7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Effect of Dielectric Barrier Discharge Plasma on Rice (Oryza sativa L.) SeedPriming

E. G. Ramirez1,2, J. D. Rey3, M. R. Vasquez Jr.2
1
College of Engineering and Agro-Industrial Technology, University of the Philippines Los Baños,
2
Department of Mining, Metallurgical, and Materials Engineering, College of Engineering,
University of the Philippines Diliman, 3 Institute of Biology, College of Science, University of thePhilippines Dilimane-mail (speaker): egramirez@up.edu.phIn the Philippines, rice is an important crop and isconsidered as a staple food. However, yield, high cost ofinput, low price of palay, lack of post-harvest facilities,
climate change, are some of the continuing challenges forfarmers.[1] Alternative technologies are being sought toaddress some of these challenges. Atmospheric plasma iscurrently being explored with its application to agriculture.
During the pre-harvest stage, decontamination,germination, and growth improvement are observed.
Meanwhile, in the post-harvest stage, preservation anddecontamination are common use of atmosphericplasma.[2]In this study, plasma technology is explored for
agricultural application. The effect of plasma treatment on
Oryza sativa L. seed germination was investigated using
a custom-designed dielectric barrier discharge (DBD)
system. The system was composed of two glass slides
acting as the dielectric barrier with a surface-to-surface
gap of 5 mm. Aluminum electrodes were attached to theouter surface of the glass, where the neon power supply
was connected. Plasma treatment was conducted in an
argon-filled chamber kept at atmospheric pressure. The
rice seeds were placed between the dielectric barrierswhen exposure to discharge was done. NSIC Rc 222 orTubigan 18 from the International Rice Research Institute
was used for testing. Seeds were exposed to plasma atdifferent times (5, 10, 20, and 30 s). The effect of plasma
treatment to the seeds was evaluated using germination
parameters (germination percentage, germination speed,and vigor index) after 7 days.

The maximum temperature of the custom-designed
DBD system was classified as nonthermal and allowable
for the rice seeds with a moisture content of 15% orless.[3,4] The plasma treatment process improved thewettability of the seed surface. There was a decrease inapparent contact angle to the plasma-treated seeds
compared to the untreated seeds. Moreover, surface
roughness of the seed has decreased due to the removal ofnodes causing the surface to become more hydrophilic. In
connection with this, water absorption was improved with
the increase of wettability. There was a slight increase in
the germination percentage for 5, 10, 20s exposure time.
Germination speed has increased for the 5 and 20sexposure time. Lastly for the vigor index, there was asignificant difference with the 20s treatment time.
However, results showed that prolonged exposure of theseeds in the used system becomes detrimental to the riceseeds. This work is supported by DOST-SEI & ERDT forthe research grant and was conducted in PMIL at
DMMME as the workstation for testing.
References[1] GRiSP, Rice Almanac. (2013)[2] P. Attri et al, Processes. 8 (2020)[3] J. Žigon et al, Holzforschung. 72 (2018)[4] K. J. Whitehouse, et al, Seed Science Research. 27(2017)

Figure 1. Actual DBD of the plasma system and the images of actual seeds that were tested for wettability(a-untreated, b-30s exposure time).