RESPIRATION RATE

Oxygen: % in the air.

Temperature: Low/high.

Describe how these factors affect the rate of aerobic respiration.

Oxygen: If the % of oxygen is reduced, the rate of respiration drops; If the process is aerobic it needs the normal air % of oxygen. This is normally supplied by such things as having a good air change rate in greenhouses/good air filled porosity ratio of potting compost/well drained soils/soils not compacted; Under conditions where oxygen is missing the respiration becomes anaerobic. This can happen in capped compost heaps resulting in smelly, slimy compost and in water logged conditions of the soil. If this is prolonged, roots can be damaged/areas of lawns or crops go yellow (due to root damage by the chemicals building up in the soil to toxic levels/alcohols).

Temperature: As the temperature raises the rate of cell metabolism, so the rate of respiration increases. But if the plant gets too hot the process of respiration shuts down (hot air temperature as well as internal plant temperature); 5ºC minimum – below which respiration is very slow; 30ºC optimum; 40ºC maximum – above which respiration ceases; Depending on the plant species. `

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