Understanding the Role of Shading on Quality and Quantity of Patchouli Essential Oil Through Changing Seasons in Subtropical Agroclimatic Zone

ABSTRACT Pogostemon cablin (Blanco) Benth., commonly known as patchouli, is extensively popular for its EO content. Plants were grown under shade net (~90%) and open environment in the three most prevalent seasons of subtropical eastern India to evaluate the quality and quantity of essential oil. The highest EO yield was obtained in summer (0.73 ± 0.11 g/plant) and monsoon (1.03 ± 0.08 g/plant) in the open environment. Plants grown under shade nets in all three seasons did not show enhanced essential oil accumulation. Among the total 20 major terpenoids identified through GC–MS analysis, patchouli alcohol (ranging from 23.15% ± 1.322% to 34.65% ± 2.975%) and γ‐curcumene (ranging from 18.57% ± 0.973% to 32.20% ± 2.142%) dominated the fragrance profile in all three seasons, reporting quite a higher percentage than any earlier reports. A dominating presence of γ‐curcumene with such a higher concentration provides the particular cultivar (CIM‐Samarth) a unique fragrance profile distinct from the commonly available patchouli. The content of patchouli alcohol was found to be significantly increased under the influence of shade nets in both winter and monsoon. The antioxidant capacity of the extracted essential oil also showed variation correlating with compositional variation across seasons. The lowest IC 50 value was reported under shade net in monsoon (2.09 ± 0.28 μg/mL), whereas the highest value was observed in open environment during winter (8.43 ± 1.3 μg/mL), with an indication of strong association between patchouli alcohol and antioxidant capacity of the EO. Although exploring the relationship between the chemical components of patchouli essential oil and environmental parameters, it has been revealed that both temperature and light intensity are the primary environmental drivers for the formation of certain sesquiterpenoids.