Efeitos do alumínio, nitrato e amônio sobre a composição de metabólitos nitrogenados e de carboidratos em Stylosanthes guianensis e S. macrocephala

Abstract

Quando o N foi suprido pela fonte nítrica, a adição do Al à solução nutritiva causou o aparecimento de sintomas de toxidez apenas em S. guianensis. Já em S. macrocephala, nessas condições, ocorreram aumentos nos teores de N-total, N-insolúvel, N-solúvel, N-nítrico e N-aminoácidos na parte aérea e nas raízes, seguidos de decréscimos nos teores de açúcares solúveis totais e redutores nas raízes.Termos para indexação: toxidez de Al, toxidez de amônio. EFFECTS OF ALUMINUM, NITRATE AND AMMONIUM ON THE METABOLIC NITROGENED COMPOSITION AND OF CARBOIDRATES IN STYLOSANTHES GUIANENSIS AND S. MACROCEPHALAABSTRACT -The effects of aluminum, nitrate and ammonium interaction, in nutritive solution, on the concentration of nitrogened compound, and of sugar in Stylosanthes 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 ammonium only in the S. guianensis. The ammonium source increased the concentrations 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. guianensis and decreased in the root system of both species. The aluminum relieved partially the ammonium toxicity in the S. guianensis. When the nitrogen was supplied by the nitric source, the addition of the aluminum to the nutritive solution caused the appearance of symptoms of toxicity only in the S. guianensis. In the S. macrocephala, under the same conditions, an increase of total N, insoluble N, soluble N, nitric N and amino acid N in the aerial part and in the roots ocurred, followed by a decrease in the total soluble sugar concentration and sugar reductor in the roots.

Transcriptional modulation of genes encoding nitrate reductase in maize (Zea mays) grown under aluminum toxicity

“…Some studies have shown that high concentrations of aluminum in the soil stimulate NR activity, as observed in the leguminous forage crop Stylosanthes macrocephala (Amaral et al, 2000) and in beans (Wang et al, 2010). Other authors have revealed that there is no change in NR activity in response to aluminum toxicity in the aerial parts of young plants of sugar cane cultivar IAC91-5155 (Carlin et al, 2012).…”

Doses de cálcio no crescimento do feijoeiro cultivado em solução nutritiva, na presença de alumínio

“…Os níveis de Al utilizados neste trabalho (15 mg dm -3 ) foram considerados nocivos para as plantas, uma vez que para outras leguminosas, como exemplo, Stylosanthes guianensis, 9mg dm -3 em solução nutritiva, por doze dias de cultivo, causaram toxidez nas plantas (Amaral et al, 2000). Nolla et al (2007) observaram que o alumínio reduz consideravelmente o crescimento radicular das plântulas de leguminosas além de aumentar a espessura das raízes, inibindo a expansão das células da raiz, culminando no seu engrossamento.…”

Effect of aluminium toxicity on the accumulation and distribution of K+, Na+, Cl- and NO3 - in Oryza sativa L. and Cicer arietinum L.

“…Aluminium reduced NO3 uptake in soybean (8)(9) and in wheat (10) . On the other hand, Al increased absorption of nitrate in Stylosanthes guianensis and S. macrocephala (11)(12) .…”