The Effects of Red Clover Seed Treatment with Cold Plasma and Electromagnetic Field on Germination and Seedling Growth Are Dependent on Seed Color

Abstract

This study aimed to estimate the effects of cold plasma (CP) and electromagnetic field (EMF) treatment of red clover (Trifolium pratense) seeds with different coat colors on germination kinetics, the content of seed phytohormones, and the growth of seedlings. Seeds of red clover cultivar ‘Arimaiciai’ were treated with radio-frequency EMF or capacitively coupled low-pressure CP for different durations. There were no differences in germination kinetics between yellow, brown, and dark purple seeds in control, but the germination rate of seeds treated with CP and EMF depended on seed color: The germination of yellow seeds was stimulated stronger compared to dark purple and brown seeds, and EMF did not stimulate germination in brown seeds. The content of phytohormones in control seeds and the shift in their amount induced by seed treatments were also strongly dependent on seed color. No relationship was found between the effect on germination kinetics and changes in phytohormone levels. In the control, seedlings growing from the yellow seeds were heavier, and the number of root nodules was 12.5 times larger compared to seedlings of dark purple seeds. Seed treatments with CP and EMF significantly increased the number of root nodules, and this effect was stronger in seedlings from dark purple seeds compared to those from yellow seeds.

The Potential of Cold Plasma and Electromagnetic Field as Stimulators of Natural Sweeteners Biosynthesis in Stevia rebaudiana Bertoni

“…Based on some our previous studies on different plant seeds [ 25 , 26 , 28 , 29 ], the chosen durations for seed treatments were 5 and 7 min for cold plasma (these treatments are further abbreviated as CP5 and CP7, respectively), and 10 min for EMF treatment (this treatment is abbreviated as EMF10). The results of in vitro germination test performed 6 days after CP and EMF treatments for the control and treated seeds of S. rebaudiana are presented in Figure 2 a.…”

“…The treatment was performed in ambient air at atmospheric pressure and room temperature. Based on some our previous studies on different plant seeds [ 25 , 26 , 28 , 29 ], the chosen duration for seed treatments was 5 and 7 min for cold plasma (this treatment is further abbreviated as CP5 and CP7, respectively), and 10 min for EMF treatment (this treatment is abbreviated as EMF10).…”

Biochemical and Physiological Plant Processes Affected by Seed Treatment with Non-Thermal Plasma

“…As shown in Table 1 , the effects of seed treatment using different NTP devices and protocols have been extensively studied in a wide variety of plants including the main strategic crops (such as wheat, corn, legumes, and oilseeds). Stimulating effects of seed treatment on seed germination in vitro have been demonstrated in most of the publications [ 37 , 41 , 42 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 ,…”

“…Differences in the effects on germination and growth have been reported even for different genetic families (half-sib) of Norway spruce [ 70 ]. In addition, the response to NTP treatment for the same lot of radish [ 78 ] or red clover [ 55 ] seeds was dependent on the color of the seeds. Such intraspecies differences and the dependence on multiple factors indicate that the response of plant germination and growth to seed treatment with NTP is determined by factors associated with slight genetic differences, peculiarities of seed structure, or physiological seed status.…”

“…Several attempts to study the NTP treatment-induced changes in the amounts of phytohormones in dry seeds have been performed using high performance liquid chromatography (HPLC) analysis [ 55 , 58 , 75 , 81 , 95 , 147 , 148 ]. Taking into account that HPLC is not sufficient for the quantitation of phytohormones, the validity of the published results must be re-evaluated using a combination of HPLC with mass spectrometry (MS), an adequate method for phytohormone analysis.…”