M. Koleva*, M. Radevska

Field Crops Institute, 6200 Chirpan, Bulgaria

(Manuscript received 14 August 2021; accepted for publication 26 October 2021)

Abstract. Seeds of five Bulgarian cotton varieties, stored for one and two years, were subjected to five pre-sowing electromagnetic treatments with different intensity and duration of exposure. It was found that the selected values of controllable factors had stimulating effect on the total length and total mass of sprout and root. The total length of sprout and root increased by 7.5-16.4% (p<0.05), the total mass of sprout and root increased by 7.8-12.7% (p<0.05). The best treatment options were 1[U=(8…5)kV, τ =(15…35)s] and 4[U=(6…3)kV, τ =(5…25)s]. Electromagnetic treatments had stronger positive effect on seeds stored for one year. Compared to the untreated control, corresponding to each storage period, the electromagnetic impact had stimulating effect for both storage periods: for the total length of sprout and root the increase was by 7.6-21.1% and 2.3-11.0% at option 4; for the total mass of sprout and root it was by 10.8-16.5% at option 1 and 4.5-9.1% at option 4, respectively, at one-year and two-year storage of seeds. In comparison with the control Chirpan-539 variety, untreated seeds, one-year storage, higher values for both studied characteristics were found only for seeds stored for one-year: for the total length of root and sprout at the varieties Natalia, treatment options 1 and 4, Nelina and Helius, options 2 and 4 and Chirpan-539, option 1; for the total mass of root and sprout at the varieties Nelina, options 1, 2 and 3 and Chirpan-539, option 5. Compared to the untreated control corresponding to each variety, the stimulating effect of the pre-sowing electromagnetic treatment for the two characteristics was found for all varieties, for both storage periods. The Helius variety was the most responsive to the electromagnetic impact, with the strongest stimulating effect for both characteristics, at the one-year storage of seeds the total length of sprout and root increased most strongly by 34.8-43.9% at options 1, 4 and 2[U=(6…3)kV, τ =(15…35)s], and the total mass of sprout and root increased by 48.5% at options 1.