**2.1. Magnetic field strength**

All living creatures are exposed to magnetic field throughout their lives. Exposing seeds to magnetic field is one of the physical treatments to increase seed germination and plant development [11–13]. It was reported that seed germination was improved by physiological changes in seeds, such as faster water assimilation and higher photosynthesis, under the effect of magnetic field [14]. Many researchers have reported that exposing seeds to a magnetic field increased seed vigor and germination [12, 13, 15–18]. Although there are many reports on the effects of magnetic field on seed germination, plant growth, protein biosynthesis, and root development, to our knowledge the effect of magnetic field on overcoming dormancy has not been reported before.

In the studies conducted with lentil (*Lens culinaris* Medik.), grass pea (*Lathyrus sativus* L.), and potato (*Solanum tuberosum* L.), magnetic field rapidly increased seed/tuber germination and seedling growth by overcoming dormancy. Seeds/tubers from lentil (cv. "Çiftçi"), grass pea (cv. "Gürbüz") and potato (cv. "Marabel") were sown in soil after keeping them in different magnetic field strengths (0-control, 75, 150, and 300 mT) for different period of times (0-control, 24, 48, and 72 h), and then lentil and grass pea were incubated for 14 days at 24 ± 1°C for a photoperiod of 16 h of light/8 h of darkness under white fluorescent light (27 μmol m−2 s−1), while potatoes were grown in a greenhouse at 24°C for 2 months. Tubers weighing 40–60 g were used in the study. Five replications were used for the lentil and grass pea, and 10 replications for the potatoes. Pots containing 10 seeds for lentil and grass pea and 1 tuber for potato were considered as an experimental unit. The study used two parallel treatments according to the "Completely Randomized Design" concept. Data were statistically analyzed with Duncan's multiple range test using IBM SPSS Statistics 22 software. Values presented in percentages were subjected to arcsine (√*X*) transformation before statistical analysis [19].

There are two types of seed dormancy in general: seed coat (physical) dormancy and internal dormancy. In seed coat dormancy, the seed coat prevents oxygen and/or water permeating into the seed. Sometimes, dormancy is caused by inhibiting chemicals inside the seed. Seeds with seed coat dormancy can remain on/in the ground without germinating until the seed coat allows water and oxygen to enter the seed or eliminate the inhibiting chemicals. Seed coat dormancy is common in California lilac (*Ceanothus*), manzanita (*Arctostaphylos*), sumac (Rhus), and members of the legume family. Scarification, hot water, dry heat, fire, acid and other chemicals, mulch, and light are the methods used for breaking seed coat

Physiological conditions causing internal dormancy arise from the presence of germination inhibitors inside the seed. The adverse effects of these inhibitors should be eliminated in order to start germination by using germination-promoting substances such as gibberellic

Sugar maple [4], Norway maple (*Acer platanoides* L.) [5], planetree maple (*Acer pseudoplatanus*) [6], European hazel (*Corylus avellana* L.) [7], white ash (*Fraxinus americana* L.) [8], apple (*Malus pumila* Mill.) [9], northern red (*Quercus rubra* L.), and English oaks [10] are the species that have ABA as an internal inhibitor. Another type of internal dormancy is caused by lack of

Seed coat and internal dormancy can be found together in a species. Seeds with this combined dormancy should be treated by overcoming the problems raised by the impermeable seed

In this chapter, the effects of magnetic field strength squirting cucumber (*Ecballium elaterium* (L.) A. Rich.) fruit juice, sodium hypochlorite solutions, and gamma radiation on overcoming

All living creatures are exposed to magnetic field throughout their lives. Exposing seeds to magnetic field is one of the physical treatments to increase seed germination and plant development [11–13]. It was reported that seed germination was improved by physiological changes in seeds, such as faster water assimilation and higher photosynthesis, under the effect of magnetic field [14]. Many researchers have reported that exposing seeds to a magnetic field increased seed vigor and germination [12, 13, 15–18]. Although there are many reports on the effects of magnetic field on seed germination, plant growth, protein biosynthesis, and root development, to our knowledge the effect of magnetic field on overcoming dormancy has not

In the studies conducted with lentil (*Lens culinaris* Medik.), grass pea (*Lathyrus sativus* L.), and potato (*Solanum tuberosum* L.), magnetic field rapidly increased seed/tuber germination and seedling growth by overcoming dormancy. Seeds/tubers from lentil (cv. "Çiftçi"), grass pea

enzymes, which is required for complete physiological maturation.

coat first, and then overcoming the internal dormancy [3].

**2. New methods for overcoming dormancy**

). The most common inhibitor is abscisic acid (ABA).

dormancy [3].

86 Advances in Seed Biology

acid (GA3) and potassium nitrate (KNO3

dormancy are discussed.

**2.1. Magnetic field strength**

been reported before.

Observations were performed on the characteristics of germination percentage, seedling growth percentage, plant height, and total chlorophyll content in lentil; germination percentage, seedling growth percentage, seedling fresh and dry weights in grass pea; and day of emergence, plant height, and total chlorophyll content in potato. Seed germination percentage was determined at the end of the 5th day in lentil and the 4th day in grass pea, while seedling growth percentage was noted at the end of the 10th day in lentil and the 14th day in grass pea [20]. For all other characteristics, observations were performed at the end of the 14th day in lentil and grass pea, and the 2nd month from the study initiation for the potato.

The total chlorophyll content was determined in leaves of plants according to the protocol of Curtis and Shetty [21]. Fresh tissue from 50 mg of leaves was put in 3 ml of methanol and kept in total darkness at 23°C for 2 h. In this way, chlorophyll in the fresh tissue passed through into the methanol. After 2 h, absorbencies were determined at wavelengths of 665 and 650 nm using UV spectrophotometer. The total chlorophyll content was calculated as μg chlorophyll/g fresh tissue.

In lentil, the lowest values were noted in the control treatment where no magnetic field was used. Lower results in germination and seedling growth percentages were the indicators of dormancy. On the other hand, the highest results in all characteristics were recorded from seeds treated with a magnetic field with a strength of 300 mT for 24 h. At this strength, the highest germination, seedling growth percentages, plant height, and total chlorophyll content were noted as 96.50 %, 100.00%, 7.16 cm, and 586.32 μg chlorophyll/g fresh tissue, respectively (**Table 1**).

There is a close relationship between photosynthesis and chlorophyll content [22–25]. The chlorophyll content of a leaf is accepted as an indicator of the photosynthetic capacity of tissues [26–28]. The total chlorophyll content was determined to be 586.32 μg of chlorophyll/g fresh tissue when treated with a magnetic field strength of 300 mT for 24 h, while it was 125.56 μg of chlorophyll/g fresh tissue in the control sample (**Table 1**).

In grass pea, the lowest results were again recorded for the control treatment, while the highest values were obtained from seeds treated with a magnetic field strength of 300 mT for 72 h. At the end of the study, the germination and seedling growth percentages, plant height, plant fresh, and dry weights were recorded as 0.00%, 75.00%, 21.66 cm, 0.556 g, and 0.131 g, respectively, for the control treatment, whereas they were 100.00%, 100.00%, 28.50 cm, 0.798 g, and 0.160 g, respectively, from seeds treated with a magnetic field strength of 300 mT for 72 h. The


Values within a column followed by different letters are significantly different at the 0.01 level.

**Table 1.** The effect of different magnetic field strengths applied to lentil seeds for different periods of time on seed germination and seedling growth in cv. "Çiftçi".

significant effect of magnetic field strength on overcoming dormancy was easily seen when the results of the control sample using a magnetic field strength of 300 mT for 72 h were compared. Germination percentage that was 0.00% in the control sample increased to 100.00% when treated with a magnetic field strength of 300 mT for 72 h (**Table 2**).

In both genotypes (lentil and grass pea), high biomass formation above ground was observed after magnetic field treatments, where the highest values were recorded, compared with the control where no magnetic field was applied (**Figure 1**). Leaf numbers were higher for the magnetic field treatment compared with the control, and it is the main reason for higher photosynthetic activity that achieves a higher yield. Higher biomass accumulation above ground gives a higher food supply for livestock. In our case, the plant fresh weight was 0.798 g when treated with a magnetic field strength of 300 mT for 72 h, while it was only 0.556 g in the control sample at the end of the study (**Table 2**). This means more than a 50% increase in fresh weight and also more than a 50% increase in food supply for livestock.

In potatoes, sprouting emerged above ground 17 days after planting with tubers treated with a magnetic field strength of 300 mT for 72 h. In the control treatment, sprouts emerged on day 39.50. There was 22.50 days difference observed between the treatment with a magnetic field and the control. In the control sample where no magnetic field was used, the lowest results in plant height and total chlorophyll content were found to be 25.56 cm and 1127.46 μg chlorophyll/g fresh tissue, respectively, at the end of the study. On the other hand, the highest values in plant height and total chlorophyll content were recorded as 90.78 cm and


Each value is the mean of five replications. All experiments were repeated two times.

significant effect of magnetic field strength on overcoming dormancy was easily seen when the results of the control sample using a magnetic field strength of 300 mT for 72 h were compared. Germination percentage that was 0.00% in the control sample increased to 100.00%

**Table 1.** The effect of different magnetic field strengths applied to lentil seeds for different periods of time on seed

In both genotypes (lentil and grass pea), high biomass formation above ground was observed after magnetic field treatments, where the highest values were recorded, compared with the control where no magnetic field was applied (**Figure 1**). Leaf numbers were higher for the magnetic field treatment compared with the control, and it is the main reason for higher photosynthetic activity that achieves a higher yield. Higher biomass accumulation above ground gives a higher food supply for livestock. In our case, the plant fresh weight was 0.798 g when treated with a magnetic field strength of 300 mT for 72 h, while it was only 0.556 g in the control sample at the end of the study (**Table 2**). This means more than a 50% increase in fresh weight and also more than a 50% increase in food supply for

In potatoes, sprouting emerged above ground 17 days after planting with tubers treated with a magnetic field strength of 300 mT for 72 h. In the control treatment, sprouts emerged on day 39.50. There was 22.50 days difference observed between the treatment with a magnetic field and the control. In the control sample where no magnetic field was used, the lowest results in plant height and total chlorophyll content were found to be 25.56 cm and 1127.46 μg chlorophyll/g fresh tissue, respectively, at the end of the study. On the other hand, the highest values in plant height and total chlorophyll content were recorded as 90.78 cm and

when treated with a magnetic field strength of 300 mT for 72 h (**Table 2**).

livestock.

**Magnetic field strength (mT)**

88 Advances in Seed Biology

**Treatment period (h)**

germination and seedling growth in cv. "Çiftçi".

**Germination (%)**

0—control 0 5.00 g 15.00 f 2.00 e 125.56 g 75 24 25.00 f 37.50 ef 2.54 e 205.48 f

150 24 55.75 cd 63.75 c 3.76 cd 378.56 d

300 24 96.50 a 100.00 a 7.16 a 586.32 a

Each value is the mean of five replications. All experiments were repeated two times. Values within a column followed by different letters are significantly different at the 0.01 level.

**Seedling growth (%)**

48 32.25 e 42.25 e 2.88 de 238.56 ef 72 44.50 d 52.00 d 3.22 d 289.75 e

48 58.00 c 67.25 c 4.45 c 399.74 d 72 62.50 c 72.50 b 4.85 bc 445.21 c

48 92.25 ab 98.25 a 6.46 ab 541.00 ab 72 88.75 b 95.75 ab 5.85 b 510.32 b

**Plant height (cm)**

**Total chlorophyll content (μg chlorophyll/g fresh tissue)**

Values within a column followed by different letters are significantly different at the 0.01 level.

**Table 2.** The effect of different magnetic field strengths applied to grass pea seeds for different periods of time on seed germination and seedling growth in cv. "Gürbüz".

**Figure 1.** Plant development of grass pea in control (a) and in a magnetic field strength of 300 mT for 72 h (b) at the end of the 14th day.

2105.74 μg of chlorophyll/g fresh tissue, respectively, for the treatment with a magnetic field strength of 150 mT for 72 h (**Table 3** and **Figure 2**).

**Figure 2.** The effect of a magnetic field strength of 150 mT applied to potato tubers for different periods (a. 0 h, b. 24 h, c. 48 h and d. 72 h) on plant development in cv. "Marabel".


Each value is the mean of five replications. All experiments were repeated two times.

Values within a column followed by different letters are significantly different at the 0.01 level.

**Table 3.** The effect of different magnetic field strengths applied to potato tubers for different periods of time on the day of emergence of sprouts, plant height, and total chlorophyll content in cv. "Marabel".
