Weed Community Composition and Diversity Indices as Affected by Long-Term Crop Rotation in Rain-Fed Wheat

Abstract

Long-term crop rotation practices play a significant role in shaping weed community structure, population dynamics, and biodiversity in rain-fed agricultural systems. The present study investigated the effects of different long-term crop rotation patterns on weed community composition and diversity indices in rain-fed wheat cultivation. Field experiments were conducted under various rotational sequences, and weed species were identified and quantified at critical growth stages of the crop. Ecological parameters including species richness, relative density, frequency, and abundance were assessed to evaluate weed community dynamics. Diversity indices such as Shannon–Wiener diversity index, Simpson’s dominance index, and species evenness were calculated to determine the impact of crop rotation on weed biodiversity. The results revealed substantial variation in weed flora composition among different crop rotation systems. Continuous wheat cultivation favored the dominance of a few aggressive weed species, resulting in lower diversity and higher weed pressure. In contrast, diversified crop rotations significantly reduced the prevalence of dominant weeds and promoted greater species diversity and ecological balance within the weed community. Rotational systems involving legumes and broadleaf crops were particularly effective in disrupting weed life cycles and suppressing problematic weed populations. Changes in soil disturbance patterns, nutrient availability, and crop canopy structure contributed to differences in weed species distribution and abundance. The findings demonstrate that long-term crop rotation can serve as an effective cultural strategy for sustainable weed management in rain-fed wheat systems. The study provides valuable insights for designing integrated weed management programs that enhance agroecosystem stability and reduce reliance on chemical herbicides.