EC is crucial in plant cultivation as it measures the electrical charge that moves through a solution, which is directly related to the concentration of dissolved ions (salts) in the solution or substrate. An optimal EC level is essential for plant growth, and deviations from this optimal level can lead to growth problems and tissue damage.
Plant Internal EC Value
- Internal EC Value: Refers to the concentration of salts within the plant body, which are the nutrients absorbed from the soil or hydroponic nutrient solution.
- Osmotic Pressure: The internal EC value of a plant is related to osmotic pressure, which is the pressure resulting from the difference in salt concentration inside and outside the plant cells, affecting the plant’s water absorption
Relationship Between Plant Growth and Internal EC Value
- Early Growth Stage: During the early stages of plant growth, it is necessary to establish a lower internal EC value to promote rapid growth and nutrient absorption.
- Nutrient Absorption: As the plant grows, it absorbs more nutrient salts, leading to an increase in the internal EC value. This helps the plant maintain its osmotic pressure, thereby more effectively absorbing and retaining water.
- Mature Growth Stage: In the later stages of plant growth, the demand for nutrients decreases, and the outer EC value should be reduced to decrease nutrient supply and prevent issues related to over-fertilization.
Impact of Internal EC Value on Plant Health
- Water Management: An increase in the internal EC value of the plant can make it more difficult for the plant to absorb water from the substrate due to the increased osmotic pressure difference between the plant cells and the surrounding environment. This can lead to a “physiological drought” state where the plant is unable to extract enough water from the substrate despite it being moist.
- Light and Temperature: When the internal EC value is too high, making water absorption insufficient, the plant may not be able to withstand intense light and high temperatures because they cannot effectively cool down through transpiration.
Strategies for Managing Internal EC Value
- Nutrient Supply: Growers should adjust the EC value of the nutrient solution according to the growth stage and needs of the plant. Use a lower EC value to promote growth in the early stages; reduce the EC value in the mature stage to decrease nutrient supply.
- Balance of Water and Nutrition: By monitoring and adjusting the EC value in the substrate, growers can ensure that plants receive the appropriate amount of water and nutrients while avoiding osmotic pressure issues related to over-fertilization.
- Environmental Control: When the internal EC value of the plant is high, it may be necessary to adjust light intensity and duration, as well as control environmental temperature, to prevent the plant from wilting due to insufficient water.
High Substrate EC Correction:
Reducing Fertilizer Rate: If the EC levels are increasing over time, it indicates that fertilizer salts are accumulating in the pot at a rate higher than the plant’s demand. The first step is to reduce the fertilizer rate to moderate the accumulation of these salts. This not only helps in correcting the EC levels but also saves on fertilizer costs by preventing wastage.
Irrigating with Clear Water: A second option, particularly useful when EC levels are extremely high, is to irrigate the substrate twice with clear water to leach out the accumulated fertilizer salts. This method helps to avoid plant burn but also flushes away the fertilizer investment. Regular monitoring during production can help prevent such elevated EC levels in the first place, saving both time and resources.
Low Substrate EC Correction:
- Increasing Fertilizer Rate: If EC levels are lower than the recommended range, it implies that the plant’s nutrient demand is higher than the supply. In this case, the fertilizer rate should be increased. Applying one or two treatments with a higher nitrogen (N) rate in the range of 250 to 400 ppm can help boost the EC levels to the desired range.
In summary, the internal EC value of plants is a key factor affecting their water absorption, nutrient management, and overall health. By carefully monitoring and adjusting the EC value, growers can optimize the growth conditions of plants and improve the yield and quality of their crops.
