Effects of copper on germination and reserve mobilization in Vicia sativa L. seeds

The effects of different copper concentrations on percentage germination, increase in fresh weight and radicle growth of Vicia sativa L. seeds were studied. Physiological studies showed that the germination rate was not affected up to a concentration of 5 × 10−3 M, but already at 10−3 M the copper stopped root elongation. Structural and ultrastructural observations of embryo and cotyledon reserve mobilization showed that inhibition of radicle growth at 10−3 M Cu concentration cannot be ascribed to nutrient shortage but probably to an effect of copper on radicle cell division and elongation. In seeds treated with 5 × 10−3 M CuBr2, the copper completely inhibited cotyledon protein mobilization, so that embryo protein mobilization supported normal growth of the radicle up to 30 h after imbibition. The particular protein content of adjacent cotyledon cells is also discussed. -- Highlights: •The effects of copper on germinative metabolism of Vicia sativa were investigated. •The limit of Cu tolerance for germinative metabolism was between 10−4 and 10−3 M. •Copper excess allowed the germination but arrested the radicle growth. •Ultrastructural studies allowed to determine the possible causes of root growth stop. -- Copper excess allowed germination but arrested radicle growth in Vicia sativa L. seeds