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Marijuana Botany by Robert Connel Clark
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<blockquote data-quote="cannebosanac" data-source="post: 20033" data-attributes="member: 1357"><p>poglavlje 3b nastavak</p><p></p><p>If possible, two or more separate lines are started, never allowing them to interbreed. In this case one acceptable staminate plant is selected along with two pistillate plants (or vice versa). Crosses between the pollen parent and the two seed parents result in two lines of inheritance with slightly differing genetics, but each expressing the desired characteristics. Each generation will produce new, more acceptable combinations. </p><p>If two inbred strains are crossed, F1 hybrids will be less variable than if two hybrid strains are crossed. This comes from limiting the diversity of the gene pools in the two strains to be hybridized through previous inbreeding. Further independent selection and inbreeding of the best plants for several generations will establish two strains which are true-breeding for all the originally selected traits. This means that all the offspring from any parents in the strain will give rise to seedlings which all exhibit the selected traits. Successive inbreeding may by this time have resulted in steady decline in the vigor of the strain. </p><p>When lack of vigor interferes with selecting phenotypes for size and hardiness, the two separately selected strains can then be interbred to recombine nonselected genes and restore vigor. This will probably not interfere with breeding for the selected traits unless two different gene systems control the same trait in the two separate lines, and this is highly unlikely. Now the breeder has produced a hybrid strain that breeds true for large size, early maturation, large sweet-smelling calyxes, and high THC level. The goal has been reached! </p><p>Wind pollination and dioecious sexuality favor a heterozygous gene pool in Cannabis. Through inbreeding, hybrids are adapted from a heterozygous gene pool to a homozygous gene pool, providing the genetic stability needed to create true-breeding strains. Establishing pure strains enables the breeder to make hybrid crosses with a better chance of predicting the outcome. Hybrids can be created that are not reproducible in the F2 generation. Commercial strains of seeds could be developed that would have to be purchased each year, because the F1 hybrids of two pure-bred lines do not breed true. Thus, a seed breeder can protect the investment in the results of breeding, since it would be nearly impossible to reproduce the parents from F2 seeds. </p><p>At this time it seems unlikely that a plant patent would be awarded for a pure-breeding strain of drug Cannabis. In the future, however, with the legalization of cultivation, it is a certainty that corporations with the time, space, and money to produce pure and hybrid strains of Cannabis will apply for patents. It may be legal to grow only certain patented strains produced by large seed companies. Will this be how government and industry combine to control the quality and quantity of "drug" Cannabis? </p><p></p><p>Acclimatization </p><p>Much of the breeding effort of North American cultivators is concerned with acclimatizing high-THC strains of equatorial origin to the climate of their growing area while preserving potency. Late-maturing, slow, and irregularly flowering strains like those of Thailand have difficulty maturing in many parts of North America. Even in a greenhouse, it may not be possible to mature plants to their full native potential.</p><p>To develop an early-maturing and rapidly flowering strain, a breeder may hybridize as in the previous example. However, if it is important to preserve unique imported genetics, hybridizing may be inadvisable. Alternatively, a pure cross is made between two or more Thai plants that most closely approach the ideal in blooming early. At this point the breeder may ignore many other traits and aim at breeding an earlier-maturing variety of a pure Thai strain. This strain may still mature considerably later than is ideal for the particular location unless selective pressure is exerted. If further crosses are made with several individuals that satisfy other criteria such as high THC content, these may be used to develop another pure Thai strain of high THC content. After these true-breeding lines have been established, a dihybrid pure cross can be made in an attempt to produce an F1 generation containing early-maturing, high-THC strains of pure Thai genetics, in other words, an acclimatized drug strain. </p><p>Crosses made without a clear goal in mind lead to strains that acclimatize while losing many favorable characteristics. A successful breeder is careful not to overlook a characteristic that may prove useful. It is imperative that original imported Cannabis genetics be preserved intact to protect the species from loss of genetic variety through excessive hybridization. A currently unrecognized gene may be responsible for controlling resistance to a pest or disease, and it may only be possible to breed for this gene by back-crossing existing strains to original parental gene pools. </p><p></p><p><a href="http://img211.imageshack.us/my.php?image=clipimage015ja5.jpg" target="_blank"><img src="http://img211.imageshack.us/img211/2470/clipimage015ja5.th.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a></p><p></p><p>Once pure breeding lines have been established, plant breeders classify and statistically analyze the offspring to determine the patterns of inheritance for that trait. This is the system used by Gregor Mendel to formulate the basic laws of inheritance and aid the modern breeder in predicting the outcome of crosses, </p><p>1 - Two pure lines of Cannabis that differ in a particular trait are located. </p><p>2 - These two pure-breeding lines are crossed to produce an F1 generation. </p><p>3 - The F1 generation is inbred. </p><p>4 - The offspring of the F1 and F2 generations are classified with regard to the trait being studied. </p><p>5 - The results are analyzed statistically. </p><p>6 - The results are compared to known patterns of inheritance so the nature of the genes being selected for can be characterized. </p><p></p><p>Fixing Traits </p><p>Fixing traits (producing homozygous offspring) in Cannabis strains is more difficult than it is in many other flowering plants. With monoecious strains or hermaphrodites it is possible to fix traits by self-pollinating an individual exhibiting favorable traits. In this case one plant acts as both mother and father. However, most strains of Cannabis are dioecious, and unless hermaphroditic reactions can be induced, another parent exhibiting the trait is required to fix the trait. If this is not possible, the unique individual may be crossed with a plant not exhibiting the trait, inbred in the F1 generation, and selections of parents exhibiting the favorable trait made from the F2 generation, but this is very difficult.</p></blockquote><p></p>
[QUOTE="cannebosanac, post: 20033, member: 1357"] poglavlje 3b nastavak If possible, two or more separate lines are started, never allowing them to interbreed. In this case one acceptable staminate plant is selected along with two pistillate plants (or vice versa). Crosses between the pollen parent and the two seed parents result in two lines of inheritance with slightly differing genetics, but each expressing the desired characteristics. Each generation will produce new, more acceptable combinations. If two inbred strains are crossed, F1 hybrids will be less variable than if two hybrid strains are crossed. This comes from limiting the diversity of the gene pools in the two strains to be hybridized through previous inbreeding. Further independent selection and inbreeding of the best plants for several generations will establish two strains which are true-breeding for all the originally selected traits. This means that all the offspring from any parents in the strain will give rise to seedlings which all exhibit the selected traits. Successive inbreeding may by this time have resulted in steady decline in the vigor of the strain. When lack of vigor interferes with selecting phenotypes for size and hardiness, the two separately selected strains can then be interbred to recombine nonselected genes and restore vigor. This will probably not interfere with breeding for the selected traits unless two different gene systems control the same trait in the two separate lines, and this is highly unlikely. Now the breeder has produced a hybrid strain that breeds true for large size, early maturation, large sweet-smelling calyxes, and high THC level. The goal has been reached! Wind pollination and dioecious sexuality favor a heterozygous gene pool in Cannabis. Through inbreeding, hybrids are adapted from a heterozygous gene pool to a homozygous gene pool, providing the genetic stability needed to create true-breeding strains. Establishing pure strains enables the breeder to make hybrid crosses with a better chance of predicting the outcome. Hybrids can be created that are not reproducible in the F2 generation. Commercial strains of seeds could be developed that would have to be purchased each year, because the F1 hybrids of two pure-bred lines do not breed true. Thus, a seed breeder can protect the investment in the results of breeding, since it would be nearly impossible to reproduce the parents from F2 seeds. At this time it seems unlikely that a plant patent would be awarded for a pure-breeding strain of drug Cannabis. In the future, however, with the legalization of cultivation, it is a certainty that corporations with the time, space, and money to produce pure and hybrid strains of Cannabis will apply for patents. It may be legal to grow only certain patented strains produced by large seed companies. Will this be how government and industry combine to control the quality and quantity of "drug" Cannabis? Acclimatization Much of the breeding effort of North American cultivators is concerned with acclimatizing high-THC strains of equatorial origin to the climate of their growing area while preserving potency. Late-maturing, slow, and irregularly flowering strains like those of Thailand have difficulty maturing in many parts of North America. Even in a greenhouse, it may not be possible to mature plants to their full native potential. To develop an early-maturing and rapidly flowering strain, a breeder may hybridize as in the previous example. However, if it is important to preserve unique imported genetics, hybridizing may be inadvisable. Alternatively, a pure cross is made between two or more Thai plants that most closely approach the ideal in blooming early. At this point the breeder may ignore many other traits and aim at breeding an earlier-maturing variety of a pure Thai strain. This strain may still mature considerably later than is ideal for the particular location unless selective pressure is exerted. If further crosses are made with several individuals that satisfy other criteria such as high THC content, these may be used to develop another pure Thai strain of high THC content. After these true-breeding lines have been established, a dihybrid pure cross can be made in an attempt to produce an F1 generation containing early-maturing, high-THC strains of pure Thai genetics, in other words, an acclimatized drug strain. Crosses made without a clear goal in mind lead to strains that acclimatize while losing many favorable characteristics. A successful breeder is careful not to overlook a characteristic that may prove useful. It is imperative that original imported Cannabis genetics be preserved intact to protect the species from loss of genetic variety through excessive hybridization. A currently unrecognized gene may be responsible for controlling resistance to a pest or disease, and it may only be possible to breed for this gene by back-crossing existing strains to original parental gene pools. [URL="http://img211.imageshack.us/my.php?image=clipimage015ja5.jpg"][IMG]http://img211.imageshack.us/img211/2470/clipimage015ja5.th.jpg[/IMG][/URL] Once pure breeding lines have been established, plant breeders classify and statistically analyze the offspring to determine the patterns of inheritance for that trait. This is the system used by Gregor Mendel to formulate the basic laws of inheritance and aid the modern breeder in predicting the outcome of crosses, 1 - Two pure lines of Cannabis that differ in a particular trait are located. 2 - These two pure-breeding lines are crossed to produce an F1 generation. 3 - The F1 generation is inbred. 4 - The offspring of the F1 and F2 generations are classified with regard to the trait being studied. 5 - The results are analyzed statistically. 6 - The results are compared to known patterns of inheritance so the nature of the genes being selected for can be characterized. Fixing Traits Fixing traits (producing homozygous offspring) in Cannabis strains is more difficult than it is in many other flowering plants. With monoecious strains or hermaphrodites it is possible to fix traits by self-pollinating an individual exhibiting favorable traits. In this case one plant acts as both mother and father. However, most strains of Cannabis are dioecious, and unless hermaphroditic reactions can be induced, another parent exhibiting the trait is required to fix the trait. If this is not possible, the unique individual may be crossed with a plant not exhibiting the trait, inbred in the F1 generation, and selections of parents exhibiting the favorable trait made from the F2 generation, but this is very difficult. [/QUOTE]
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