ITS: insulin, transferrin and selenous
acid, bovine serum albumin, linoleic acid.
5 mM glucose, 10% fetal bovine serum, 100 U/mL penicillin-streptomycin, 2 mM L-glutamate, 25 mM HEPES, and ITS Premix (5 mg insulin, 5 mg transferrin, and 5 [micro]g selenous
acid, and 3 mL of 30% hydrogen peroxide and heated samples 1 h at 400[degrees]C with a block digestor (model 2040, Tecator, Herndon, VA).
The remaining dried soil was kept for analyses of total nitrogen (N) with the indophenol method and phosphorus (P) with the molybdenum blue method, after digesting 250 mg of soil in a sulfuric acid and selenous
acid mixture for 1 h (Kedrowski 1983).
A 100 mg subsample of the plant material was digested in a mixture of sulphuric and selenous
acid (Kedrowski 1983) and analyzed for nitrogen (N) by the salicylate method, for phosphorus (P) by the molybdate method, and for potassium (K), magnesium (Mg) and calcium (Ca) by atomic absorption spectrophotometry.