Allelopathic Potential of Barley (Hordeum vulgare) and Belladonna (Atropa belladonna) Residues for Weed Management in Transplanted Aman Rice

Abstract

Weeds remain one of the most persistent constraints to profitable rice (Oryza sativa L.) production, competing aggressively with the crop for nutrients, moisture, light, and space throughout the vegetative stage. Sustainable, low-input weed management strategies are therefore needed to reduce reliance on manual weeding. This study evaluated the allelopathic potential of barley (Hordeum vulgare L.) and belladonna (Atropa belladonna L.) residues as a bioherbicidal tool for weed suppression in transplanted Aman (T. Aman) rice at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh. A two-factor experiment was arranged in a randomised complete block design with three replications, combining three rice varieties (BRRI dhan49, Binadhan-13, and BR11) with five weed-management treatments — no residue (control), barley residue (2.5 t ha⁻¹), belladonna residue (2.5 t ha⁻¹), a combined barley–belladonna residue (1.0 t ha⁻¹ each), and hand weeding. Four weed species dominated the experimental field — Scirpus juncoides, Monochoria vaginalis, Echinochloa crusgalli, and Marsilea quadrifolia — and their density, biomass, and percentage inhibition were assessed alongside rice yield performance. Hand weeding produced the highest weed inhibition (78.88–91.46%), followed by the combined barley–belladonna residue treatment, whereas the control (no residue) recorded the lowest suppression. Belladonna residue alone also suppressed weed density and biomass relative to the control, indicating a previously uncharacterised allelopathic effect in this species. Although BRRI dhan49 exhibited the highest weed density, it also showed high weed inhibition relative to its own control, whereas Binadhan-13 had the lowest weed density but lower inhibition. At harvest, BRRI dhan49 produced the highest grain yield and yield-contributing traits. Notably, the combined application of barley and belladonna residues (1 t ha⁻¹ each; 2 t ha⁻¹ total) resulted in greater weed suppression and yield benefits than the individual residue treatments (2.5 t ha⁻¹ each) and the control. Within the literature considered in this manuscript, this is the first report of belladonna's weed-suppressive potential, alone or in combination with barley. The results suggest a potentially synergistic effect between barley and belladonna residues and indicate the potential value of using lower quantities of plant residues while enhancing weed suppression and crop productivity.