Sufficiency ranges for lemon balm and nutrient removals in aboveground phytomass

ABSTRACT

A set of fertilizer experiments were conducted during three growing seasons with the aim of establishing sufficiency ranges and crop nutrient removals for Melissa officinalis L. Critical nutrient concentrations were determined by the Cate–Nelson method or by removing 10% of extreme high and low values, respectively if a positive response to a given nutrient was recorded or not. Sufficiency ranges for macro, micronutrients, and SPAD-readings were set as: 27.0–40.0 g N kg⁻¹; 0.8–2.7 g P kg⁻¹ (May–August); 1.5–3.8 g P kg⁻¹ (September–November); 10.0–25.0 g K kg⁻¹ (May–August); 18.0–32.0 g K kg⁻¹ (September–November); 5.0–25.0 g Ca kg⁻¹; 3.5–8.5 g Mg kg⁻¹; 18–125 mg B kg⁻¹; 5–25 mg Cu kg⁻¹; 75–500 mg Fe kg⁻¹; 20–300 mg Zn kg⁻¹; 30–250 g Mn kg⁻¹; 30–45 SPAD-units. These results will allow laboratories to use plant analysis as an important tool in improving the fertilizer recommendations for this species.

KEYWORDS:

• critical concentrations
• Melissa officinalis
• plant analysis
• SPAD readings
• threshold values

Acknowledgment

The authors wish to thank José Montanha for meteorological data.

Additional information

Funding

The project “Sustainable management of medicinal and aromatic plants” (PRODER 46025) provided financial support.