Evaluation of salinity tolerance of cow cockle (Vaccaria hispanica) ecotypes at germination and adult plant stages

This study aimed to investigate the response of cow cockle (Vaccaria hispanica (Mill.) Rauschert) ecotypes from northwest Iran to salinity stress at the germination and adult plant stages via a factorial experiment based on a completely randomized design with three replications in 2021. The results showed significant differences among the ecotypes regarding the germination components and morpho-physiological traits, indicating the existence of genetic diversity among them. Germination percentage and its components decreased with increasing salinity levels. So, at the NaCl concentrations greater than 120 mM, seed germination was inhibited in all studied ecotypes. This indicated that the cow cockle is a salinity-sensitive species and does not tolerate high salt concentrations. At the adult plant stage, salinity decreased plant height, root and stem dry weights, chlorophyll a and b content, and increased shoot sodium content and sodium to potassium ratio. The estimation of the multi-trait genotype-ideotype distance index (MGIDI) for different ecotypes based on various traits showed that the E3, E8, and E6 ecotypes having the lowest MGIDI values under salt stress conditions at both germination and adult plant stages, were the most tolerant ecotypes. Moreover, the E7 and E1 ecotypes had the highest MGIDI values at both growth stages and showed a higher sensitivity to salt stress. The more tolerant ecotypes selected based on the MGIDI indicator can be used for further research and selection in the breeding programs of this plant.