Genetics

Genetics explains why a seed can show different traits from its mother plant. The articles start with inheritance and the sex of the plant. They then cover the methods breeders use to fix lines and test for hermaphrodites.

Where strains and landraces come from is covered under Origins and Lineage.

  • Inheritance and Sex

  • Parental Inheritance

    Does the aroma come from the mother plant? The short answer first, then step by step the genetics behind it: nuclear genes from both parents, sex from the father, cytoplasm from the mother.

  • Segregation F1–F3

    Why a first filial generation is only uniform when both parents are true-breeding, why the familiar three-to-one ratio applies to a single trait, and what selfing and backcrossing actually do to a breeding line.

  • Sex Determination

    How cannabis sets its sex through XY chromosomes, why the visible flower type can still switch, and how the sex can be determined at the seedling stage by PCR – hedged and sourced.

  • Ethylene and Flower Sex

    The plant hormone ethylene promotes female flowers in cannabis, and blocking its action with STS makes females form pollen.

  • Breeding Methods

  • Homozygous Parent Lines

    True-breeding parent lines in a dioecious species arise either through sib-mating or through chemically induced selfing, and the two routes differ in speed, in lethal load and in which traits they fix along the way.

  • Backcrossing in Breeding

    What a backcross recovers on paper, which two conditions are missing from most short accounts, and why the genome structure of cannabis leaves a larger donor segment behind than the arithmetic suggests.

  • Feminized Seeds

    Feminized seeds come from a female made to form pollen with silver thiosulfate, and the calculator gives the weights and dates for it.

  • Male Selection

    How to recognise a good breeding male: stem rub aroma, vigour and structure, resin, flower traits, the right timing and the taste test – hedged and sourced.

  • Stress Test for Hermaphrodites

    A stress test with cold and an abrupt light switch shows whether a mother or pollen donor tends to turn hermaphrodite before it enters breeding.