High-precise determination of the drought and cold resistance of forage seeds using terahertz time-domain...

Owing to the complicated geographical locations and climates, cultivation and selection of forage seeds are challenging. For the first time, we qualitatively distinguished the drought and cold resistance of forage seeds with the time domain and refractive index spectra using terahertz (THz) time-domain spectroscopy. A multilayer structure propagation (MSP) model was developed based on the effective medium and light transport theory to reveal the underlying biological mechanisms of drought and cold resistance of forage seeds. The proposed MSP model accurately explained the behavior of the THz waves transmitted through the forage seeds, with a high accuracy rate of 94.433%. The impact of THz wave transmission was influenced by the presence of various biological components in the alfalfa seeds, particularly protein and carbohydrate. More interestingly, the cold and drought resistance of forage seeds can be effectively differentiated with the ratio of the thickness-dependent argument parameter (Ψ) of protein and carbohydrate components. The obtained results offered important insights into the interaction mechanism between THz wave and forage seeds, and proposed a promising MSP model in the screening process for selecting high-quality forage seeds based on their stress resistance characteristics.