When it comes to science and math and probabilities and data logging and analyzing and quantification of information about our past grows, most of us growers just roll one up and get nice and stoned while we ponder and think about all the possibilities and come to some “high in the clouds” conclusion all on our own that is, pardon my French, fucking mind blowing! I, just like most of you; know that in our industry keeping records sometimes means stringing your own noose. But a lot of old timers or pirate growers from back in a dark ages before medicinal marijuana, we understand that to get the PERFECT cross or grow the PERFECT plant means keeping track of many things such as nutrient strength for that specific strain, yield size, tips or tricks you learned and do not want to forget. In the breeding game, recording seed variables is an absolute MUST!
When creating a brand new strain from regular seeds, one must figure out what they want the outcome to be so they can know where to start. Obviously stating, that if one wants a short and stout plant they will not use two tall and lanky sativa strains. Instead it would be wise to choose short and stout plants to easily create a short and stout new genetic. Now if someone loves a certain sativa strain that is just too damn big for indoor grows and they want to try to stabilize a shorter version of the genetic than this is what you need to figure out before you start.
One of the most used variation of strain development is creating shorter versions of sativa strains for inside or closet growers. Let’s say you take a tall Durban Poison strain and you decide to shorten it. You would select a male that will pass the short and stout
traits on. Once you select your male you will breed the two plants together by introducing both plants into the bloom period at the same time. Once you have the new seeds its best to find a female and a male from the new generation of seeds. Select a female that is short and cross it with the original male pollen you used in the first cross. Now select a male that is identical looking to the original male used in the first cross and cross that male with the original female. These two new crosses are F2 genetics and should produce “more stable genetics.” Never cross sister and brother seeds! Yes, plants can have incest and yes sometimes it will produce severely disabled genetics.
What “more stable genetics” means is that in your original cross of Durban Poison you might end up with any number of variations from 2 to 10 to hundreds. Each one of these variations will grow in a different manor. Some might yield more some less, some might grow tall some short, some may have sativa looking leaves whilst others produce indica looking leaves. Each variation of this cross will create different probability in the next generation. This is where Punnett Squares and having a little bit of a grip on science or breeding will be significantly beneficial. A friend of mine races horses and we can talk for hours about breeding and probabilities. Some stallions have dominant genes that pass on to the foal whilst some others allow the foal to get the dominant genes from the mother. This is why keeping records becomes important so you can figure out which strains are dominant and which are not and which specific characteristic traits of the plant will be dominant and which not.
Let me take a second to explain the diagram below and how to insert this into your own crosses. Let us say the little “a” means BIG YEILD when the uppercase “A” means SMALL YIELD. Now let’s say the little “b” stands for SHORT & STOUT when the uppercase “B” means TALL & LANKY. Now if we were trying to create a short and stout version of Durban Poison like we were discussing earlier then we would obviously want the black square where the outcome is guaranteed “aabb”. When crossing, each parent plant will pass on certain genes to the next generation. The top of the square should indicate the MOTHER and the potential for the next generation to have those traits, BIG YEILD (“a”) versus SMALL YEILD (“A”) or SHORT (“b”) versus TALL (“B”). The same applies for the FATHER plant which is displayed on the left portion of the diagram. Since we want a plant with a big yield and short and stout we want a plant with all lower case letters. As you can see the chances of getting a guaranteed “aabb” plant is 1:16. All of the plants with double upper case letters would be a variable genetic that we do not want so those would be discarded during breeding so their traits do not pass on to the next generation. Any variable with double lower case letters would be one worthy of playing with due to its potential to pass its genetics on to the next generation.
Sometimes simple experimentation is enough to discover something perplexing. To discover which traits are dominant and which recessive on a particular strain one must cross the strain with other strains and save a clone of the original genetics to always fall back on. I always keep mother and father plants in my garden. Layman’s terms, a mother or father plant is a plant that will never leave the growing or vegetative state of plant life. As the plant grows it can yield more and more healthy clones. Remember always clone from the tippy top of the plant canopy as to get the healthiest and most vigorous growing clone. These clones will fuel your future crosses and stabilizations. After you have crossed a male and female plant with other genetics you should get a good feel for the dominance of the genetic’s traits. It is important to remember or record the trait variables and dominance so that you can create a Punnett square for your cross to determine the seeds potential genetic traits, variance of genetics between brother and sister plants, and lock in information other growers will want to know about your strain such as how many different phenotypes the strain possesses. For the sake of argument, let’s say you bought a pack of 10 seeds. If a strain has 6 different phenotypes then chances are you will have one or two matching plants which makes it hard to grow because if you are looking for a specific one of the six phenotypes (for example one of the six is purple when the rest are plain mary jane green) then you have on average a 1:36 chance of getting that phenotype again in any particular single seed. This means that you need iat least 36 seeds to guarantee that you will have 2 identical looking plants with identical genetics.
When you take your time and keep track of your variables and phenotypes then it makes it easier to create that masterpiece you desire. The plant has specific DNA that tells the cells what to do and how to grow and everything else. You can’t change the DNA of a plant you can only breed it and stabilize the genetics to make the new strain exactly how you want. It just takes selecting the right plant to cross. You would never choose a “AABB” plant to stabilize because you want that 1 in 16 “aabb” because it will pass its dominant recessive genes to the next generation.