SUN VERSUS SHADE PLANTS
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.
