Effect of copper on soil bacteria and fungus population, on mycorrhizal association and on production of Eucalyptus grandis W. Hill ex Maiden, Pinus elliottii Engelm and Peltophorum dubium (Sprengel) Taubert seedlings

Abstract

O cobre \ue9 um metal pesado que pode exercer efeitos t\uf3xicos para micro-organismos e plantas. Os fungos ectomicorr\uedzicos s\ue3o capazes de proteger a planta hospedeira da toxidez dos metais pesados, mas a presen\ue7a de certas concentra\ue7\uf5es de metais pode inibir o crescimento destes, prejudicando a simbiose micorr\uedzica e alterar o desenvolvimento das plantas. O objetivo deste trabalho foi avaliar o efeito de doses de cobre na popula\ue7\ue3o de bact\ue9rias e fungos do solo, bem como seus efeitos na associa\ue7\ue3o ectomicorr\uedzica e no desenvolvimento de mudas de eucalipto, pinus e canaf\uedstula. O levantamento da popula\ue7\ue3o de micro-organismos do solo foi realizado em casa de vegeta\ue7\ue3o durante 60 dias e os tratamentos foram doses de sulfato de cobre aplicadas ao solo (0,7; 0,708; 0,716; 0,724 mg kg-1 de solo) e mudas de eucalipto e pinus. No segundo experimento, mudas de eucalipto e canaf\uedstula inoculadas e n\ue3o inoculadas com Pisolithus microcarpus (Cooke & Massee) Cunn (UFSC Pt 116) receberam doses de cobre de 0, 100, 200 e 300 mg kg-1 de solo. Aos 110 dias, avaliaram-se a massa fresca da parte a\ue9rea e radicular, massa seca da parte a\ue9rea, altura, di\ue2metro do colo e porcentagem de coloniza\ue7\ue3o ectomicorr\uedzica. No primeiro experimento, a popula\ue7\ue3o total de bact\ue9rias e fungos do solo foi alterada pela presen\ue7a do cobre, por\ue9m as mudas de eucalipto e pinus n\ue3o mostraram efeitos da adi\ue7\ue3o do cobre. No segundo experimento, a inocula\ue7\ue3o das mudas de eucalipto e canaf\uedstula com o isolado UFSC Pt 116 favoreceu o desenvolvimento da massa fresca da parte a\ue9rea e radicular e a altura das plantas. Conforme os resultados obtidos, a canaf\uedstula foi capaz de realizar associa\ue7\ue3o ectomicorr\uedzica com o isolado testado. O desenvolvimento das pl\ue2ntulas de eucalipto e canaf\uedstula foi inibido pelos n\uedveis de cobre, mesmo inoculadas com o isolado UFSC Pt 116.Copper is a heavy metal that can have toxic effects on microorganisms and plants. Ectomycorrhizal fungi are able to protect the plant from heavy metal toxicity, but the presence of certain metal concentrations can inhibit the growth of this fungus, damage the mycorrhizal symbiosis and also altering the development of the plants. The aim of this study was to evaluate the effect of copper on soil bacteria and fungus population, as well as the effects on the ectomycorrhizal association in the development of Eucalyptus grandis , Pinus elliottii and Peltophorum dubium seedlings. The survey of the soil microorganism population was carried out in a greenhouse during 60 days and the treatments consisted of applications of copper sulphate (0.7; 0.708; 0.716; 0.724 mg Kg-1) to the soil and to eucalyptus and pinus seedlings. Eucalyptus and Peltophorum dubium seedlings inoculated and not inoculated with Pisolithus microcarpus (Cooke and Massee) Cunn (UFSC Pt 116) received copper levels of 0, 100, 200 and 300 mg kg-1. The height, stem diameter, shoot and root fresh biomass, shoot and root dry biomass and ectomycorrhizal colonization were evaluated at 110 days. Soil bacteria and fungus population were altered by the presence of copper and the eucalyptus and pinus seedlings were not affected by copper addition. The inoculation of the eucalyptus and canaf\uedstula seedlings with isolate UFSC Pt 116 favored the height of the plants and the development of shoot and root fresh biomass. According to the results, canaf\uedstula was able to form an ectomycorrhizal association with the isolate tested. The eucalyptus and canaf\uedstula seedling development was inhibited by copper following inoculation with the UFSC Pt 116 isolate