Predicting Stem Elongation and Leaf Expansion: Percent far-red is a better predictor than PPE - With Dr. Bruce Bugbee

[GMO]

In this video Dr. Bruce Bugbee explains why the measurement of percent far-red photons can be a better predictor of stem elongation and leaf expansion than the phytochrome photo-equilibrium (PPE). Measuring and controlling this is critical in crops grown under electric grow lights like leafy greens and cannabis.

Phytochrome photo-equilbrium (PPE) has long been a standard measurement in photobiology research, but the phytochrome molecule is shielded by multiple layers of chlorophyll and thus responds to transmitted photons more than incident photons. Recent studies under diverse LED spectral quality have found that stem elongation is poorly predicted by the PPE. In these studies, a simple measurement of percent far-red photons better predicted stem elongation and leaf expansion.