Thirty soybean (Glycine max (L.) Merr.) genotypes showed a wide range in tolerance to Mn toxicity when grown in nutrient solutions containing from 0.1 to 20 ppm Mn. The varieties ‘Hill’, ‘Dare’, ‘Davis’, ‘Delmar’, and ‘Bragg’ were very sensitive and ‘Hawkeye’, ‘Custer’, ‘Lee’ and ‘Amredo’ very tolerant to Mn toxicity. Field observations showed similar symptoms and varietal differences when soybeans were grown on an acid soil high in available Mn.

This work was designed to study the effect of copper in the medium on growth and mineral composition of the coffee plant, bearing in mind the possibility of accumulation of toxic residues in the soil as a consequence of the treatments against rust. - Young plants of the varieties Mundo Novo and Catuaí were grown in nutrient solution in the presence of Cu concentrations from 0.02 to 200 ppm. Toxic effects were found to be darkening and cessation of root growth; wilt, necrosis and leaf drop; abnormalities in the epidermis, parenchyma and chloroplasts. The threshold level for copper toxicity in around 30 ppm in the leaves. Mundo Novo seems to be more sensitive to copper toxicity. - Under soil conditions it was found that the joint use of lime and stable manure eliminates the toxicity of an application of 200 ppm of copper. | A sensibilidade das variedades Catuaí e Mundo Novo ao nível de cobre no substrato foi estudada em condições controladas. Em solução nutritiva verificou-se que a primeira variedade parece ser mais resistente à toxidez. Ensaios com três tipos de solos mostraram que a elevação do pH a 6,5 e a adição conjunta de matéria orgânica neutralizam a toxidez correspondente a 200 ppm do elemento no meio.

Estudam-se os modelos de cristalização de cloreto de cobre obtidos na presença de extratos de sementes de feijoeiro (P. vulgaris L.). São descritos e comparados os modelos obtidos em 11 séries de cristalização, com 5 repetições. Os fatores de variação envolvidos são: 3 variedades (roxinho, pintado, preto), 2 procedências (solos e solução nutritiva), 2 processos de obtenção de extrato (sementes secas e sementes úmidas) e 3 concentrações (0,05:0,5; 0,025:0,5 e 0,025:0,75). A conclusão principal é que o cloreto de cobre produz modelos de cristalização característicos e específicos para extratos de sementes de feijoeiro. Menos específicos são os efeitos de variedade c procedência, embora alguns caracteres possam ser assinalados. | Crystallization models of copper chloride obtained in the presence of bean seed extracts (P. vulgaris L.) are studied. The models obtained in 11 crystallization series, replicated 5 times, are described and compared. The sources of variation considered are as follows: 3 bean varieties (roxinho, pintado, preto), 2 origins (soils and nutrient solution), 2 extracting procedures (dry seeds and humid seeds) and 3 concentrations (0,05: 0,5; 0,025:0,5 and 0,025:0,75). The main conclusion is that copper chloride yields crystallization models that are specific and characteristic for bean seeds extract. The effects of variety and origin though less pronunced contribute to the appearance of some characters.