Nanosecond Pulsed Atmospheric-Pressure Plasma Enhanced the Germination of Melon ( Cucumis melo L.) Seeds

Melon ( Cucumis melo L.) is a nutritious fruit with high economic value. As melon seeds have a relatively thick shell, they are susceptible to bacterial pathogens, seed germination is slow and seedling growth is compromised. This research employed a dielectric barrier discharge (DBD) array electrode structure plasma with nanosecond pulse stimulation to promote the germination of melon seeds at room temperature. The effects of applied voltage and discharge time on seed germination were investigated. Under the conditions of 22 kV applied voltage and 1.5 min discharge duration, the germination potential of melon seeds increased by 47%, the germination rate improved by 14%, the seed vigor index expanded by 91%, and the average root length increased by 59%. The scanning electron microscope (SEM) demonstrates that plasma treatment induces strong corrugation of the seed shell surface and greatly reduces the content of pathogenic microorganisms. The water contact angle showed that the nanosecond pulse discharge enhanced the water uptake of seedlings. The attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy results revealed that the increased hydrophilicity of the seed shell may be due to the formation of the functional group C=O carbonyl, thus accelerating seed germination at low temperatures. This study indicates that plasma-assisted breeding is a viable strategy before melon planting.