Investigating organic molecules responsible of auxin-like activity of humic acid fraction extracted from vermicompost.
This work studied the auxin-like activity of humic acids (HA) obtained from vermicomposts produced using leather wastes plus cattle dung at different maturation stages (fresh, stable and mature). Bioassays were performed by testing HA concentrations in the range of 100-6000mgcarbonL(-1). (13)C CPMAS-NMR and GC-MS instrumental methods were used to assess the effect of biological processes and starting organic mixtures on HA composition. Not all HAs showed IAA-like activity and in general, IAA-like activity increased with the length of the vermicomposting process. The presence of leather wastes was not necessary to produce the auxin-like activity of HA, since HA extracted from a mix of cattle manure and sawdust, where no leather waste was added, showed IAA-like activity as well. CPMAS (13)CNMR revealed that HAs were similar independently of the mix used and that the humification process involved the increasing concentration of pre-existing alkali soluble fractions in the biomass. GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids and amino acids. The concentration of active molecules, rather than their simple presence in HA, determined the bio-stimulating effect, and a good linear regression between auxin-like activity and active stimulating molecules concentration was found (R(2)=-0.85; p<0.01, n=6).
Gruppo Ricicla Labs - DiSAA, Università degli Studi di Milano, Via Celoria 2, Italy. Electronic address: barbara.scaglia@unimi.it.
Barbara
B
Scaglia
Laboratório de Química Ambiental, Universidade de São Paulo, Instituto de Química de São Carlos, Avenida Trabalhador São Carlense, 400, São Carlos, Brazil.
Ramom Rachide
RR
Nunes
Laboratório de Química Ambiental, Universidade de São Paulo, Instituto de Química de São Carlos, Avenida Trabalhador São Carlense, 400, São Carlos, Brazil.
Maria Olímpia Oliveira
MOO
Rezende
Gruppo Ricicla Labs - DiSAA, Università degli Studi di Milano, Via Celoria 2, Italy.
Fulvia
F
Tambone
Gruppo Ricicla Labs - DiSAA, Università degli Studi di Milano, Via Celoria 2, Italy. Electronic address: fabrizio.adani@unimi.it.
Fabrizio
F
Adani
D000818:Animals; D018533:Biomass; D000076282:Composting; D006812:Humic Substances / Q000032:analysis*; D007210:Indoleacetic Acids; D008372:Manure / Q000032:analysis*; D009835:Oligochaeta
D006812:Humic Substances; D007210:Indoleacetic Acids; D008372:Manure
Auxin-like property; Humic acid; Organic compounds; Tannery effluent; Vermicomposting