This reaction produces energy in the form of heat. Respiration is a basic reaction of all plant material, both in the field and after harvest. It is a continuing process in the growing plant as long as the leaves continue to make carbohydrates, and cannot be stopped without damage to the growing plant or harvested produce. Fresh produce cannot replace carbohydrates or water after harvest. Effect of air supply on respiration .
Respiration depends on a good air supply.
Air contains about 20 percent of the oxygen essential to normal plant respiration, during which starch and sugars are converted to carbon dioxide and water vapour. When the air supply is restricted and the amount of available oxygen in the environment falls to about 2 percent or less, fermentation instead of respiration occurs. Fermentation breaks down sugars to alcohol and carbon dioxide, and the alcohol produced causes unpleasant flavours in produce and promotes premature ageing. The effect of carbon dioxide on respiration . Poor ventilation of produce because of restricted air supply leads also to the accumulation of carbon dioxide around the produce.