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Plants primarily absorb nutrients through their roots from the soil. However, there are specific circumstances where plants can also absorb nutrients through the stomata (small pores on leaves and stems) and the cuticle (outer waxy layer of leaves). While these pathways are not the primary route for nutrient uptake, they play a role in nutrient absorption under certain conditions.

1. Uptake through Stomata:

  • Foliar Fertilization: Nutrients can be absorbed through stomata when applied as foliar fertilizers (liquid fertilizers sprayed on leaves). This method is especially effective for micronutrients and some macronutrients.
  • Gaseous Nutrient Absorption: Plants can absorb certain gaseous nutrients, such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), through stomata. These gases can be converted into nutrient forms that the plant can utilize.

2. Uptake through Cuticle:

  • Hydrophilic Nutrients: Hydrophilic (water-soluble) nutrients can be absorbed through the cuticle, especially if the cuticle is thin, damaged, or has pores. This is more common in young leaves where the cuticle is not as developed.
  • Nutrient Movement with Water: Nutrients that dissolve in dew, rain, or irrigation water can penetrate the cuticle and reach the leaf cells.

Factors Affecting Nutrient Uptake through Stomata and Cuticle:

  • Molecular Size and Charge: Nutrients with smaller molecular sizes and appropriate charges are more likely to pass through the stomata and cuticle.
  • Concentration Gradient: Nutrient absorption through stomata and the cuticle is influenced by the concentration of the nutrient on both sides (inside and outside the leaf).
  • Plant Physiology and Health: The health and physiological state of the plant, including the condition of stomata and the cuticle, affect nutrient uptake through these pathways.
  • Leaf Age and Type: Younger leaves with thinner cuticles and more active stomata may facilitate greater nutrient absorption compared to mature leaves.
  • Environmental Conditions: Environmental factors like humidity, temperature, wind, and light intensity influence stomatal behavior and, consequently, nutrient uptake through stomata.
  • Nutrient Form and Solubility: Nutrient form and solubility in the applied solution or as part of foliar sprays affect their availability for absorption.

While nutrient uptake through stomata and the cuticle is not the primary mode of nutrient absorption, foliar fertilization can be an effective means to quickly supply specific nutrients to plants, especially micronutrients. It’s important to consider the factors affecting nutrient uptake and choose appropriate application methods based on the plant’s needs and environmental conditions.

Talk to your OMEX representative today to learn more about the use of foliars in order to correct deficiencies, promote growth and development, and enhance grain fill and health.