BLOG #48

TYPE OF BIOSTIMULANTS

FOCUS ON: HUMIC SUBSTANCES

Humic substances, together with organic residues, are organic matter essential components.
Humic substances are a mixture of complex organic compounds formed by transformation (humification) of organic residues of plants, animal-by substances and soil micro-organisms. They represent the most stable component of the organic substance and tend to associate in complex structures stable and resistant to degradation.

Facts and figures:
Organic matter is essential because soil fertility, considered as the attitude to support crop growth and productivity over time, totally depends on it.

Humic-substances

HUMIC SUBSTANCES

Humic Acids

  • Not soluble in water under acidic conditions (pH < 2)
    They are not absorbed, they remain fixed on the external walls of the cells.

Humins

  • Not soluble in water at any pH value
    Most inert component.

Fulvic Acids

Soluble under all pH conditions
More hydrophilic fraction and of higher acidity. Responsible for chelation and mobilization of metal ions. They can permeate the plasma membrane and be assimilated by plants.

For a more sustainable production system: Synthetic humic compounds
-> like ligno – humates, with a high biological activity

HOW DO THEY WORK ON PLANTS?

HUMIC SUBSTANCES*:
Able to influence plant growth and development and to improve yield in two ways

Plant-growth

1) INDIRECT WAY

Modification of the chemical-physical and biological characteristics of the SOIL


They influence:
– Soil structure (a good soil structure counteracts erosion, promotes root penetration and the development of microorganisms)
– Bulk density
– Water retention capacity
– Soil capacity to resist pH variations (buering capacity – help maintain optimal pH values)

2) DIRECT WAY

Action on METABOLISM and VEGETAL NUTRITION

↓
HORMON-LIKE ACTION

↓
ROOT LEVEL

root-level

Increase in size and complexity of the root system.
Better macro and micronutrients intake:
– Increase in carbon and nitrogen metabolism
– Increase in photosynthetic efficiency
– Increase in carbohydrates metabolism

↓
TOLERANCE TO ENVIRONMENTAL STRESS LEVEL

Enhancement of plant protection against stress:
– Activation of secondary metabolism: synthesis of phenotic compounds
– Activation of the gene linked to the stress response
– Activation of oxidative stress enzymes

*The knowledge of their chemical structures is incomplete due to their heterogeneity and variety of reactions

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