Jat. Do Amaral et al., Effects of aluminum, nitrate and ammonium on the metabolic nitrogened composition and of carboidrates in Stylosanthes guianensis and S-macrocephala, PESQ AGROP, 35(2), 2000, pp. 313-320
The effects of aluminum, nitrate and ammonium interaction, in nutritive sol
ution, on the concentration of nitrogened compound, and of sugar in Stylosa
nthes guianensis and S. macrocephala, sensitive and tolerant, respectively,
both to aluminum and to ammonium were studied under controlled conditions.
The ammonium nutrition caused the appearance of toxicity symptoms of ammon
ium only in the S. guianensis. The ammonium source increased the concentrat
ions of N-soluble, N-ammonium and N-amino acid mainly in the aerial part of
the S. guianensis and in the root system of the S. macrocephala, while the
total soluble sugar concentration increased in the aerial part of the S. g
uianensis and decreased in the root system of both species. The aluminum re
lieved partially the ammonium toxicity in the S. guianensis. When the nitro
gen was supplied by the nitric source, the addition of the aluminum to the
nutritive solution caused the appearance of symptoms of toxicity only in th
e S. guianensis. In the S. macrocephala, under the same conditions, an incr
ease of total N, insoluble N, soluble N, nitric N and amino acid N in the a
erial part and in the roots occurred, followed by a decrease in the total s
oluble sugar concentration and sugar reductor in the roots.