Classification of organisms according to temperature tolerance and regulationnd
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Although both plants and animals experience and exist within the same external energy environment, there exist fundamental differences. Plants cannot move to escape adverse effects of heat or cold, and their metabolic heat is derived from absorbed solar rays.
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Plants has been divided into the following four categories on the basis of their heat tolerating capacity : (i) Megatherms: plants growing in regions where high temperatures prevail throughout the year, e.g., desert vegetation and tropical rain forests, (ii) Mesoderms: plants of the regions where high temperature alternating with low temperature, e.g., tropical deciduous forests and aquatic plants, (iii) Microtherms: plants of the regions where low temperature prevail throughout the year, e.g., mixed coniferous forests, (iv) Hekistotherms: plants growing in regions with very low temperature, e.g., alpine vegetation.
Except for the time they sprout from seeds or vegetative cuttings, plants receive all of their energy from radiation in the environment and from convection. To balance the input, plants lose heat by radiation, convection and evapotranspiration. They have some control over the latter by opening and closing the stomata and by changing the shape and position of the leaf.
Further, the ability to endure low temperature extremes varies among plants. They are not equally resistant at all stages of the life cycle. Flowers are more sensitive to low temperatures than are fruits and leaves, and young leaves are more resistant than old ones. Trees may be more severly injured than herbaceous plants. In general, adaptations among plants to endure low temperatures are primarily protoplasmic (Smith, 1977).
On the basis of temperature tolerance, fungi have also been classified into the following three kinds: thermotolerant, thermophilic and mesophilic fungi (R. Emerson, 1968), Thermophilic fungi require optimum temperature 45°C for growth and they occur in man-made self-heated habitats and also in natural habitats where geothermal heat, body heat of warm blooded animals, microbial metabolism and perhaps sun heating provide elevated temperature required for their growth. Thermophilic fungi has been reported in nesting material of American alligator (Tansey, 1973) and of birds. T. Satyanarayana, B. N. Johri and S. B. Saksena (1977) have reported the occurrence and seasonal variation of mycoflora of nesting material of the following Indian birds: crow (Corvus splendens), house sparrow (Passer domesticus), pipit (Anthus rufulus), bee-eater (Merops superviliesus) and crow-pheasant (Centropus sinensis).
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Plants has been divided into the following four categories on the basis of their heat tolerating capacity : (i) Megatherms: plants growing in regions where high temperatures prevail throughout the year, e.g., desert vegetation and tropical rain forests, (ii) Mesoderms: plants of the regions where high temperature alternating with low temperature, e.g., tropical deciduous forests and aquatic plants, (iii) Microtherms: plants of the regions where low temperature prevail throughout the year, e.g., mixed coniferous forests, (iv) Hekistotherms: plants growing in regions with very low temperature, e.g., alpine vegetation.
Except for the time they sprout from seeds or vegetative cuttings, plants receive all of their energy from radiation in the environment and from convection. To balance the input, plants lose heat by radiation, convection and evapotranspiration. They have some control over the latter by opening and closing the stomata and by changing the shape and position of the leaf.
Further, the ability to endure low temperature extremes varies among plants. They are not equally resistant at all stages of the life cycle. Flowers are more sensitive to low temperatures than are fruits and leaves, and young leaves are more resistant than old ones. Trees may be more severly injured than herbaceous plants. In general, adaptations among plants to endure low temperatures are primarily protoplasmic (Smith, 1977).
On the basis of temperature tolerance, fungi have also been classified into the following three kinds: thermotolerant, thermophilic and mesophilic fungi (R. Emerson, 1968), Thermophilic fungi require optimum temperature 45°C for growth and they occur in man-made self-heated habitats and also in natural habitats where geothermal heat, body heat of warm blooded animals, microbial metabolism and perhaps sun heating provide elevated temperature required for their growth. Thermophilic fungi has been reported in nesting material of American alligator (Tansey, 1973) and of birds. T. Satyanarayana, B. N. Johri and S. B. Saksena (1977) have reported the occurrence and seasonal variation of mycoflora of nesting material of the following Indian birds: crow (Corvus splendens), house sparrow (Passer domesticus), pipit (Anthus rufulus), bee-eater (Merops superviliesus) and crow-pheasant (Centropus sinensis).
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