Reduction of copper phytotoxicity by liming: A study of the root anatomy of young vines ( Vitis labrusca L.)

Abstract

Frequent applications of copper (Cu)-based fungicides on vines causes the accumulation of this metal in vineyard soils, which can cause toxicity in young vines. However, liming may reduce these toxic effects. The present study aimed to evaluate the effects of Cu toxicity on the root anatomy of young vines and the alleviation of Cu toxicity by lime applications to contaminated sandy soil. The treatments consisted of the addition of lime (0.0, 1.5 and 3.0 Mg ha(-1)) and two Cu concentrations (0 and 50 mg kg(-1)) to Typic Hapludalf soil. Young vines 'Niágara Branca' (Vitis labrusca L.) were obtained by micropropagation and cultivated for 70 days. The young vines grown with Cu and without liming presented a disorganized root structure; reduced root cap size; increased diameter (47%), cortex area (128%), vascular cylinder area (93%), and number of cortical layers and cells containing phenolic compounds (132%); and reduced root (41%), stem (44%) and leaf dry mass (21%) and height increase (55%). Moreover, Cu exposure reduced Ca concentrations (13%) and increased Cu concentrations (371%) in the roots. Liming, primarily with the highest tested dose, increased the soil pH (from 4.4 to 5.4-6.1), decreased the Cu concentration in the soil (extracted by CaCl2), increased the calcium (Ca) and magnesium (Mg) uptake by plants, prevented root anatomical changes and benefited young vine growth in soil with higher Cu concentrations.

Heavy Metals in Vineyards and Orchard Soils

“…Vines and cover crops grown in vineyard soils with high concentration of Cu have roots with shorter and thicker root apex, because of the changes in cell division and in the arrangement of tissues (AMBROSINI et al, 2015). The number of lateral roots can increase and in the epidermis plasmolysis of some cells can occur, with a reduction of the density of root hair normally observed (ZHANG et al, 2014).…”

“…It may also be observed a change in the organization of cells in the root apex, increasing the areas of the cortex and of the vascular cylinder and, consequently, of the root diameter, with a reduction of the growth young vines (AMBROSINI et al, 2015) in soil with sandy texture, low organic matter and high concentration of Cu (40 mg kg -1 of EDTA extractable Cu). Moreover, the same authors reported that exposure to Cu caused accumulation of phenolic compounds in the cortex cells of the root apex, reduction of the calcium concentration in the roots and increase of Cu concentration and accumulation in roots.…”

“…The addition of lime in contaminated soils of vineyards and orchards in production or after their removal promotes the increase of OH -concentration in solution, encouraging the deprotonation of H + from the surface of functional groups, which, in turn, promotes the increase of the of CEC and the adsorption of Cu, decreasing its concentration in soil solution and its potential toxicity (AMBROSINI et al, 2015). In addition, OH -in the solution, derived from lime dissociation, can react with Cu, forming Cu hydroxide which precipitates and, therefore, reduce the activity of free Cu species in solution.…”

“…The high levels of heavy metals such as Cu and Zn in the soil can cause shortening and thickening of the root apex of fruit trees and vine (AMBROSINI et al, 2015), increase in the number of lateral roots and plasmolysis in the epidermis of some cells, thus reducing the density of root hairs (CHEN et al, 2013;ZHANG et al, 2014). The excess of Cu in plants shoots can decrease the concentration of photosynthetic pigments and the rate of C fixation, and can increase the oxidative stress at cellular level (CAMBROLLÉ et al, 2013;CAMBROLLÉ et al, 2015).…”

“…However, the toxicity of heavy metals such as Cu and Zn in soils cultivated with fruit trees can be reduced by the adoption of some agronomic practices, including soil addition of lime, fertilizers, organic products, the cultivation of cover crops in orchard rows and interrow, and the inoculation of young fruit trees with arbuscular mycorrhizal fungi (AMF) before transplantation (FERREIRA et al, 2014;AMBROSINI et al, 2015). This review aims to compile and present information about the effects of increasing concentrations of heavy metals (especially Cu and Zn), in orchard and vineyard soils and to provide some agronomic practices of remediation.…”