title: The physico-chemical properties and biostimulative activities of humic substances regenerated from lignite.
abstract: The positive effect of humic acids on the growth of plant roots is well known, however, the mechanisms and role of their physical structure in these processes have not been fully explained yet. In this work, South-Moravian lignite was oxidized by means of nitric acid and hydrogen peroxide to produce a set of regenerated humic acids. The elemental composition, solid state stability and solution characteristics were determined and correlated in vitro with their biological activity. A modified hydroponic method was applied to determine the effects of their potassium salts on Zea mays seedlings roots with respect to the plant weight, root length, root division, and starch and protein content. The relations between the determined parameters were evaluated through Principal Component Analysis and Pearson's correlation coefficients. The results indicated that the most important factor determining the biological activity of South-Moravian lignite potassium humates is related to the nature of self-assemblies, while the chemical composition had no direct connection with the root growth of Zea mays seedlings. It was demonstrated a controlled processing that provided humic substances with different chemical and physicochemical properties and variable biological activity.
authors.affiliation: Institute of Environmental Sciences, Soil and Environmental Chemistry, University of Koblenz-Landau, Fortstrasse 7, D-76829 Landau, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: David
authors.affiliation: Contipro Pharma, Dolní Dobrouč 401, CZ-561 02 Dolní Dobrouč, Czech Republic.
authors.forename: Daniela
authors.initials: D
authors.lastname: Smejkalová
authors.affiliation: Faculty of Mathematics and Physics, Department of Probability and Mathematical Statistics, Charles University in Prague, Sokolovská 83, CZ-186 75 Prague 8, Czech Republic.
authors.forename: Sárka
authors.initials: S
authors.lastname: Hudecová
authors.affiliation: Institute of Environmental Sciences, Soil and Environmental Chemistry, University of Koblenz-Landau, Fortstrasse 7, D-76829 Landau, Germany.
authors.forename: Oldřich
authors.initials: O
authors.lastname: Zmeškal
authors.affiliation: College of Science, Department of Chemistry, University of Idaho, 804 South Rayburn Street, Renfrew Hall Rm 116, PO Box 442343, Moscow, 83844-2343 ID USA.
authors.forename: Ray
authors.initials: R
authors.lastname: von Wandruszka
authors.affiliation: Faculty of Agronomy, Department of Food Technology, Mendel University in Brno, Zemědělská 1, CZ-613 00 Brno, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Gregor
authors.affiliation: Institute of Environmental Sciences, Soil and Environmental Chemistry, University of Koblenz-Landau, Fortstrasse 7, D-76829 Landau, Germany.
authors.forename: Jiří
authors.initials: J
authors.lastname: Kučerík
keywords: Biological activity; Chromatography; Lignite humic substances; Modification; Spectroscopy; Thermal analysis