Effect of humic substance in soil and plant system: A review

Abstract

Humic substances (HS) are the humified organic matter fraction in soils and play a key role in various soil and plant functions. HS influence the adaptation of plants to conditions of environmental stress by increasing the nutrient availability. They also have a direct effect on plant metabolic processes related to growth and development. The biochemical and molecular mechanisms underlying these events are only partially known. HS have been shown to contain auxin and an “auxin-like” activity of humic substances has been proposed, but support to this hypothesis is fragmentary. In this review article, giving an overview Effect of humic substance on soil and plant system, with special emphasis on their hormone activities.