Before feminized seed became a reality, regular seeds were the preferred option for growers looking to cultivate new strains. Like their feminized counterparts they offer many advantages but do require careful sexing to ensure that all female plants are harvested.
This process requires time, effort and expertise to identify male plants and remove them. However, sexing plants becomes easier over time as they age.
The frequency with which good seed years occur varies considerably. The occurrence of good seed crops can be improved by preventing deficient pollination, by thinning to improve vigour, by increasing foliar nutrition and by providing protection from climatic dangers, cone-destroying insects and animals and fruit-damaging fungi.
Comprehensive national certification schemes for tree seed and plants are now in operation in most countries. The object of these is to maintain and make available to practicing foresters seeds, plants and propagating materials of superior provenances or cultivars and to guarantee their quality.
These national schemes require large seed pools, and so can have a limited impact on the diversity of cultivated varieties. This is a constraint on breeding: both public and private breeders need to be able to multiply their new varieties with a reasonable amount of seed, while maintaining the high standard of seed quality. This requires that some phenotype variation is reduced by selection, cloning or other means.
Clones are cuttings taken from a vegetative mother plant, which makes them an exact genetic copy of the original plant. While clones provide greater security with their genetics, they also require a more complicated growing process.
The cloning process begins with the selection of a healthy plant to take a cutting from. This mother can be purchased from a cannabis breeder or obtained from your current garden. It is important to select a sexless, or hermaphrodite, plant as male plants will produce pollen sacs, which detract from the bud yield.
Once the desired branch is selected, it is cut from the parent plant and immediately placed into a cup of water. Allowing air to reach the cut end for more than a few seconds can result in an irreparable air embolism and damage the clone.
Rooted clones are then planted into soil or a hydroponic medium. It is recommended that you use a balanced plant nutrition solution to help the clones establish roots.
Genetic stability is an important attribute required for the production of regular seed. Seeds age over time, resulting in a loss of viability and quality. This process is associated with different genetic modifications such as point mutations, DNA fragmentation and accumulation of reactive oxygen species (ROS).
A high level of genetic stability in a regular seed crop can be achieved by following strict genetic management practices. These practices include promoting fertility uniformity and synchronization.
In mammalian production cell lines that express a transgene, the genetic stability of the cells is essential. This is evaluated during the molecular characterization of the production cell bank. This is a requirement by regulatory bodies worldwide. Genetic instability results in mutations that may impact the final vaccine product. These mutations can result in the deletion, rearrangement or replacement of genomic sequences that are required for the correct expression of a gene. In addition, they can result in a change in the cell phenotype or expression profile that is not desired for the vaccine product.
As with all living organisms, phenotype variation is the consequence of basic heritable genetic variance and environmental influence. Heritable variation is produced through mutation, gene flow, and sexual reproduction. Environmental influence occurs when individuals move into or out of a population and interact with others in new environments.
Phenotypic variation is an essential part of the evolutionary process. It enables natural selection to function. Without phenotypic variation, there can be no evolution through natural selection.
A good example of phenotypic variation is the coloration of Labrador Retrievers. Although labradors are genetically all the same, they can be any color from black to yellow to brown. This is a result of environmental influences such as food, water, shelter and exposure to the sun. Similarly, the growing conditions of cannabis plants can cause a variation in phenotype. For instance, hermaphroditis can occur if the plant is irrigated with salty water or exposed to intense heat and light.