Nitrogen Effects on the Essential Oil and Biomass Production of Field Grown Greek Oregano (Origanum vulgare subsp. hirtum) Populations

Elissavet Ninou,Athanasios L Tsivelikas,Catherine M Cook,Vasilis Aschonitis,Fokion Papathanasiou,Parthenopi Ralli,Ilias Avdikos,Stefanos Stefanou,Ioannis Mylonas

doi:10.3390/agronomy11091722

Elissavet Ninou, Athanasios L Tsivelikas + Show 7 more

Open Access

https://doi.org/10.3390/agronomy11091722

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Abstract

This study investigates the effect of different nitrogen fertilization levels on the agronomic traits of five Greek oregano populations. Nitrogen supply positively affected dry bio-mass production, with the highest accumulation recorded at 80 kg N ha−1 (N2), which was 59% higher compared to the control plots (no additional nitrogen). In contrast, the essential oil content (mL 100 g−1 DW) was reduced, with the control treatment showing a 15% higher value compared to the mean value of the nitrogen treatments. However, nitrogen supply positively affected the essential oil yield (L ha−1), and the highest value was recorded at 80 kg N ha−1, (N2), showing a 40% increase compared to the control. A wide phenotypic variation among the five populations was also observed. In the three-year analysis, the population with the highest dry biomass production was Papadates (92% higher), that with the highest essential oil content was Vytina (25% higher), and the highest essential oil yield was observed for Papadates and Litochoro (57% and 51% higher, respectively), compared to the least yielding population. Significant interactions were also found between nitrogen levels and populations, implying that, in all cases, nitrogen levels should be specified for each population in order to optimize oregano productivity in sustainable farming systems.

Highlights

Over recent decades, a growing interest in the use of medicinal and aromatic plants worldwide has been observed [1]
The dry biomass production (Mg ha−1 ) and essential oil yield (L ha−1 ) of field grown oregano (Origanum vulgare subsp. hirtum) were positively affected by the application of nitrogen fertilizer up to 80 kg N ha−1, the essential oil content was reduced by up to 18% at this nitrogen supply level
The effects of nitrogen fertilization were similar throughout the 3-year experimentation, indicating that nitrogen supply can have a beneficial role in commercial agriculture, even though Greek oregano is adapted to the hot, dry, and low fertile soils of the Mediterranean environment

Summary

Introduction

A growing interest in the use of medicinal and aromatic plants worldwide has been observed [1]. This increased demand has endangered the native plant resources through the uncontrolled collection of plants from the wild. Many studies to date have focused on botanical aspects of the genus Origanum, but further work is required for crop domestication and the selection of the most suitable populations for cultivation [6,7]. It will be beneficial to utilize the genetic variability observed in wild oregano populations in order to select plants with optimal characteristics for introduction into cultivation, with a potential economic return as an essential commodity in food and health products

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