Genotype-by-Environment Effects on Physiology
Design comparisons that separate genetic, environmental, and genotype-by-environment effects and avoid turning one cultivar response into a universal cannabis rule.
Educational reference · evidence, sources, and limits shown below
Design comparisons that separate genetic, environmental, and genotype-by-environment effects and avoid turning one cultivar response into a universal cannabis rule.
Terms to know
- Genotype
- Genetic constitution of an individual or line at the scale relevant to the trait.
- Environment
- Physical, chemical, biological, and management conditions experienced by the plant.
- Phenotypic plasticity
- Capacity of one genotype to express different phenotypes across environments.
- Genotype-by-environment interaction
- Difference among genotypes in the direction or magnitude of response across environments.
Core science
Phenotype reflects genotype, environment, their interaction, development, and history. A genotype-by-environment interaction occurs when genotypes do not respond in parallel: one may gain more from higher light, tolerate drought better, allocate more to flowers, or change chemical profile differently. Ranking can even reverse between environments.
Clonal propagation reduces segregation but does not standardize source-plant condition, pathogen status, physiological history, explant or cutting position, rooting quality, or culture history; genetic identity still requires verification when consequential. Seed-derived siblings add segregation. Reliable GxE work therefore needs verified identity, balanced replication, randomization or blocking, consistent sampling, and more than one meaningful environment.
Recent cannabis studies demonstrate genotype-specific differences in photosynthesis, drought response, biomass partitioning, nutrient allocation, light response, and cannabinoid profile. These studies make the case for cultivar qualification; they do not define universal superiority. A genotype selected for one production goal or environment may underperform in another.
Why this matters in cultivation
- Qualify each important genotype across the actual range of light, root zone, temperature, irrigation, density, and crop stages expected in production. Keep a common reference clone when comparing cycles.
- Change one planned factor or use a factorial design. When light, nutrition, container, and irrigation all change together, the result cannot identify which interaction mattered.
Measure and record
Identity
Genotype/clone/seed family, source, lot, generation, verification, mother, and pathogen status.
Design
Factors, treatment levels, blocks, randomization, replicate unit, sample size, and exclusions.
Environment
Measured light, temperature, RH/VPD, CO2, root zone, water, nutrition, density, and timing.
Physiology
Gas exchange, leaf area, water status, growth, development, biomass allocation, and health.
Analysis
Main effects, interaction, uncertainty, effect size, repeat cycles, and transfer limits.
Common misconceptions
Correction: Clones can express different phenotypes and retain different health or physiological histories.
Correction: Ranking depends on environment, management, stage, and production objective.
Correction: Environment, labeling, health status, and measurement error must also be excluded.
Evidence limits
A single genotype in one environment cannot estimate GxE. Small cannabis studies often have limited cultivar and facility coverage, so effect sizes and rank stability require independent replication.
Related encyclopedia topics
- THC-ENC-001–005, THC-ENC-061–079, THC-ENC-141–160, THC-ENC-181–200, and controlled-trial/recordkeeping lessons.
Source notes
- Pena MM et al. Genotypic Variation in Photosynthesis and Biomass Partitioning Underlies Agronomic Performance and Cannabinoid Profile in Cannabis sativa Under Drought. Plants. 2025. Open source
- Jost R et al. Sink Strength, Nutrient Allocation, Cannabinoid Yield, and Associated Transcript Profiles Vary in Two Drug-Type Cannabis Chemovars. Journal of Experimental Botany. 2025;76:152-174. Open source
- Collado CE et al. Supplemental Greenhouse Lighting Increased the Water Use Efficiency, Crop Growth, and Cutting Production in Cannabis sativa. Frontiers in Plant Science. 2024;15:1371702. Open source
- THC – Teaching Healthy Cultivation. Cannabis Plant Science Source Packet v1. May 2026. Project source packet.
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.