TLS Online TPP Program

#Id: 4988

#Unit 6. System Physiology – Plant

As shading increases, the R:FR ratio decreases.

TLS Online TPP Program

#Id: 4989

#Unit 6. System Physiology – Plant

The greater proportion of far-red light converts more Pfr to Pr, and the ratio of Pfr to total phytochrome (Pfr/Ptotal) decreases.

TLS Online TPP Program

#Id: 4991

#Unit 6. System Physiology – Plant

When stimulated natural radiation was used to vary the far-red content, it was found that for so-called sun plants, the higher the far-red content (i.e., the lower the Pfr:Ptotal ratio), the higher the rate of stem extension.

TLS Online TPP Program

#Id: 4992

#Unit 6. System Physiology – Plant

For a “sun plant” or “shade-avoiding plant” there is a clear adaptive value in allocating its resources toward more rapid extension growth when it is shaded by another plant.

TLS Online TPP Program

#Id: 4993

#Unit 6. System Physiology – Plant

It can enhance its chances of growing above the canopy and acquiring a greater share of unfiltered, photosynthetically active light.

TLS Online TPP Program

#Id: 4994

#Unit 6. System Physiology – Plant

To favoring internode elongation is usually reduced leaf area and reduced branching, but at least in the short run this adaptation to canopy shade seems to work.