Plants are threatened by many biologically harmful aspects of the physical environment, such as drought, waterlogged soils, and extreme temperatures (Table 38.2). Plants cope with environmental stresses through adaptation or acclimation.
| Condition | Effect on plants |
|---|---|
| Drought | Reduced water potential, dehydration |
| Flooding | Reduced O2 and respiration |
| High temperature | Changes in membrane fluidity and in proteins |
| Low temperature | Changes in membrane fluidity, damage by ice crystals |
| Salinity | Reduced water potential, dehydration |
| Metal element toxicity | Disruption of metabolism |
Adaptation is genetically encoded strategy for maximizing survival and reproduction in a particular environment. A plant may have structures or biochemical properties that aid in its survival in the face of environmental challenges. Adaptations are the result of evolution by natural selection.
Acclimation is increased tolerance for environmental extremes because of prior exposure to them. An individual plant previously exposed to extreme cold, for example, may be more likely to survive the subsequent winter.
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Plants living in water-
Most plant responses to drought are constitutive, but under extreme conditions plants rely on inducible responses.
Only certain plants, called halophytes, are adapted to salty soils; they are able to take up and excrete excess salt.
Phytoremediation takes advantage of hyperaccumulators (plants that take up heavy metals) to clean up toxic environments.
Media Clip 38.2 Leaves for Every Environment
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