Genotype by environment interaction (GxE) means the effect of the environment depends on the genotype. Two cultivars may rank one way under one light, feed or climate and the other way under another. Phenotypic plasticity is the related idea that one genotype can produce different phenotypes in different conditions.
In practice
GxE is why "test your cultivar" is GenetixBay's stance. One clone may love 24/0 veg and 13/11 flower; another stalls. Some cultivars thrive with a mild late dry-back; others lose yield. One mother handles heavy defoliation; her sister sulks. Ca and Mg demand also varies by cultivar, more than by light type.
For breeders, GxE means selections should be tested in more than one environment before release. A keeper selected under one grower's lights in one climate may disappoint in a cooler, more humid room. Tester grows across many members are a practical way to see GxE.
Don't confuse with
- Genotype: the DNA, which does not change between rooms.
- Environmental effect: when every genotype shifts the same way (all plants yield less in a cold room), that is not GxE.
- Genetic drift: clones do not drift genetically because they are moved to a new room.
The genotype is the set of alleles a plant actually carries, either at one locus or across its whole genome, as opposed to the traits you can see.The phenotype is what a plant visibly and measurably is (shape, colour, smell, chemistry, timing), the result of its genotype acting in a particular environment.24/0 means lights on 24 hours a day with no dark period; GenetixBay endorses it for veg, as cannabis does not need a sleep period before flowering.13/11 is a flowering schedule of 13 hours light and 11 hours dark; GenetixBay endorses it, as most cultivars still flower while gaining extra daily light.Dryback is the drop in a substrate's water content between irrigations, usually expressed as a percentage of its content at full saturation.Schwazzing is an aggressive defoliation method that strips almost all fan leaves on day 1 and again around day 21 of flower.Genetic drift is random change in allele frequencies between generations of a seed population, strongest in small populations; clones do not drift this way.Heritability is the share of a trait's variation within a population that is due to genetic differences rather than environment, on a scale from 0 to 1.A test grow (tester grow) is growing out a sample of a new seed line, often by several independent growers, to measure uniformity, vigour, chemistry and herm rate before release.A quantitative trait varies continuously (yield, height, flowering time, cannabinoid content) because it is controlled by many genes of small effect plus the environment.
