The influence of the color of the seed coat on the germination and amount of phytohormones in the seeds of Red clover (trifolium pratense l.) after treating the seeds with cold plasma and electromagnetic field

Abstract

The objective of this study was to evaluate the effects of seed coat color on the germination of red clover (Trifolium pratense L.) seeds, seedling growth and the amount of phytohormones in seeds induce with electromagnetic field (EMF) and cold plasma (CP). Red clover seeds of the commercial variety ‘Vyčiai’ and ‘Arimaičiai’ were used in this study. Before the sowing, red clover seeds of different seed coat color were processed using two types of physical stressors, EMF and CP. The effects treatments on seed germination were estimated using an in vitro germination test. Kinetic parameters of germination were determined: Vi - the final germination percentage, Me - the median germination time, Qu – quartile deviation, uniformity germination in seed population. Morphometric analysis of seedlings was performed 7 days after sowing. Extracts for estimation of phytohormone content in seeds were prepared on the sowing day, phytohormone analysis was performed using high-performance liquid chromatography. The number of root nodules was measured for cultivar “Arimaičiai” that was growing in the substrate for 5 weeks. It was established that germination kinetics in vitro of the red clover cultivars ‘Arimaičiai’ and ‘Vyčiai’ control seeds were independent of the seed coat color. The pre-sowing treatment of seeds with CP and EMF improved kinetic parameters of seed germination for both cultivars: the increase in germination rate (decreased Me) was largest for yellow seeds, smaller for black seeds and the smallest for brown seeds. The effect of seed treatment with stressors on the early growth of ‘Arimaičiai’ and ‘Vyčiai’ seedlings were also dependent on the color of the seed coat: the strongest positive effects for the ‘Vyčiai’ were obtained on the morphometric parameters of sprouts from the black seeds, whereas even negative effects were shown for the brown seed sprouts. [...]