Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop Could bio-stimulators affect flower, essential oil yield, and its composition in organic lavender (Lavandula angustifolia) cultivation? Kyriakos D. Giannoulis a, *, Vasileios Evangelopoulos b , Nikolaos Gougoulias b , Eleni Wogiatzi b a University of Thessaly, Dept of Agriculture, Crop Production and Rural Environment, Laboratory of Agronomy and Applied Crop Physiology, Fytokoy Str., 38446 Volos, Greece b University of Thessaly, General Department, 41110 Larissa, Greece ARTICLE INFO Keywords: Lavender Bio-Stimulators Flower Yield Essential oil ABSTRACT Soil-climatic conditions of Greece and Mediterranean basin in general are favor for the development of aromatic- medicinal plants. A great aromatic-medicinal plant that is cultivated on a large scale in Greece and in Mediterranean basin in general for its essential oil is lavender. Lavender organic cultivation is facing a serious problem with Rhizoctonia and Fusarium fungal infections resulting in the most cases to the destruction of the cultivation. The aim of the current study was to investigate the effect of bio-stimulators to flower and essential oil yield and its composition. For the purposes of the study field experiments were established in Microkastro Vojo Kozanis (40°14′44.25″N, 21°30′25.87″E) in 2018 and 2019, using a complete randomized experimental design. There was investigated the effect of different treatments (i). control, (ii). amalgerol 15000 mL ha -1 , (iii). millerplex450 ml ha -1 , (iv). sugarXpress 12000 mL ha -1 , in three equal applications) on flower, essential oil yield and composition under five replicates. The results refer to the sixth and seventh lavender’ growing year. It was found that flower (spike) yield was decreased by 50% at the second experimentation year while the use of the bio-stimulators had a statistically significant effect compared with control, indicating their positive effect. In essential oil content case, amalgerol treatment was found to have the same content for both growing years. Finally, the identified essential oil components were 48, and there were found many differences to the com- position between the tested treatments. 1. Introduction Lamiaceae family has been described to be rich in essential oil (Adorjan and Buchbauer, 2010) and the most known genus of this fa- mily, which is cultivated in many regions of Europe, Middle East, Asia and Northern Africa, is Lavandula. This genus includes 39 species (Kara and Baydar, 2013; Paton et al., 2004; Upson and Andrews, 2004). These species are characterized as highly aromatic plants due to the presence of essential oil produced on the surface of their flowers and leaves (Blažeković et al., 2012). Only three species of them are widely grown for their essential oil (Woronuk et al., 2011; Kıvrak, 2018). One of them is Lavandula angustifolia Mill, a perennial crop with a typical productive life of about 10 years, cultivated in many European countries. Lavender is a small evergreen woody-based sub-shrub of 20–60 cm height. Its leaves are linear or lance-shaped with a char- acteristic gray-green color. Flowering shoots are terminals branched spikes (Tucker, 1985) and on the axis of the spikes, there are 24–84 florets of violet-blue color (Curtis, 2005). Lavender plantation can take place from spring till autumn and due to its perennial nature flower yield of the establishment year is lower comparing to the following years (Sönmez et al., 2018). Lavandula species are mostly of Mediterranean origin, characterized of its high adaptation in sloping fields (Baydar, 2010). Furthermore, it has been reported that the average annual yield under Mediterranean climate, ranges between 5.6 and 15 tons per hectare (Ceylan et al., 1996, Arabaci and Bayram, 2005). Lavender is cultivated for its essential oil which has pharmacolo- gical effects and it has been used for medicinal purposes, for perfumes and cosmetics (Paul et al., 2004; Kageyama et al., 2012; Koulivand et al., 2013; Wojtunik et al., 2014). Lavender’ essential oil yield ranges from 1.1–9.3% (Jianu et al., 2013; Kara and Baydar, 2013; Robu et al., 2011; Raev et al., 1996). Many hectares with lavender cultivation have been established since 2000 in Greece and in Mediterranean basin in general. Nowadays lavender cultivation is facing a serious problem with Rhizoctonia and Fusarium fungal infections (personal data, Garibaldi et al., 2013) https://doi.org/10.1016/j.indcrop.2020.112611 Received 12 April 2020; Received in revised form 17 May 2020; Accepted 20 May 2020 ⁎ Corresponding author. E-mail address: kgiannoulis@uth.gr (K.D. Giannoulis). Industrial Crops & Products 154 (2020) 112611 0926-6690/ © 2020 Elsevier B.V. All rights reserved. T