Benefits of using L.M.W. Carboxylic Acids in foliar fertilization

Primitive plants such as algae had no roots to absorb water; the organs responsible for the nutrient absorption were the leaves, a feature that has not been lost over time.

Foliar feeding is a fertilizer application method widely used throughout the world, and an important tool for crop management.

Used correctly it is more respectful with the environment and more efficient than traditional fertilization via soil or edaphic because the nutrients are applied directly on the tissues (localized use) and in specific periods (timely use) of maximum demand of the crop.

The absorption of nutritive solutions by the surface of the plant can occur through:

• Via cuticle.
• Along cuticular cracks or imperfections.
• Through modified epidermal structures such as stomata, trichomes or lenticels

Factors affecting the efficacy of foliar fertilizers

Parameters of the vegetable surface:

• The contact angle of the drop with the surface of the leaf (α).
• The adhesion work of the drop to the surface of the leaf: hydrophobic or hydrophilic surfaces.
• The degree of surface wetting: the water is repelled or adhered to the leave depending on the surface roughness.

Physiological parameters of the plant:

• Plant species and variety: different composition and structure of the leaves determine the repellency-adherence to plant surfaces.
• Plant architecture: canopy size and leaves distribution.
• Leaf type and age: absorption decreases with age, although the decrease of its hydrophobic character, can help the absorption of polar nutrients.
• Leaf structure: the distribution and quantity of stomata, presence of trichomes, hairs, thickness, and composition of the cuticle.
• State and metabolic activity: nutritional and water levels of the plant are very important; for example, water stress reduces absorption (especially of boron and phosphorus). 

Physico-chemical parameters affecting absorption:

• Solubility: the more soluble and stable are the molecules are, the more assimilable are.
• Molecular weight: low molecular weight promotes absorption.
• Electric charge (absence): The positive charges are rejected by the cuticle, and the negative ones are repelled by the cytoplasm.
• Concentration: high concentrations decrease absorption.
• pH (neutral): favors the absorption, although it affects the stability of the element.
• Speed of drying: there are solutions that are dried quickly, for example, phosphorus.
• Adjuvants (tensoactives or surfactants): They reduce the surface tension and the contact angle.
• Moisturizers - Point of deliquescence: decrease the relative humidity at which the salts become liquid - drying time.

Environmental parameters:

• Relative humidity: high RH% increases the drying time and the permeability of the cuticle.
• Temperature: affects the rate of evaporation of the drop.
• Light intensity: the more intense is the light, the widest is the leaf structure, and the greater is the quantity of waxes; consequently there is less absorption by diffusion. However, some aspects related to active absorption can be increased because it promotes the stomatal opening.
• Wind: shorter drying time of the solution makes more difficult the application and the use of treatments.

When is foliar fertilization advisable?

When soil or water conditions limit the use of applications via soil (cold soil, senescence, etc.)

• When there are large nutrient loss ratios.
• When the conditions of the crop require it: excessive load, peaks of demand, physiopathies, competition between roots and shoots, etc.
• With limitations in the transport of immobile elements in the phloem or organs with inadequate vascular connectivity or with low transpiration.
• Preventively in high-value crops.
• During flowering and fructification in deciduous species with increases in the demand for elements that participate in critical functions, for example, boron or copper for the development and production of pollen.
• It has been proved that they increase the quality of the crops.

Benefits of using L.M.W. Carboxylic Acids in foliar fertilization.

• They are not photosensitive: they do not decompose with sunlight.
• Neutralization of positive and negative electric charges.
• High power of complexation of the nutrient.
• Defined composition.
• Easy absorption due to its low molecular weight.
  • Succinic acid: 118 g/mol
  • Gluconic acid: 196 g/mol
• They are intermediaries in the synthesis of certain compounds of the plant.
• Improve the internal transport of nutrients in the phloem.
• They are harmless with plant tissues
• They regulate the opening and closing of stomata.
• Improve the translocation of nutrients to the fruit during critical phenological stages.