Cadmium toxicity on seed germination and seedling growth of wheat Triticum aestivum/Toxicidade do cadmio na germinacao de sementes e no crescimento de Triticum aestivum

Cadmium toxicity in seed germination and seedling growth of wheat (Triticum aestivum, var. IAC-370) is assessed. The ecotoxicological effects of six experimental concentrations of cadmium (0.03; 0.06; 0.12; 0.6; 1.2; 2.4; 4.8 mM), and control were evaluated. All assays were performed in quadruplicates with 25 seeds per replication in Petri dishes. Responses for toxic effect comprised the variables germination percentage, index of velocity of germination (IVG), length of aerial section and root of the seedlings, green and dry mass of the seedlings. Results showed that T. aestivum seeds exposed to cadmium decreased their normal germination percentage as from 0.03 mM concentration, with a 31% reduction of germination percentage and a 20% decrease in IVG. Cadmium's inhibition effect on initial growth of seedlings influenced growth of roots and aerial part as from concentration 0.12 mM and reduced the production of green and dry mass of seedlings as from 0.06 mM. The presence and accumulation of cadmium in the soil cultivated with T. aestivum may trigger liabilities in productivity and/or viability caused by its toxicity as from 0.03mM concentrations absorbed by the plant roots. Keywords: ecotoxicology, metal, contamination. Esta pesquisa avaliou os efeitos toxicos do cadmio na germinacao e crescimento inicial do trigo (Triticum aestivum, var. IAC-370). Foram avaliados os efeitos ecotoxicologicos de seis concentracoes de cadmio (0,03; 0,06; 0,12; 0,6; 1,2; 2,4; 4.8 mM). Os experimentos foram em quadruplicatas, com 25 sementes por replicata, em placas de Petri. As variaveis respostas foram o percentual de germinacao, o indice de velocidade de germinacao (IVG), o comprimento da parte aerea e da raiz das plantulas, a massa fresca e seca das plantulas. Os resultados reportaram que as sementes de T. aestivum expostas ao cadmio apresentaram decrescimo do seu percentual germinativo de plantulas normais a partir a concentracao de 0,03 mM, com reducao de 31% do percentual germinativo e decrescimo de 20% no IVG. O efeito inibitorio do cadmio no crescimento inicial das plantulas afetou o crescimento das raizes e da parte aerea a partir da concentracao 0,12 mM, causando a reducao da producao de massa fresca e seca das plantulas a partir de 0,06 mM. A presenca e acumulacao do cadmio, no solo de cultivo da T. aestivum, podera causar perdas de produtividades e/ou viabilidade provocadas pela sua toxicidade a partir de concentracoes de 0,03 mM que estejam absorvidos pela raiz d