Hibernation of Plants
The Hibernation is a mechanism that allows many animals escape the cold and lack of food during the winter. Hibernation is more predictive than consistent. An animal prepares for hibernation by increasing the fatty tissue layer during late summer and autumn, it provides energy during the dormancy period. During hibernation the animal undergoes many physiological changes, including decreased heart rate (up to 95%) and decreased body temperature . Among the animals that hibernate are the bats , woodchucks and other rodents, mouse lemurs, the common European Hedgehog and other insectivores , monotremos and marsupials .
The diapause is a strategy which is genetically predetermined predictive. Diapause is common in many insects, allowing them to suspend development between winter and spring and in mammals such as the European red deer , in which the embryo implantation in the uterus takes time, allowing the baby born in the spring when conditions are more favorable.
The aestivation is an example of consequential dormancy occurs in response to very hot or dry conditions. It is common in invertebrates such as snails of the genus Helix and earthworms , but can also occur in other animals such as the lungfish .
The brumación is an example of dormancy in reptiles , similar to hibernation. 1 2 differs from hibernation in the metabolic processes involved. 3
Reptiles generally begin the brumación late fall, the specific date varies by species. They often wake up to drink and go back to sleep. They can feed at this stage but may go for months without food. Reptiles may want to eat more than usual just before the brumación, but when the temperature drops just eat less or nothing. But need to drink water. The brumación is a period of one to four months depending on ambient temperature, age, size and health of the reptile. During the first year of life in many reptiles do not make a complete brumación simply reduce their activity and feeding. The brumación not be confused with hibernation. In mammals , when hibernate, sleep truly live their fat reserves and their metabolism decreases to the point they do not need to eat. During brumación, the activity decreases and reptiles need to eat less. Some reptiles can go all winter without eating. The brumación is activated by cold (no heat) and reduced daylight hours during winter.
In plant physiology dormancy is the resting state of the plant growth. It is a strategy of many species of plants that allows them to survive when weather conditions are not suitable for growth, and during the winter or dry season.
Plants that exhibit dormancy have a biological clock that follows the circadian cycle , informing them that reducing the activity of living tissues in preparation for a period of frost or water shortages. After a period of normal growth, dormancy comes because of the shorter days, falling temperatures and reduced rainfall.
When a seed is in favorable conditions but does not germinate is said to be sleeping. 4 There are two basic types of seed dormancy. The first is called the seed coat dormancy or external dormancy, which is caused by the presence of a hard cover that protects the seed and prevents ingress of water or oxygen to the embryo , so it can not be activated. The second type is called embryo dormancy or internal dormancy which is caused by the condition of the embryo that does not allow germination . (Black M, Butler J, Hughes M. 1987). The oldest seed that has come to germinate and produce a viable plant is the fruit of lotus recovered from the dry lakebed in northeastern China. Its age is estimated at 1300 years.
Many species of trees are well developed dormancy that can be artificially reduced to some extent but never completely. For example, if the Japanese maple ( Acer palmatum ) is given an eternal summer through manipulation of the daylight hours grow continuously for two years at most. However, eventually sink into dormancy regardless of conditions. Plants deciduous lose their leaves, evergreen reduce regrowth. Pass through a forced eternal summer and enter a dormant automatic below is very stressful for the plant and may even be fatal. The mortality rate can approach 100% if the plant does not go through a period of low temperature required to exit dormancy. Most plants require a certain number of hours of cold with temperatures between 0 ° C and 10 ° C to get out of dormancy (Bewley JD, Black M. (1994).
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