Influence of Water Quality and Harvest Times on Biomass Yield and Essential Oil of Lemon Verbena (Aloysia triphylla) under a Drip Irrigation System

Abstract

The impact of water quality-fresh water (FW), mixed water (MIX), and treated wastewater (TWW)–and number of harvests–three (H3), two (H2), and one (H1)–during the season on biomass yield and essential oil quantity and quality of lemon verbena(Aloysia triphylla) were studied. The production variables (fresh, air-dry, oven-dry weight, and dry matter percent) of lemon verbena biomass were affected by the harvesting times but not by the water types. Dry matter percent was the highest (50.57 %) and the lowest (30.07 %) with the treatments combinations of FWH2 and TWWH3, respectively. The mean essential oil yield varied from 9.04 Lha⁻¹ (TWWH2) to 3.47 Lha⁻¹ (MIXH1). The Pb concentrations in essential oil were low (0.001 gm L⁻¹) in all treatment combinations. The highest mean concentration of Ni in the essential oil of lemon verbena (0.573 mgL⁻¹) was obtained with the treatment combination TWWH3 and the lowest (0.186 mgL⁻¹) with FWH3. The highest mean Cd concentration (0.177 mgL⁻¹) was found in the treatments of TWWH3 and the lowest (0.128 mgL⁻¹) in FWH2.

Keywords:

• Treated wastewater
• crop irrigation
• heavy metals
• oil quality

Acknowledgments

The authors thank the Jordan University of Science and Technology for funding this research (number 186/2007).