Effect of Ascorbic Acid on the Yield and Quality of Essential Oils in Indian Dark Variyali Sowa (Anethum sowa)

Abstract

Indian dark variyali sowa was given pre-sowing and foliar spray treatments with 10 and 50 mg 1⁻¹ ascorbic acid (AA) and fruits were analysed for total volatile oil yield and various constituents at young, mature green and mature dark grey stages. AA treatment slightly decreased the yield of fruits, but increased the oil yield and quality. Carvone and dihydrocarvone accumulated rapidly in the developing fruits up to mature green fruit stage. The undesirable phenolic ether dillapiole accumulated actively during the color change of the fruits from green yellow to dark grey. Ascorbic acid treatment hastened the formation of carvone and dihydrocarvone and retarded dillapiole synthesis. Treatment with 50 mg l-¹ AA yielded oil with high concentrations of carvone/dihydrocar-vone and lowest amount of dillapiole, a trend seen at all three stages of fruit development. Mature green fruits of 50 mg 1-' AA treated plants yielded the best quality oil which showed a high concentration of carvone and dihydrocarvone and only 3% dillapiole.