## 2 Materials and Methods  
Red clover seeds of the variety 'Arimaiciaiai' harvested in 2018 were received from the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry, Lithuania. _Seeds were stored in sealed bags in ventilated seed chambers at 3 \({}^{\circ}\)C temperature and were_ visually checked for quality before the experiment. From the seed lot with a characteristic mixed color pattern (Figure 1a), seeds of three colors--yellow, brown, and dark purple (Figure 1b, bottom to top)--were manually selected into separate groups, while all seeds with the intermediate coloration were eliminated from the experiment. All groupsof seeds, including the original ones, were subjected to digital color code measurement using ColorFlex EZ spectrophotometer (HunterLab) in three-dimensional coordinates [33], i.e., L* (lightness), a* (red-green), b* (yellow-blue), in the CIE 1976 L* a* b* (CIELAB) color space, using color standard L* 52.9; a* 24.7; b* 16.0. The color code detected for the original seed lot was: L* 49.4; a* 5.8; b* 27.4, while the seed groups separated by colors were characterized by the following codes: yellow seeds-L* 59.0; a* 3.5; b* 37.5; brown seeds-L* 46.4; a* 6.1; b* 24.4; dark purple seeds: L* 31.5; a* 6.0; b* 9.2. Yellow seeds comprised the major part (53%) of the seed lot used for this study, while the relative amount of seeds of intermediate color was 30%, and of dark violet color-15%. Brown seeds comprised only 2% of the seed lot. Red clover seeds were treated with CP and EMF to increase their germination rate and stimulate seedling growth [16; 32]. The equipment and treatment conditions have been described previously [10; 34]. The conditions of seed treatment with radiofrequency (RF) EMF created at a frequency of 5.28 MHz were as follows: The root-mean-square value of the magnetic component \(H\) of EMF strength was 590 A/m (\(B\approx\) 0.74 mT) with amplitude value \(H*=\sqrt{2H}\) of 835 A/m (\(B\approx\) 1 mT), and the electric component \(E\) was equal to 12.7 kV/m with amplitude value \(E*=\sqrt{2E}\) of 17.96 kV/m. Seeds were placed at the center of the induction coil of the RF generator, and the treatment was performed for 10 and 15 min (these treatments are further abbreviated as EMF10 and EMF15, respectively) at atmospheric pressure and room temperature. Seed treatments with CP were performed in a planar geometry reactor consisting of two plane-parallel, water-cooled copper electrodes (120 mm diameter) placed in a stainless-steel hermetic chamber. Capacitively coupled RF discharge operated at 5.28 MHz at a pressure of 200 Pa, and RF input power density was 0.025 W/cm\({}^{3}\). An open sterile Petri dish with evenly dispersed seeds was placed on a grounded electrode and then air was pumped out from the chamber for 7 min aiming to achieve a pressure of 200 Pa before plasma ignition. CP treatment lasted 5 and 7 min (these treatments are further abbreviated as CP5 and CP7, respectively). All experiments were performed in three replicates. Control, CP-, and EMF-treated seeds were stored at room temperature (19-22 \({}^{\circ}\)C) until further investigation. Germination tests in vitro were performed four days after seed treatments. Seeds were evenly distributed on two layers of filter paper in 9-mm diameter plastic Petri dishes (three replicates of 50 seeds each) and watered with 3 mL of distilled water. Petri dishes with imbibed seeds were placed in a climatic chamber with automatic control of moisture (60%), light, and temperature. Alternating light and temperature regimes were maintained in the chamber (darkness: 14 \({}^{\circ}\)C for 10 h; light: 21 \({}^{\circ}\)C for 14 h). Seeds were provided with additional water  
Figure 1: Variation of colors in a natural red clover seed lot (**a**); seeds of yellow, brown, and dark purple colors selected for the study (**b**). in a Petri dish to prevent drying. Germinated seeds (as judged by the appearance of a visible 1 mm radicle) were counted every day until their number stopped increasing.