Document Type : Original Article
Authors
1
Medicinal and aromatic plants research/ national research centre Egypt
2
National Research Centre Cairo Egypt
3
Zhejiang Chinese Medical University, Hangzhou China
4
Faculty of Agriculture and Natural resources, Aswan University, Aswan 81528, Egypt
Abstract
This study conducted during the 2020/2021 and 2021/2022 seasons investigated the influence of Zinc (Zn) and Magnesium (Mn), alone or combined, on oregano plants' growth, yield, and essential oil composition. Results revealed that oregano height peaked with 50 ppm Zn, while 100 ppm Zn and a combination of 50 ppm Zn with 50 ppm Mn produced the highest number of shoots and branches. Optimal fresh and dry yields occurred with 50 ppm Zn and 100 ppm Mn. The greatest essential oil percentage resulted from the combination of 100 ppm Zn and 50 ppm Mn. Zn and Mn, independently or combined, led to a significant reduction in chlorophyll "a," "b," and carotenoids, with 50 ppm Zn most affecting chlorophyll "a" and "b" and the combination of 100 ppm Zn and 50 ppm Mn predominantly impacting carotenoids. Total phenolic and flavonoid levels increased with the addition of Zn and Mn, particularly with 100 ppm Zn and 50 ppm Mn. Antioxidant activity, assessed by the DPPH assay, reaching its peak it 100 ppm Zn and 100 ppm Mn. GC-MASS analysis identified 22 compounds, with carvacrol and thymol as major constituents, carvacrol consistently surpasses thymol in concentration across treatments. Interestingly, low concentrations of Zn or Mn, when applied individually, had a more pronounced impact than their combination, particularly on carvacrol. Conversely, Mn exhibited a more noticeable effect on thymol compared to Zn. These findings suggest that incorporating Zn and Mn, especially at low concentrations, in oregano fertilization enhances both yield and quality.
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