Data/hora: 10/06/2024 08:39:01

Biblioteca(s): | Embrapa Agrobiologia.
Data corrente: | 05/06/2000
Data da última atualização: | 05/06/2000
Autoria: | JONES, D. L.
Título: | Amino acid biodegradation and its potential effects on organic nitrogen capture by plants.
Ano de publicação: | 1999
Fonte/Imprenta: | Soil Biology and Biochemistry, Oxford, v. 31, p. 613-622, 1999.
Idioma: | Inglês
Conteúdo: | It has been reported that plant roots can directly utilise soil organic-N in the form of amino acids without prior mineralisation by the soil's microbial biomass. To critically assess this, however, requires a knowledge of microbial amino acid-N turnover times in soil. The effects of soil type, depth and temperature on the uptake and partitioning of a mixture of 15 14C-labelled amino acids by the soil's microbial biomass was therefore studied in 10 contrasting soil types. The results indicated that the degradation of amino acids was soil dependent but that the mean half-life in topsoils at 18 graus centigrafos was 1.7 mais ou menos 0.6 h, whilst in subsoils the mean half-life was 12.2 mais ou menos 3.3 h. On average 34% of the amino acid-C was respired as CO2 whilst 66% was utilised for new cell biomass. Amino acid decomposition increased with soil temperature, however, rapid rates of amino acid uptake and assimilation were also observed at 5 graus centigrafos (mean half-life in topsoil = 2.9 mais ou menos 1.5h). Little correlation was observed between amino acid half-life and either microbial yield, soil arginase activity or organic matter content (r2 menor 0.40), however, decomposition did appear to be weakly related with soil respiration. The high concentration of amino acids used here (5 mM) was intended to simulate amino acid release after root cell lysis. For previously reported lower concentrations in the bulk soil solution, half lives can be predicted to be even less based on microbial amino acid transport kinetics. The significance of this previously overlooked microbial decomposition of amino acids in the utilisation of organic N by plants is discussed.
Palavras-Chave: | Biomassa microbiana; Decomposition.
Thesagro: | Aminoácido; Biodegradação; Decomposição; Matéria Orgânica; Solo; Temperatura.
Thesaurus Nal: | amino acids; biodegradation; degradation; microbial biomass; organic matter; soil; temperature.
Categoria do assunto: | --
Registro original: | Embrapa Agrobiologia (CNPAB)
Exemplares: | CNPAB - (24550-1) - ADD - SP - -- -  -  - 22363 - DIS