Landraces, Heirlooms, In-bred Lines, and Hybrids

(Photo Credit: Nebula Haze @ growweedeasy.com)

Ah mother nature, the giver of everything we have. Including, mercifully, sweet, sticky, sugary, Cannabis.

I often wonder what it must have been like to be the first human to discover the magic of cannabis. Did they eat it? Did they throw a bunch on a campfire and get stoned out of their minds when the campfire smoke blew in their face? We'll never know, but we do know that cannabis has been a part of human history for many thousands of years, throughout many cultures and places.

(Photo credit: lingqi xie/Getty)

Scientists think that Cannabis evolved on the high Tibetan plateau, pictured above, and subsequently spread around the world both through natural means and with human help.

This natural and "assisted" spread created isolated pockets of cannabis that slowly naturally diverged from one another in the process of adapting to best survive their environment. This is how pockets of landraces formed over the millenia.

Perhaps you've heard the word "landrace" before and didn't know what it meant or maybe heard your mother talking about her "heirloom tomatoes".

So what are landrace strains? Heirlooms? IBL? Hybrids?

Time for a quick glossary to cover our terms:

Homozygous: is a genetic condition where an individual inherits the same alleles for a particular gene from both parents.
Heterozygous: refers to having inherited different forms of a particular gene from each parent. A heterozygous genotype stands in contrast to a homozygous genotype, where an individual inherits identical forms of a particular gene from each parent.

(Photo credit: National Human Genome Research Institute)

Landrace: essentially a wild variety of cannabis that has been living in a specific geographic pocket in a specific environment free of human interference. Cannabis is a tough plant that can adapt to different environments. Over thousands of generations wild cannabis that grows in the Thailand jungle, or in the Nepal highlands, or the dry arid environment of Afghanistan, or the equatorial sun of Ethiopia will adapt to that specific environment developing traits relative to their environment. Landraces are a natural reservoir of cannabis and are the one and only source where all cannabis originates from. A landrace will most likely be a IBL, this is not universally 100% true, some of the old world landraces will have hidden recessive traits, but for all intents and purposes, landrace strains will have genetically interbred with their own genetic pool enough that they will have bred out any heterozygous traits naturally.
Heirloom: When a human farmer finds a wild landrace cultivar and brings it home to their farm, and begins to selectively breed the plant, that plant can be said to be an heirloom. It is a loose term that basically means an old, original cultivar used early on in the process of domesticating a wild species. The process of domestication is basically selective breeding to maximize the plants output so that the farmer can replicate the results every time.
In-bred Line: a strain can be said to be IBL or "true breeding" when its genes are either dominant homozygous, or recessive homozygous. This type of strain is genetically stable, meaning the seeds will be identical to the parent plants, and every plant will express the same traits. This is highly desirable trait for breeders beginning a new breeding program. By starting with stable IBL, you reduce the number of genetic variables, and you can have better control over how your genetics cross.
Hybrid: A hybrid is a heterozygous plant, it is made by crossing two different strains together. This produces something genetically unique, but also it now has a heterozygous genetic state. If this plant is bred with another it will NOT produce uniform offspring, the offspring will display a range of dominant and recessive traits.

Why is this important?

Landrace cannabis is the origin of all the great cannabis we love and enjoy today. Landrace genetics represent a source of clean, unsullied, pristine genetics directly from the source of nature. Landrace strains also represent an insurance policy against the encroachment of undesirable genetic traits like hermaphroditism.

Understanding this, and armed with a little bit of knowledge of genetics, it becomes possible for a breeder to intentionally cross strains with desirable traits to create a custom strain with those traits... if you know what you are looking for!

Someone didn't stumble across a cannabis plant that tastes like chocolate mint cookies out in the wild, nay, it was created specifically for that intent, someone did it deliberately. This is the beauty of knowing a bit of genetics and combining that with growing knowledge -- you have an opportunity to create something brand new and awesome!

Blending inheritance works by evoking a specific trait over several generations of breeding. It is an abstract example of selectively breeding for a specific trait over multiple generations.

(Photo Credit: Squididdly via wikimedia)

Selective Breeding

Gregor Mendel is credited with the first experiments in genetics, coming up with the theory of genetic inheritance. Mendel noticed that when he crossed a true breeding plant with one characteristic, such as purple flowers, with a true breeding plant with the opposite characteristic, such as white flowers, one trait hid or masked the other characteristic.

Mendel concluded that there must be two forms of the same gene for each trait he studied. Different forms of the same gene are called alleles. When one trait is “stronger” than the other trait, the “stronger” trait is called dominant trait or allele, and the one that is hidden is called the recessive trait or allele.

A capital letter is used to represent the dominant form of an allele or gene, and a lower case letter is used to represent the recessive form of the allele. In general, the first letter of the dominant trait is used to determine the symbol.

When biologists describe the traits of an organism, they are referring to the organism’s phenotype. For example, for seed color, a pea plant can display a phenotype of yellow or green.

This means if you can figure out which alleles in which IBL strains are dominant and which are recessive, you can more easily craft your desired end strain.

For example, lets say you wanted to produce a new purple indica strain that would be a consistent heavy yield crop.

First we would need two IBL strains to work with.

P1: Blueberry
P2: Pakistan Chitral Kush

Blueberry is a stable IBL of legendary proportions, with Afghani and Thai genetics. PCK is a landrace from the hindu kush valley region. PCK has a mellow body high, that unlike its Hindu Kush cousin, won't glue you to the couch.

PCK has another interesting feature: its genes for purple colored buds are dominant! How do I know this? Ace seeds sells landrace PCK seeds, and they also sell F1 hybrids of PCK crossed with various other varieties. Check out the purpleness of all these F1's:

PCK x Kali China:

PCK x Malawi:

PCK x Panama:

PCK x Bubba Kush:

I am certain that crossing Blueberry with PCK would result in a very purple indica, with a very heavy yield, and a world class indica dominant high.

F1 Hybrid Vigor

Landrace strains also allow you to take advantage of an interesting facet of genetics: F1 Hybrid Vigor.

Crossing two genetically different plants produces a hybrid seed. This can happen naturally, and includes hybrids between species (for example, peppermint is a sterile F1 hybrid of watermint and spearmint). In agronomy, the term “F1 hybrid” is usually reserved for agricultural cultivars derived from two parent cultivars. These F1 hybrids are usually created by means of controlled pollination, sometimes by hand-pollination. For annual plants such as tomato and maize, F1 hybrids must be produced each season.

True hybrid vigor (a.k.a. "heterosis") is created when you cross two IBL strains together. That first generation cross will be a healthy, sturdy, high yielding plant.

For mass-production of F1 hybrids with uniform phenotype, the parent plants must have predictable genetic effects on the offspring. Inbreeding and selection for uniformity for multiple generations ensures that the parent lines are almost homozygous. The divergence between the (two) parent lines promotes improved growth and yield characteristics in offspring through the phenomenon of heterosis ("hybrid vigor" or "combining ability").

Farmers have been using this fact to produce more food from the same amount of land for many decades to keep up with the growing demand for food worldwide.

Two populations of breeding stock with desired characteristics are subjected to inbreeding until the homozygosity of the population exceeds a certain level, usually 90% or more. Typically this requires more than ten generations. Thereafter the two strains must be crossed, while avoiding self-fertilization. Normally this is done with plants by deactivating or removing male flowers from one population, taking advantage of time differences between male and female flowering or hand-pollinating.

Advantages of Hybrid Vigor

Homogeneity and predictability: The genes of individual plant or animal F1 offspring of homozygous pure lines display limited variation, making their phenotype uniform and therefore attractive for mechanical operations and easing fine population management. Once the characteristics of the cross are known, repeating this cross yields exactly the same result. F1 hybrids mature at the same time when raised under the same environmental conditions. They all ripen simultaneously increasing predictability.
Higher performance: As most alleles code for different versions of a protein or enzyme, having two different versions of this allele amounts to having two different versions of the enzyme. This increases the likelihood of an optimal version of the enzyme being present and reduces the likelihood of a genetic defect.
Genetic Lock: When F1 cultivars are used as parents, their offspring (F2 generation) vary greatly from one another. Some F2s are high in homozygous genes, as found in their grandparents, and these will lack hybrid vigour. From the point of view of a commercial seed producer who does not wish customers to produce their own seed via seed saving, this genetic assortment is a desired characteristic.

Conclusion

Hopefully you have a better understanding of what Landrace strains are, why they are important, how they fit into the larger picture of breeding new and interesting cannabis varieties! Landrace cannabis represents the cultural heritage of cannabis, which needs to be safe guarded for the next generation of growers and breeders to enjoy! Landrace and stable IBL lines provide insurance against negative genetic traits and help provide the foundation to create new strains that with time and effort will eventually become IBL themselves, thus increasing the diversity of the whole genetic pool.

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