Physiological and biochemical responses induced by spruce bark aqueous extract and deuterium depleted water with synergistic action in sunflower (Helianthus annuus L.) plants

Abstract

The use of natural regulators, such as polyphenols compounds in combination with deuterium depleted water can act in growth stimulation and also influence biosynthesis, the photosynthesizing pigments, and secondary metabolites in plants. The aim of this study was to evaluate the effect of spruce bark (Picea abies L.) polyphenolic extract (SBPE) and deuterium depleted water (DDW) as bioregulators in sunflower (Helianthus annuus L.) plant cultivation. SBPE was characterized in terms of total polyphenolic content using Folin Ciocalteau method. For identification of the polyphenols biosynthesized in plants, a HPLC analysis was performed. The field experiment was performed over a period of 120 days, for two consecutive years, measuring main physiological indices from treated plants. Sunflower plants, treated with SBPE have gained the highest amount of biomass. The physiological processes (assimilation rate, transpiration rate, sub-stomatal cavity CO2 concentration) were significantly intensified in the presence of SBPE (130mg EAG/dm3) and DDW. The highest stimulatory effects of the studied products on biosynthesis of chlorophyll a, b and carotene pigments were registered in the presence of combination of DDW with spruce bark extract – SB1. Moreover, the presence of these two synergic regulators cause an increase in the catechine amount in sunflower leaves, increasing the defense capability and therefore improving plant resistance, growth, and development. DDW and SBPE accessible as byproducts could be properly used as natural bioregulators in order to improve the yield of sunflower crop. At the same time, the results of this research have the potential to contribute greatly to ecological agricultural production and stability of crops.