Forage grasses tolerance to cadmium and bioavailability on soil.

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T13:30:35Z No. of bitstreams: 5 40.pdf: 671743 bytes, checksum: 01827bc0544b1bc747825b4da796144b (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5)Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T16:26:30Z (GMT) No. of bitstreams: 5 40.pdf: 671743 bytes, checksum: 01827bc0544b1bc747825b4da796144b (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5)Made available in DSpace on 2015-02-27T16:26:30Z (GMT). No. of bitstreams: 5 40.pdf: 671743 bytes, checksum: 01827bc0544b1bc747825b4da796144b (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5) Previous issue date: 2012Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes)Esse trabalho foi desenvolvido com os objetivos de avaliar a toler?ncia de gram?neas forrageiras e a absor??o, ac?mulo e disponibilidade no solo de c?dmio (Cd). Os experimentos foram instalados em condi??es de casa de vegeta??o do Departamento de Agronomia da Faculdade de Ci?ncias Agr?rias da Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina (MG). As forrageiras estudadas foram: Panicum maximum cv. Aruana e cv. Tanz?nia e Brachiaria decumbens cv. Basilisk, Brachiaria brizantha cv. Xara?s e cv. Marandu e as doses de Cd foram 0, 5, 10 e 20 mg L-1 de solu??o nutritiva e 0, 2, 4 e 12 mg kg-1 de solo. O delineamento experimental foi inteiramente casualizado, com quatro repeti??es, sendo o per?odo experimental de 90 dias, em ambos os experimentos. Determinou-se a massa seca e os teores de Cd na parte a?rea, colmo e ra?zes das forrageiras. Os conte?dos de Cd foram calculados com base nos teores e nas produ??es de massa seca em cada parte da planta. No caso do experimento em solo, para avalia??o do teor de Cd foram utilizados os extratores Mehlich-1, DTPA pH 7,3, teor semitotal - USEPA 3051 e teor total - USEPA 3052. O crescimento relativo das forrageiras foi reduzido pelas doses de Cd, tanto na solu??o nutritiva quanto no solo, configurando a fitotoxidade do Cd nessas plantas. Por?m a sequ?ncia de suscetibilidade foi diferenciada para os experimentos, sendo a ordem decrescente de suscetibilidade na solu??o nutritiva a seguinte: Aruana > Tanz?nia > Xara?s > Basilisk > Marandu, enquanto no solo a sequ?ncia foi: Marandu > Xara?s > Aruana > Tanz?nia > Basilisk. Essa diferen?a de suscetibilidade ? atribu?da ?s diferentes intera??es das forrageiras com o solo. Em ambos os experimentos o teor de Cd nas forrageiras aumentou em fun??o das doses Cd. Por?m a presen?a de Cd na solu??o nutritiva fez com que o ac?mulo e ?ndice de transloca??o apresentassem resposta diferenciada para as forrageiras. Os extratores Mehlich-1 e DTPA foram eficientes para expressar o crescimento da planta. De toda forma, as forrageiras foram incapazes de limitar a absor??o e transloca??o de Cd, acarretando em toxicidade e redu??o de crescimento e altos teores de Cd em todas as partes da planta, n?o proporcionando barreira ? entrada do Cd na cadeia alimentar.Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2012.ABSTRACT This work was carried out in order to evaluate the forage grasses tolerance and the absorption, accumulation and bioavailability of cadmium (Cd) on soil. The experiments were settled under conditions of greenhouse on the Department of Agronomy of the College of Agricultural Sciences of the Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina (MG), Brazil. The forages grasses evaluated were: Panicum maximum cv. Aruana and cv. Tanz?nia and Brachiaria decumbens cv. Basilisk, Brachiaria brizantha cv. Xara?s and cv. Marandu and the four doses of Cd were: 0, 5, 10, and 20 mg l-1 and the nutrients in solution 0, 2, 4 and 12 mg kg-1 for soil, respectively. The experimental design was completely randomized with four replications, and the trial period of 90 days, in both experiments. The dry weight and concentration of Cd in shoots, stems and roots of forages were determined. The Cd content had been calculated based on the dry matter yield and content in each part of the plant. In the soil experiment, to measure the levels of Cd, there had been used the extractors Mehlich-1, DTPA pH 7.3, semi total content - USEPA 3051 and total content - USEPA 3052. The relative growth of the forage grasses was reduced with doses of Cd applied, both in the nutrient solution and on the soil, setting the phytotoxicity of Cd in these plants. However the sequence of susceptibility was different t tohe experiments, the decreasing order of susceptibility in the nutrient solution was: Aruana> Tanzania> Xara?s> Basilisk > Marandu, while in soil the sequence was: Marandu> Xara?s> Aruana> Tanzania> Basilisk. This difference in susceptibility is attributed to the different interactions of forage with soil. In both experiments (soil and nutrient solution) the Cd content in the forage increased due of increasing doses of Cd. Nevertheless the presence of Cd in the nutritive solution has made the accumulation and translocation index differently for the forages. Mehlich-1 and DTPA showed high positive correlation with relative growth of forages. The forages were unable to limit the absorption and translocation of Cd, resulting in toxicity and declining growth and high levels of Cd in all parts of the plant, providing no barrier to entry of Cd into the food chain