Sustainable production of Origanum syriacum L. using fish effluents improved plant growth, yield, and essential oil composition

The concept of Integrating Aquaculture with Agriculture (IAA) is considered the right path towards achieving sustainable agriculture in semi and arid areas. With the increase of global water scarcity, the double utilization of water for both fish and crop production is gaining more attention since it ensures maximizing the productivity of every unit of water used. This study investigated the effect of fish effluent irrigation on the herbage growth, essential oil content, and composition of Origanum syriacum L. The experiment followed a randomized complete design of three irrigation treatments with three replicates, i.e., control with 100% chemical fertilizers (CT), full irrigation with fish effluent (FT), and the mixed treatment (MT) with 50% CT and 50% FT. Study findings showed that FT reached 49 branches/plant, gained maximum plant height (58.8cm), and highest fresh and dry herbage yield reaching 17.76 and 6.722 tons ha-1, respectively, in the second cut. Essential oil content reached the maximum in FT at 64.02dm(3) ha-1 and 143.5dm(3) ha-1, while the lowest in CT at 15.95dm(3) ha-1 and 109.33dm(3) ha-1 for the first cut and second, respectively. Carvacrol was the main constituent of the excreted essential oil, representing a maximum of 80.87% for FT in the first cut and 74.69% for MT in the second cut. It was closely followed by p-Cymene (10.75% - CT, 6.38% - FT) and γ-Terpinene (5.06% - CT, 8.49% - FT) for the first and second cut respectively. The importance of these major chemical components stems from their use in both the food and pharmaceutical industries.