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EFFECT OF LIGHT INTENSITY ON PHOTOSYNTHESIS/RESPIRATION RELATIONS OF
SUN VERSUS SHADE PLANTS
   
Relationship between Photosynthesis, Respiration and Light Intensity
Photosynthesis makes fixed carbon compounds and respiration burns fixed carbon compounds.  At light intensities above the photosynthesis light saturation range (1,200-2,000 ft-c), the rate of photosynthesis is much higher than the rate of respiration, up to 10-times higher.  Thus, plants produce a great excess of fixed carbon.  But, as the light intensity decreases the rate of photosynthesis goes down.  Eventually, a light intensity is reached where the rates of photosynthesis and respiration are equal; this is called the light compensation point.  At light intensities below the light compensation, the plant is starved because its rate of photosynthesis is less than its rate of respiration.

Why do Shade or Acclimatized Plants Grow Well At Low Light Intensities
The relationships discussed in the figure above apply to sun plants, which are plants that grow best at very high light intensities.  Shade plants grow best at lower light intensities, such as would be found on a forest/jungle floor.  Notice in the figure below, the shade plants have: a) a lower maximum photosynthesis rate, b) a lower light saturation range, but  most importantly c) a lower light compensation point.  Thus, shade plants are adapted to grow best at lower light intensities, which is why they make good indoor plants.  An acclimatized plant is a sun plant that is "conditioned" to behave like a shade plant.