Seedling Growth and Responses to Exogenous Factors

• Exogenous factors

  External factors that control plant growth
• Endogenous factors


  Internal factors that control plant growth
• Plants would grow better if they were provided exogenously with the optimum environment- enough water, oxygen, the optimum temperature, and enough light
• The environment can shape plants morphologically
• Mungbean (Vigna radiata)


  • Used in the experiment
• Materials

  • Mungbean (Vigna radiata)
  • 9 pcs plastic cups
  • Plate
  • Cotton
  • Tissue paper
  • Spray bottle
• Effect of Light

  1. Soak the mung bean seed in warm water overnight or for about 6 hours

  2. Spread the partly germinated seed in a paper towel

  3. Label your cups treatment A (direct sunlight), treatment B (shaded area) and treatment C (dark)

  4. Put cotton in each cup, the cotton will serve as a substrate for the roots

  5. Place at most 10 seeds in each cup

  6. Place 3 sets of A cups in place directly exposed to the sunlight, another 3 sets of B cups in areas of the house with low light or areas inside your house with indirect light and lastly another 3 sets of cups C in complete darkness

  7. Water (spray) each cup daily

  8. Observe and describe growth of the seedlings in the 3 treatments for a week, record the data on the length coloration, and the number of leaves for each of the treatments

  9. Take a photo and measurements and make a table of observations

  10. For epinastic movement, describe the growth of the plan specimen based on the number of fully expanded leaves and the measurement of the angle of bending
• Effects of water

  1. Take 30 partially germinated mung beans to be placed 10 pieces in each of the 3 cups

  2. Place cotton on each cup to act as a substrate to the growing seedling

  3. Place the 3 cups in place with direct sunlight

  4. Water each cup using a sprayer. Cup A will be watered everyday while cup B every other day, and never water cup C

  5. Observe and describe growth of the seedlings in the 3 treatments for a week, record the data on the length, coloration, and the number of leaves for each of the treatments

  6. Take a photo and measurements and make a table of observations
• Effects of Stress

  1. Take 30 partially germinated mung beans to be placed 10 pieces in each of the 3 cups

  2. Place cotton on each cup to act as a substrate to the growing seedling

  3. Place the 3 cups in place with direct sunlight

  4. Subject cup B to stress by exposing it to a direct strong wind (you may use an electric fan) for 5 minutes twice a day, one in the morning and another in the afternoon

  5. Subject cup C to stress by exposing it also to a direct strong wind (you may use an electric fan) for 5 minutes once a day

  6. Observe and describe growth of the seedlings in the 3 treatments for a week, record the data on the length, coloration, and the number of leaves for each of the treatments

  7. Take a photo and measurements and make a table of observations
• Exogenous factors:

  • water
  • optimum temperature
  • enough light
  • oxygen
• Objective: to assess seedling growth and response to external factors such as light, water, and physical stress