Effect of Corona Treatment and Dielectric Separation on Seed Vigor of Hybrid Rice

[Objectives] The aim was to investigate the effects of corona field and dielectric separation on the seed vigor of hybrid rice.[Methods] The seeds of 6 hybrid rice varieties were processed with corona field, dielectric separation and corona field ＋ dielectric separation.[Results] When the field intensity was 200 km/m and the processing time was 4 min, the seed vigor was significantly increased. The seed vigor of Y Liangyou 9918 （2014） increased the most, and the germination potential and the germination rate increased by 17 and 12 percentage points respectively compared to the control. Corona field reduced seed conductivity, and for seedlings, it decreased their MDA content, increased proline content, improved peroxidase activity, and enhanced root activity. When the rotating speed of the drum was 30 r/min, the dielectric separation voltage of 4 500 V could achieve good separation effect, and the vitality of seeds at different grades was significantly different. Under the optimized corona field combined with optimized voltage processing of dielectric separation, the seed vigor at all grades from the separation was significantly higher than that of the dielectric separation processing alone. The combined separation processing separated no seeds with germination rate of higher than 80% from the hybrid rice seeds with germination rate of lower than 60%, yet it could effectively separate the seeds with germination rate of higher than 80% from the hybrid rice seeds with germination rate of 65%-70%. After the combined processing, the germination rates of separated Grade I seeds of Wangliangyou 6 （2015）, N Liangyouhuazhan （2015）, Wangliangyou 6 （2016） increased by 20, 15, 20 percentage points from the germination rates of the control, while the germination rates of N Liangyouhuazhan （2016） and Y Liangyou 9918 （2016）, which had the germination rates of higher than 80%, increased by 3 and 9 percentage points from the control, suggesting insignificant separation effect.[Conclusions] This study provided a new technical approach for the processing of hybrid rice seeds.

Development of a dimensionless parameter for characterization of dielectric barrier discharge devices with respect to geometrical features

Non-thermal plasma（NTP） devices produce excited and radical species that have higher energy levels than their ground state and are utilized for various applications. There are various types of NTP devices, with dielectric barrier discharge（DBD） reactors being widely used. These DBD devices vary in geometrical configuration and operating parameters, making a comparison of their performance in terms of discharge power characteristics difficult. Therefore, this study proposes a dimensionless parameter that is related to the geometrical features, and is a function of the discharge power with respect to the frequency, voltage, and capacitance of a DBD. The dimensionless parameter, in the form of a ratio of the discharge energy per cycle to the gap capacitive energy, will be useful for engineers and designers to compare the energy characteristics of devices systematically, and could also be used for scaling up DBD devices.From the results in this experiment and from the literature, different DBD devices are categorized into three separate groups according to different levels of the energy ratio. The larger DBD devices have lower energy ratios due to their lower estimated surface discharge areas and capacitive reactance. Therefore, the devices can be categorized according to the energy ratio due to the effects of the geometrical features of the DBD devices, since it affects the surface discharge area and capacitance of the DBD. The DBD devices are also categorized into three separate groups using the Kriegseis factor, but the categorization is different from that of the energy ratio.