Response of potted grapevines to increasing soil copper concentration

Copper accumulation in soil may promote phytotoxicity in grapevines. Nutritional implications of potted vines to increasing concentrations of copper (Cu) in either clay loam soil or clay loam soil mixed with 85% sand were tested on Vitis vinifera (L.) cv Sangiovese and crop toxicity threshold and symptoms determined. Soils were mixed at planting with Cu at the rates (mg Cu/kg) of 0 (control, native soil Cu only), 50, 100, 200, 400, 600, 800 and 1000, and non-bearing vines were grown in these for two seasons. Reduction of root growth was observed after addition of >= 400 mg Cu/kg to both soils; reduction of shoot growth, leaf number and chlorosis of leaf edges were detected only in sand-enriched soil. Root Cu concentration increased in response to soil Cu addition. Unlike that of leaf Cu and N, the amount of P and Fe (in both soils) and Mg and Ca (in sand-enriched soil only) were reduced by soil Cu. Vines grown in sand-enriched soil tolerated lower concentrations of Cu than in clay loam soil, probably because of the lower nutritional status and the higher root Cu concentration. Results provide information on the concentration of soil Cu that grapevine can tolerate and on the nutrients involved in the response to toxic levels of soil Cu in clay loam and sandy clay loam soils.