Shade Effects on Growth, Yield, and Oil Quality of Cymbopogon winterianus in the Deccan Plateau

Background and Objective: Java citronella (Cymbopogon winterianus var. Bio-13) cultivation faces challenges in optimizing growth and essential oil yield under varying shade conditions, particularly in the Deccan Plateau Region. The present study aimed to evaluate the effects of different shade levels on vegetative growth, essential oil yield, composition, and biochemical parameters to identify optimal cultivation conditions. Materials and Methods: A field experiment was conducted at CSIR-CIMAP Research Centre, Hyderabad (2023-24), using a randomized block design (RBD) with four replications. Shade levels of 0, 25, 50, 70, and 90% were applied to assess plant growth, herbage yield, essential oil content and composition, chlorophyll, and phenolic contents. Gas chromatography was used for essential oil analysis. Statistical analysis included Principal Component Analysis and standard ANOVA to determine treatment effects with 0.05 significance level. Results: Maximum vegetative growth was recorded under 90% shade (plant height:142.3 cm, leaf length:113 cm, canopy width:119.5 cm). However, 50% shade resulted in optimal essential oil production (0.95%; 156.7 kg/acre), fresh herbage yield (19.4 t/acre), and dry herbage weight (16.5 t/acre), outperforming full sunlight (0.94%; 35.96 kg/acre). Chemical composition was superior under 50% shade, with citronellal (35.32%) and geraniol (23.42%) reaching peak levels. Biochemical parameters, including total chlorophyll (2.5 mg/g FW) and phenolic content (30.4 mg GAE/g DW), were also maximized under 50% shade. Principal Component Analysis indicated that shade treatments accounted for 78.5% of the total variance. Conclusion: Moderate shade (50%) provides optimal conditions for maximizing essential oil yield, quality, and biochemical composition in Java citronella, while higher shade levels promote vegetative growth. These findings offer practical recommendations for improving citronella cultivation under Deccan Plateau conditions.