Competitive Interference of Polygonum persicaria in Soybean Fields Under Different Row Spacing and Planting Densities

Abstract

Polygonum persicaria is a competitive broadleaf weed commonly infesting soybean production systems, where it interferes with crop growth through competition for light, nutrients, water, and space. Severe infestations can reduce soybean establishment, suppress canopy development, and cause substantial yield losses, particularly under suboptimal crop management conditions. Crop spatial arrangement, including row spacing and planting density, plays an important role in influencing crop competitiveness and weed suppression. The present study was conducted to evaluate the competitive interference of P. persicaria in soybean fields under different row spacing and planting density regimes. Field experiments were established using varying soybean row spacings and plant populations under natural and controlled weed infestation conditions. Data on weed density, weed biomass, soybean growth parameters, canopy development, and yield components were recorded throughout the growing season to assess crop–weed interactions. The results demonstrated that P. persicaria significantly reduced soybean growth and yield, with the severity of interference varying according to crop spatial arrangement. Wider row spacing and lower planting densities resulted in greater weed growth, increased weed biomass, and stronger competitive effects on soybean productivity. In contrast, narrow row spacing combined with higher planting density enhanced crop canopy closure, reduced light availability to weeds, and significantly suppressed P. persicaria emergence and biomass accumulation. Improved crop competitiveness under dense planting conditions contributed to higher soybean yield and reduced weed interference. The findings highlight the importance of crop spatial management as a cultural strategy for weed suppression in soybean production systems. Optimizing row spacing and planting density can improve crop competitiveness and reduce the negative impact of P. persicaria without excessive reliance on chemical herbicides. The study provides valuable insights for developing integrated weed management practices aimed at enhancing soybean productivity and promoting sustainable agricultural production.