# Differential Response of Stem and Leaf Oil Yield and Main Quality of Cymbopogon citratus (DC.) Stapf to Different Radiation Intensities

## TL;DR

This study shows that lemongrass leaf oil under natural light has higher yield and better quality than stem oil, regardless of radiation intensity.

## Contribution

The study identifies leaf oil under natural light as optimal for lemongrass essential oil quality and proposes a cultivation strategy for high-value products.

## Key findings

- Leaf oil yield was 54.48% higher than stem oil, with no significant difference in refractive index or chromatic aberration.
- Leaf oil contained higher levels of heterocyclic compounds, ethers, and aldehydes, while hydrocarbons were lower compared to stem oil.
- Key volatile components like geraniol and citral were significantly more abundant in leaf oil than in stem oil under natural light.

## Abstract

Cymbopogon citratus (DC.) Stapf (lemongrass), a globally significant medicinal and aromatic plant, is widely used in food and pharmaceutical industries owing to its bioactive essential oil. However, conventional whole‐plant extraction methods face challenges such as inconsistent oil quality and suboptimal stability. To elucidate the effects of cultivation environments and plant tissues on oil quality, this study categorized lemongrass plants into shaded and natural light exposure groups. Essential oils were extracted from leaves and stems using steam distillation, followed by compositional analysis using Headspace Solid‐Phase Microextraction (HS‐SPME) coupled with Gas Chromatography–Mass Spectrometry (GC–MS). The investigation focused on how varying radiation intensities influenced physicochemical properties and volatile components of essential oils from various plant parts. Results demonstrated that both physicochemical properties and volatile compositions of lemongrass essential oils exhibited minimal sensitivity to variations in radiation intensity treatments. Leaf‐derived essential oil exhibited a significantly higher yield than stem oil by 54.48%, but their refractive indices and chromatic aberration values did not differ substantially. Leaf oil contained markedly elevated levels of heterocyclic compounds, ethers, and aldehydes than those in stem oil by 14.61%, 10.83%, and 1.57%, respectively, while hydrocarbons were lower by 6.1%. The primary volatile constituents characterizing lemongrass quality—geraniol and citral (specifically 2,6‐octadienal, 3,7‐dimethyl‐, (E)‐)—were significantly more abundant in the leaves than in the stems by 8.64% and 7.20%, respectively (p < 0.01). Therefore, lemongrass essential oil extracted from leaves cultivated under natural light conditions demonstrated the highest oil yield and superior quality attributes. The integration of natural light cultivation with selective leaf harvesting proposes a promising strategy to enhance lemongrass oil quality. This methodology establishes a theoretical basis for advancing downstream processing techniques and developing high‐value products derived from lemongrass essential oil.

Lemongrass leaf oil quality exceeds stems, featuring higher key component content. Natural light rather than shading maintain essential oil physicochemical properties. Cultivating and harvesting leaf under natural light can enhance essential oil quality.