What is a phenotype and what does phenotype mean?

  Added by: 10k  Last edited by: 10k  Viewed: 957 times  Rated by 25 users: 9.00/10
Contributed by: Chimera

Phenotype is one of the most incorrectly used terms on marijuana grow forums in my opinion.

What does phenotype really mean?

Phenotype is the observable/qualifiable/quantifiable representation of a trait.

So what does that mean?

Most folks say there are two main genres, sativa dominant and indica dominant, when actually there is a wide range of leaf phenotypes... the skinny sativa like class, thick indica type class, and many intermediate phenotypes in between the two.

This can be further compounded by leaves that are pinnate, webbed (ducks foot), curly, pointy tipped, round tipped, single or double serrations etc etc. A quick look in the book MJ botany will show a page of many different leaf phenotypes.

In this case we are talking about LEAF phenotype. All of these phenotypes can also show purple leaf, or green leaf, The green leafs can be classified as lime green or dark green.. thick leaved, thin leaved (texture).

Any of these plants may also show purple buds, or green buds... or even red buds.

See where this is going? There are multiple phenotypes for each and every discernable trait, well more than two. If you examine a pure indica population, you will see variation across the population with respect to many traits.

We have still only looked at two parts of the plant.... the leaf and the buds.

The buds can further be broken down into many different characteristics.

Highly resinous buds vs not quite as resinous. High THC content, or high CBD content. We also have mixed CBD/THC content. This can be further expanded to low overall levels of the primary cannabinoid (THC, CBD, or mixed), or high levels of the primary cannabinoid.

What about bud density? Dense, airy, or somewhere in between?. Large calyxes or small? Round tipped smaller buds, or long pointy tipped buds? What about large round buds? Small pointy ones? Small airy ones? Large airy ones?

Smells... fruity, skunky, piney? If fruity, citrus or berry? Citrus? Grapefruit? lemon? Orange? Strawberry? Blueberry? Grape?

All of these traits can come together in any combination... when we start thinking about which traits are associated, we are actually thinking about something called linkage.

For example, myself and another breeder have found that orange seems to segregate (appear most often) along with the pointy tipped bud characteristic.

In order to determine linkage, we have to calculate the frequency of occurrence of these two traits, or phenotypes, in the same plant, over an entire population... the larger the population, the more confident we can be that our conclusions about linkage are accurate.

So when you see a breeder or seed maker say "I selected the most Thai dominant males", you should ask how did that seed maker determine which were the most "Thai dominant".

If he says leaf traits, you should laugh!!


Because leaf traits are not known to segregate with the overall positive characteristics of Thai's... there is no assurance that the selection for thin leaves, will in turn guarantee the selection for the uplifting, soaring, STRONG Thai type of high. Get it?

The only way to select for the Thai high is to cross MANY males to the chosen/desired females, and examine the progeny of each lot individually, in order to determine which male(s) contributed the desired genes.

If you want my honest opinion.... seed descriptions are a scam. They are advertising tools, and should be looked at as such by the seed buying public. If you notice, many seed makers have started giving "probable outcomes" of plants that they have not grown. A quick look through some of our sponsors shows this in droves.

Don't be on the lookout for any plant that say have a "grape" flavour, just because the "breeder" says says these are the most potent. The grape one might have been the most potent in the 10 to 15 seedlings he grew (LOL), but overall the grape flavoured one may be less potent on average.

If a claim is made to look for any phenotype, ask how they came to that conclusion.

You should only be on the look out for the grape flavour if that is the most important criteria for you.

If you want the most potent, keep clones of each and after you have harvested only keep the clones from the most potent plants. It just depends on what YOU find important... to me, when growing drug cannabis, I look for drug content.

OK, so I got off topic a little, but I hope you can see what I was trying to say... there are many possible observable phenotypes for each trait, not just two. It is far more complex than just sativa or indica. Beware of seed makers that make it seem this easy is my advice. If you don't believe me, just grow a couple of packs of any given strain and see the many differences.
  Last modified: 09:12 - Aug 25, 2003 

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