Evaluation of relationships between traits of anise (Pimpinella anisum L.) genotypes in response to drought stress using the structural equation modeling and biplot method

Water deficit is a main abiotic factor that seriously influences the production of crop plants such as anise and the lack of effective selection criteria has made it difficult to develop tolerant genotypes. This experiment aimed to investigate the relationship between seed yield and related characteristics in anise to evaluate genotype x trait interaction emphasis genotype x water treatment interaction. According to this aim, 21 Iranian endemic anise genotypes were evaluated under both water deficit and control conditions in a nursery. Genotypic variance and correlation coefficients estimates calculated from pooled analysis of control and water deficit conditions were used in structural equation modeling (SEM) and genotype x trait (G x T) biplot analysis. The G x T biplot visually showed the interrelationships among traits and facilitate graphical comparison of genotypes. Based on the SEM, predictors used in the causal diagram could explain 97.6%, 93.9%, 78.7%, 69.8%, and 65.9% of the total variation in seed yield per plant (SYPP), thousand seed weight (TSW), seed number per plant (SNPP), net photosynthesis (NPh) and stomatal conductance (g(s)), respectively. The G x T biplots explained 77.5% of the total variation in control condition, 59.4% in water deficit stress and 64.6% in the pooled conditions. SNPP, TSW, NPh and g(s) must be regarded as a priority for developing new genotypes anise to get more tolerant and productive genotypes to water deficit and selection criteria. Also, G11 (tolerant) and G21 (susceptible) can be considered as parents in crossing schemes to genetic architecture studies and heritability for improvement in drought tolerance.