ABSTRACT
Vineyard soils can be contaminated by copper (Cu) due to successive applications of fungicides and organic fertilizers. Soil remediation can be addressed by altering soil properties or selecting efficient Cu-extracting cover crops tolerant to Cu toxicity. Our objectives were to synthesize the Cu-extracting efficiency by plant species tested in Brazil, classify them according to Cu resistance to toxicity, and assess the effect of soil properties on attenuating Cu toxicity. We retrieved results from 41 species and cultivars, totaling 565 observations. Freshly added Cu varied between 50 and 600 mg Cu kg-1 of soil across studies. The partition of Cu removal between the above- and below-ground portions was scaled as a logistic variable to facilitate data synthesis. The data were analyzed using the Adaboost machine learning model. Model accuracy (predicted vs. actual values) reached R2 = 0.862 after relating species, cultivar, Cu addition, clay, SOM, pH, soil test P, and Cu as features to predict the logistic target variable. Tissue Cu concentration varied between 7 and 105 mg Cu kg-1 in the shoot and between 73 and 1340 mg Cu kg-1 in the roots. Among soil properties, organic matter and soil test Cu most influenced the accuracy of the model. Phaseolus vulgaris, Brassica juncea, Ricinus communis, Hordeum vulgare, Sorghum vulgare, Cajanus cajan, Solanum lycopersicum, and Crotolaria spectabilis were the most efficient Cu-extracting cover crops, as shown by positive values of the logistic variable (shoot removal > root removal). Those Cu-tolerant plants showed differential capacity to extract Cu in the long run.
Subject(s)
Soil Pollutants , Biodegradation, Environmental , Farms , Brazil , Soil Pollutants/analysis , Copper/analysis , Soil/chemistry , Crops, AgriculturalABSTRACT
ABSTRACT: Phytoremediation is an alternative technique used to treat copper-contaminated soils. The objective of this research was to explore the behavior of nine summer cover crops regarding the growth, absorption and translocation of copper in soils with contamination levels exceeding the Value of Prevention, with a view to selecting plants for phytoremediation programs. In the experiments the Cambisol was contaminated with copper, added in doses of 0, 100, 200, 400, 500 and 600mg kg-1, in which the following nine plants were cultivated under greenhouse conditions: Canavalia ensiformis, Cajanus cajan, Dolichos lablad, Mucuna cinereum, Mucuna aterrima, Crotalaria juncea, Crotalaria spectabilis, Pennisetum glaucum and Paspalum notatum. At 90 days after sowing the plants were evaluated for dry mass of shoot and root, Cu, N, P, K, Ca, Zn, and Fe levels in the shoot and Cu in the roots. High soil Cu levels induced a decline in the phosphorus absorption by the plants. Canavalia ensiformis displayed high potential for phytoextraction as these plants could translocate high copper concentrations to the aerial plant parts, while the Mucuna cinereum and M. aterrima are indicated for the copper phytostabilization programs, due to the high copper accumulation in their root systems.
RESUMO: A fitorremediação é uma alternativa para o tratamento de solos contaminados com cobre. O objetivo do trabalho foi conhecer o comportamento de nove plantas de cobertura de verão quanto ao crescimento, absorção e translocação do cobre em solos com contaminação acima dos Valores de Prevenção, com vistas a seleção de plantas para programas de fitorremediação. Um Cambissolo foi contaminado com doses de 0, 100, 200, 400, 500 e 600mg kg-1 de cobre e cultivado em casa de vegetação com nove plantas: Canavalia ensiformis, Cajanus cajan, Dolichos lablad, Mucuna cinereum, Mucuna aterrima, Crotalaria juncea, Crotalaria spectabilis, Pennisetum glaucum e Paspalum notatum. Aos 90 dias após a semeadura as plantas foram avaliadas quanto à produção de massa seca de parte aérea e raízes, teores de Cu, N, P, K, Ca, Zn, e Fe na parte aérea e de Cu nas raízes. As altas concentrações de Cu no solo reduziram a absorção de fósforo pelas plantas. O feijão-de-porco apresenta potencial para a fitoextração, pois apresentou translocação de altas concentrações de cobre para os tecidos aéreos, enquanto que as mucunas preta e cinza são indicadas para programas de fitoestabilização de cobre, pois acumularam elevada concentração de cobre no sistema radicular.
