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Soil gases (soil atmosphere [1]) are the gases found in the air space between soil components. The spaces between the solid soil particles, if they do not contain water, are filled with air. The primary soil gases are nitrogen, carbon dioxide and oxygen. [2] Oxygen is critical because it allows for respiration of both plant roots and soil ...
Aerenchyma in stem cross section of a typical wetland plant. Aerenchyma or aeriferous parenchyma [1] or lacunae, is a modification of the parenchyma to form a spongy tissue that creates spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases between the shoot and the root. [2]
Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
The pineapple is an example of a CAM plant.. Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions [1] that allows a plant to photosynthesize during the day, but only exchange gases at night.
Soil respiration is a key ecosystem process that releases carbon from the soil in the form of CO 2. CO 2 is acquired by plants from the atmosphere and converted into organic compounds in the process of photosynthesis. Plants use these organic compounds to build structural components or respire them to release energy.
For example, when the stomata are closed to prevent water loss during drought: this limits the CO 2 supply, while O 2 production within the leaf will continue. In algae (and plants which photosynthesise underwater); gases have to diffuse significant distances through water, which results in a decrease in the availability of CO 2 relative to O 2.
Plant species with the greatest photosynthetic rates and Kranz anatomy showed no apparent photorespiration, very low CO 2 compensation point, high optimum temperature, high stomatal resistances and lower mesophyll resistances for gas diffusion and rates never saturated at full sun light. [109]
As stems and roots mature lenticel development continues in the new periderm (for example, periderm that forms at the bottom of cracks in the bark). [citation needed] Lenticels are found as raised circular, oval, or elongated areas on stems and roots. In woody plants, lenticels commonly appear as rough, cork-like structures on young branches.