Stomata are cellular structures that control the plant's hydric balance, macro and micronutrient absorption, and absorption of gases. The opening of stomata is controlled by external factors (light, humidity, temperature and salt concentration) and internal factors (amino acids concentration, abscisic acid, etc.). When the stomata are closed, they close when light and humidity are low, temperature and salt concentration are high, photosynthesis and transpiration are reduced (low absorption of macro and micronutrients) and respiration is increased (Carbohydrate breakdown). In this case, the metabolic balance of the plant is negative. Catabolism is higher than anabolism. This means slow metabolism and stops plant growth. L-glutamic acid acts as a cytoplasmic osmotic agent of "guard cells". Thus, it facilitated the opening of stomas.

Amino acids have a chelating effect on micronutrients. When applied with micronutrients,

It is easier to absorb and transport micronutrients in the plant. This effect depends on the chelation effect and the effect of cell membrane permeability. L – Glycine and L – Glutamic acid are known to be very effective chelating agents. Amino acids and phytohormones: Amino acids are precursors or activators of phytohormones and growth agents. L – Methionine, ethylene

and 5-Adenosyl Methionine is the precursor of growth factors such as Espermine and Espermidine. L – Tryptophan is the precursor of Auxin synthesis. L - Tryptophan is only used in plants in L - Form. L – Tryptophan can only be used if hydrolysis of the protein is carried out by the enzyme. If hydrolysis is carried out with acid or alkali, as in many European countries,

L – Tryptophan is destroyed. L – Arginine induces the synthesis of flower and fruit related hormones.