Weed Flora Richness and Composition in Irrigated vs. Rainfed Chickpea Fields Under Different Crop Rotation Systems

Abstract

Weed flora richness and composition were assessed in irrigated and rainfed chickpea (Cicer arietinum L.) fields under different crop rotation systems to understand the influence of water regime and cropping history on weed community structure. Field surveys were conducted across representative agroecological zones, and weed species were recorded at different crop growth stages, followed by quantification of density, frequency, and abundance. Results indicated higher weed species richness and diversity in irrigated chickpea fields compared to rainfed systems, reflecting enhanced moisture availability and prolonged weed emergence windows. Rainfed fields exhibited lower diversity but higher dominance of drought-tolerant species adapted to moisture-limited environments. Crop rotation systems significantly influenced weed composition, with diversified rotations reducing the prevalence of dominant weed species and promoting a more balanced weed community structure, while continuous chickpea cultivation favored the buildup of specific competitive weed species. Seasonal dynamics showed peak weed emergence during early crop establishment stages in both systems, with irrigated fields exhibiting extended emergence periods due to sustained soil moisture. Multivariate analysis revealed clear separation of weed communities based on irrigation regime and rotation history, indicating strong environmental and management-driven structuring of weed flora. Competitive interactions between chickpea and weeds were more intense in irrigated systems due to higher weed density, although crop growth was less moisture-limited. The study highlights the combined influence of irrigation and crop rotation on shaping weed biodiversity in chickpea agroecosystems. These findings emphasize the importance of integrated weed management strategies incorporating diversified rotations, timely interventions, and water management to maintain weed balance and sustain chickpea productivity under varying production systems.