plants Article Biochemical and Histo-Anatomical Responses of Lavandula angustifolia Mill. to Spruce and Beech Bark Extracts Application Corneliu Tanase 1, * , Ruxandra S , tefănescu 2, * ,Béla Darkó 1 , Daniela Lucia Muntean 3 , Anca Corina Fărca¸ s 4 and Sonia Ancu¸ ta Socaci 4 1 Department of Pharmaceutical Botany, “George Emil Palade” University of Medicine, Pharmacy, Sciences and Technology of Târgu Mures , , 38 Gheorghe Marinescu Street, Târgu Mures , , 540139 Mures , , Romania; bela.darko@umfst.ro 2 Department of Pharmacognosy and Phytotherapy, “George Emil Palade” University of Medicine, Pharmacy, Sciences and Technology of Târgu Mures , , 38 Gheorghe Marinescu Street, Târgu Mures , , 540139 Mures , , Romania 3 Department of Analytical Chemistry and Drug Analysis, University of Medicine, Pharmacy, Sciences and Technology, 540139 Târgu Mures , , Romania; daniela.muntean@umfst.ro 4 Department of Food Science, Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine, 400372 Cluj-Napoca, Romania; anca.farcas@usamvcluj.ro (A.C.F.); sonia.socaci@usamvcluj.ro (S.A.S.) * Correspondence: corneliu.tanase@umfst.ro (C.T.); ruxandra.stefanescu@umfst.ro (R.S.) Received: 6 June 2020; Accepted: 3 July 2020; Published: 7 July 2020   Abstract: This paper aims to assess the biological responses of Lavandula angustifolia Mill. to beech and spruce bark crude extract application. Thus, the biological activity of bark extracts was assessed by determining the germination capacity, biomass production, histo-anatomical aspects and photo-assimilatory pigment accumulation, and by quantitative and qualitative volatile compounds analysis. The application of spruce bark extract (500 mg dry bark/100 mL solvent) resulted in a better development of the leaf tissue and an increase in foliar biomass. We observed the stimulating effect of photo-assimilating pigments accumulation, for all experimental variants, compared to the control. Also, the amount of volatile oil was significantly higher in the treated plants with spruce bark extract (500 mg dry bark/100 mL solvent). Some volatile compounds (cyclen, borneol, cryptone, santalen, and caryophyllene oxide β—farnesene) were identified only in the experimental variants. Also, in the experimental variants, an increase in the quantity of limonene, linalyl acetate and lavandulol was observed. These preliminary results showed that the beech and spruce bark extracts can have biological activities and influence the production of volatile oil in Lavandula angustifolia, causing significant changes in the phytochemical profile of the essential oil. Thus, forest waste bark extracts could be recommended as natural bioregulators in lavender crops. Keywords: bark extracts; beech; bioactive compounds; lavender; spruce; volatile compounds 1. Introduction Lavender is a globally well-known aromatic and medicinal herb from the Lamiaceae family. The essential oil obtained through distillation is the main product used from this plant. Its unspecific condition for cultivation has increased the agricultural production of lavender, and it is considered to be a sustainable crop. Although many lavender species exist, only three are considered to be important sources of lavender oil: the genuine lavender—Lavandula angustifolia Mill. (sin. Lavandula officinalis Chaix), spike lavender—Lavandula latifolia Mill. and lavandin—Lavandula hybrida Revr. Plants 2020, 9, 859; doi:10.3390/plants9070859 www.mdpi.com/journal/plants