Genotype-by-Environment Interaction
Recognize and measure when genotypes respond differently across environments, including changes in ranking.
Educational reference · evidence, sources, and limits shown below
Recognize and measure when genotypes respond differently across environments, including changes in ranking.
Terms to know
- GxE
- Statistical and biological dependence of genotype performance on environment.
- Crossover interaction
- Genotypes change rank across environments.
- Stability
- Consistency defined for a trait and target range, not an absolute property of a cultivar.
- Target population of environments
- Production conditions for which a breeding or selection decision is intended.
Core science
A main genotype effect describes average differences; a main environment effect describes average shifts; GxE describes different response patterns. If two cultivars both gain the same amount under higher light, the environment changed the mean without crossover. If one gains and the other declines, the interaction changes cultivar choice.
Environment includes more than geographic site. Room, season, photoperiod, spectrum, density, substrate, irrigation, fertility, temperature, disease pressure, and operator practice can create different test environments. Confounding all factors at once can show that rooms differ but cannot identify why.
Stability is trait-specific. A cultivar can be stable for flowering date but unstable for yield, cannabinoid concentration, disease severity, or architecture. Mean performance and stability must be reported together; a consistently poor genotype is stable but not useful.
Why this matters in cultivation
- Trial promising cultivars across the real production envelope before scaling. Include a common check genotype and replicated positions so room drift and spatial gradients can be separated from genetics.
- Use matched chemistry sampling and harvest maturity. Comparing one cultivar at peak maturity with another on the same calendar day can create a developmental artifact that looks like GxE.
Measure and record
Target environments
Sites or rooms, seasons, management ranges, expected stresses, and market objective.
Design
Genotypes, checks, replicates, blocks, randomization, and common protocol.
Covariates
Actual light, temperature, humidity, root-zone EC/pH, water, disease, and maturity.
Analysis
Genotype, environment, GxE terms, rank changes, uncertainty, and missing-data treatment.
Decision
Broad adaptation, environment-specific placement, retest conditions, and rejected extrapolations.
Common misconceptions
Correction: Crossover interactions can reverse rankings.
Correction: Stability requires defined variation across multiple relevant environments.
Correction: Interactions can be reproducible and central to local adaptation.
Evidence limits
Multi-environment cannabis datasets remain much stronger for hemp than for controlled-environment drug-type germplasm. Environment categories must be measured, not inferred from room labels.
Related encyclopedia topics
- THC-ENC-080, THC-ENC-145-146, THC-ENC-191-200, THC-ENC-341-360, and THC-GROW-030.
Source notes
- Campbell B.J. et al. (2019). Genotype x environment interactions of industrial hemp cultivars. Agrosystems, Geosciences & Environment 2:1-11.
- Petit J. et al. (2020). Genetic variability of morphological, flowering, and biomass quality traits in hemp. Frontiers in Plant Science 11:102.
- Stack G.M. et al. (2023). Correlations among morphological and biochemical traits in high-cannabinoid hemp. Plant Direct 7:e503.
- THC Cannabis Plant Science Source Packet v1.1 (project source, May 2026).
This lesson summarizes the source material and its evidence limits for education. Use direct measurement, controlled comparison, and the cited sources when conditions differ or a decision carries meaningful risk.