Cannabis Polyploidy: Tetraploids, Triploids and Colchicine.

Almost everyone has heard of triploids, but few understand what they actually are or how they work. Yet polyploidy is one of the few remaining ways to create something genuinely new. Let us break it down in plain language, starting with the basics. Spin the model below and toggle the ploidy — it makes things much clearer.

The diploid: our starting point.

Cannabis, like humans, is a diploid organism (2n): it has a double set of chromosomes. Most organisms in nature are built this way. Binarity is fundamental in general — from the plus/minus of an electric charge to sexual reproduction itself.

In ordinary crossing, the double set (2n) splits into two haploid cells (1n): the mother contributes 1n, the father contributes 1n, and a new 2n organism is formed. Simple.

Polyploidy is a natural process.

It is worth dispelling the fear right away: scientists did not invent polyploidy — we merely learned how to use it. In nature it is especially common among flowering plants. Sometimes errors occur during cell division — caused by cold, heat or radiation — and the chromosome set doubles. So talk of dangerous tricks cooked up by scientists is beside the point here.

The tetraploid: stabilised power.

Under the action of colchicine or oryzalin, a 2n cell does not split into 1n + 1n. Then, when crossed, it produces a 2n + 2n = 4n organism, a tetraploid. It is an amplified version of its diploid ancestor — the so-called gigantism effect. This is enhancement rather than creating something new:

• yield and stature often increase;
• resin production doubles, and the amount of enzymes grows, including terpenes;
• the aromatic profile stays similar to the parent but becomes richer and deeper.

Since the number of sets is even, the tetraploid divides reliably — which means it is fertile and produces offspring (though fewer seeds than a diploid). A fundamentally new aroma is possible, but only if you cross two different tetraploids from different strains: that yields a tetraploid hybrid with a combination of alleles that was impossible in the diploid ancestor.

The triploid: genetic chaos.

If a tetraploid (4n) is crossed with an ordinary diploid (2n), the offspring inherits 2n from the tetraploid mother and 1n from the diploid father. The total is 3n, a triploid. Three sets of chromosomes cannot divide evenly during meiosis, and a genomic shock occurs. The plant ends up under extreme stress, and this can switch on powerful production of secondary metabolites — terpenes, flavonoids and others.

Heterosis on steroids

Triploids often possess hybrid vigour, but not the stable kind found in F1. Their heterosis is unstable and explosive. The metabolism runs at its limit, sometimes yielding not just more terpenes but unpredictable combinations of them. A pleasant bonus: some triploids are able to accumulate terpenes without degradation, preserving a live aroma even after drying.

Why triploids are sterile

Everyone knows that triploids produce no seeds (seedless mandarins and watermelons are exactly that). The reason is simple: during division, half of the chromosomes are inherited from each parent, and 3 cannot be divided by 2 without a remainder. You cannot tear a single chromosome into two halves — hence the sterility.