Effect of soil P addition on growth, nutritional status and photosynthesis of potted grapevine plants grown under soil copper excess

The continuous use of copper (Cu)-based fungicides in viticulture to counteract fungal diseases has resulted in an accumulation of Cu in the topsoil, sometimes reaching toxic levels that can cause plant stress and reduce soil fertility. A possible strategy to mitigate the negative effects of Cu could include its incorporation into chemical compounds with phosphorous (P). The aim of this study was to evaluate the effectiveness of soil P addition on alleviating the toxic effect of Cu when applied in excess to potted grapevines plants. Micro-propagated plants of 1103 Paulsen rootstock were grown according to a factorial experimental design with two factors: Cu (4 levels: 0, 100, 200 and 300 mg kg-1 dw) and P (2 levels: 0 and 100 mg kg-1 dw) and three replicates. Sixty days after transplant, P was not effective in preventing the accumulation of Cu in vines. The total plant biomass was not influenced by soil Cu addition, while P increased plant growth by enhancing plant nutritional status. In addition, Cu reduced nutrient (P, K and Zn) content in plants. Net photosynthesis and efficiency of photosystem II decreased as a consequence of the increase of Cu concentration in soil. The effect of P in mitigating Cu toxicity was mainly related to the ability of plants to restore nutrient uptake