Vapor Pressure Deficit Response

Vapor Pressure Deficit (VPD) response describes how cannabis plants regulate volatile terpene expression and stomatal behavior in relation to humidity and temperature gradients. Plants experiencing low VPD (high humidity, low temperature differential) often exhibit reduced volatile emission and altered secondary metabolite profiles compared to those in high VPD conditions. Breeders and cultivators observe that certain genetics show more stable or enhanced terpene output across varying VPD ranges, while others display pronounced phenotypic drift. This trait is environmentally responsive rather than fixed, meaning the same genotype may express different aromatic profiles under different VPD conditions. Understanding VPD response helps breeding programs select for cultivars suited to specific climate zones or controlled-environment systems.

Breeders working in high-humidity or low-humidity regions prioritize genetics with consistent terpene stability across VPD fluctuations. Selecting for VPD resilience improves crop predictability and reduces aroma-profile variance in commercial cultivation.