Introduction
It has long been recognized that humic substances (HS) have many beneficial effects on soil and plant growth.
These heterogeneous and complex molecules, ubiquitous in the environment, can produce various morphological,physiological and biochemical effects on higher plants.
The influence of humic material on plant growth, have been investigated on biometric factors and numerous studies have shown that humic substances enhance root, leaf and shoot growth but also stimulate the germination of various crop species.
These positive effects are explained by the direct interaction of HS with physiological and metabolism processes.
The addition of HS increase nutrient uptake, cell permeability and modify mechanisms involved in plant growth stimulation.