Numerical and graphical assessment of relationships between traits of the Iranian Coriandrum sativum L. core collection by considering genotype × irrigation interaction

• SCCIGFS, UNPP, FNPP, BNPP, SDWPP and DTEOF identified as secondary traits to improve FWPP.
• DC + YPr data was suitable to study GI interaction in GT-biplot analysis.
• Results of GT-biplot and SEM analysis were same but GT-biplot was more informative.
• G16 and G13 were identified as drought sensitive and tolerant genotypes, respectively.
• G12 had the lowest yield in both WW and WS conditions.

Drought is a worldwide problem seriously influencing production of agricultural plants such as coriander, but development of tolerant genotypes is inhibited by a lack of effective selection criteria. The objective of this study was to interpret the relationship between fruit yield and related traits in coriander to evaluate genotype by trait interaction by considering genotype × irrigation interaction. According to this aim, 16 Iranian endemic coriander genotypes were grown in a glasshouse under well watered (WW) and water stressed (WS) conditions. Structural equation modeling (SEM) was used, based on genotypic correlation coefficients and genotypic variance estimates obtained from combined analysis of WW and WS conditions and genotype-trait (GT) biplot analysis. Applying both types of analyze to the multiple trait data revealed that SEM and DC + YPr data based GT biplot results are similar. The GT biplot graphically displayed the interrelationships among traits and facilitated visual comparison of genotypes for selection. Predictors in the causal diagram could explain 70.8%, 80.9%, 100% and 41.7% of the total variation in fruit weight per plant (FWPP), fruit number per plant (FNPP), day to end of flowering (DTEOF) and umbel number per plant (UNPP), respectively. Also, the GT biplots explained 81.2% for WW data, 74% for WS data and 79.7% for DC + YPr data. It was found that selection for high SPAD chlorophyll content in the grain filling stage (SCCIGFS), UNPP, FNPP and branch number per plant (BNPP), and low shoot dry weight per plant (SDWPP) and DTEOF should be considered as priorities in breeding programs for coriander aiming for more productive and drought tolerant genotypes. Furthermore, G13 (TN-59-353) can be used as a drought tolerance donor in breeding programs.