PlantDefenses213-page2

PlantDefenses213-page2 - Plant Stress and Defense...

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Plant Stress and Defense Mechanisms - 2 Oxygen We mentioned in our root structures section the specialized roots, pneumatophores, that many swamp trees have to obtain oxygen in waterlogged soils. Some plants, such as cattails, have large air spaces in their stems and leaves so that oxygen can more readily diffuse towards roots. An in some experimental situations, plants respond to water-logged substrate with development of air spaces within the stem tissue. Unfortunately, many house plants die of suffocation when pots are set in saucers and water is allowed to sit in the saucer, causing the soil to become waterlogged. Such plants cannot develop adequate aeration. Heat Plants have poor heat-regulating mechanisms. Their metabolism, in particular, can be seriously impacted by hot temperatures. Although transpiration cools the plant through evaporation, when it’s hot the plant is most likely to have a water deficit, closing stomata, and that shuts down transpiration. Plants synthesize a class of
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