Weed seed bank characterization and its contribution to weed management in rice-wheat cropping system

In northern Bihar, especially in the Koshi area, the rice-wheat cropping system is the most common form of agriculture practiced, sustaining millions of marginal farmers. Although this cropping system is critical for the region's food security and income, it faces unprecedented challenges from multifaceted and chronic weed infestations. Weeds like Phalaris minor, Avena fatua, and Echinochloa crus galli are especially problematic because of aggressive cropping practices, minimal crop rotation, and developed herbicide resistance. Integrated approaches to weed control within this context require knowledge of the entire life cycle of a weed seed, which comprises its production, dispersal, dormancy, germination behavior, and persistence in the soil seed bank. The alternating hydrological conditions of the rice-wheat rotation, which include flooded paddies during the kharif season and dry tilled fields during the rabi season, support an extensive array of weed species, each with unique flood adaptive ecological strategies for survival and reproduction. This review aims to fill the literature gap to explain how the temporal and spatial patterns of seed dormancy along with emergence moderated by local eddies and climatic factors influence reactive management strategies while weed seed banks are treated as passive. This paper synthesizes current research on seed ecology within the rice-wheat system of North Bihar and emphasizes its implications for integrated weed management (IWM). Cultural practices such as crop residue retention, stale seedbed techniques, timely sowing, and rotation with legumes are reviewed alongside chemical and emerging biological strategies. Targeting seed input and depleting the soil seed bank are identified as key pillars for long-term control. Finally, the review highlights region-specific challenges, including the spread of herbicide-resistant biotypes and climate variability, calling for the development of adaptive, ecology-based IWM approaches tailored to the agroecological conditions of the Koshi region.