Propagation/Greenhouse Management
6 | Unit 1.3
Instructor’s Lecture 1 Outline
ii. Chemical dormancy: Internal chemical/metabolic conditions that prevent seed
germination until appropriate environmental conditions have been met through
leaching, cold/moist stratification, fire scarification, depending on species needs
- Environmental factors involved in germination
a) Temperature
b) Moisture
c) Aeration
d) Light
- Physiological steps in germination
a) Phase I: Imbibation
b) Phase II: Interim or lag phase
c) Phase III: Root radical emergence
- Early seedling development
a) Continued division-extension of root radical
b) Emergence of plumule or growing point of the shoot
c) Seedling weight increases, storage tissue weight decreases
d) Respiration and water uptake increase
e) Development of branched root system
f) Development of true leaves
D. Management of Environmental Conditions During Germination, Development,
and Seedling Maturation
- Use of propagation structures/infrastructure to optimize environmental conditions
during germination
a) Temperatures
b) Air circulation
c) Moisture delivery
- Continued management of environmental conditions for seedling development
a) Temperature management remains critical
b) Maintenance of good air circulation continues
c) Moisture delivery
d) Availability of light for photosynthesis
- Seedling maturation, or hardening off through exposure to outdoor growing conditions
a) Day/night temperature fluctuation
b) No buffering from natural air circulation or prevailing wind patterns
c) Moisture delivery: Decrease in frequency but increase in depth/volume
d) Exposure to sunlight conditions comparable to field conditions