Growth Responses of Chemically Root-pruned Cork Oak Seedlings in the Nursery

Abstract

Cork oak ( Quercus suber L.) seedlings of two Iberian provenances (PA-SR and SM-Lp) were grown for one growing season in non-treated containers or in containers treated on their interior surfaces with white exterior latex paint containing 80 g CuCO 3 /liter. Copper carbonate-treated containers effectively prevented root deformation and decreased the amount of circled, kinked and matted roots formed at the container wall-medium interface. Root morphology was altered by the copper coating, so elongation of lateral roots contacting CuCO 3 -treated surfaces was more reduced than that of the tap root (82.7% vs 1.5%). These lateral roots showed higher branching frequency than roots contacting untreated container walls. CuCO 3 treatment decreased root collar diameter, but did not influence seedling height, leaf area and tap root length. No sign of copper toxicity was observed in any seedling treated with CuCO 3 . Provenance had a significant effect on height, root collar diameter, tap root length and root weight per unit length; these results may reflect differences in growth habit of the two provenances. Other growth parameters measured were affected by a copper × provenance interaction. Seedlings of the PA-SR provenance produced less root and plant dry wt when grown in CuCO 3 -treated than in control containers, but shoot:root ratio was not influenced.