Propagation Environment

• Propagation is most successful when both the environment AND techniques can be optimized
• Propagation does not have to happen in a controlled environment
• microclimatic conditions: environmental factors such as relative humidity, temperature, light, gas, etc. in the immediate vicinity of the propagule during propagation
• edaphic factors: factors influenced by the soil or propagation medium
• biotic factors: interaction of propagules with other organisms such as bacteria, fungi, pathogens, insects, etc.
• environmental factors:

  • light
  • temperature
  • water/humidity
  • gases
  • nutrition
• light is critical for:

  • rooting of cuttings
  • germinating seeds
  • growth of seedlings
  • shoot multiplication of explants during tissue culture propagation
• light can be measured by:

  • quantity (irradiance)
  • duration (daylength or photoperiod)
  • quality (wavelength)
• Irradiance is the most accurate way to measure light
• Quantum sensor measures photosynthetic flux in units of µmol m-2 s-1
• Pyranometric sensor measures irradiance in units of watts per square meter
• irradiance: relative amount of light as measured by radiant energy per unit area
• daylength/photoperiodism: developmental responses of plants to the relative lengths of light and dark period
• Dark period is most critical to initiation of reproductive growth
• Photoperiod affects flowering, dormancy, and germination
• long day: flowers when the critical photoperiod of light is equal or exceeded
• short day: flower when the critical photoperiod is not exceeded
• day neutral: flowering is not triggered by photoperiod
• photodormancy: seeds remain in a dormant state and require either light or dark conditions to germinate
• Photoperiod can be extended by using incandescent lights or HID lights or LEDs
• Photoperiod can be shortened by covering stock plants and cuttings with black cloth or plastic