Minor effects of nitrogen availability on organic-acid exudation from roots of young Picea abies plants

Geringe Effekte der Stickstoffverfügbarkeit auf die Exsudation organischer Säuren aus Wurzeln junger Fichten (Picea abies)

Weinheim

2005

1 Abb., 9 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

4181

200124736

Microorganisms use root exudates as an easily degradable carbon substrate, leading to enhaced microbial activity and mineralization int he rhizosphere. In tree species, organic acids and amino acids are the quantitatively most important components of these exudates, but the amount and composition are dependent on, e.g., plant age and availability of mineral nutrients (Grayston et al., 1996). Nitrogen is the main growth-limiting mineral element in boreal forests. This element also stimulates the microbial decomposition of organic matter, and a low C : N ratio may increase its decompostion rate (Alexander, 1977). It is thus possible that a change in N availability can lead to changes in root-exudate composition and, on a longer term, affect rhizosphere processes and microbial decomposition. In the present experiment, we tested to which extent root exudates from young Norway spruce, collected by micro-suction cups, differed in organic-acid and amino composition in response to changes in N fertilization.