Publication Date:
1988-08-01
Description:
The effects of humus on plant metabolism are conditioned by the release of the hormone-like activities contained in HEf bound to HSp. HEf and HSp are both humic fractions that can be separated from each other by acidification with acetic acid or other organic acids. HEf is composed of small molecules and shows hormone-like activities; HSp possesses higher molecular weight and works as a support for HEf. The molecular sizes of the separated HEf and HSp are both low enough to permit root absorption. The dispersion and solubilization of humic molecules are essential to the release of cytokinin-like activity from HSp, but are only preliminary to the release of auxin- and gibberellin-like activities. These can be released by a partial acidification of the humic extracts that do not result in complete depolycondensation. The process appears to regulate the delivery of the hormone-like substances and is influenced by their particular arrangement in the humic aggregate. Key words: Humus fractions, biological effect, nitrate uptake, hormone-like activity
Print ISSN:
0008-4271
Electronic ISSN:
1918-1841
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
