Raman-based diagnostics of drought, heat and light-induced stresses in three different varieties of hemp

Main conclusion Hand-held Raman spectroscopy can be used for highly accurate differentiation between drought, heat and light-triggered stresses in hemp. The differentiation is based on the changes in the biochemistry of plants caused by such stresses. Hemp farming is a rapidly growing industry. This dioecious plant is primarily cultivated for its fibers, seeds, and cannabinoid-rich oils. The yield of these materials can be drastically lowered by many abiotic stresses, such as drought, heat and light. It becomes critically important to develop robust and reliable approaches that can be used to diagnose such abiotic stresses in hemp. In this study, we investigate the accuracy of Raman spectroscopy, an emerging tool within crop monitoring, in the confirmatory identification of drought, heat, and light-induced stresses in three varieties of hemp. Our results showed that mono, double and triple stresses uniquely alter plant biochemistry that results in small spectroscopic changes detected in the Raman spectra acquired from the hemp leaves. These changes could be used for the 80–100% accurate identification of individual abiotic stresses and their combinations in plants. These results demonstrate that a hand-held Raman spectrometer can be used for highly accurate, non-invasive, non-destructive, and label-free diagnostics of hemp stresses directly in the greenhouse or in the field.