Copper Stress in Maternal Plants, Yet No Effects on Seeds: Insights from Barley Grown in Soils Polluted by Copper Mining

Seed quality is a critical factor in ensuring successful germination and uniform crop development. However, the relationship between metal stress in maternal plants and the agronomic quality of their seeds remains debated. In this study, barley (Hordeum vulgare L.) plants and their associated rhizosphere soils were sampled along visible gradients of copper (Cu) phytotoxicity in two areas historically affected by Cu mining in Russia. Soils at the study sites were classified as Calcic Chernozem (Aric) in the Orenburg Region and Phaeozem (Albic) in the Republic of Tatarstan. Total soil Cu concentrations reached up to approximately 4500 mg/kg. Concentrations of other elements were comparable to background levels, indicating Cu-dominated contamination. Our results show that Cu contamination reduced barley shoot dry weight and the number of seeds per plant. Yes, the agronomic quality of first-generation seeds, assessed through germination and radicle length, was not significantly affected by Cu stress in maternal plants. Although the initial hypothesis was not supported, these findings contribute to a more complete understanding of plant responses to metal stress. Reporting such outcomes is essential for accurately representing the range of responses in contaminated agricultural systems.