal plants, is required. Fennel with variety of secondary metabolites in the treatment of flatulence, cough, digestive disorders and increases milk, used as one of the important medicinal plants. Drought stress is one of the most important non-polluting environmental stresses affecting crop production. To study the direct and indirect effects of evaluated traits on grain yield of fennel, an experiment was conducted in a randomized complete block design in two control and limited irrigation conditions separately with three replications on 19 fennel populations in the Agricultural Research Station, University of Tabriz. Combined analysis of variance revealed a significant differences between two irrigation conditions and evaluated populations at %1 probability level for some studied traits. As well as the population × conditions interaction effect was significant at 1% probability level for most traits. Correlations of grain yield with number of umbel in plant, plant height, internode number and biomass were significant positively in both irrigation conditions. Stepwise regression analysis showed that the number of grain per umbel and the number of umbel per plant, have the greatest impact on grain yield under optimum irrigation (R2=0.88). Also in the water deficit condition, number of umbels per plant and plant height had the greatest impact on grain yield (R2=0.60). Path analysis revealed that the number of umbel per plant had greatest direct effect on grain yield under control (0.90) and stress (0.53) condition respectively. Whereas the indirect effects were very inconsiderable in both conditions, therefore it is suggested that to selection of superlative populations for grain yield, the number of umbel per plant should be considered.