Irrigation and fertilizer treatments affecting rosmarinic acid accumulation, total phenolic content, antioxidant potential and correlation between them in peppermint (Mentha piperita L.)

One of the greatest challenges in recent years is providing enough food to feed the increasing world population, while available freshwater resources become limited. However, effective fertilizer management has also a fundamental role to improve yield quality and quantity. A field experiment was conducted over 2 years, using a split-plot arrangement in a randomized complete block design. The experiments had three water deficit severity treatments: 25% (control), 40% (mild stress), and 55% (severe stress) depletion from the available water. The subplot division consisted of six fertilizer treatments; FR1: unfertilized (control), FR2: 140 kg ha(-1) urea; FR3: 105 kg ha(-1) urea + 3.3 ton ha(-1) vermicompost; FR4: 70 kg ha(-1) urea + 6.6 ton ha(-1) vermicompost; FR5: 35 kg ha(-1) urea + 10 ton ha(-1) vermicompost, and FR6: 13.5 ton ha(-1) vermicompost. The maximum essential oil (0.97%) was observed under mild water deficit stress. The highest antioxidant activity (DPPH) and superoxide dismutase activity could be monitored under unfertilized and 140 kg ha(-1) urea fertilized conditions, respectively. Vermicompost-treated soils reduced antioxidant features, total phenol, and rosmarinic acid content under water deficit. These results indicate that mild drought stress can increases the synthesis of medical compound and vermicomposting can alleviate the impact of drought by conserving soil moisture and improve nutrient uptake. Therefore, the results suggest that using vermicompost as a fast-acting nitrogen amendment can improve the leaf area index.

Automated summary

Effective fertilizer management plays a fundamental role in improving yield quality and quantity. Mild water deficit stress can increase the synthesis of medicinal compounds, while vermicompost can alleviate the impact of drought.