Study: Melatonin and Zinc Oxide Nanoparticles Boost Growth, Stress Tolerance, and Cannabinoid Production in Cannabis sativa

The study was published in the journal Plant Nano Biology and examined how these compounds interact under controlled greenhouse conditions. The researchers tested melatonin alongside zinc oxide nanoparticles at concentrations of 5 and 10 parts per million, both individually and in combination. While zinc oxide nanoparticles emerged as the primary driver of growth-related improvements, melatonin played a key role in reducing oxidative stress and selectively influencing secondary metabolites. Plants receiving the combined treatment showed higher shoot and root biomass, improved water retention, stronger membrane stability, and increased photosynthetic pigments compared to untreated controls.

Measures of oxidative stress, including hydrogen peroxide and malondialdehyde, were substantially lower in treated plants. The most pronounced reductions were observed when melatonin was paired with zinc oxide nanoparticles, indicating an additive protective effect against cellular damage. These improvements in stress regulation coincided with marked increases in secondary metabolites, including flavonoids, phenolics, alkaloids, cannabidiol, and tetrahydrocannabinol.

Zinc oxide nanoparticles were especially effective at increasing cannabinoid levels, with cannabidiol rising by more than 120% at the highest concentration tested. Melatonin alone reduced tetrahydrocannabinol levels while increasing cannabidiol, suggesting a selective influence on cannabinoid biosynthesis. The treatments also enhanced the accumulation of essential nutrients such as potassium, magnesium, iron, manganese, and zinc, further supporting overall plant performance.

The findings suggest that combining zinc oxide nanoparticles with melatonin may offer a practical strategy to improve cannabis productivity and biochemical quality. According to the researchers, future work should examine long-term effects, field-scale applications, and the molecular mechanisms behind selective cannabinoid regulation.