Morphological and phenological characteristic, oil yield, quality and economics of Lemon bee balm (Monarda citriodora Cerv. ex-Lag) at diverse environment condition, India

Abstract

Lemon bee balm (Monarda citriodora Cerv. ex-Lag) is a noble industrial medicinal and aromatic plant species, which is used as digestive, antifungal, anti-inflammatory and menstrual irregularity remedies in traditional medicine. It is a common source of thymol and other active constituents with recognized antimicrobial properties. A multilocation field trial was performed to evaluate essential oil (EO) yield stability, secondary metabolites and economic returns in eight diverse geographical environment conditions (GEC) in India. The secondary metabolites viz., essential oil content and oil yield were found to be highest in tropical and sub-tropical regions. The essential oil content was found to be higher in inflorescence part at all the experimental sites and found to be highest (0.85±0.21%) at BR-JALAUN. The highest EO yield (130.25±3.25 kg ha−1), net return (Rs. 1,22,125.00±245.21 ha−1) and benefit cost (B:C) ratio (2.67±0.17) was recorded at FFDC-KANNAUJ. The thymol content percentage was found to be highest on physiological maturity (>95% flowering) [PM] and on 75% flowering [FS-II] and it began to decline on seed formation stage at all the experimental sites. The significantly highest thymol content percentage was found on PM (86.65±3.91%) and on FS-II (84.21±3.78%) at TBR-JHANSI. On the basis of the gas chromatography and mass spectrophotometry analysis, twenty constituents were isolated. The inflorescence EO contains more thymol than the EO from leaves with stem which in turn was characterized by a higher content of p-cymene, γ-terpinene, carvacrol, α-phellandrene, α-pinene, myrcene, α-terpinene, citral and β-caryophyllene.