The light compensation point is the light intensity at which a leaf fixes exactly as much CO2 through photosynthesis as it releases through respiration. Below it the leaf is a net consumer of sugars; above it the leaf is a net exporter. For sun-adapted crops it typically sits in the tens of µmol/m²/sbeing reviewed. It rises with temperature, because respiration speeds up faster than photosynthesis.
In practice
The idea explains why deep, shaded lower growth contributes little. Leaves and bud sites sitting in heavy shade at the bottom of a dense canopy may be near or below their compensation point for much of the day, so they consume more than they produce. That is the logic behind lollipopping and removing the lowest larf.
It is also a reason not to over-strip. A leaf receiving moderate light is still a net producer feeding nearby buds. GenetixBay's preference is "tuck, don't pluck": train and tuck leaves to open light paths before removing working leaves.
Don't confuse with
- Light saturation point: the high end, where extra light stops helping.
- CO2 compensation point: the CO2 concentration at which photosynthesis balances respiration at a given light level.
