Cannabis Trait Dominance Charts
Contents
- Understanding Trait Dominance
- Morphological Traits
- Chemotype Traits
- Physiological Traits
- Breeding Implications
Understanding Trait Dominance
Trait dominance refers to how alleles (alternative forms of a gene) interact to produce observable characteristics. In cannabis breeding, understanding dominance patterns helps predict offspring phenotypes and design effective breeding strategies.
Key Terms
- Dominant (D): An allele that fully expresses its trait when present, even in a single copy
- Recessive (r): An allele that only expresses its trait when two copies are present
- Incomplete Dominance (I): When heterozygotes show an intermediate phenotype between the two homozygotes
- Codominance (C): When both alleles in a heterozygote are fully expressed simultaneously
- Polygenic (P): Traits controlled by multiple genes
Note: Many cannabis traits show complex inheritance patterns, often with incomplete dominance or polygenic control. This reference provides general patterns observed, but specific crosses may show variations.
Morphological Traits
Physical characteristics that affect plant structure and appearance.
Cannabis Morphological Trait Dominance
| Trait | Dominant Expression | Recessive Expression | Inheritance Pattern | Notes |
|---|---|---|---|---|
| Plant Height | Tall | Short | Incomplete (I) | Polygenic with environmental influences |
| Leaf Width | Broad leaflets | Narrow leaflets | Incomplete (I) | Classic indica vs. sativa leaf structure |
| Internode Length | Long | Short | Incomplete (I) | Affects overall plant structure |
| Branching Pattern | High branching | Low branching | Incomplete (I) | Bushier plants tend to have dominant expression |
| Stem Color | Purple/Red | Green | Dominant (D) | Temperature-dependent expression |
| Leaf Serration | Deeply serrated | Shallow serration | Incomplete (I) | Multiple genes involved |
| Trichome Density | High density | Low density | Polygenic (P) | Complex trait affected by multiple genes |
| Bud Structure | Dense | Loose/Airy | Incomplete (I) | Influenced by environmental factors |
| Leaf Variegation | Variegated | Solid color | Recessive (r) | Rare in cannabis |
| Webbed Leaves | Non-webbed | Webbed | Dominant (D) | Webbed leaf mutations are recessive |
Chemotype Traits
Chemical characteristics affecting cannabinoid and terpene profiles.
Cannabis Chemotype Trait Dominance
| Trait | Dominant Expression | Recessive Expression | Inheritance Pattern | Notes |
|---|---|---|---|---|
| CBD:THC Ratio | CBD-dominant | THC-dominant | Codominant (C) | Determined by BD and BT alleles at a single locus |
| THCV Production | High THCV | Low/No THCV | Incomplete (I) | Present in specific landraces (African) |
| CBG Accumulation | Low CBG | High CBG | Recessive (r) | Requires mutation in cannabinoid synthase genes |
| Myrcene Content | High myrcene | Low myrcene | Incomplete (I) | Common in indica-dominant varieties |
| Limonene Content | High limonene | Low limonene | Polygenic (P) | Complex terpene inheritance |
| Pinene Content | High pinene | Low pinene | Incomplete (I) | Common in sativa-leaning varieties |
| Caryophyllene Content | High caryophyllene | Low caryophyllene | Polygenic (P) | Multiple genes involved |
| Linalool Content | High linalool | Low linalool | Incomplete (I) | Environmental factors affect expression |
| Terpinolene Content | High terpinolene | Low terpinolene | Recessive (r) | Less common terpene expression |
CBD:THC Inheritance Model
CBD:THC Inheritance Patterns
| Genotype | Chemotype | Typical Cannabinoid Ratio |
|---|---|---|
| BT/BT | Type I (THC-dominant) | THC:CBD = 20:1 or higher |
| BT/BD | Type II (Mixed ratio) | THC:CBD = approximately 1:1 to 4:1 |
| BD/BD | Type III (CBD-dominant) | CBD:THC = 20:1 or higher |
| B0/B0 | Type IV (CBG-dominant) | CBG high, minimal THC/CBD |
Physiological Traits
Traits related to plant development, metabolism, and environmental responses.
Cannabis Physiological Trait Dominance
| Trait | Dominant Expression | Recessive Expression | Inheritance Pattern | Notes |
|---|---|---|---|---|
| Flowering Response | Photoperiod-dependent | Autoflowering | Dominant (D) | Autoflowering is recessive, controlled by mutation in the ALF gene |
| Flowering Time | Long flowering | Short flowering | Polygenic (P) | Multiple genes affect flowering duration |
| Cold Tolerance | High tolerance | Low tolerance | Incomplete (I) | Multiple genes with additive effects |
| Drought Tolerance | High tolerance | Low tolerance | Polygenic (P) | Complex trait with multiple mechanisms |
| Mold Resistance | Resistant | Susceptible | Incomplete (I) | Multiple resistance mechanisms |
| PM Resistance | Resistant | Susceptible | Polygenic (P) | Powdery mildew resistance is complex |
| Hermaphroditism | Monoecious tendency | Stable sex expression | Recessive (r) | Environmental factors significantly influence expression |
| Root Development | Vigorous | Limited | Incomplete (I) | Important for nutrient uptake efficiency |
Autoflowering Inheritance
The autoflowering trait follows simple Mendelian inheritance with the autoflowering allele (a) being recessive to the photoperiod allele (A).
Autoflowering Inheritance Patterns
| Cross | F1 Genotype | F1 Phenotype | F2 Ratio |
|---|---|---|---|
| Photoperiod (AA) × Autoflower (aa) | 100% Aa | 100% Photoperiod | 3:1 (Photoperiod:Autoflower) |
| F1 (Aa) × F1 (Aa) | 25% AA, 50% Aa, 25% aa | 75% Photoperiod, 25% Autoflower | 3:1 (Photoperiod:Autoflower) |
| F1 (Aa) × Autoflower (aa) | 50% Aa, 50% aa | 50% Photoperiod, 50% Autoflower | 1:1 (Photoperiod:Autoflower) |
Breeding Implications
Practical applications of trait dominance in cannabis breeding programs.
Strategic Breeding Approaches
- For recessive traits: Develop homozygous parent lines and expect expression in F2 or backcross generations
- For dominant traits: Can be selected directly in F1 populations
- For complex traits: Use recurrent selection methods to increase the frequency of desired alleles
- For multiple traits: Apply index selection weighing the relative importance of each trait
Breeding Strategies by Trait Type
| Inheritance Pattern | Example Traits | Recommended Strategy |
|---|---|---|
| Simple Dominant | Stem color, photoperiod dependency | Direct selection in F1, use test crosses to identify heterozygotes |
| Simple Recessive | Autoflowering, certain terpene profiles | Self-pollinate F1 or backcross to recessive parent, select in F2 |
| Codominant | CBD:THC ratio | Chemical testing to identify phenotypes, verify with test crosses |
| Polygenic | Yield, flowering time, terpene profile | Recurrent selection, progeny testing, larger population sizes |
| Environment-Sensitive | Hermaphroditism, pigmentation | Test in multiple environments, stress testing, replicated trials |