Allelopathic Effect of Lamiaceous Weeds on Seed Germination and Early Growth of Aromatic Rice (Oryza sativa 'Gobindobhog')

The present study reveals the allelopathic effect of aqueous leaf and root extracts of Hyptis suaveolens (L.) Poit. and Leucas cephalotes (Roth) Spreng. on seed germination and early growth of Oryza sativa tobindobhog: Leaf and root extracts at different concentrations (0.5%, 1%, 2.5%, 4%, and 5%) were used to study the effect in laboratory-based experiments. After 5 days of incubation, seed germination and root and shoot length of rice seedlings were measured, and both H. suaveolens and L. cephalotes showed allelopathic effects on seed germination and growth parameters. Hyptis suaveolens showed a more pronounced effect at 5% concentration of aqueous leaf and root extracts than L. cephalotes. The inhibitory effects were as follows: root length > seed germination > shoot length. Both H. suaveolens and L. cephalotes impede seed germination and early growth of rice by releasing water-soluble allelochemicals from their leaves and roots.