Circadian Expression

Circadian Expression refers to the temporal variation in volatile organic compound (VOC) production throughout a 24-hour cycle in cannabis plants. Terpene and aromatic compound concentrations—including limonene, pinene, and myrcene—can fluctuate significantly based on light-dark cycles and circadian rhythms in the plant's physiology. This phenomenon is well-documented in cannabis cultivation research, where harvest time and sampling methodology directly impact measured aroma profiles. Breeders and researchers working with regulated genetics have observed that the same cultivar may express different dominant terpenes depending on collection timing. Understanding circadian expression is essential for accurate phenotyping, breeding stock selection, and standardized testing protocols.

Breeders tracking circadian expression patterns use time-controlled sampling to establish true aromatic baselines for a cultivar, preventing misattribution of traits across generations. Selecting for stable, consistent VOC production across varying light conditions helps develop more predictable commercial varieties.