Figure 1
Process involved in plasma seed treatment, along with performance and surface sanitization benefits that are implied by data from literature review.
Table 1
Experimental parameters of plasma agriculture experiments.
| Reference | Seed | Carrier gas | Experimental parameter | Plasma | Primary focus of investigation | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Type | Amount | Type | Flow rate | Pressure | Seed holder material type | Treatment time | Type | Power | Indication of success (±/0) | |
| (Filatova et al., 2013) | Spring wheat (Triticum aestivum L.), blue lupine (Lupinus angustifolius), and maize (Zea mays L.) | (1) 50 (2) 60 | Air | N/A | (1) 0.5 Torr (2) 0.3–0.5 Torr | Petri dish | (1) 2.5 min, 5 min, 8 min, 10 min (2) 1 min, 5 min, 7 min, 10 min, 20 min | RF | (1) 5.28 MHz; 0.2–0.6 W/cm2 (2) 13.56 MHz; 50 W, 100 W, and 200 W | Germination (+); Seedling health (±) treatment dependent; microorganisms (±) treatment dependent |
| (Shapira et al., 2018) | Lentil (Lens culinaris), pepper (Capsicum annuum) | 2 (1 pair) | Air | N/A | 0.5 Torr | Silk wires inside a capacitor | 60 s | RF | Frequency: 13.56 MHz; RF discharge: 18 W; voltage: 6 kV | Surface charge density and kinetics (+); wettability: (+) |
| (Filatova et al., 2009) | Grain crops (rye, wheat, barley), legumes (peas and narrow-leaved lupin), and aster | 100 | Air | N/A | 0.3–0.7 Torr | Two parallel round Cu electrodes | 7 min, 15 min, and 30 min | RF | 5.28 MHz; RF discharge: 5.28 MHz; power: 0.9 W/cm3 | Germination (+); pathogenic microbes (+) (Escherichia coli ATCC 8739, Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633) |
| (Ling et al., 2015) | Soybean (Glycine max (L.) Merr) | N/A | He | N/A | 1.1 Torr | Polar plates | 15 s | RF | 0 W, 60 W, 80 W, 100 W, and 120 W | Germination (+); growth (+); water uptake (+); soluble sugar and protein content (+) |
| (Li et al., 2016) | Peanut | N/A | He | N/A | 1.1 Torr | Conveyer belt | 15 s | RF | 60–140 W; 13.56 MHz | Germination (+); yield (+); growth (+) |
| (Ono et al., 2017) | Cabbage | 1,000 | (1) Air, (2) O2 | N/A | 0.45 Torr | Plastic pot | 0–3 h | RF | 13.56 MHz, 100 W | Inactivation of bacteria on plant seed (+) |
| (Shapira et al., 2017) | Pepper, lentil | N/A | N/A | N/A | 0.5 Torr | N/A | 60 s | RF | 13.56 MHz, 18 W | Seed surface charging (0) |
| (Selcuk et al., 2008) | Wheat, barley, oats, lentil | 1–8 g | Air and SF6 | N/A | 500 mTorr | Quartz tube | 30 s to 30 min | Low pressure cold plasma | 1 kHz, 300 W, 20 kV | Microbial reduction (+);germination (+) |
| (Ahn et al., 2019) | Yellow dent corn hybrid | (1) 1,500 (2) 120; 1,512 total (3) N/A (4) 1,500 | (1) N2 (2) He + N2 (3) He (4) He + air | (1) N/A (2) 15 + 3 LPM (3) 10 LPM (4) 10 + 5 LPM | (1) 100 mTorr, 10−6 Torr (2) Atm. (3) Atm. (4) Atm. | (1) Mesh plate (2) Al mesh plate (3) Plate (4) Al mesh plate | (1) 2 min., 10 min (2) 3 s (3) 10 s (4) 10 min | (1) RF (2) MW (3) DBD (4) MW | (1) 800 W, 13.56 MHz (2) 500 W (3) 15 kV; 35 kHz (4) 800 W | Seed growth (0); germination (0); yield (0) |
| (Sinegovskaya et al., 2019) | Soybean | N/A | (1) Air (2) Ar + air | N/A | Atm. | N/A | N/A | (1) DBD (2) MW jet | (1) 28–32 kHz, 6–12 kV, AC (2) 2.45 GHz | Germination (±) treatment dependent |
| (Ji et al., 2016) | Spinach (Spinacia oleracea (L.)) | (1) 50 (2) 25 | (1) Air + N2 (2) N/A | (1) 1.5 LPM (2) N/A | Atm. | (1) Petri dish (2) Wire gauze | 30 s, 1 min, 3 min | (1) DBD (2) Pulsed | N/A | Germination (±); growth (±); treatment dependent |
| (Gómez-Ramírez et al., 2017) | Quinoa | N/A | Air | (1) N/A (2) 0.005 LPM | (1) 375 Torr (2) 0.08 Torr | (1) Quartz plate (2) N/A | 10 s, 30 s, 60 s, 180 s, 900 s | (1) DBD (2) RF | (1) 6.4 W (2) 15 W, 13.56 MHz | Germination (±); treatment dependent; surface chemistry (+) |
| (de Groot et al., 2018) | Cotton | 350 | (1) Air (2) Ar | 1 LPM | Atm. | Borosilicate glass cylinder | (1) 0 min, 3 min, 27 min (2) 81 min | DBD | N/A | Germination (+); water uptake (+) |
| (Guo et al., 2018) | Wheat | 50 | Air | 1.5 LPM | Atm. | Wire netting in a plexiglass cylinder | 4 min | DBD | Discharge voltage: 0.0 kV, 9 kV, 11 kV, 13 kV, 15 kV, and 17 kV, 50 Hz | Vitality (+); growth (+); water uptake (+) |
| (Kitazaki et al., 2014) | Radish sprouts | 10 per line | Air | N/A | Atm. | Glass plate | 180 s | DBD | 10 kHz AC. P2P discharge voltage and current 9.2 kV/0.2 A. Discharge power: 1.49 W/cm2 | Growth (+); NO x and O3 emissions (0) |
| (Wang et al., 2017) | Cotton | 120 g | Air N2 | 1 SLPM | Atm. | Needle-plate structure | 3 min, 9 min, 27 min | DBD | 19 kV, 1 kHz AC | Seed spectral characteristics (0); water uptake (+) |
| (Khamsen et al., n.d.) | Rice | 25 | Air, air + Ar | N/A | Atm. | Glass plate | 15 s, 30 s, 45 s, 1 min, 2 min | DBD | N/A | Sterilization(+); germination (+); water uptake (+) |
| (da Silva et al., 2017) | Mimosa caesalpiniafolia Benth | 100 | N/A | N/A | Atm. | Glass tubes, metal mesh screen | 3 min, 9 min, 15 min | DBD | 17.5 kV, 990 Hz | Seed wettability (+); imbibition (+); germination (+) |
| (Hayashi et al., 2014) | Rice | N/A | Air | N/A | Atm. | Dish (unknown material) | 20 min | DBD | 10 kHz | Surface sterilization of seed and fruit surfaces (+) |
| (Dobrin et al., 2015) | Wheat | 105 | N/A | N/A | Atm. | Glass plate | 5 min, 15 min, 30 min | DBD | 2.7 W, 15 kV, 50 Hz | Germination (+); water absorption (+); root length (+) |
| (Pérez-Pizá et al., 2019) | Soybean (Glycine max (L.) Merrill) | 500 | (1) O2 (2) N2 | 6 NL min−1 | Atm. | N/A | 60–180 s | DBD | 50 Hz,0–25 kV, AC | Pathogenic reduction (+); plant growth (+) |
| (Butscher et al., 2016) | Sprout seeds: onion (Alliumcepa), radish (Raphanus sativus), cress (Lepidiumsativum), alfalfa (Medicago sativa) | 10 g | Ar | 5.6 NL min−1 | Atm. | PC | 500 ns | DBD | 2.5–10 kHz, 6–10 kV | Germination (+); microbial inactivation (+) (Salmonella and E. coli) |
| (Nishioka et al., 2016) | Brassicaceous (Brassica campestris var. amplexicaulis) | 20 | Ar | 0.5–1 LPM | 10.7–16.0 kPa | Mesh sheet, unknown material | 0 min, 5 min, 10 min, 20 min, 40 min | DBD | AC, 10 kHz, 2.5–5.5 kV | Disinfection and DNA of pathogen (+) (Xanthomonas campestris pv. Campestris) |
| (Jo et al., 2014) | Rice (Oryza sativa L.) | 3–5 | Air | N/A | Atm. | Aluminum holder | 0 min, 0.5 min, 1 min, 2 min, 3 min | DBD | 30 kV, 22 kHz, 3 W dishcarge | Fungal pathogen reduction (+) (Gibberella fujikuroi and cnoidia) |
| (Mitra et al., 2014) | Chickpea (Cicer arietinum) | NA | Air | N/A | Atm. | Polyoxymethylene–copolymer | 0.5–5 min | DBD | 17 kVpp, 5 kVpp, 0 kVpp | Germination (+); microbial reduction (+) |
| (Feizollahi et al., 2020) | Barley grain | 11–12 | Air | N/A | Atm. | Plastic cup | 0 min, 2 min, 4 min, 6 min, 8 min, 10 min | DBD | 0–34 kV; 3,500 Hz; duty cycle 70%; 1 Amp; 300 W | Microbial reduction of DON (+); germination (+) |
| (Kordas et al., 2015) | Winter wheat grain | 200 | Air | N/A | Atm. | Packed bed | 3 s, 10 s, 30 s | PBDBD | 100 Hz, 83 kHz, 8 kV (AC) | Fungus colonization reduction (+) |
| (Anna Zahoranová et al., 2018) | Maize (Zea mays L; cv. Ronaldinio) | 200–250 | Air | N/A | Atm. | Ceramic plate | 30–300 s | DCSBD | 14 kHz, up to 20 kV, 400 W, AC | Inhibition of surface microorganisms (+); seedling growth (+/0) treatment dependent |
| (A. Zahoranová et al., 2016) | Wheat (Triticum aestivum L. cv. Eva) | 100–300 | Air | N/A | Atm. | Ceramic plate | 30–300 s | DCSBD | 14 kHz, up to 20 kV, 400 W, AC | Inhibition of surface microorganisms (+); germination (+); water uptake (+) |
| (Štěpánová et al., 2018) | Cucumber (Cucumis sativus L.), Pepper (Capsicum annuum L.) | 100 | Air | N/A | Atm. | Ceramic | 20–50 s 4–12 s | DCSBD | 400 W, 20 kV, 15 kHz AC | Germination (+); Pathogenic microbes (+) (Didymella licopersici spores) |
| (Waskow et al., 2018) | Lentil | 1 g | Air | N/A | Atm. | Alumina ceramic plate | 0–10 min | DCSBD | 400 W | Germination (+); microbial inactivation (+) (several strains of bacteria and fungi) |
| (Mošovská et al., 2018) | Black peppercorn | 5 g | Air | N/A | Atm. | Ceramic plate | 60 s, 120 s, 180 s, 240 s, and 300 s | DCSBD | 400 W DC, 18 kHz, 10 kV | Pathogenic bacteria inhibition (+) |
| (Puligundla et al., 2017) | Radish | 3 g | Air | 2.5 m/s | Atm. | Petri dish | 0–3 min | Plasma jet | 20 kV DC, 1.5 A, 58 kHz | Germination (±); treatment dependent; decontamination (+) |
| (Matra, 2016) | Radish | 10 | Ar | 4 LPM | Atm. | Acrylic box | 2 min, 4 min, 6 min | Plasma jet | (1) 90 W (21.2 kV) (2) 140 W (30 kV) | Germination (+) |
| (Takemura et al., 2014) | Black pepper | 1 g | (1) Ar (2) Ar + CO2 (3) Air (4) Ar + H2O | (1) 20 LPM (2) 0.5 LPM, 20 LPM (3) 20 LPM (4) 20 LPM | Atm. | Petri dish | 5 min | Plasma jet | Pulse – 280 V, 8 A, 16–20 kHz | Sterilization (±) treatment dependent |
| (Kim et al., 2017) | Broccoli (Brassica oleracea var. kialica plen.) | 1 g | N/A | N/A | N/A | Petri plate | 0–3 min | Plasma jet | 220 V AC, 20 kV DC, 58 kHz | Microbial reduction (+); germination (+) |
| (Bafoil et al., 2018) | Arabidopsis Thaliana | 150–300 seeds | (1) Air (2) He (2b)He | (1) N/A (2) 3 L/min | (1) Atm | (1) Glass plate (2) Eppendorf tube (2b) Glass beaker | (2) 15 min | (1) DBD (2) Plasma jet (2b) Plasma jet/DBD | (1) HV (2) 10 kV, 9.7 kHz, | Germination (+); growth (+) |
[i] (+), plasma had positive impact on primary focus of investigation; (−), plasma a negative impact on primary focus of investigation; 0, plasma had a neutral or no impact on primary focus of investigation; AC, alternating current; Ar, argon; Atm., atmospheric; Al, aluminum; DON, deoxynivalenol; DBD, dielectric barrier discharge; DCSBD, diffuse coplanar surface barrier discharge; DC, direct current; g, gram; hr, hour(s); He, helium; SLPM, standard liters per minute; min, minutes; N2, nitrogen; O2, oxygen; PBDBD, packed bed dielectric barrier discharge; PC, polycarbonate; RF, radiofrequency; s, seconds.
Figure 2
A. RF plasma experimental set-up: Alternator (1), vacuum chamber (2), electrodes (3, 3′), quartz window of discharge chamber (4), inductor (5,5′), voltage meter (6), tuning capacitor (7), Rogowski coil (8), lens (9), monochromator (10). (Filatova et al., n.d.); B. RF plasma system for treating lentil and pepper seeds.(Shapira, Chaniel, and Bormashenko 2018); C. Low plasma and vibrating stirring device with seeds. (Ono et al. 2017); D. Non-thermal plasma to sterilize rice seeds (Khamsen et al., n.d.); E. Micro DBD plasma for sanitizing spinach seeds. (Ji et al. 2016); F. Plasma system cross section view and equipment on shaker (de Groot et al. 2018); G. Schematic diagram of discharge plasma reaction system.(Guo et al. 2018).
Figure 3
A. Picture of wheat seeds between two electrodes showing UV irradiation. (Guo et al. 2018); B. Needle-plate set-up on cotton seeds (Wang et al. 2017); C. Plasma and UV light for sterilizing fruits and seeds (Hayashi et al. 2014); D. Plasma irradiation on radish seeds via DBD plasma (Kitazaki et al. 2014); E. Germicidal treatment system (Takemura et al. 2014); F. Plasma experimental setup (Matra 2016); G. Schematic diagram for DCSBD plasma treatment of maize (Zahoranová et al. 2018); H. DCSBD plasma tool sterilizing black peppercorn sample.(Mošovská et al. 2018); I. Surface discharge plasma made of 13 copper wire (Dobrin et al. 2015).
Table 2
Potential reactions in the plasma discharge region.
| Eq. # | Equation | Reference |
|---|---|---|
| (1) | e− + H2O → e− + OH* + H | (Takemura et al., 2014) |
| (2) | e− + CO2 → CO + O + e− | |
| (3) | e− + O2 → O(1D) + O (3P) + e− | |
| (4) | O(1D) + H2O → OH* + OH* | |
| (1) | e + O2 → 2O + e | (Kitazaki et al., 2014) |
| (2) | O + O2 + M → O3 + M, k = 3.4 × 10−34cm6/s | |
| (3) | e + N2 → e + 2N | |
| (4) | N + O2 → NO + O, k = 7.7 × 10−17cm3/s | |
| (5) | N+ O3 → NO + O2, k = 3.7 × 10−13cm3/s | |
| (6) | O + NO2 → NO + O2, k = 9.7 × 10−12cm3/s | |
| (7) | NO + O3 → NO2 + O2, k = 2.1 × 10−14cm3/s | |
| (8) | H2O + e → OH + H + e | |
| (9) | H + O2 + M → HO2 + M, k = 1.8 × 10−32cm3/s | |
| (10) | NO + HO2 → NO2 + OH, k = 7.8 × 10−12cm3/s |