basis of the success of any breeding - genetic diversity of material and selection methods.The use of such raw materials allows to obtain new hybrids and varieties, with a variety of characteristics and properties.Breeding Basics laid famous scientists in the world:
- Mendel (laid the foundations of genetics, discovered the principle of the discreteness);
- Darwin (founded theory of the origin, spent a lot of experiments on the crossing);
- T. Fairchild (in 1717 received the first artificial hybrids carnations);
- I. Gerasimov (discovered change in the number of nuclei and hereditary changes associated with mutation);
- MF Ivanov (introduced genetic principles in the breeding of animals);
- Koltsov (create a basis for molecular genetics).
- Vavilov (discovered the law of homologous series);
- Michurin (brought a lot of fruit hybrids).
main methods of selection of plants and animals have been developed on the basis of all previous discoveries and improved ever since.Breeders in their work using different selection methods: inbreeding, artificial mutagenesis, polyploidy, hybridization.Here are the most commonly used methods for breeding new plant varieties and animal breeds.
main plant breeding techniques: hybridization and selection.Cross-pollinated plant selektsioniruyut by mass selection of those individuals that have desirable properties.For the most pure lines, that is, the genetic uniformity of the variety, using the individual selection, in which self-pollination is achieved by obtaining the progeny of a single individual that has all the best features.The disadvantage of this method is the fact that this is often observed adverse manifestations of recessive genes.The main reason for this is to move a large number of genes in the homozygous state.Over time, the accumulation of recessive mutant genes, passing in the homozygous state, can cause adverse hereditary changes.Under natural conditions, self-pollinating plants recessive genes transferred into a state of homozygotes and a plant quickly dies.
When using the method of self-pollination is often reduced productivity.To improve its conduct cross-pollination of different self-pollinating plant lines and get high-yielding hybrid.Such methods are called selection of interlinear hybridization.The highest yields have the first generation hybrids.At the same time there is a well-known effect of heterosis, according to which, when crossed "clean" lines obtained powerful hybrids.They are resistant to adverse effects, because they eliminated the harmful effects of recessive genes, and the strong association of dominant genes enhances the effect of the parent plants.
often in breeding different plants using experimental polyploidy.Thus obtained plants have large size, provide a good harvest, and growing rapidly.Artificial polyploids obtained under the influence of chemicals that deplete the division spindle.As a result, the chromosomes are doubled in a single core.
New varieties and output using artificial mutagenesis.An organism that by mutation have new properties, has weak viability, however is eliminated by natural selection.For the selection and evolution of new varieties and breeds essential rare individuals with a neutral or favorable mutations.
animal breeding methods do not differ from the basic methods of plant breeding.Working with them - their sexual reproduction and few offspring.The selection of the type of parents and crosses carried with certain objectives set by the breeder.All animals received an assessment not only of their external characteristics, but also on the quality and origin of offspring.Therefore, it is important to know their ancestry.The selection is most often used are 2 ways of crossing:
- inbreeding (closely related) - crossed parents, sisters, brothers.This crossing can not be held indefinitely.It is used generally for improving the properties of the formation;
- outbreeding (an irrelevant) - Representatives of one or crossing different breeds, and strict selection of offspring with better properties.
hybridization of animals is much less effective than the hybridization of plants.Such interspecific hybrids are often fruitless.
