1. bookVolume 5 (2021): Issue 4 (October 2021)
Journal Details
License
Format
Journal
eISSN
2564-615X
First Published
30 Jan 2017
Publication timeframe
4 times per year
Languages
English
access type Open Access

Unrevealing the impact of pulsed electric fields (PEF) on cucumber seed vigour and surface disinfection

Published Online: 21 Oct 2021
Volume & Issue: Volume 5 (2021) - Issue 4 (October 2021)
Page range: 180 - 193
Journal Details
License
Format
Journal
eISSN
2564-615X
First Published
30 Jan 2017
Publication timeframe
4 times per year
Languages
English
Abstract

Chemicals used for seed treatments help to increase the agricultural production by preventing pests and pathogens but also cause environmental and health problems. Thus, environmentally-friendly technologies need to be developed for a seed treatment that inactivates surface microflora and improves seed vigor. One such pulsed electric field (PEF) treatment applied to cucumber seeds in the range of 1.07-17.28 Joule (J) significantly enhanced a mean germination rate (MGR) by up to 9%, a normal seedling rate by 25.73%, and a resistance to 100 and 200 mM salt stresses by 96% and 91.67%, respectively, with a stronger and faster growth of roots and seedlings. PEF treatment provided 3.34 and 3.22 log-reductions in the surface microflora of total mold and yeast and total aerobic mesophilic bacteria, respectively. The electrical conductivity (EC) values of the control samples increased over time, from 4 to 24 h. Those of the PEF-treated samples after 4, 12, and 24th hours were also more affected by the measurement time not by the PEF treatment.

The joint optimization of 18 responses based on the best-fit Gaussian process model pointed to 19.78 s and 17.28 J as the optimal settings. The PEF treatment appeared to improve seed germination ability and stress resistance with the adequate inactivation of surface microflora.

Keywords

Introduction

Chemical seed treatments are usually applied to agricultural products for pest control. However, some of these methods have been costly, while the others have caused adverse environmental and public health impacts. Non-chemical and physical treatments have been on demand since they have reduced the pesticide releases and their residues into the environment. Some of the non-chemical methods include use of steam (13), solarization of soil (18), microwave, electron beam irradiation (58), hot water, and magnetic fields (58). Resistance inducers and plant-derived products such as Bion 50 WG, Chitoplant, salicylic acid, jasmonic acid, Comcat, Milsana flüssig, Kendal, and plant essential oils were also practiced (2) to influence physiological and biochemical processes involved to improve seed vigor and crop stand.

The germination ability of seeds is adversely affected by many factors. For example, increased salinity of soil is a critical factor in agricultural production and one of the major problems in (semi-)arid regions (2,35). Soil salinity is mostly caused by increased sodium chloride concentration (35,56), reduces the rate of germination, and retards the cucumber seed initiation (Cucumis sativus L.) (2,16,55,65). Thus, it is important to increase germination and induce mechanisms for salt-stress resistance in cucumber seeds to maximize yield.

Pulsed electric fields (PEF) at high frequencies are applied to biological membrane though specifically designed electrodes (55). Electric field at higher magnitude is lethal, and thus, used for microbial inactivation (34,57). However, electric field at a lower magnitude is sub-lethal and used to improve extraction yield (21,32), increase drying efficacy (21,32), and modify tissue and cell cultures (10) depending on both cell structure and treatment parameters. Low-intensity PEF is also used to promote barley germination (24,26), extract oil from papaya seeds (45), investigate antioxidant metabolism of wheatgrass (Triticum aestivum L.) seeds (40), determine early germination of Arabidopsis thaliana seeds (53), disinfect vegetable seeds and grains (28), growth parameters of wheat and nutritional properties of wheat plantlets juice (4), and inactivate endogenous bacteria of winter wheat, barley, and vegetable seeds (29). However, existing knowledge regarding the impact of PEF on germination of cucumber seeds, their resistance to salt, and inactivation of surface microflora is limited in related literature. Thus, the objectives of the study were to 1) determine PEF processing parameters to treat cucumber seeds; 2) evaluate the effectiveness of the PEF treatment on mean germination rate, normal seedling rate, conductivity, root formation, and resistance to salt as well as inactivation of surface microflora; and 3) optimize the PEF processing parameters and responses. Germination ability of the seedling and root formation was also given to determine the positive effect of PEF on the seedling growth.

Materials and Methods
Seed samples

Beith alpha cucumber Cucumis sativus L. (cv. Hokus) seed samples kindly provided by the seed company (Nadide Tohum, Antalya, Turkey) were kept at ambient temperature in air-tight containers until they were treated.

Pulsed electric field treatment

A pilot-scale PEF system constructed by our research team at Bolu Abant Izzet Baysal University (Turkey) was used to treat cucumber seeds in response to 110, 140, 160, and 180 Hz frequencies and 2.47, 7.42, 12.37, and 19.79 sec treatment times with 1.07 to 17.28 Joule (J) energies. Applied treatment times and energy levels were derived from the treatment parameters mentioned above (15).

Germination tests

Control and PEF-treated cucumber seed samples (50 seeds) in three replications were placed on a filter paper moistened with sprayed water. The quantity of water used for irrigation was 2.5 times the substrate weight. All the samples were settled in a germinator at 25 oC for 2-4 days under a constant light, while germination was checked every day. Two mm radicle emergence was the criteria to determine germination expressed in percentage (63). Seedling was checked on a daily basis in terms of good shoot and root developments (normal), curling, and abnormal and glass-like body (not normal) (63).

Electrical conductivity measurement

Electrical conductivity (EC) measurement was performed using a Sension 5 model conductivity meter (HACH, CO, USA). Conductivity was measured at 4, 8, and 24 h (30).

Effect of salt stress on germination

Germination under salt stress was performed at two levels. Conductivity of the water used to irrigate seedling was adjusted to 10.8 and 19.8 mS cm-1 EC with addition of NaCl. Fifty cucumber seeds of PEF-treated and control samples were planted in four cm soil, and then, all the samples were placed in a temperature controlled cabinet. Each pot was irrigated with 100 mL of salted water for each level at first day; whereas, 50 mL of salted water was added for the following 13 days. All experiments were repeated in triplicate (30,63).

Inactivation of surface microflora

Number of total mold and yeast (TMY) and total aerobic mesophilic bacteria (TAMB) as a representative of surface flora were quantified. Seed samples diluted with 0.1% peptone water at the ratio of 1:9 (v/v) were surface plated on plate count agar (PCA) (Fluka, Steinheim, Germany) for TAMB and potato dextrose agar (PDA) (Fluka, Steinheim, Germany) plates in triplicate, respectively. PCA and PDA plates were incubated at 35 ± 2 oC for 24-48 h and 22 ± 2 oC for 3-5 days, respectively. Results were calculated as log cfu/ g (30).

Statistical analyses

Seed quality and microbial inactivation data were analyzed by one-way analysis of variance (ANOVA) with Tukey’s multiple comparison tests (Minitab Statistical Software 17.1.0, MiniTab Inc., PA, USA). Stepwise regression analyses were used to estimate the changes and the interactions in the response variables. Joint optimization was also conducted to determine composite desirability with the most optimal solutions.

The best-fit Gaussian process (GP) model was used to obtain a prediction formula on which the joint optimization was carried out. The objective function of the joint optimization was set to minimize the responses. The parameters are as follows: μ is the Gaussian Process mean, σ2 is the Gaussian Process variance, theta corresponds to the values of θk in the definition of R. This model assumes that Y is normally distributed with mean μ and covariance matrix σ2R. The elements of the R matrix are defined as follows:

r i j = exp k = 1 K θ k x i k x j k 2 $$\mathrm{r}_{\mathrm{ij}}=\exp \left(-\sum\nolimits_{\mathrm{k}=1}^{\mathrm{K}} \theta_{\mathrm{k}}\left(\mathrm{x}_{\mathrm{ik}}-\mathrm{x}_{\mathrm{jk}}\right)^{2}\right)$$

where K = # of continuous predictors, θk = theta parameter for the kth predictor, xik = the value of the kth predictor for subject i,xjk = the value of the kth predictor for subject j.

Factors with small theta values have little (or no) impact on the prediction formula. Total sensitivity is a measure of the sum of influence and explains % of the variation in the response. Main effect is the ratio of the functional main effect and the total variation for each factor in the model. Effects of interaction are also calculated similar to main effects.

Results

Physical properties of seeds such as moisture content, size, and shape are important parameters to determine the magnitude electric field energy and duration of treatment time for PEF. Initial experiments were conducted to determine the PEF processing conditions for cucumber seeds. Based on preliminary experiments, 18 kV of output voltage with 110, 140, 160, and 180 Hz frequencies were applied to cucumber seeds. Treatment times and applied energies were calculated as 2.47, 7.42, 12.37, and 19.79 sec and 1.07, 1.36, 1.92, 2.16, 3.21, 4.08, 5.35, 5.76, 6.48, 6.80, 8.55, 9.60, 10.80, 10.89, 15.36, and 17.28 J, respectively.

Compared to the control samples, all the PEF treatments provided a significant difference in the mean germination rate (MGR) on the 2, 3, and 4th days with 8.9% increase on the 2nd and 3rd days, and 6.7% increase on the 4th day. As the germination rate increased from 2nd to 4th day, MGR of the most of the samples significantly increased by the time (Table 1).

Germination rate (%) of the control and PEF-treated cucumber seed samples

Energy (J) Germination rate (%)
2.day 3.day 4.day
0.00 90.00 ± 0.00bB 91.11 ± 1.92cB 93.33 ± 0.00cA
1.07 95.56 ± 1.92aA 95.56 ± 1.92bA 96.67 ± 0.00bA
1.36 93.33 ± 1.33aB 96.67 ± 3.33abA 98.89 ± 1.92abA
1.92 95.56 ± 1.92Aa 96.67 ± 3.33abA 98.89 ± 1.92abA
2.16 98.89 ± 1.92aA 98.89 ± 1.92abA 100.00 ± 0.00aA
3.21 95.33 ± 1.33aA 100.00 ± 0.00aA 100.00 ± 0.00aA
4.08 96.67 ± 1.33aB 100.00 ± 0.00aA 100.00 ± 0.00aA
5.35 96.67 ± 1.33aB 96.67 ± 0.00bB 100.00 ± 0.00aA
5.76 95.56 ± 4.09aA 98.89 ± 1.92abA 100.00 ± 0.00aA
6.48 93.33 ± 3.33aA 94.44 ± 1.92bA 97.78 ± 1.92abA
6.80 96.67 ± 1.33aA 96.67 ± 1.33bA 98.89 ± 1.92abA
8.55 95.56 ± 1.92aB 95.56 ± 1.92bB 100.00 ± 0.00aA
9.60 93.33 ± 0.00aC 96.67 ± 0.00bB 100.00 ± 0.00aA
10.80 96.67 ± 1.33aB 97.78 ± 1.92bB 100.00 ± 0.00aA
10.89 95.56 ± 1.92aB 96.67 ± 0.00bB 100.00 ± 0.00aA
15.36 96.67 ± 0.00ab 96.67 ± 0.00bB 100.00 ± 0.00aA
17.28 98.89 ± 1.92aB 97.78 ± 1.92bB 100.00 ± 0.00aA

*Means in the same column with lowercase superscript letter and in the same row with uppercase superscript letter are significantly different (p ≤ 0.05)

Normal seedling rate of control samples significantly increased with all the PEF treatments (p ≤ 0.05). The lowest and highest normal seedling rates were 75.86 ± 0.00% with 1.07 J and 95.56 ± 1.92% with 17.28 J, respectively. Compared to the control samples, the PEF treatment provided a 25.7% increase in the normal seedling rate (Table 2). Except for those treated with 4.08, 10.80, 10.89, and 17.28 J, all the other PEF treatments provided an earlier and better germination, a stronger body formation, taller seedlings (Figure 1 ), and a stronger root formation (Figure 2 ).

Figure 1

Impact of PEF treatment on germination ability of cucumber seeds.

Figure 2

Impact of PEF treatment on root formations of cucumber seeds.

Normal seedling rate (%) of the control and PEF-treated cucumber seed samples

Energy (J) Normal seedling rate (%)
0.00 72.62 ± 2.06d
1.07 75.86 ± 0.00c
1.36 89.81 ± 6.11b
1.92 96.63 ± 0.47a
2.16 95.18 ± 1.92a
3.21 86.67 ± 2.00b
4.08 86.67 ± 6.67b
5.35 85.56 ± 5.09b
5.76 92.22 ± 3.85ab
6.48 94.37 ± 3.78ab
6.80 83.14 ± 6.67b
8.55 85.56 ± 6.94b
9.60 93.33 ± 3.33ab
10.80 92.22 ± 5.09ab
10.89 83.33 ± 5.77b
15.36 91.11 ± 5.09ab
17.28 95.56 ± 1.92a

*Means in the same column with lowercase superscript letter are significantly different (p ≤ 0.05)

Changes in electrical conductivity (μS cm-1g-1) of the control and PEF-treated cucumber seed samples

Energy (J) Electrical conductivity (μS cm-1g-1)
4 hour 8 hour 24 hour
0.00 7.29±0.79abcA 8.06±0.67aAB 9.65±0.58abA
1.07 7.17±0.76abcB 8.22±0.17aB 9.82±0.14abA
1.36 5.92±1.82abcB 8.65±0.62aA 9.02±0.57bA
1.92 6.48±1.06abcC 8.79±0.56aB 9.74±0.57abA
2.16 7.44±0.18abcC 9.07±0.50aB 10.17±0.05abA
3.21 7.56±0.21abcC 8.75±0.27aB 9.62±0.37abA
4.08 6.91±0.21abcB 8.45±0.84aAB 9.73±0.64abA
5.35 7.24±0.32abcB 8.35±1.34aB 10.19±0.43abA
5.76 6.42±0.07abcC 8.84±0.23aB 10.33±0.08abA
6.48 5.57±0.40bcC 8.56±0.18aB 9.55±0.29abA
6.80 6.17±0.66abcC 7.85±0.39aB 8.98±0.47bA
8.55 6.28±0.69abcB 8.36±0.21aA 9.09±0.56bA
9.60 6.07±1.72abcC 8.93±0.46aB 10.41±0.73abA
10.80 5.87±0.11abcC 7.98±0.49aB 9.47±0.30abA
10.89 5.43±0.29cC 7.65±1.38aB 9.74±1.04abA
15.36 7.75±0.08abcC 8.88±0.07aB 9.85±0.67abA
17.28 7.94±0.79abC 9.18±0.28aB 10.61±0.15aA

*Means in the same column with lowercase superscript letter and in the same row with uppercase superscript letter are significantly different (p ≤ 0.05)

The EC values of the control samples increased over time, namely from 4 to 24 h. Those of the PEF-treated samples after 4, 8, and 12th hours were also more affected by the measurement time not by the PEF treatment. The EC values of the PEF-treated samples for 4, 8, and 12th h ranged from 5.43 ± 0.29 μS cm-1g-1 with 10.89 J to 7.94 ± 0.79 μS cm-1g-1 with 17.28 J, from 8.22 ± 0.17 μS cm-1g-1 with 1.07 J to 9.18 ± 0.28 μS cm-1g-1 with 17.28 J, and from 8.98 ± 0.47 μS cm-1g-1 with 6.80 J to 10.61 ± 0.15 μS cm-1g-1 with 17.28 J, respectively (Table 3).

The control samples had no germination until 12th day, whereas some PEF-treated samples started to germinate on the 9th day when exposed to salinity level of 100 mM NaCl. The samples treated with 5.35, 6.48, and 6.80 J on 9th day, 2.16, 3.21, 5.35, 6.48, 6.80, 8.55, 10.80, 10.89, and 17.28 J on 10th day; 2.16, 3.21, 5.35, 6.48, 6.80, 8.55,10.80, 10.89, and 17.28 J on 11th day; 2.16, 3.21, 5.35, 6.48, 6.80, 8.55, 10.80, 10.89, 15.36, and 17.28 J on 12th day; and all the PEF-treated samples on the 13th day presented significantly higher germination rate under salinity level of 100 mM NaCl (Table 4). Except for the samples treated with 17.28 J, the PEF-treated and control samples did not germinate on 8 and 9th days under 200 mM NaCl salt stress. The control samples only showed germination with 3.33 ± 0.30% on 13th day, whereas the PEF-treated samples with 8.55, 10.80, 10.89, 15.36 and 17.28 J on 10th day; 8.55, 9.60, 10.80, 10.89, 15.36 and 17.28 J on 11th day; 1.07, 1.92, 3.21, 4.08, 5.35, 8.55, 9.60, 10.80, 10.89, 15.36 and 17.28 J on 12th day; and all the PEF-treated samples on 13th day showed germination. The samples treated with 17.28 J presented a significantly higher germination rate, and 100.00 ± 0.00% germination was observed on both 12 and 13th days. Samples treated by PEF presented significantly higher germination under salt stress of 200 mM NaCl (Table 5). Germination rate significantly increased over time as the seed samples exhibited higher germination rate closer to the end rather than beginning of germination studies (Tables 4 and 5). Maximum of 100, 75, 89, 89, and 70% increases were observed on 9, 10, 11, 12, and 13th day of germination under 100 mM NaCl stress, whereas 100% increase on 8, 9, 10, 11 and 12th day, and 92% increase on 13th day were observed for germination under salinity level of 200 mM NaCl, respectively.

Germination rate (%) of the control and PEF-treated cucumber seed samples under 100 mM NaCl salt stress

Energy (J) Germination rate (%)
8. day 9. day 10. day 11. day 12. day 13. day
0 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 3.33 ± 0.30hA
1.07 0.00 ± 0.00aA 0.00 ± 0.00cA 0.00 ± 0.00eA 0.00 ± 0.00gA 0.00 ± 0.00gA 8.33 ± 0.00Ga
1.36 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 16.67 ± 0.30fA
1.92 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 16.67 ± 0.30fA
2.16 0.00 ± 0.00aB 0.00 ± 0.00cB 8.33 ± 0.00dA 8.33 ± 0.00fA 8.33 ± 0.00fA 8.33 ± 0.00gA
3.21 0.00 ± 0.00aE 0.00 ± 0.00cE 8.33 ± 0.00dD 16.67 ± 0.30eC 25.00 ± 0.00dB 33.33 ± 0.00dA
4.08 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 16.67 ± 0.30fA
5.35 0.00 ± 0.00aE 16.67 ± 0.00aD 25.00 ± 0.30bC 33.33 ± 0.00cB 33.33 ± 0.30cB 41.67 ± 0.40cA
5.76 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 8.33 ± 0.00gA
6.48 0.00 ± 0.00aD 16.67 ± 0.00aC 16.67 ± 0.30cC 25.00 ± 0.00dB 33.33 ± 0.30cA 33.33 ± 0.00dA
6.80 0.00 ± 0.00aD 8.33 ± 0.00bC 8.33 ± 0.30dC 16.67 ± 0.00eB 16.67 ± 0.00eB 25.00 ± 0.00eA
8.55 0.00 ± 0.00aD 0.00 ± 0.00cD 8.33 ± 0.00dC 25.00 ± 0.00dB 25.00 ± 0.00dB 33.33 ± 0.00dA
9.60 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 16.67 ± 0.30fA
10.80 0.00 ± 0.00aA 0.00 ± 0.00cA 16.67 ± 0.00cD 41.67 ± 0.40bC 58.33 ± 0.00bB 75.00 ± 0.30bA
10.89 0.00 ± 0.00aC 0.00 ± 0.00cC 8.33 ± 0.00dB 8.33 ± 0.00fB 16.67 ± 0.20eA 16.67 ± 0.00fA
15.36 0.00 ± 0.00aC 0.00 ± 0.00cC 0.00 ± 0.00eC 0.00 ± 0.00gC 8.33 ± 0.00fB 16.67 ± 0.30fA
17.28 0.00 ± 0.00aD 0.00 ± 0.00cD 33.33 ± 0.00aC 75.00 ± 0.00aB 75.00 ± 0.00aB 83.33 ± 0.00aA

*Means in the same column with lowercase superscript letter and in the same row with uppercase superscript letter are significantly different (p ≤ 0.05)

Germination rate (%) of the control and PEF-treated cucumber seed samples under 200 mM NaCl salt stress

Energy (J) Germination rate (%)
8. day 9. day 10. day 11. day 12. day 13. day
0 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
1.07 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 8.33 ± 0.60dA 8.33 ± 0.60eA
1.36 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
1.92 0.00 ± 0.00bC 0.00 ± 0.00bC 0.00 ± 0.00dC 0.00 ± 0.00dC 16.67 ± 0.00cB 25.00 ± 0.00cA
2.16 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
3.21 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 8.33 ± 0.60dA 8.33 ± 0.60eA
4.08 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 8.33 ± 0.60dA 8.33 ± 0.60eA
5.35 0.00 ± 0.00bC 0.00 ± 0.00bC 0.00 ± 0.00dC 0.00 ± 0.00dC 8.33 ± 0.60dB 16.67 ± 0.00dA
5.76 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
6.48 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
6.80 0.00 ± 0.00bA 0.00 ± 0.00bA 0.00 ± 0.00dA 0.00 ± 0.00dA 0.00 ± 0.00eA 8.33 ± 0.60eA
8.55 0.00 ± 0.00bD 0.00 ± 0.00bD 8.33 ± 0.60cC 8.33 ± 0.00cB 8.33 ± 0.60dB 16.67 ± 0.00dA
9.60 0.00 ± 0.00bD 0.00 ± 0.00bD 0.00 ± 0.00dD 8.33 ± 0.00cC 16.67 ± 0.00cB 66.67 ± 0.00bA
10.80 0.00 ± 0.00bE 0.00 ± 0.00bE 25.00 ± 0.50bD 41.67 ± 0.00bC 50.00 ± 0.60bB 66.67 ± 0.00bA
10.89 0.00 ± 0.00bB 0.00 ± 0.00bB 8.33 ± 0.00cA 8.33 ± 0.00cA 8.33 ± 0.60dA 8.33 ± 0.00eA
15.36 0.00 ± 0.00bD 0.00 ± 0.00bD 8.33 ± 0.00cC 8.33 ± 0.00cC 16.67 ± 0.00cB 66.67 ± 0.00bA
17.28 8.33 ± 0.00aD 8.33 ± 0.00aD 41.67 ± 0.00aC 83.33 ± 0.70aB 100.00 ± 0.00aA 100.00 ± 0.90aA

*Means in the same column with lowercase superscript letter and in the same row with uppercase superscript letter are significantly different (p ≤ 0.05)

Best-fit non-linear regression models for the response variables of cucumber seed samples.

Response variable Goal Model R2 (%) R2pred (%) SE p DW
2nd day germination (%) Max 90.64+0.03362X1 21.26 16.20 2.94 0.001 1.949
3rd day germination (%) Max 91.15+0.0876X1-0.000303 X1*X1 31.14 22.38 2.22 0.008 1.578
4rd day germination (%) Max 93.379+0.0735X1+0.1887X2-0.000246 X1* X1 65.63 60.94 1.14 0.005 1.499
Normal seedling rate (%) Max 75.53+0.000623X1*X1 58.89 55.83 5.05 0.000 1.596
Cold test 24 °C- 5 day (%) Max 68.89+0.1715X1-0.000000X1*X1*X1*X1+ 0.000007X1*X3*X3*X3 43.72 33.18 4.96 0.047 1.215
EC- 4 h (μS cm-1g-1) Target (7.30) 7.335+0.000054X3*X3*X3*X3-0.000000X1*X1*X1*X2 35.59 28.36 0.88 0.000 1.754
TAMB (log cfu mL-1) Min 6.026-0.01320X1-0.000031X3*X3*X3*X3+0.000000X1* X1*X1*X3 55.42 48.86 0.52 0.001 1.233
TMY (log cfu mL-1) Min 9.4140-0.01034X1+0.000000 X1*X1*X1*X1-0.000005 X3*X3*X3*X3 71.93 68.17 0.17 0.000 1.578
8th day (200mM NaCI)(%) Max -0.000000+0.000043X1-0.000001X1*X1*X1+ 0.1300X3*X3*X3+ 0.000093X1*X3*X3-0.005486X1*X3*X3+0.0 00063X1*X2*X-0.003200 X3*X2*X+0.000000X1*X1*X1*X+ 0.02446X3*X3*X3*X-0.000001X1*X1*X1*X+ 221330.000034X1*X1*X3*X3+0.000003X1*X2*X3*X3-0.000783X1*X3*X3*X3-0.1035X2*X3*X3*X3+ 0.02328X3*X3*X2*X2-0.004283X3*X2*X2*X2 100 100 0.00 * *
9th day (200mM NaCI)(%) Max -0.000000+0.000043X1-0.000001X1*X1*X1+ 0.1300X3*X3*X3+0.000093X1*X1*X3-0.005486X1*X3*X3+ 0.00006X1*X3*X-0.003200X3*X2*X+ 0.00000022X1*X1*X1*X+0.02446X3*X3*X3*X-0.00000X1*X3321311 *X1*X3+0.000034X1*X1*X3*X3+0.000003X1*X2*X3*X3-0.000783X1*X3*X3*X3-0.1035X2*X3*X3*X3+ 0.02328X3*X3*X2*X2-0.004283 X3*X2*X2*X2 100 100 0.00 * *
10th day (100mM NaCI) (%) Max 8.316+0.10445X1-16.635X2-0.24945X1*X3+ 0.01730X1*X2+ 19.458X2*X3+0.6244X2*X2- 0.024510X1*X3*X2-2.570X2*X2*X3-0.16956X2*X3*X3-0.04402X2*X2*X2*X2+0.000006X1*X1*X1*X1 +0.002509X1*X2*X3*X2+0.13530 X2*X2*X2*X3 99.97 99.95 0.18 0.000 1.122
10th day (200mM NaCI)(%) Max 0.000-3.313X2-0.000397X1*X1+ 0.2139X1*X3 +0.3253X3*X3*X3-0.000749X1*X1*X3+ 0.004663X2*X2*X2- 0.05417X1*X3*X3-0.008062X3*X3*X3*X3+ 0.000196X1*X1*X3*X3-0.00494X2*X3*X3*X3 99.53 99.30 0.86 0.000 1.039
11th day (100mM NaCI) (%) Max 8.310-0.04121X1+3.9408X2*X2-0.001377X1*X1*X3-0.013595X1*X3*X3- 0.06285X2*X2*X2*X2+0.000008X1*X1*X 1*X3+0.000050X1*X1*X3*X3+0.012250 X2*X2*X3*X2 99.52 99.41 1.50 0.000 1.099
11th day (200mM NaCI)(%) Max -1.310+0.009838X1*X2*X2-0.019665X1*X3*X3+0.000106 X1*X1*X3*X3 97.06 96.76 3.78 0.000 1.000
12th day (100mM NaCI) (%) Max 8.55-0.0908X1+0.1832X1*X2-0.002519X1*X1*X3-0.00435X2*X2*X2*X2+0.000012X1*X1*X1*X3 94.54 93.18 5.28 0.000 0.673
12th day (200mM NaCI)(%) Max -0.39+0.1158 X1+0.009501X1*X2*X2-0.02382X1*X3*X3-0.001925X3*X3*X3*X3-0.000002X1*X1*X1*X3+0.000169 X1*X1*X3*X3 96.54 95.66 4.96 0.000 0.869
13th day (100mM NaCI) (%) Max 23.61-0.1593X1+1.699X2*X2+0.1132X1*X2-0.002365X1*X1*X3-0.01960 X2*X2*X2*X2+0.000012 X1*X1*X1*X3 91.66 88.83 7.60 0.021 0.905
13th day (200(%) mM NaCI) Max 5.32+0.615X2*X2-0.1553X3*X3*X3+ 0.000913X1*X3*X3*X3 57.29 53.13 17.93 0.011 0.790

*X1: frequency X2: treatment time X3: energy

The mean initial TAMB and TMY counts were reported as 6.25 ± 0.26 and 9.38 ± 0.05 log cfu g-1, respectively. Except for 1.07 J, the other PEF treatments significantly reduced the mean initial TAMB count. The lowest number of TAMB and TMY were detected as 3.03 ± 0.10 and 6.04 ± 0.02 log cfu g-1 after treated by 17.28 J energy revealing 3.22 and 3.34 log reductions in TAMB and TMY, respectively (Figure 3 ).

Figure 3

Inactivation of cucumber seed endogenous microflora treated by PEF a) total aerobic mesophilic bacteria (TAMB) and b) total mold and yeast (TMY).

Normal seedling rate was significantly affected by frequency in addition to interaction of the treatment time and frequency with R2 and R adj 2 $\text{R}^2_\text{adj}$values of 0.591 and 0.507, respectively. Treatment time, frequency, and interaction of frequency and treatment time significantly affected inactivation of TAMB with R2 and R adj 2 $\text{R}^2_\text{adj}$values determined as 0.508 and 0.407. TMY inactivation was significantly affected by treatment time with the interactions of frequency and frequency, and treatment time and frequency with R2 and R adj 2 $\text{R}^2_\text{adj}$values of 0.618 and 0.540.

Nonlinear regression modeling revealed the R2 values higher 90% for 8, 9, 10, 11, 12, and 13th day germination under both 100 and 200 mM NaCI salt stresses, indicating variation of a dependent variable is strongly explained by the independent variable(s) in a regression model (Table 6). The joint optimization of the 18 responses (Table 7) showed that the optimum process parameters were 17.28 J and 19.78 s for TAMB (3.52 log cfu g-1) and TMY (7.29 cfu g-1) counts, respectively (Figure 4 ).

Figure 4

Optimization of Gaussian process model.

Three best solutions for the joint optimization of the 18 responses (R) as a function of the PEF treatments for cucumber seeds with the composite desirabilities of 0.868, 0.432 and 0.416.

Solution Response variable The three best solutions
1 2 3
1 2nd day germination (%) 96.692 95.795 95.752
2 3rd day germination (%) 97.104 97.461 97.468
3 4th day germination (%) 100.136 99.879 99.957
4 Normal seedling (%) rate 95.724 90.181 89.940
5 Cold test 24 °C-5 day (%) 86.611 85.060 85.174
6 Electrical conductivity-4 h (μS cm-1g-1) 8.050 4.788 4.850
7 TAMB (log cfu/g) 3.335 4.002 4.020
8 TMY (log cfu/g) 8.168 8.374 8.369
9 8th day (200mM NaCI) (%) 8.333 3.705 2.995
10 9th day (200mM NaCI) (%) 8.333 3.705 2.995
11 10th day (100mM NaCI)(%) 33.322 15.469 0.743
12 10th day (200mM NaCI)(%) 41.715 1.849 7.273
13 11th day (100mM NaCI)(%) 74.977 63.537 63.512
14 11th day (200mM NaCI)(%) 85.361 43.076 49.439
15 12th day (100mM NaCI)(%) 78.818 143.255 151.728
16 12th day (200mM NaCI)(%) 101.526 60.239 66.096
17 13th day (100mM NaCI)(%) 89.275 126.314 134.443
18 13th day (200mM NaCI)(%) 91.636 23.407 26.173
Discussion

Plants have evolved several stress response mechanisms such as increased and accelerated growth rate, increased biomass production, and diminished adverse effect on the plant tissue. Increased calcium concentration triggered by several external stimuli like ozone, temperature, salinity, and mechanical signals (39,47,51) may lead to changes such as growth, physiology, and development of organisms as well as development of the control mechanisms of stimulus. Effect of PEF on the growth stimulation may be related to the stress response mechanisms of the plants (27). For example, H2O2 production as a plant response to the PEF stress and cell wall healing to reduce permeability was revealed for potato cells (33,50). It is possible that PEF may provide the conversion of intracellular calcium stores to free cytosolic calcium in order to compensate stress and induce growth mechanisms (27). This mechanism in seedlings in response to the PEF stress may increase the germination rate and provide an earlier germination and a stronger body and root formation in the cucumber seeds.

Some other physical treatments were also reported to increase the germination of cucumber seeds. For example, the combination of magnetic field (MF) treatment and UV-B irradiation accelerated germination and growth of seedling for the cucumber seeds (61). PEF applied at 5 kV cm-1 electric field for 3 min along with hydropriming significantly enhanced the germination percentage for Bingo I cucumber seeds (36). Average leaf area of A. thaliana was positively affected by PEF with 10 nanosecond electrical pulses and 5-20 kV cm-1 electric field a few days after germination. Significantly positive effect of PEF applied at 10 kV cm-1 with 80% increase was observed in the 2nd week after the treatments (53). Positive effect of PEF with 4 kJ kg-1 energy level on growth development of A. thaliana was clear at 7th day of germination (53). Growth of soy seedlings were also positively affected by static PEF treatment with 50/60 Hz application. Application of 36 V cm-1 electric field with 50 Hz provided a 12% increase in soy seedling length (22). Acceleration in tomato seed germination was reported after application of electric field in the range of 4 and 12 kV cm-1 (43). Seed yield before sowing was positively influenced by PEF treatment with 4 kV cm-1 for 12 min (23). Growth stimulation effect of PEF changed by applied treatment parameters. For example, while barley growth was positively stimulated by 0.5 kV cm-1 electrostatic field application for 5-day exposure, 2 kV cm-1 electric fields presented no growth promoting action (7). Exposing seeds to electric fields was reported to improve germination performance of soybean (64), tomato (43), and cucum

ber (19) seeds. Similar to the present study, most of the earlier reports indicated that PEF treatment provides 10-20% increase in plant growth and germination rate.

The PEF treatment enhanced the germination performance and altered the membrane permeability of the cucumber seeds. When subjected to electric fields, cellular membrane is the first organelle subjected to electric fields related damage in the cell (46). Effect of PEF on cell membrane is also moisture-dependent as it is important in transmission of applied electric fields to cell membrane. If moisture content is higher than 20%, the cell membrane remains fully hydrated. With the lower water content, on the other hand, the fluid phase could transit to a more compressed state like the gel phase in a dry seed and hydration of the seeds force it back to the fluid phase. During fluid-gel phase transition, this reorientation of membrane components could take place (41), and such reorientation of the membrane components may induce the damage repair and preserve the membrane integrity.

Electrolyte leakage of plant tissue indicating increased tissue permeability and membrane damage is utilized in seed vigor tests to estimate emergence of some seeds in fields. The increased EC resulted in higher leaching of solutes as well as water and nutrient uptake from soil but decreased the seed quality (41,42,54). Changes in EC by the PEF treatments and time are correlated with the changes in both membrane fluidity and membrane permeability in the cucumber seeds (3,6,48).

Both percentage and rate of germination were reduced by the increased salinity level (1,31,37). Salt tolerance in some crops was linked with antioxidant systems (AOS) (12) as it acted as the control mechanisms to reactive oxygen species (ROS) (5) lethally damaging the cell membrane in plants (62). Even though PEF-induced resistance to salt tolerance mechanism is not explained and not fully understood, antioxidant systems may have an important function for seeds to germinate even under 200 mM NaCl salt concentration.

Due to an increase in seed-related contaminations and the reduction in crop yields, alternative decontamination methods are on the high demand. The U.S. Food and Drug Administration (52) recommended the application of calcium hypochlorite solution at 20.000 ppm providing 1-3 log cfu g-1 inactivation for seed disinfection. The treatment of mung bean seeds by moderate temperatures is one of the most popular decontamination method in Japan (9). The application of moderate temperatures (57 or 60 ºC) for 5 min provided 1 log reduction

in Salmonella ssp. without adversely affecting germination abilities of seeds. Although the applied temperatures and treatment times were not effective to provide the seed disinfection (38), the increased temperature significantly decreased the seed germination. The combination of heat treatment with chlorine-based or organic sanitizers to achieve acceptable microbial inactivation with preserving germination abilities was not adequate for a complete inactivation of microbial load (25). Inhibitory effect of peroxyacetic acid, ethanol, fatty acids, and lactic acid for seed disinfection (14,17) was not satisfactory for seed disinfection. Among the physical treatments, cold atmospheric pressure plasma (CAPP) treatment of sprout provided an 8.8-log reduction after 10 min in Staphylococcus aureus and Listeria monocytogenes. A 5.2-log reduction in Escherichia coli and 1-2 log reductions in Geobacillus stearothermophilus endospores on lentils were accomplished with shorter CAPP treatment of 3 min (59). High pressure processing was also evaluated for seed disinfection. Application of pressure at room temperatures with 500-600 MPa for 2 min provided 3.50 log reductions on alfa alfa seeds (44). Irradiation treatment at 2.0 kGy provided 3.18 log reductions in endogenous microflora, but showed adverse effects on the germination properties and physical properties of seedling in addition to nutrient loss such as vitamin C (49). Inactivations of TMAB and total fungi (TF) ranged from 0.22 to 2.85 log in cabbage, lettuce, garden rocket, and wheat by PEF treatment (28). Both increased treatment time and frequency enhanced inactivation of Fusarium graminearum, Xanthomonas campestris pv. campestris, Alternaria brassica, and Drechslera graminea inoculated onto red cabbage seeds (29).

Overall, the PEF treatment enhanced germination rate and normal seedling rate with earlier germination, better body and root formations, and resistance to salt stress. EC was mostly affected by time rather than the PEF treatment. The changes in the conductivity under the different energy levels still remain poorly understood due to the existing knowledge gaps about the physiological and biochemical mechanisms of the PEF treatment for seeds. PEF appeared to influence the biochemical processes involving free radicals and antioxidant enzyme activity, thus resulting in seed invigoration (20). Adverse effects of active radicals on seed deterioration have been long known (46). Highly aggressive free radicals produced by autoxidation in dry seeds can react with the majority of biomolecules, causing cellular damages such as membrane dysfunction, and enzyme inactivation. Free radical production is elevated rapidly increasing respiratory activities resulting in oxidative stress to cellular components. The success of germination largely depends upon the activity of antioxidative systems to prevent cellular components from being damaged by the free radicals (8,11).

Modelling studies performed with PEF treatment of wheat grains revealed 93.9, 85.3, 65.0, and 58.2% variations in A. parasiticus % inhibition, peroxide number, b* value, and total color difference, respectively with the most optimal operational conditions of 19.58 s treatment time, 107.54 Hz frequency, and 3.84 J of, energy for the 12 responses (15). Lower PEF treatment values of frequency (161.8 Hz), energy (6.1 J), and treatment time (19.5 s) with 0.52 desirability were determined as optimal settings for PEF treated wheat grains (15).

Conclusion

Demands for a reduction in the chemical use in the agriculture and chemical-free crop production have increased recently due to their adverse effect on the environmental and public health. The PEF treatment is of a high potential for the chemical-free seed provision and organic farming as it provides healthy seeds and propagation materials. This is the first report involving effect of the PEF treatment at the different energies applied to cucumber seed with the improvement of seed vigor, germination, and salt tolerance. The PEF-treated seedling had more leaves, stronger root formation, and longer fine roots. The significant reduction in the endogenous microflora without adversely affecting the seed germination ability presented the superiority of PEF for seed vigor. The PEF treated cucumber seeds increased the germination rate by 9% and normal seedling rate by 25.73% with earlier germination. Increased salt tolerance, improved germination rate and normal seedling and shortened germination time are important indicators as they affect quality, yield, and profitability. The exact mechanism of PEF on the seed metabolism is not clear, but it is possible that membrane permeability and other metabolic activities for plant tissue might be influenced by the PEF treatment, and the impact of PEF was identical to the other stress conditions. PEF can be a feasible alternative to the chemical applications, but further studies are needed to better quantify the seed responses to PEF-related stresses and associated biochemical changes such as enzyme and free radical activities.

Figure 1

Impact of PEF treatment on germination ability of cucumber seeds.
Impact of PEF treatment on germination ability of cucumber seeds.

Figure 2

Impact of PEF treatment on root formations of cucumber seeds.
Impact of PEF treatment on root formations of cucumber seeds.

Figure 3

Inactivation of cucumber seed endogenous microflora treated by PEF a) total aerobic mesophilic bacteria (TAMB) and b) total mold and yeast (TMY).
Inactivation of cucumber seed endogenous microflora treated by PEF a) total aerobic mesophilic bacteria (TAMB) and b) total mold and yeast (TMY).

Figure 4

Optimization of Gaussian process model.
Optimization of Gaussian process model.

Germination rate (%) of the control and PEF-treated cucumber seed samples

Energy (J) Germination rate (%)
2.day 3.day 4.day
0.00 90.00 ± 0.00bB 91.11 ± 1.92cB 93.33 ± 0.00cA
1.07 95.56 ± 1.92aA 95.56 ± 1.92bA 96.67 ± 0.00bA
1.36 93.33 ± 1.33aB 96.67 ± 3.33abA 98.89 ± 1.92abA
1.92 95.56 ± 1.92Aa 96.67 ± 3.33abA 98.89 ± 1.92abA
2.16 98.89 ± 1.92aA 98.89 ± 1.92abA 100.00 ± 0.00aA
3.21 95.33 ± 1.33aA 100.00 ± 0.00aA 100.00 ± 0.00aA
4.08 96.67 ± 1.33aB 100.00 ± 0.00aA 100.00 ± 0.00aA
5.35 96.67 ± 1.33aB 96.67 ± 0.00bB 100.00 ± 0.00aA
5.76 95.56 ± 4.09aA 98.89 ± 1.92abA 100.00 ± 0.00aA
6.48 93.33 ± 3.33aA 94.44 ± 1.92bA 97.78 ± 1.92abA
6.80 96.67 ± 1.33aA 96.67 ± 1.33bA 98.89 ± 1.92abA
8.55 95.56 ± 1.92aB 95.56 ± 1.92bB 100.00 ± 0.00aA
9.60 93.33 ± 0.00aC 96.67 ± 0.00bB 100.00 ± 0.00aA
10.80 96.67 ± 1.33aB 97.78 ± 1.92bB 100.00 ± 0.00aA
10.89 95.56 ± 1.92aB 96.67 ± 0.00bB 100.00 ± 0.00aA
15.36 96.67 ± 0.00ab 96.67 ± 0.00bB 100.00 ± 0.00aA
17.28 98.89 ± 1.92aB 97.78 ± 1.92bB 100.00 ± 0.00aA

Normal seedling rate (%) of the control and PEF-treated cucumber seed samples

Energy (J) Normal seedling rate (%)
0.00 72.62 ± 2.06d
1.07 75.86 ± 0.00c
1.36 89.81 ± 6.11b
1.92 96.63 ± 0.47a
2.16 95.18 ± 1.92a
3.21 86.67 ± 2.00b
4.08 86.67 ± 6.67b
5.35 85.56 ± 5.09b
5.76 92.22 ± 3.85ab
6.48 94.37 ± 3.78ab
6.80 83.14 ± 6.67b
8.55 85.56 ± 6.94b
9.60 93.33 ± 3.33ab
10.80 92.22 ± 5.09ab
10.89 83.33 ± 5.77b
15.36 91.11 ± 5.09ab
17.28 95.56 ± 1.92a

Best-fit non-linear regression models for the response variables of cucumber seed samples.

Response variable Goal Model R2 (%) R2pred (%) SE p DW
2nd day germination (%) Max 90.64+0.03362X1 21.26 16.20 2.94 0.001 1.949
3rd day germination (%) Max 91.15+0.0876X1-0.000303 X1*X1 31.14 22.38 2.22 0.008 1.578
4rd day germination (%) Max 93.379+0.0735X1+0.1887X2-0.000246 X1* X1 65.63 60.94 1.14 0.005 1.499
Normal seedling rate (%) Max 75.53+0.000623X1*X1 58.89 55.83 5.05 0.000 1.596
Cold test 24 °C- 5 day (%) Max 68.89+0.1715X1-0.000000X1*X1*X1*X1+ 0.000007X1*X3*X3*X3 43.72 33.18 4.96 0.047 1.215
EC- 4 h (μS cm-1g-1) Target (7.30) 7.335+0.000054X3*X3*X3*X3-0.000000X1*X1*X1*X2 35.59 28.36 0.88 0.000 1.754
TAMB (log cfu mL-1) Min 6.026-0.01320X1-0.000031X3*X3*X3*X3+0.000000X1* X1*X1*X3 55.42 48.86 0.52 0.001 1.233
TMY (log cfu mL-1) Min 9.4140-0.01034X1+0.000000 X1*X1*X1*X1-0.000005 X3*X3*X3*X3 71.93 68.17 0.17 0.000 1.578
8th day (200mM NaCI)(%) Max -0.000000+0.000043X1-0.000001X1*X1*X1+ 0.1300X3*X3*X3+ 0.000093X1*X3*X3-0.005486X1*X3*X3+0.0 00063X1*X2*X-0.003200 X3*X2*X+0.000000X1*X1*X1*X+ 0.02446X3*X3*X3*X-0.000001X1*X1*X1*X+ 221330.000034X1*X1*X3*X3+0.000003X1*X2*X3*X3-0.000783X1*X3*X3*X3-0.1035X2*X3*X3*X3+ 0.02328X3*X3*X2*X2-0.004283X3*X2*X2*X2 100 100 0.00 * *
9th day (200mM NaCI)(%) Max -0.000000+0.000043X1-0.000001X1*X1*X1+ 0.1300X3*X3*X3+0.000093X1*X1*X3-0.005486X1*X3*X3+ 0.00006X1*X3*X-0.003200X3*X2*X+ 0.00000022X1*X1*X1*X+0.02446X3*X3*X3*X-0.00000X1*X3321311 *X1*X3+0.000034X1*X1*X3*X3+0.000003X1*X2*X3*X3-0.000783X1*X3*X3*X3-0.1035X2*X3*X3*X3+ 0.02328X3*X3*X2*X2-0.004283 X3*X2*X2*X2 100 100 0.00 * *
10th day (100mM NaCI) (%) Max 8.316+0.10445X1-16.635X2-0.24945X1*X3+ 0.01730X1*X2+ 19.458X2*X3+0.6244X2*X2- 0.024510X1*X3*X2-2.570X2*X2*X3-0.16956X2*X3*X3-0.04402X2*X2*X2*X2+0.000006X1*X1*X1*X1 +0.002509X1*X2*X3*X2+0.13530 X2*X2*X2*X3 99.97 99.95 0.18 0.000 1.122
10th day (200mM NaCI)(%) Max 0.000-3.313X2-0.000397X1*X1+ 0.2139X1*X3 +0.3253X3*X3*X3-0.000749X1*X1*X3+ 0.004663X2*X2*X2- 0.05417X1*X3*X3-0.008062X3*X3*X3*X3+ 0.000196X1*X1*X3*X3-0.00494X2*X3*X3*X3 99.53 99.30 0.86 0.000 1.039
11th day (100mM NaCI) (%) Max 8.310-0.04121X1+3.9408X2*X2-0.001377X1*X1*X3-0.013595X1*X3*X3- 0.06285X2*X2*X2*X2+0.000008X1*X1*X 1*X3+0.000050X1*X1*X3*X3+0.012250 X2*X2*X3*X2 99.52 99.41 1.50 0.000 1.099
11th day (200mM NaCI)(%) Max -1.310+0.009838X1*X2*X2-0.019665X1*X3*X3+0.000106 X1*X1*X3*X3 97.06 96.76 3.78 0.000 1.000
12th day (100mM NaCI) (%) Max 8.55-0.0908X1+0.1832X1*X2-0.002519X1*X1*X3-0.00435X2*X2*X2*X2+0.000012X1*X1*X1*X3 94.54 93.18 5.28 0.000 0.673
12th day (200mM NaCI)(%) Max -0.39+0.1158 X1+0.009501X1*X2*X2-0.02382X1*X3*X3-0.001925X3*X3*X3*X3-0.000002X1*X1*X1*X3+0.000169 X1*X1*X3*X3 96.54 95.66 4.96 0.000 0.869
13th day (100mM NaCI) (%) Max 23.61-0.1593X1+1.699X2*X2+0.1132X1*X2-0.002365X1*X1*X3-0.01960 X2*X2*X2*X2+0.000012 X1*X1*X1*X3 91.66 88.83 7.60 0.021 0.905
13th day (200(%) mM NaCI) Max 5.32+0.615X2*X2-0.1553X3*X3*X3+ 0.000913X1*X3*X3*X3 57.29 53.13 17.93 0.011 0.790

Three best solutions for the joint optimization of the 18 responses (R) as a function of the PEF treatments for cucumber seeds with the composite desirabilities of 0.868, 0.432 and 0.416.

Solution Response variable The three best solutions
1 2 3
1 2nd day germination (%) 96.692 95.795 95.752
2 3rd day germination (%) 97.104 97.461 97.468
3 4th day germination (%) 100.136 99.879 99.957
4 Normal seedling (%) rate 95.724 90.181 89.940
5 Cold test 24 °C-5 day (%) 86.611 85.060 85.174
6 Electrical conductivity-4 h (μS cm-1g-1) 8.050 4.788 4.850
7 TAMB (log cfu/g) 3.335 4.002 4.020
8 TMY (log cfu/g) 8.168 8.374 8.369
9 8th day (200mM NaCI) (%) 8.333 3.705 2.995
10 9th day (200mM NaCI) (%) 8.333 3.705 2.995
11 10th day (100mM NaCI)(%) 33.322 15.469 0.743
12 10th day (200mM NaCI)(%) 41.715 1.849 7.273
13 11th day (100mM NaCI)(%) 74.977 63.537 63.512
14 11th day (200mM NaCI)(%) 85.361 43.076 49.439
15 12th day (100mM NaCI)(%) 78.818 143.255 151.728
16 12th day (200mM NaCI)(%) 101.526 60.239 66.096
17 13th day (100mM NaCI)(%) 89.275 126.314 134.443
18 13th day (200mM NaCI)(%) 91.636 23.407 26.173

Changes in electrical conductivity (μS cm-1g-1) of the control and PEF-treated cucumber seed samples

Energy (J) Electrical conductivity (μS cm-1g-1)
4 hour 8 hour 24 hour
0.00 7.29±0.79abcA 8.06±0.67aAB 9.65±0.58abA
1.07 7.17±0.76abcB 8.22±0.17aB 9.82±0.14abA
1.36 5.92±1.82abcB 8.65±0.62aA 9.02±0.57bA
1.92 6.48±1.06abcC 8.79±0.56aB 9.74±0.57abA
2.16 7.44±0.18abcC 9.07±0.50aB 10.17±0.05abA
3.21 7.56±0.21abcC 8.75±0.27aB 9.62±0.37abA
4.08 6.91±0.21abcB 8.45±0.84aAB 9.73±0.64abA
5.35 7.24±0.32abcB 8.35±1.34aB 10.19±0.43abA
5.76 6.42±0.07abcC 8.84±0.23aB 10.33±0.08abA
6.48 5.57±0.40bcC 8.56±0.18aB 9.55±0.29abA
6.80 6.17±0.66abcC 7.85±0.39aB 8.98±0.47bA
8.55 6.28±0.69abcB 8.36±0.21aA 9.09±0.56bA
9.60 6.07±1.72abcC 8.93±0.46aB 10.41±0.73abA
10.80 5.87±0.11abcC 7.98±0.49aB 9.47±0.30abA
10.89 5.43±0.29cC 7.65±1.38aB 9.74±1.04abA
15.36 7.75±0.08abcC 8.88±0.07aB 9.85±0.67abA
17.28 7.94±0.79abC 9.18±0.28aB 10.61±0.15aA

Germination rate (%) of the control and PEF-treated cucumber seed samples under 100 mM NaCl salt stress

Energy (J) Germination rate (%)
8. day 9. day 10. day 11. day 12. day 13. day
0 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 3.33 ± 0.30hA
1.07 0.00 ± 0.00aA 0.00 ± 0.00cA 0.00 ± 0.00eA 0.00 ± 0.00gA 0.00 ± 0.00gA 8.33 ± 0.00Ga
1.36 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 16.67 ± 0.30fA
1.92 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 16.67 ± 0.30fA
2.16 0.00 ± 0.00aB 0.00 ± 0.00cB 8.33 ± 0.00dA 8.33 ± 0.00fA 8.33 ± 0.00fA 8.33 ± 0.00gA
3.21 0.00 ± 0.00aE 0.00 ± 0.00cE 8.33 ± 0.00dD 16.67 ± 0.30eC 25.00 ± 0.00dB 33.33 ± 0.00dA
4.08 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 16.67 ± 0.30fA
5.35 0.00 ± 0.00aE 16.67 ± 0.00aD 25.00 ± 0.30bC 33.33 ± 0.00cB 33.33 ± 0.30cB 41.67 ± 0.40cA
5.76 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 8.33 ± 0.00gA
6.48 0.00 ± 0.00aD 16.67 ± 0.00aC 16.67 ± 0.30cC 25.00 ± 0.00dB 33.33 ± 0.30cA 33.33 ± 0.00dA
6.80 0.00 ± 0.00aD 8.33 ± 0.00bC 8.33 ± 0.30dC 16.67 ± 0.00eB 16.67 ± 0.00eB 25.00 ± 0.00eA
8.55 0.00 ± 0.00aD 0.00 ± 0.00cD 8.33 ± 0.00dC 25.00 ± 0.00dB 25.00 ± 0.00dB 33.33 ± 0.00dA
9.60 0.00 ± 0.00aB 0.00 ± 0.00cB 0.00 ± 0.00eB 0.00 ± 0.00gB 0.00 ± 0.00gB 16.67 ± 0.30fA
10.80 0.00 ± 0.00aA 0.00 ± 0.00cA 16.67 ± 0.00cD 41.67 ± 0.40bC 58.33 ± 0.00bB 75.00 ± 0.30bA
10.89 0.00 ± 0.00aC 0.00 ± 0.00cC 8.33 ± 0.00dB 8.33 ± 0.00fB 16.67 ± 0.20eA 16.67 ± 0.00fA
15.36 0.00 ± 0.00aC 0.00 ± 0.00cC 0.00 ± 0.00eC 0.00 ± 0.00gC 8.33 ± 0.00fB 16.67 ± 0.30fA
17.28 0.00 ± 0.00aD 0.00 ± 0.00cD 33.33 ± 0.00aC 75.00 ± 0.00aB 75.00 ± 0.00aB 83.33 ± 0.00aA

Germination rate (%) of the control and PEF-treated cucumber seed samples under 200 mM NaCl salt stress

Energy (J) Germination rate (%)
8. day 9. day 10. day 11. day 12. day 13. day
0 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
1.07 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 8.33 ± 0.60dA 8.33 ± 0.60eA
1.36 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
1.92 0.00 ± 0.00bC 0.00 ± 0.00bC 0.00 ± 0.00dC 0.00 ± 0.00dC 16.67 ± 0.00cB 25.00 ± 0.00cA
2.16 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
3.21 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 8.33 ± 0.60dA 8.33 ± 0.60eA
4.08 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 8.33 ± 0.60dA 8.33 ± 0.60eA
5.35 0.00 ± 0.00bC 0.00 ± 0.00bC 0.00 ± 0.00dC 0.00 ± 0.00dC 8.33 ± 0.60dB 16.67 ± 0.00dA
5.76 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
6.48 0.00 ± 0.00bB 0.00 ± 0.00bB 0.00 ± 0.00dB 0.00 ± 0.00dB 0.00 ± 0.00eB 8.33 ± 0.60eA
6.80 0.00 ± 0.00bA 0.00 ± 0.00bA 0.00 ± 0.00dA 0.00 ± 0.00dA 0.00 ± 0.00eA 8.33 ± 0.60eA
8.55 0.00 ± 0.00bD 0.00 ± 0.00bD 8.33 ± 0.60cC 8.33 ± 0.00cB 8.33 ± 0.60dB 16.67 ± 0.00dA
9.60 0.00 ± 0.00bD 0.00 ± 0.00bD 0.00 ± 0.00dD 8.33 ± 0.00cC 16.67 ± 0.00cB 66.67 ± 0.00bA
10.80 0.00 ± 0.00bE 0.00 ± 0.00bE 25.00 ± 0.50bD 41.67 ± 0.00bC 50.00 ± 0.60bB 66.67 ± 0.00bA
10.89 0.00 ± 0.00bB 0.00 ± 0.00bB 8.33 ± 0.00cA 8.33 ± 0.00cA 8.33 ± 0.60dA 8.33 ± 0.00eA
15.36 0.00 ± 0.00bD 0.00 ± 0.00bD 8.33 ± 0.00cC 8.33 ± 0.00cC 16.67 ± 0.00cB 66.67 ± 0.00bA
17.28 8.33 ± 0.00aD 8.33 ± 0.00aD 41.67 ± 0.00aC 83.33 ± 0.70aB 100.00 ± 0.00aA 100.00 ± 0.90aA

Abdel-Farid IB, Marghany MR, Rowezek MM, Sheded MG. Effect of salinity stress on growth and metabolomic profiling of Cucumis sativus and Solanum lycopersicum. Plants. 2020;9:1626. Abdel-Farid IB Marghany MR Rowezek MM Sheded MG Effect of salinity stress on growth and metabolomic profiling of Cucumis sativus and Solanum lycopersicum Plants 20209162610.3390/plants9111626Search in Google Scholar

Abogadallah GM, Serag MM, El-Katouny TM, Quick WP. Salt tolerance at germination and vegetative growth involves different mechanisms in barnyard grass (Echinochloa crusgalli L.) mutants. Plant Growth Regul. 2010;60:1–12. Abogadallah GM Serag MM El-Katouny TM Quick WP Salt tolerance at germination and vegetative growth involves different mechanisms in barnyard grass (Echinochloa crusgalli L.) mutants Plant Growth Regul 2010601 1210.1007/s10725-009-9413-9Search in Google Scholar

Ahmadi M, Souri MK. Growth characteristics and fruit quality of chili pepper under higher electrical conductivity of nutrient solution ınduced by various salts. AGRIVITA J Agric Sci. 2020;42:143–52. Ahmadi M Souri MK Growth characteristics and fruit quality of chili pepper under higher electrical conductivity of nutrient solution ınduced by various salts AGRIVITA J Agric Sci 202042143 5210.17503/agrivita.v42i1.2225Search in Google Scholar

Ahmed Z, Manzoor MF, Ahmad N, Zeng X-A, Din Z ud, Roobab U, et al. Impact of pulsed electric field treatments on the growth parameters of wheat seeds and nutritional properties of their wheat plantlets juice. Food Sci Nutr. 2020;8:2490–500. Ahmed Z Manzoor MF Ahmad N Zeng X-A Din Z ud Roobab U et al Impact of pulsed electric field treatments on the growth parameters of wheat seeds and nutritional properties of their wheat plantlets juice Food Sci Nutr 202082490 50010.1002/fsn3.1540Search in Google Scholar

Allen RD. Dissection of oxidative stress tolerance using transgenic plants. Plant Physiol. 1995;107:1049–54. Allen RD Dissection of oxidative stress tolerance using transgenic plants Plant Physiol 19951071049 5410.1104/pp.107.4.1049Search in Google Scholar

Amritphale D, Sreenivasulu Y, Singh B. Changes in membrane fluidity and protein composition during release of cucumber seeds from dormancy by a higher temperature shift. Ann Bot. 2000;85:13–8. Amritphale D Sreenivasulu Y Singh B Changes in membrane fluidity and protein composition during release of cucumber seeds from dormancy by a higher temperature shift Ann Bot 20008513 810.1006/anbo.1999.0992Search in Google Scholar

Bachman CH, Reichmanis M. Some effects of high electrical fields on barley growth. Int J Biometeorol. 1973;17:253– 62. Bachman CH Reichmanis M Some effects of high electrical fields on barley growth Int J Biometeorol 197317253–6210.1007/BF01804618Search in Google Scholar

Bailly C. Active oxygen species and antioxidants in seed biology. Seed Sci Res. 2004;14:93–107. Bailly C Active oxygen species and antioxidants in seed biology Seed Sci Res 20041493 10710.1079/SSR2004159Search in Google Scholar

Bari ML, Enomoto K, Nei D, Kawamoto S. Practical evaluation of Mung bean seed pasteurization method in Japan. J Food Prot. 2010;73:752–7. Bari ML Enomoto K Nei D Kawamoto S Practical evaluation of Mung bean seed pasteurization method in Japan J Food Prot 201073752 710.4315/0362-028X-73.4.752Search in Google Scholar

Berg H. Electrostimulation of cell metabolism by low frequency electric and electromagnetic fields. Bioelectrochem Bioenerg. 1993;31:1–25. Berg H Electrostimulation of cell metabolism by low frequency electric and electromagnetic fields Bioelectrochem Bioenerg 1993311 2510.1016/0302-4598(93)86102-7Search in Google Scholar

Black M, Bewley JD. Seed technology and its biological basis. Sheffield, England; Boca Raton, FL: Sheffield Academic Press ; CRC Press; 2000. Black M Bewley JD Seed technology and its biological basis Sheffield, England; Boca Raton, FL Sheffield Academic Press ; CRC Press 2000Search in Google Scholar

Bor M, Özdemir F, Türkan I. The effect of salt stress on lipid peroxidation and antioxidants in leaves of sugar beet Beta vulgaris L. and wild beet Beta maritima L. Plant Sci. 2003;164:77–84. Bor M Özdemir F Türkan I The effect of salt stress on lipid peroxidation and antioxidants in leaves of sugar beet Beta vulgaris L. and wild beet Beta maritima L Plant Sci 200316477 8410.1016/S0168-9452(02)00338-2Search in Google Scholar

Braun AL, Supkoff DM. Options to methyl bromide for the control of soil-borne diseases and pests in California with reference to the Netherlands. 1994; Braun AL Supkoff DM Options to methyl bromide for the control of soil-borne diseases and pests in California with reference to the Netherlands 1994Search in Google Scholar

Buchholz A, Matthews KR. Reduction of Salmonella on alfalfa seeds using peroxyacetic acid and a commercial seed washer is as effective as treatment with 20 000 ppm of Ca(OCl)2. Lett Appl Microbiol. 2010;51:462–8. Buchholz A Matthews KR Reduction of Salmonella on alfalfa seeds using peroxyacetic acid and a commercial seed washer is as effective as treatment with 20 000 ppm of Ca(OCl)2 Lett Appl Microbiol 201051462 810.1111/j.1472-765X.2010.02929.xSearch in Google Scholar

Bulut N, Atmaca B, Evrendilek GA, Uzuner S. Potential of pulsed electric field to control Aspergillus parasiticus, aflatoxin and mutagenicity levels: Sesame seed quality. J Food Saf. 2020;40:e12855. Bulut N Atmaca B Evrendilek GA Uzuner S Potential of pulsed electric field to control Aspergillus parasiticus, aflatoxin and mutagenicity levels: Sesame seed quality J Food Saf 202040e1285510.1111/jfs.12855Search in Google Scholar

Cesur A, Tabur S. Chromotoxic effects of exogenous hydrogen peroxide (H2O2) in barley seeds exposed to salt stress. Acta Physiol Plant. 2011;33:705–9. Cesur A Tabur S Chromotoxic effects of exogenous hydrogen peroxide (H2O2) in barley seeds exposed to salt stress Acta Physiol Plant 201133705 910.1007/s11738-010-0594-7Search in Google Scholar

Chang S, Redondo-Solano M, Thippareddi H. Inactivation of Escherichia coli O157:H7 and Salmonella spp. on alfalfa seeds by caprylic acid and monocaprylin. Int J Food Microbiol. 2010;144:141–6. Chang S Redondo-Solano M Thippareddi H Inactivation of Escherichia coli O157:H7 and Salmonella spp. on alfalfa seeds by caprylic acid and monocaprylin Int J Food Microbiol 2010144141 610.1016/j.ijfoodmicro.2010.09.011Search in Google Scholar

Chellemi DO, Olson SM, Mitchell DJ, Secker I, McSorley R. Adaptation of soil solarization to the ıntegrated management of soilborne pests of tomato under humid conditions. Phytopathology®. 1997;87:250–8. Chellemi DO Olson SM Mitchell DJ Secker I McSorley R Adaptation of soil solarization to the ıntegrated management of soilborne pests of tomato under humid conditions Phytopathology® 199787250 810.1094/PHYTO.1997.87.3.250Search in Google Scholar

Cheng Z, ZhengNong F, GuangWen Z. The effect of HVEF treatment on lipid peroxidation of aged cucumber seeds. J Zhejiang Univ Agric Life Sci. 2000;26:127–30. Cheng Z ZhengNong F GuangWen Z The effect of HVEF treatment on lipid peroxidation of aged cucumber seeds J Zhejiang Univ Agric Life Sci 200026127 30Search in Google Scholar

Chiabrera A, Bianco B. The Role of the Magnetic Field in the EM Interaction with Ligand Binding. In: Blank M, Findl E, editors. Mechanistic approaches to ınteractions of electric and electromagnetic fields with living systems. Boston, MA: Springer US; 1987. p. 79–95. Chiabrera A Bianco B The Role of the Magnetic Field in the EM Interaction with Ligand Binding In Blank M Findl E editors Mechanistic approaches to ınteractions of electric and electromagnetic fields with living systems Boston, MA Springer US 1987 p 79 9510.1007/978-1-4899-1968-7_5Search in Google Scholar

Cogalniceanu G, Radu M, Fologea D, Moisoi N, Brezeanu A. Stimulation of tobacco shoot regeneration by alternating weak electric field. Bioelectrochem Bioenerg. 1998;2:257–60. Cogalniceanu G Radu M Fologea D Moisoi N Brezeanu A Stimulation of tobacco shoot regeneration by alternating weak electric field Bioelectrochem Bioenerg 19982257 6010.1016/S0302-4598(97)00074-3Search in Google Scholar

Costanzo E. The influence of an electric field on the growth of soy seedlings. J Electrost. 2008;66:417–20. Costanzo E The influence of an electric field on the growth of soy seedlings J Electrost 200866417 2010.1016/j.elstat.2008.04.002Search in Google Scholar

Cramariuc R, Donescu V, Popa M, Cramariuc B. The biological effect of the electrical field treatment on the potato seed: agronomic evaluation. J Electrost. 2005;63:837–46. Cramariuc R Donescu V Popa M Cramariuc B The biological effect of the electrical field treatment on the potato seed: agronomic evaluation J Electrost 200563837 4610.1016/j.elstat.2005.03.082Search in Google Scholar

Criddle RS, Breidenbach RW, Hansen LD. Plant calorimetry: how to quantitatively compare apples and oranges. Thermochim Acta. 1991;193:67–90. Criddle RS Breidenbach RW Hansen LD Plant calorimetry: how to quantitatively compare apples and oranges Thermochim Acta 199119367 9010.1016/0040-6031(91)80175-ISearch in Google Scholar

Ding H, Fu T-J, Smith MA. Microbial contamination in sprouts: How effective ıs seed disinfection treatment? J Food Sci. 2013;78:R495–501. Ding H Fu T-J Smith MA Microbial contamination in sprouts: How effective ıs seed disinfection treatment? J Food Sci 201378R495 50110.1111/1750-3841.1206423464679Search in Google Scholar

Dymek K, Dejmek P, Panarese V, Vicente AA, Wadsö L, Finnie C, et al. Effect of pulsed electric field on the germination of barley seeds. LWT - Food Sci Technol. 2012;47:161–6. Dymek K Dejmek P Panarese V Vicente AA Wadsö L Finnie C et al Effect of pulsed electric field on the germination of barley seeds LWT - Food Sci Technol 201247161 610.1016/j.lwt.2011.12.019Search in Google Scholar

Eing CJ, Bonnet S, Pacher M, Puchta H, Frey W. Effects of nanosecond pulsed electric field exposure on arabidopsis thaliana. IEEE Trans Dielectr Electr Insul. 2009;16:1322–8. Eing CJ Bonnet S Pacher M Puchta H Frey W Effects of nanosecond pulsed electric field exposure on arabidopsis thaliana IEEE Trans Dielectr Electr Insul 2009161322 810.1109/TDEI.2009.5293945Search in Google Scholar

Evrendilek GA, Tanasov I. Configuring pulsed electric fields to treat seeds: an innovative method of seed disinfection. Seed Sci Technol. 2017;45:72–80. Evrendilek GA Tanasov I Configuring pulsed electric fields to treat seeds: an innovative method of seed disinfection Seed Sci Technol 20174572 8010.15258/sst.2017.45.1.13Search in Google Scholar

Evrendilek GA, Karatas B, Uzuner S, Tanasov I. Design and effectiveness of pulsed electric fields towards seed disinfection. J Sci Food Agric. 2019;99:3475–80. Evrendilek GA Karatas B Uzuner S Tanasov I Design and effectiveness of pulsed electric fields towards seed disinfection J Sci Food Agric 2019993475 8010.1002/jsfa.956630623440Search in Google Scholar

Evrendilek, Gulsun Akdemir G, Atmaca B, Bulut N, Uzuner S. Development of pulsed electric fields treatment unit to treat wheat grains: Improvement of seed vigour and stress tolerance. Comput Electron Agric. 2021;185:106129. Evrendilek, Gulsun Akdemir G Atmaca B Bulut N Uzuner S Development of pulsed electric fields treatment unit to treat wheat grains: Improvement of seed vigour and stress tolerance Comput Electron Agric 202118510612910.1016/j.compag.2021.106129Search in Google Scholar

Fan H, Ding L, Xu Y, Du C. Seed germination, seedling growth and antioxidant system responses in cucumber exposed to Ca(NO3)2. Hortic Environ Biotechnol. 2017;58:548–59. Fan H Ding L Xu Y Du C Seed germination, seedling growth and antioxidant system responses in cucumber exposed to Ca(NO3)2 Hortic Environ Biotechnol 201758548 5910.1007/s13580-017-0025-4Search in Google Scholar

Fincan M, DeVito F, Dejmek P. Pulsed electric field treatment for solid-liquid extraction of red beetroot pigment. J Food Eng. 2004;64:381–8. Fincan M DeVito F Dejmek P Pulsed electric field treatment for solid-liquid extraction of red beetroot pigment J Food Eng 200464381 810.1016/j.jfoodeng.2003.11.006Search in Google Scholar

Galindo FG, Vernier PT, Dejmek P, Vicente A, Gundersen MA. Pulsed electric field reduces the permeability of potato cell wall. Bioelectromagnetics. 2008;29:296–301. Galindo FG Vernier PT Dejmek P Vicente A Gundersen MA Pulsed electric field reduces the permeability of potato cell wall Bioelectromagnetics 200829296 30110.1002/bem.2039418163439Search in Google Scholar

Góngora-Nieto MM, Pedrow PD, Swanson BG, Barbosa-Cánovas GV. Energy analysis of liquid whole egg pasteurized by pulsed electric fields. J Food Eng. 2003;57:209– 16. Góngora-Nieto MM Pedrow PD Swanson BG Barbosa-Cánovas GV Energy analysis of liquid whole egg pasteurized by pulsed electric fields J Food Eng 200357209 1610.1016/S0260-8774(02)00299-6Search in Google Scholar

Gou T, Chen X, Han R, Liu J, Zhu Y, Gong H. Silicon can improve seed germination and ameliorate oxidative damage of bud seedlings in cucumber under salt stress. Acta Physiol Plant. 2020;42:12. Gou T Chen X Han R Liu J Zhu Y Gong H Silicon can improve seed germination and ameliorate oxidative damage of bud seedlings in cucumber under salt stress Acta Physiol Plant 2020421210.1007/s11738-019-3007-6Search in Google Scholar

Huang R, Sukprakarn S, Phavaphutanon L, Juntakool S, Chaikul C. A comparison of electric field treatments to hydropriming on cucumber seed germination enhancement. Agric Nat Resour. 2006;40:559–65. Huang R Sukprakarn S Phavaphutanon L Juntakool S Chaikul C A comparison of electric field treatments to hydropriming on cucumber seed germination enhancement Agric Nat Resour 200640559 65Search in Google Scholar

Iqbal P, Ghani MA, Ali B, Shahid M, Iqbal Q, Ziaf K, et al. Exogenous application of glutamic acid promotes cucumber (Cucumis sativus L.) growth under salt stress conditions. Emir J Food Agric. 2021;407–16. Iqbal P Ghani MA Ali B Shahid M Iqbal Q Ziaf K et al Exogenous application of glutamic acid promotes cucumber (Cucumis sativus L.) growth under salt stress conditions Emir J Food Agric 2021407 1610.9755/ejfa.2021.v33.i5.2699Search in Google Scholar

Jaquette CB, Beuchat LR, Mahon BE. Efficacy of chlorine and heat treatment in killing Salmonella stanley inoculated onto alfalfa seeds and growth and survival of the pathogen during sprouting and storage. Appl Environ Microbiol. 1996;62:2212–5. Jaquette CB Beuchat LR Mahon BE Efficacy of chlorine and heat treatment in killing Salmonella stanley inoculated onto alfalfa seeds and growth and survival of the pathogen during sprouting and storage Appl Environ Microbiol 1996622212 510.1128/aem.62.7.2212-2215.1996Search in Google Scholar

Lecourieux D, Mazars C, Pauly N, Ranjeva R, Pugin A. analysis and effects of cytosolic free calcium ıncreases in response to elicitors in Nicotiana plumbaginifolia cells. Plant Cell. 2002;14:2627–41. Lecourieux D Mazars C Pauly N Ranjeva R Pugin A analysis and effects of cytosolic free calcium ıncreases in response to elicitors in Nicotiana plumbaginifolia cells Plant Cell 2002142627 4110.1105/tpc.005579Search in Google Scholar

Leong SY, Burritt DJ, Oey I. Electropriming of wheatgrass seeds using pulsed electric fields enhances antioxidant metabolism and the bioprotective capacity of wheatgrass shoots. Sci Rep. 2016;6:25306. Leong SY Burritt DJ Oey I Electropriming of wheatgrass seeds using pulsed electric fields enhances antioxidant metabolism and the bioprotective capacity of wheatgrass shoots Sci Rep 201662530610.1038/srep25306Search in Google Scholar

Marcos-Filho J. Seed vigor testing: An overview of the past, present and future perspective. Sci Agric. 2015;72:363–74. Marcos-Filho J. Seed vigor testing: An overview of the past, present and future perspective Sci Agric 201572363 7410.1590/0103-9016-2015-0007Search in Google Scholar

Melo PAFR de, Martins CC, Alves EU, Vieira RD. Development of methodology to test the electrical conductivity of Marandú grass seeds. Rev Ciênc AGRONÔMICA. 2019;50. Melo PAFR de Martins CC Alves EU Vieira RD Development of methodology to test the electrical conductivity of Marandú grass seeds Rev Ciênc AGRONÔMICA 20195010.5935/1806-6690.20190013Search in Google Scholar

Moon J-D, Chung H-S. Acceleration of germination of tomato seed by applying AC electric and magnetic fields. J Electrost. 2000;48:103–14. Moon J-D Chung H-S Acceleration of germination of tomato seed by applying AC electric and magnetic fields J Electrost 200048103 1410.1016/S0304-3886(99)00054-6Search in Google Scholar

Neetoo H, Ye M, Chen H. Factors affecting the efficacy of pressure inactivation of Escherichia coli O157:H7 on alfalfa seeds and seed viability. Int J Food Microbiol. 2009;131:218–23. Neetoo H Ye M Chen H Factors affecting the efficacy of pressure inactivation of Escherichia coli O157:H7 on alfalfa seeds and seed viability Int J Food Microbiol 2009131218 2310.1016/j.ijfoodmicro.2009.02.02819339075Search in Google Scholar

Parniakov O, Roselló-Soto E, Barba FJ, Grimi N, Lebovka N, Vorobiev E. New approaches for the effective valorization of papaya seeds: Extraction of proteins, phenolic compounds, carbohydrates, and isothiocyanates assisted by pulsed electric energy. Food Res Int. 2015;P4:711–7. Parniakov O Roselló-Soto E Barba FJ Grimi N Lebovka N Vorobiev E New approaches for the effective valorization of papaya seeds: Extraction of proteins, phenolic compounds, carbohydrates, and isothiocyanates assisted by pulsed electric energy Food Res Int 2015P4711 710.1016/j.foodres.2015.03.031Search in Google Scholar

Priestley DA. Seed Aging: Implications for Seed Storage and Persistence in the Soil. 1st Ed edition. Ithaca, N.Y: NCROL; 1986. 304 p. Priestley DA Seed Aging: Implications for Seed Storage and Persistence in the Soil. 1st Ed edition Ithaca, N.Y NCROL 1986 304 pSearch in Google Scholar

Qi F, Zhang F. Cell cycle regulation in the plant response to stress. Front Plant Sci. 2020;10:1765. Qi F Zhang F Cell cycle regulation in the plant response to stress Front Plant Sci 202010176510.3389/fpls.2019.01765700244032082337Search in Google Scholar

Radjabov A, Ibragimov M, Eshpulatov N. The study of the electrical conductivity of apples and grapes as an object of electrical processing. Hendroko Setyobudi R, Winaya A, Burlakovs J, Mel M, Anne O, editors. E3S Web Conf. 2021;226:00002. Radjabov A Ibragimov M Eshpulatov N The study of the electrical conductivity of apples and grapes as an object of electrical processing Hendroko Setyobudi R Winaya A Burlakovs J Mel M Anne O editors E3S Web Conf 20212260000210.1051/e3sconf/202122600002Search in Google Scholar

Rajkowski KT, Thayer DW. Alfalfa seed germination and yield ratio and alfalfa sprout microbial keeping quality following irradiation of seeds and sprouts. J Food Prot. 2001;64:1988–95. Rajkowski KT Thayer DW Alfalfa seed germination and yield ratio and alfalfa sprout microbial keeping quality following irradiation of seeds and sprouts J Food Prot 2001641988 9510.4315/0362-028X-64.12.1988Search in Google Scholar

Razem FA, Bernards MA. Reactive oxygen species production in association with suberization: evidence for an NADPH-dependent oxidase. J Exp Bot. 2003;54:935–41. Razem FA Bernards MA Reactive oxygen species production in association with suberization: evidence for an NADPH-dependent oxidase J Exp Bot 200354935 4110.1093/jxb/erg09412598564Search in Google Scholar

Rogowska A, Szakiel A. The role of sterols in plant response to abiotic stress. Phytochem Rev. 2020;19:1525–38. Rogowska A Szakiel A The role of sterols in plant response to abiotic stress Phytochem Rev 2020191525 3810.1007/s11101-020-09708-2Search in Google Scholar

Sikin AM, Zoellner C, Rizvi SSH. Current intervention strategies for the microbial safety of sprouts. J Food Prot. 2013;76:2099–123. Sikin AM Zoellner C Rizvi SSH Current intervention strategies for the microbial safety of sprouts J Food Prot 2013762099 12310.4315/0362-028X.JFP-12-43724290689Search in Google Scholar

Songnuan W, Kirawanich P. Early growth effects on Arabidopsis thaliana by seed exposure of nanosecond pulsed electric field. J Electrost. 2012;70:445–50. Songnuan W Kirawanich P Early growth effects on Arabidopsis thaliana by seed exposure of nanosecond pulsed electric field J Electrost 201270445 5010.1016/j.elstat.2012.06.004Search in Google Scholar

Szemruch C, Gallo C, Murcia M, Esquivel M, García F, Medina J, et al. Electrical conductivity test for predict sunflower seeds vigor. 2019; Szemruch C Gallo C Murcia M Esquivel M García F Medina J et al. Electrical conductivity test for predict sunflower seeds vigor 2019Search in Google Scholar

Teissie J, Golzio M, Rols MP. Mechanisms of cell membrane electropermeabilization: a minireview of our present (lack of ?) knowledge. Biochim Biophys Acta. 2005;1724:270– 80. Teissie J Golzio M Rols MP Mechanisms of cell membrane electropermeabilization: a minireview of our present (lack of ?) knowledge Biochim Biophys Acta 20051724270 8010.1016/j.bbagen.2005.05.00615951114Search in Google Scholar

Tinivella F, Hirata LM, Celan MA, Wright SAI, Amein T, Schmitt A, et al. Control of seed-borne pathogens on legumes by microbial and other alternative seed treatments. Eur J Plant Pathol. 2009;123:139–51. Tinivella F Hirata LM Celan MA Wright SAI Amein T Schmitt A et al Control of seed-borne pathogens on legumes by microbial and other alternative seed treatments Eur J Plant Pathol 2009123139 5110.1007/s10658-008-9349-3Search in Google Scholar

Toepfl S, Heinz V, Knorr D. High intensity pulsed electric fields applied for food preservation. Chem Eng Process Process Intensif. 2007;46:537–46. Toepfl S Heinz V Knorr D High intensity pulsed electric fields applied for food preservation Chem Eng Process Process Intensif 200746537 4610.1016/j.cep.2006.07.011Search in Google Scholar

Vashisth A, Nagarajan S. Exposure of seeds to static magnetic field enhances germination and early growth characteristics in chickpea (Cicer arietinum L.). Bioelectromagnetics. 2008;29:571–8. Vashisth A Nagarajan S Exposure of seeds to static magnetic field enhances germination and early growth characteristics in chickpea (Cicer arietinum L.) Bioelectromagnetics 200829571 810.1002/bem.2042618512697Search in Google Scholar

Waskow A, Betschart J, Butscher D, Oberbossel G, Klöti D, Büttner-Mainik A, et al. Characterization of efficiency and mechanisms of cold atmospheric pressure plasma decontamination of seeds for sprout production. Front Microbiol. 2018;0. Waskow A Betschart J Butscher D Oberbossel G Klöti D Büttner-Mainik A et al Characterization of efficiency and mechanisms of cold atmospheric pressure plasma decontamination of seeds for sprout production Front Microbiol 2018010.3389/fmicb.2018.03164630572230619223Search in Google Scholar

Waskow A, Betschart J, Butscher D, Oberbossel G, Klöti D, Büttner-Mainik A, et al. Characterization of efficiency and mechanisms of cold atmospheric pressure plasma decontamination of seeds for sprout production. Front Microbiol. 2018;9. Waskow A Betschart J Butscher D Oberbossel G Klöti D Büttner-Mainik A et al Characterization of efficiency and mechanisms of cold atmospheric pressure plasma decontamination of seeds for sprout production Front Microbiol 2018910.3389/fmicb.2018.03164Search in Google Scholar

Yao Y, Li Y, Yang Y, Li C. Effect of seed pretreatment by magnetic field on the sensitivity of cucumber (Cucumis sativus) seedlings to ultraviolet-B radiation. Environ Exp Bot. 2005;54:286–94. Yao Y Li Y Yang Y Li C Effect of seed pretreatment by magnetic field on the sensitivity of cucumber (Cucumis sativus) seedlings to ultraviolet-B radiation Environ Exp Bot 200554286 9410.1016/j.envexpbot.2004.09.006Search in Google Scholar

Yin H, Chen Q, Yi M. Effects of short-term heat stress on oxidative damage and responses of antioxidant system in Lilium longiflorum. Plant Growth Regul. 2008;54:45–54. Yin H Chen Q Yi M Effects of short-term heat stress on oxidative damage and responses of antioxidant system in Lilium longiflorum Plant Growth Regul 20085445 5410.1007/s10725-007-9227-6Search in Google Scholar

Zhang N, Zhao B, Zhang H-J, Weeda S, Yang C, Yang Z-C, et al. Melatonin promotes water-stress tolerance, lateral root formation, and seed germination in cucumber (Cucumis sativus L.). J Pineal Res. 2013;54:15–23. Zhang N Zhao B Zhang H-J Weeda S Yang C Yang Z-C et al Melatonin promotes water-stress tolerance, lateral root formation, and seed germination in cucumber (Cucumis sativus L.) J Pineal Res 20135415 2310.1111/j.1600-079X.2012.01015.x22747917Search in Google Scholar

Zhao J, Ma F, Yang W, Wen S. Effects of high voltage electrostatic field (HVEF) on inbibition of soybean seeds at low temperatur. Vol. 11, Shengwu Wuli Xuebao. 1995. p. 595–8. Zhao J Ma F Yang W Wen S Effects of high voltage electrostatic field (HVEF) on inbibition of soybean seeds at low temperatur. Vol. 11 Shengwu Wuli Xuebao 1995 p. 595 8Search in Google Scholar

Zheng C, Jiang D, Liu F, Dai T, Liu W, Jing Q, et al. Exogenous nitric oxide improves seed germination in wheat against mitochondrial oxidative damage induced by high salinity. Environ Exp Bot. 2009; Zheng C Jiang D Liu F Dai T Liu W Jing Q et al Exogenous nitric oxide improves seed germination in wheat against mitochondrial oxidative damage induced by high salinity Environ Exp Bot 200910.1016/j.envexpbot.2009.05.002Search in Google Scholar

Recommended articles from Trend MD

Plan your remote conference with Sciendo