Pre-sowing Treatment Using Plasma-Activated Water to Enhance the Germination of Cucumber Seeds Under Salt Stress

The present work is focused on the effects on the germination of cucumber seeds by plasma activated water (PAW) treatment in simulated saline environment, to evaluate the improvement on the saline tolerance of cucumber seeds from PAW treatment. PAW was prepared by self-made gas–liquid two-phase underwater pulsed spark discharge plasma reactor, which was driven by self-made microsecond bipolar pulse power at constant frequency of 100 Hz. The processing durations of PAW was set as 0, 10, 20, and 30 min, respectively. The detection indicators were chosen as physical characteristics including oxidation reduction potential, pH and electrical conductivity and chemical parameters including nitrates and hydrogen peroxide. The germination experiment of cucumber seeds was performed after immersing in PAW processed for different durations, and during the experiment the seeds were kept wet by PAW processed for the same duration. The saline environments were simulated by different concentrations of NaCl solution. The germination of cucumber seeds was recorded every 12 h. The images of surface morphology was captured by scanning electron microscope to observe the changes of seeds due to immersing in PAW. The result showed that the improvement of germination of seeds treated by PAW processed for 10 min was most significantly, of which the germination rate and the mean germination time in various simulated salt environment were improved quite a lot. This work provides a new direction of a promising seed pretreatment research and application in saline environments.