Dormancy
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Dormancy reproduction |
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The dormancy is a form of dormancy (retardation). It occurs in both plants and animals. In the case of animals, one speaks of egg rest or presentation time .
Dormancy in plants
In plants of the temperate climate, the dormancy of the mature seeds is the rule. Through this protective mechanism of the plants, the climatic seasonality is taken into account to the effect that the germination takes place at a favorable season and the seedling finds optimal growth opportunities.
The duration of the dormancy is very different for the individual plant species, as are the factors that lead to the degradation of the dormancy. The following influencing factors should be mentioned: humidity, temperature fluctuations, lighting conditions and nutrient medium (soil).
The dormancy must be over when seeds are placed in the seedbed . While the dormancy of rye ends only a few days after ripening, it is several weeks for wheat and barley , and apple kernels only germinate after being exposed to winter frost. The artificial degradation of the dormancy is called stratification in this case .
Dormancy in animals
In animals, dormancy describes the phenomenon that a fertilized egg cell of a mammal does not immediately develop continuously into an embryo . The fertilized egg ( zygote ) nests in the uterine lining , but does not initially divide. Only after the dormancy does normal embryonic development begin. The resulting prolonged gestation period allows the birth during a favorable for the breeding season .
In the case of deer, for example, fertilization occurs during the leaf season at the end of July. But embryonic growth does not begin until the end of November. This means that the fawns are planted in spring (around May) with plenty of vegetation. In Europe , the dormancy occurs regularly not only in deer but also in badgers , martens , ermines , seals , otters and brown bears . The dormancy of marsupials is particularly long in relation to the actual gestation period .
See also
literature
- Ernst Klapp : Textbook of arable and crop production . 5 edition. Parey, Berlin 1958.