Cannabis breeding for stable lines and new varieties. Crossing, selection and stabilisation over several generations.
Cannabis breeding enables the development of unique strains with desired characteristics:
Breeding basics:
Mendelian inheritance:
- Dominant and recessive traits
- F1, F2, F3 generations
- Understanding genetic splitting
- Phenotype vs. genotype
- Predictable inheritance patterns
Cannabis-specific genetics:
- Dioecious plant (male/female)
- X/Y chromosome system
- Complex trait inheritance
- Polygenic traits
- Environmental gene interactions
Basic breeding concepts:
P1 generation (parents):
- Select original breeding animals
- Complementary traits
- Favour known genetics
- Health and vitality
- Documented origin
F1 generation (first cross):
- Hybrid vigour possible
- Uniform but not stable
- Best characteristics of both parents
- High variation in F2
- Commercial production
F2 generation (F1 x F1):
- High genetic splitting
- Selection possibilities
- Isolate desired traits
- Large populations necessary
- Basis for stabilisation
Selection criteria:
Morphological traits:
- Growth habit and structure
- Leaf shape and colour
- Internode spacing
- Branching pattern
- Overall appearance
Flowering characteristics:
- Flowering time and duration
- Bud structure and density
- Resin production
- Calyx-to-leaf ratio
- Finishing characteristics
Chemical profiles:
- THC/CBD ratios
- Terpene profiles
- Total potency
- Cannabinoid diversity
- Stability of the profiles
Cultivation properties:
- Disease resistance
- Stress tolerance
- Nutrient efficiency
- Yield per unit time
- Processing properties
Pollen collection and storage:
Male plant identification:
- Early sex determination
- Pollen sac development
- Isolation before opening
- Timing critical
- Ensure purity
Pollen harvest:
- Collect mature pollen bags
- Drying at room temperature
- Sieving for purity
- Clean working method
- Avoid contamination
Pollen storage:
- Dry, cool conditions
- Airtight containers
- Freezer storage possible
- Rice/silica for dryness
- Labelling with date
**Controlled pollination
Isolation techniques:
- Separate rooms/tents
- Temporal separation
- Plastic bags over branches
- Precise control
- Avoid cross-contamination
Pollination methods:
- Brush for precise application
- Pollen-water suspension
- Direct pollen application
- Multiple applications
- Documentation important
Timing of pollination:
- 2-3 weeks in flower
- Fresh, receptive pistils
- Several pollination dates
- Weather-dependent outdoor
- Wait for optimal conditions
Seed development:
Maturation process:
- 4-6 weeks after pollination
- Calyx swells
- Seed colour develops
- Check hardness and ripeness
- Patience for complete ripening
Seed harvest:
- Fully ripe seeds
- Dark and hard
- Clean extraction
- Drying before storage
- Quality grading
Population management:
Large population sizes: