The effect of botanical composition of vegetation cover and peat-forming species on the concentration of indole-3-acetic acid and chemical compounds in peat

Abstract

Indole-3-acetic acid (IAA) is one of the most important auxin/phytohormones for plant growth. The effect of peat botanical composition of various vegetation cover and peat-forming species at 13 sampling points located in fens, bogs and drained peatlands on the content of IAA, hot water extractable organic carbon (CHWE), total organic carbon (TOC), total nitrogen (TN) and C/N quotient was assessed. The objective of this study was to analyse comparatively the quantities of IAA, TOC, CHWE, TN and C/N in peats of varying genesis with respect to the peculiarities of their origin due to the botanical composition of vegetation cover and peat-forming species. A high content of IAA, CHWE and TN was found in the top layers of the peatlands, indicating the formation of IAA mainly by the roots of peat-forming species and rhizosphere bacteria, because of the rich supplies of chemical and biochemical compounds exuded from the roots. Drainage of the peatlands did not have a significant effect on the amounts of IAA and TOC, but contributed to the release of large amounts of CHWE (mainly representative of labile carbon). High TOC contents and C/N quotients in deeper layers of the peat deposits indicated a decline in the rate of soil organic matter (SOM) mineralisation and accumulation of the recalcitrant fraction. Varying C/N quotients of peat-forming species may reflect the initial botanical composition of the vegetation cover or peat-forming species, or differences in the degree of decomposition and/or TN content of the peats.

Keywords

• bog peat
• hot water extractable organic carbon
• iaa
• total nitrogen
• total organic carbon