Plant Transpiration Lab Notes

Objective

• Evaluate the effect of different conditions on the transpiration rate of plants.
• Use Impatiens (or any available plant) for experimentation.

Materials

• Plants (e.g., Impatiens)
• Plastic bags
• Ties
• Labels/tags
• Balance (for measuring mass)
• Spray bottle (for misting)
• Fan and light source
• Large bags (for humid environment simulation)

Procedure

Initial Setup

1. Preparation of Plants

   • Remove plants from containers and take out root balls.
   • Recently watered plants are preferable.
   • Place each root ball into a plastic bag.
   • Tie the bag around the root ball at the plant base to ensure water loss is only through transpiration.
   • Label each plant with its initial mass.

2. Initial Mass Recording

   • Record initial mass for each plant:
     • Plant 1: 96.61 grams
     • Plant 2: 92.36 grams
     • Plant 3: 74.49 grams
     • Plant 4: 89.40 grams

3. Condition Placement

   • Control: Room conditions
   • Light: Place under a light source
   • Fan: Place in area with a fan (e.g., a fume hood with fan)
   • Mist: Create humid environment using a large bag and misting inside it

Observation Periods

• 1st Observation (After 2 days)

  • Measure and record mass after plants have stayed in respective conditions:
    • Light: 85.55 grams
    • Fan: 83.26 grams
    • Room (Control): 72.16 grams
    • Mist: 96.97 grams (note potential water absorption due to bag moisture)

• 2nd Observation (Next class period)

  • Measure and record mass:
    • Light: 62.22 grams
    • Fan: 64.16 grams
    • Room (Control): 67.27 grams
    • Mist: 96.93 grams (similar observation about moisture)

Analysis

• Identify which condition caused the greatest change in mass, indicating higher transpiration.
• Class average data will be collected and graphed for a comprehensive analysis.
• Compare changes to the control plant's data.

Conclusion and Follow-up

• Determine the environmental factor that has the greatest effect on plant transpiration.
• Analyze class data and discuss findings in comparison to control conditions.