The basics, explained simply

Short explanations of the technical terms that show up in the lexicon articles. Each entry answers one question: what does this word mean, without the jargon? If a longer article leaves you stuck on a term, the plain version is here.

Inheritance and Genetics

• B-Locus: the spot in the genome that sets THC or CBD

  What the B-Locus is, how the codominant BT and BD alleles fix the THC-CBD chemotype, why F2 offspring split 1:2:1, and where the single-locus model reaches its limits.

• Backcross – Crossing an Offspring Back to a Parent

  A backcross recovers one parent's genome step by step while keeping a single trait from the other line, and its reach depends on two conditions.

• Cytoplasmic Inheritance: the genes outside the nucleus

  What cytoplasmic inheritance is, why chloroplasts and mitochondria pass through the mother only in most plants, how that pollen exclusion works, and where the rule breaks down.

• Double Cross – Four Lines in Two Steps

  In a double cross, four true-breeding lines are joined first in pairs and then across, so that commercial seed grows on a vigorous cross rather than on a weakened line.

• Filial Generation – F1, F2 and F3 in a Breeding Sequence

  Filial generations count the daughter generations of a cross, and only the second of them reveals which trait combinations can actually be selected.

• Heterosis – the Gap Between an Offspring and the Mean of Its Parents

  Heterosis is the gap between an offspring and the average of its two parents, and measured on a single cross that number is hard to read.

• Heterozygosity – Mixed Inheritance and Its Share in Cannabis

  Heterozygosity means a plant carries two different variants at one place in its genome, and in cannabis that is the normal state rather than the exception.

• Homozygosity – True-Breeding Lines, Their Route and Their Proof

  Homozygosity means a plant carries the same variant twice at one place in its genome, and it is the condition under which a cross always yields the same progeny.

• Inbreeding Depression: why close crossing weakens plants

  What inbreeding depression is, how rising homozygosity exposes recessive harmful alleles, why vigour and yield decline, and what purging means in breeding.

• Linkage Drag – Why an Introgressed Gene Brings Its Neighbours Along

  Moving a single gene from an outside line into a variety always brings a piece of chromosome with it, and how large that piece stays is decided not by the number of crosses but by the position in the genome.

• Maternal Inheritance: when a trait comes from the mother only

  What maternal inheritance means, how it shows up in reciprocal crosses, why in cannabis it concerns the organelle genes, and why aroma still comes from both parents.

• QTL: the genome region behind a measurable trait

  What a quantitative trait locus is, why continuous traits like terpene content or plant height depend on several loci, and how QTL mapping locates them in the genome.

• Reciprocal Cross: the test for a parent-of-origin effect

  What a reciprocal cross is, how swapping the parent roles reveals whether a trait sits in the nucleus or with the mother, and what the test showed for cannabis aroma.

• Recombination – How Alleles Rearrange in a Cross

  Recombination is the rearrangement of alleles during the formation of gametes, and in some stretches of the genome it happens so rarely that linked traits stay together.

• Selfing: crossing a plant with itself

  What selfing is, why both halves of the genome come from one plant, how recessive traits surface, and why continued selfing leads into inbreeding depression.

• Sex Reversion – Induced Flowers of the Opposite Sex

  In sex reversion a genetically female plant forms fertile male flowers, or a male plant fertile female ones, triggered through the ethylene pathway, and both feminised seed and selfing rest on it.

• Single Seed Descent – One Seed per Plant and Generation

  In single seed descent exactly one seed from each plant carries the next generation, and in cannabis the method reaches functionally true-breeding lines in about six rounds.

• Transgression – Offspring Beyond the Parental Range

  Transgression describes offspring whose trait values fall outside the range of both parents, and in the case measured it arose from similar parents rather than distant ones.

• XY-System: how cannabis decides its sex

  What the XY system means in cannabis, why females carry XX and males XY, why the Y holds almost no active genes, and why the sex-determining gene is thought to sit on the X.

Biochemistry and Metabolism

• Cannabigerolic acid: the acid form the cannabinoids come from

  What cannabigerolic acid is, why the plant makes it rather than its neutral form, and why the difference between CBGA and CBG decides how a lab result should be read.

• Cannabinoid synthase: the enzymes that decide the chemotype

  What a cannabinoid synthase does, why THCA and CBDA synthase resemble each other so closely, and why the switch between THC and CBD separates less cleanly in the lab than in the textbook diagram.

• Chemotype: the chemical identity of a cannabis strain

  What a chemotype is, how Small and Beckstead defined types I to III by the THC-CBD ratio in 1973, what the rarer types IV and V mean, and why chemotype says more than indica or sativa.

• Terpene Synthase: the enzyme behind cannabis aroma

  What a terpene synthase is, how it builds the scent compounds of cannabis from GPP and FPP, why one enzyme often makes several terpenes, and what that means for breeding terpene profiles.

• Tetrahydrocannabinolic acid (THCA) – acid form, conversion and calculation

  What THCA is, why the plant builds almost nothing but the acid form, and why the conversion factor of 0.877 describes an upper limit rather than a yield achieved.

Botany and Development

• Adventitious Root: A Root That Forms Where None Was Planned

  What an adventitious root is, which tissues it can arise from, and why propagation from cuttings would be impossible without it.

• Anthesis: the zero point flowering time is counted from

  What anthesis means, why it is not the same as switching the lights, and how that difference can make two statements about harvest timing impossible to compare.

• Dormancy: the rest period of a viable seed

  What dormancy means, why South African landraces respond to dormancy breakers and industrial hemp does not, and what cold stratification actually achieves.

• Germination Capacity: The Share of Normal Seedlings in a Defined Test

  Germination capacity is a count made under defined conditions, and those conditions belong to every percentage figure quoted.

• Germination Energy: The Interim Count on Day Three

  Germination energy records only the well-developed seedlings at day three and therefore says something about a lot's speed rather than its yield.

• Normal Seedling: The Assessment Class That Produces the Germination Figure

  Whether a seedling counts as normal decides every germination figure, and the call rests on root and shoot rather than on the hull splitting open.

• Rhizosphere: the patch of soil a root shapes for itself

  What the rhizosphere is, why breakdown processes occur there that do not occur in bulk soil, and how that differs from removing a substance with the harvest.

• Seed Dormancy: The State in Which a Living Seed Does Not Germinate

  Seed dormancy means a seed is alive and still does not germinate; in freshly harvested hemp it lasted five to six weeks in one study and made germination tests come out worse than the seed really was.

• Seed Vigour: What a Seed Still Delivers Under Poor Conditions

  Seed vigour describes performance under adverse conditions, and for hemp the major testing bodies carried no procedure for it in 2019.

• Viability: Whether a Seed Is Alive, Regardless of Whether It Can Germinate Now

  Viability is determined by staining a cut seed and answers in two days what a germination test only settles after a week.

Soil and Contaminants

• Bioaccumulation factor: how strongly a plant concentrates a substance

  The bioaccumulation factor compares how much of a substance sits in the plant against how much sits in the soil, and a high value alone does not make a good remediation crop.

• Cation Exchange Capacity: How a Substrate Holds Nutrients and Gives Them Back

  Cation exchange capacity measures how many positively charged nutrient particles a substrate can bind and release to the plant as needed.

• Phytoextraction: pulling contaminants out of soil with the harvest

  In phytoextraction a plant takes up a contaminant and carries it off the site with the harvest, and whether that is enough is decided by the mass hauled away, not by the idea.

• Phytostabilisation: locking a contaminant into the soil instead of harvesting it

  How phytostabilisation differs from phytoextraction, how roots and their exudates bind a substance, and why the effect has not been studied for cannabis specifically.

• Transfer factor: how much of the soil load reaches the harvest

  What the transfer factor stands for, why a low value means clean produce and an ineffective clean-up at the same time, and why German soil law lacks trigger values because of it.

Processing

• Equilibrium Moisture Content: the level a seed settles at

  Equilibrium moisture content is the level at which a seed stops giving up water to the surrounding air, and it depends on the humidity rather than on the drying time.

• Lecithin – emulsifier in preparations

  What lecithin does as an emulsifier, what is established about bioavailability, and how bound residual water affects shelf life.

• Maceration – extraction into a liquid medium

  What maceration means, what the yield depends on, and how it differs from decarboxylation.

• Seed Moisture Content: definition, measurement and target values

  The moisture content of a seed is expressed against its fresh weight, and because the standard measurement destroys the sample, practice works with a calculated target weight.

• Sorption Isotherm: the curve between humidity and moisture content

  A sorption isotherm shows which moisture content a seed takes on in air of a given humidity, and it comes out differently for every species and even every variety.