Varietal Differences in Copper Accumulation, Tolerance, and Functional Traits in Radish (Raphanus Sativus)
摘要
Copper (Cu) is an essential micronutrient, but excessive soil Cu can impair plant function and threaten food safety. While Cu toxicity has been widely studied physiologically, the underlying trait-based mechanisms supporting growth and regulating accumulation remain poorly understood. This study examined how increasing soil Cu concentrations affect functional traits, biomass allocation, and Cu accumulation in three Raphanus sativus varieties (18 Jours, Écarlate and Flamboyant), with the aim of identifying morphological adjustments linked to metal accumulation and growth maintenance. A greenhouse experiment was conducted using soil spiked with five Cu concentrations (0, 50, 100, 250, and 500 mg kg⁻¹). Germination, biomass distribution, photosynthetic efficiency, Cu concentration in plant tissues, and leaf and root functional traits were measured. R. sativus exhibited high tolerance, maintaining germination and photosynthetic efficiency even at 500 mg kg− 1 Cu. Leaf dry matter content decreased in response to Cu contamination, indicating structural rather than physiological alterations of leaves. Copper was largely retained in belowground tissues, limiting translocation to shoots. Root morphology responded strongly, with reduced specific root length and increased diameter and branching density, reflecting a shift toward thicker and denser root systems. Among varieties, Écarlate accumulated the most Cu and showed reduced growth and failure to develop the edible organ, whereas 18 Jours combined low accumulation with stable biomass. Flamboyant displayed an intermediate response, maintaining biomass while accumulating Cu in belowground tissues. Varietal differences highlight the potential for selecting varieties that combine stable productivity with reduced Cu accumulation, supporting safer crop production.