The Cannabis Breeder's Bible (30 page)

This warping of the leaf is permanent and is a mutation that can be bred true in the offspring. Warped leaf by Growmaster420.

TWINNING

Twining is another common mutation that has passed into the gene pool. Some seeds germinate to produce two seedlings from the same seed. One seedling rarely ever makes it because of the competition and being root-bound. The twins will not share the same roots and stem and will not be Siamese, but if you have any more information on this please be sure to visit us at
www.cannabisbook.com
.

WARPING

Warping is another common mutation that is found in in-bred lines and clones that have been propagated through cuttings for a long time. The warping is usually seen in the leaves that curl sideways like a hook instead of up or down as they do when there’s a nutrient problem. The stem may also be warped or bent with large blister-like surface points developing on the sides.

AUTO-TOPPING

Auto-topping is not very common and is usually the result of a mutation lower down in the plant that has caused the plant to automatically split into two stems. A whorled phylotaxy seems to cause this condition. So if you got a whorled phylotaxy then chances are your plant will auto-top itself.

POLYPLOIDS

The polyploid condition, as discussed before, appears as a result of a mutation.

A severely mutated polyploid cannabis plant. Photographs by HombredelMonte.

LEAF BUDS (BULBILS)

Another very strange mutation is flowers developing on the leaf. Where the branch meets the leaf a node may form and from the node a calyx and flower will grow. These types of mutations have been found in plants that grow around Nepal and the Himalayas. It is quite possible that this type of mutation is a translocation mutation. It does crop up in some hybrid plants now and again. It does not appear to affect the plant in any way.

Leaf buds that have developed on several petioles. Photograph by Kryptonite.

A large percentage of chromosome mutations do nothing to the plant but sometimes these mutations may add up with other smaller mutations over a long period of time to cause an effect on the plant. As we have seen, cloning through constant cuttings can do this. Another large percentage of chromosome mutations render a plant sterile or can cause a female to abort seed production or to produce nonviable seeds.

This is the case with many of the mutations mentioned above. They do not appear to harm the plant in any way, but the plant will also try and compensate for some of the problems. For example splitting and warping of a leaf or branch will result in the extra node above working harder to produce a new leaf and branch. The plant may even try and produce a new leaf or branch at the very same node as the mutation. A noticeable way to see this is with fan leaf mutations. If a fan leaf suffers from a mutation or warping the node may develop a new fan leaf or the next node above will develop a new fan leaf. The cannabis plant rarely fails to produce a new fan leaf if one is mutated or even if it is just cut away. In fact, if you prune a fan leaf early on, a new fan leaf will develop on the next node level. However, it has been noted that the higher up the fan leaf tries to develop, the more it looks like a hybrid between a fan and the trim leaves.

Single-bladed leaves may also develop. Single-blade leaves are not really a mutation
per se.
Single blade leaves are developed naturally by the plant as it tries to gather as much light as quickly as possible for photosynthesis. If a warping or splitting occurs then the next node level above may produce a single blade leaf in order to access light as quickly as possible because the warped leaf is not doing its job correctly or efficiently. You will notice this with clones. If you take a clone and root it, the clone will probably develop several single-blade leaves to try and receive light as soon as possible. I have even seen plants that have grown three feet high with single-bladed leaves all over. It is not a mutation, just a natural act of self-preservation.

On the left a clone is developing single-bladed leaves. Photograph by strawdog.

On the right a clone has continued to produce single bladed leaves all over. Photograph by Kryptonite.

17

EVOLUTIONARY CONDUIT OF CANNABIS

THE REPRODUCTIVE ASSURANCE OF CANNABIS PLANTS

When we deal with nonrandom mating between related individual plants, including selfing (also called
autogamy;
the opposite normal condition of cross pollinating between separate male and female plants is called
allogamy
), we can see problems in a population with regard to the fitness of the progeny. Darwin noted that the progeny of inbred plants were not as vigorous as outcrosses. Nature does not seem to produce mostly hermaphrodite cannabis populations but they can still be found in small pockets in the wild. Because dioecious plants are more common we assume that the hermaphrodite condition is not suited to most of the environments in which cannabis is found. But this assumption needs to be debated, because inbreeding can make a strain more suitable for a specific environment and man has played a role in both hermaphrodite and dioecious cannabis plant propagation. The small pockets of wild hermaphrodite cannabis plants around the world also seem to indicate that the trait is not entirely unsuitable for the cannabis family.

In 1941, Ronald Alymer Fisher proposed the “automatic transmission advantage.” Fisher’s papers can be read on-line at
http://www.library.adelaide.edu.au/digitised/fisher/index.html
.

Fisher discovered that there was an automatic selection advantage during selfing. A selfed plant will contribute both the ovule and the pollen, as a single hermaphrodite parent, to offspring that it will create. In populations that are not selfed the males contributes pollen to separate female plants. The selfed plants however will contain an allele encouraging the hermaphrodite trait (selfing) and Fisher found that this allele has a 3:2 transmission advantage over plants that do not self. This means that selfed plants will usually contain the allele for spreading the selfed trait to further populations unless equilibrium is not maintained and the gene is deleted from the gene pool. In short, selfed plants appear to have natural selective pressures to stay hermaphrodite and to spread the condition to its offspring, however it does not mean that a selfed hermaphrodite population cannot eventually become a dioecious population that does not self.

Cannabis seeds are heavy. Although they can travel over longer distances via animals or birds, in most cases seeds are going to grow in close proximity to the mother plant that they came from. Gravity is responsible for this. The vast majority of mother cannabis plants terminate their lives before the offspring can mature and so there is a low chance of any natural backcrossing occurring. However, if she does survive, the chances of a wild backcross are much higher.

We know that cannabis wants to prevent this because it is an annual plant and a high percentage of cannabis strains show traits that prevent natural backcrossing. We know that sometimes the plant will abort the seed or not use the pollen if selfed. This is called “homomorphic incompatibility” or “cryptic self-incompatibility”.

Anthesis
is the time when a flower opens or becomes sexually functional—the time and process of budding and unfolding of blossoms. Male and female plants show a clear difference in anthesis times. The male produces faster than the female, usually before the female even starts to flower. The hermaphrodite condition reproduces itself mostly in the flowering phase of the female plant. If pollen is already available from another male flowering plant before hermaphrodites appear in a population, then the pollen that is most readily available will be used by the females in the population. A ‘seeded’ female will rarely ever start to hermaphrodite after receiving pollen unless it goes through very stressful growing conditions after being pollinated.

So what are the benefits for which evolution has allowed the hermaphrodite trait to continue? It simply boils down to variations in strains promoting higher chances of adaptability and fitness in the offspring.

If you want reproductive assurance, you’ve got it with selfing. If a strain suits an environment without any problems, you might wonder why it doesn’t just settle down and concentrate on reproduction by selfing? Selfing is mostly recognized as a process of self-preservation where stress has put the plant into a crisis bid to reproduce itself. But even in a cozy environment, wouldn’t it also be in the plant’s best interest to settle down and reproduce itself by autogamy? We are back to the same problem again. Is the hermaphrodite trait an extreme of both of these conditions? This does tell us that this mating system is strongly related to inbreeding.

Since inbreeding has a depression (which we will explain in a moment) in the variation possibilities and overall adaptability of a plant we can compare this with the offspring of the same strain that has not been involved in autogamy or selective breeding processes. The formula is expressed as:

1 - (
Ws/W0
)

Ws
is the measured vigor of the selfed offspring and
W0
is the measured vigor of non-selfed offspring. Vigor is measured by traits for nearly every stage of the plant’s development and how well it copes with the environment. The reason for a depression can be found in strains that have higher amounts of homozygous traits in a population.

The best place to look for inbreeding depression is with pure lines. If two unrelated purebred lines meet they will produce the first F1 hybrid offspring, which should have some vigorous characteristics in the population.
Heterosis
is the tendency of a crossbred individual, a hybrid, to show qualities superior to those of both parents. It is also called “hybrid vigor.”