Depolymerized carrageenan ameliorates growth, physiological attributes, essential oil yield and active constituents of Foeniculum vulgare Mill

► The foliar spray of IC at 80 mg L−1 enhanced growth attributes. ► The foliar spray of IC at 80 mg L−1 enhanced essential oil yield. ► The foliar spray of IC at 80 mg L−1 enhanced components of essential oil, viz. fenchone and anethole.