Community Research and Development Information Service - CORDIS


In order to study the macromolecular behaviour of humic substances, humic material was treated either with exudates from 10-day old seedlings obtained in axenic condition from three maize cultivars or with the organic acids present in the exudates and the change in molecular size distribution was followed. Results are evidence of the micellar behaviour of humic substances in solution and of the importance of hydrophobic bounds in holding humic molecules together.

Exudates were also used to separate soil organic fractions from the same soil. Soil organic extracts were characterized by low pressure gel permeation chromatography, hormone-like activities, and (1)H-nuclear magnetic resonance (NMR). The data indicate that maize exudates, fumaric and succinic acids mobilize soil organic fractions in small quantities, but these extracts are endowed with auxin-like and/or gibberellin-like activity Water extract and maize exudates exhibit no hormone-like activity, while KOH extract shows a negligible one. Only Polaris and Sandek exudates and succinic acid are able to disaggregate an organic fraction with low apparent molecular size from the bulk of the soil. Water and succinic extracts are largely composed of carbohydrate and aliphatic constituents, Sandek exudate and fumaric acid can liberate aromatic component, Polaris exudate releases carbohydrate from soil, while Paolo slightly influences the aliphatic constituents.

The role or organic acids releases by maize seedlings in mobilizing soil organic fractions is presented. ed.

Additional information

Authors: NARDI S, Università di Padova, Dipartimento di Biotecnologie Agrarie (IT);CONCHERI G, Università di Padova, Dipartimento di Biotecnologie Agrarie (IT);RENIERO F, JRC Ispra (IT)
Bibliographic Reference: Article: Chemosphere
Record Number: 199710792 / Last updated on: 1997-07-02
Original language: en
Available languages: en