Pre-sowing Norway spruce seed treatment with cold plasma and electromagnetic field induces long-term effects in plants and affected plant response to environmental stress

Abstract

Norway spruce (Picea abies (L.) Karst.) is a tough conifer, that occupies about 20 % of forest area in Lithuania and is important tree in the forest economy of Lithuania. We investigated the effects of presowing Norway spruce seed treatment with physical stressors – cold plasma (CP, 2, 5 and 7 min), electromagnetic field (EMF, 5, 10 and 15 min) and vacuum (7 min, V) on seed germination and plant performance. We reported earlier, that all applied seed treatments, except CP (7 min), stimulated germination and later observations revealed that CP (5 min) and CP (7 min) seed treatments increased 17 month-age seedlings height and branching in comparison to the control. In this study we report results on long-term effects of pre-sowing seed treatments estimated by changes in the morphometric traits and secondary metabolite concentrations in spruce needles. In 39-month period after sowing plants grown from V and CP (5 min) treated seeds were higher (by 26 and 17 %, respectively) and had larger (by 33 and 21 %, respectively) number of branches, as compared with control group. In CP (7 min) treated group the number of trichomes in the matured needles was almost twice as higher as in control group. There was no changes among treated groups in total phenolic compounds concentration but pre-sowing seed treatment with CP (5 and 7 in) and EMF (10 and 15 min) reduced UVB stress-induced decrease in concentration of phenolic compounds in matured Norway spruce needles. Thus, the obtained data indicate that short time pre-sowing treatment of seeds with V, CP and EMF induce multiple and long-term response leading to modulation of economically important plant traits – improved germination, stimulation of plant growth and change in plant response to stress.