Influence of plant density and spatial orientation on the competitive ability of spring wheat against weeds

Weed infestation poses a significant challenge to wheat production worldwide. Effective weed management is crucial, yet depending solely on chemical herbicides or mechanical removal can be costly and environmentally unfavourable. This study aims to evaluate the effects of different plant densities and spatial arrangements on the ability of spring wheat to suppress weed growth. Five seed rates, viz. 100, 120, 140, 160, and 180 kg/ha and three seeding methods viz, continuous sowing in 20 cm, 15 cm, and 10 cm apart lines, were tested using a randomised complete block design with three replicates. Results revealed that an increase in seed rate and the practice of narrower row spacings led to a consistent decline in weed density and weed biomass. The highest wheat dry matter accumulation, yield parameters and grain yield were achieved with 160 kg/ha seed rate sown in 15 cm lines. A significant negative correlation was found between the grain yield of wheat and weed density as well as weed dry matter, indicating that increases in weed infestation adversely affect wheat production. Regression analysis demonstrated that grain yield decreases by 59.4 kg/ha for each additional gram of weed dry matter per square meter. Based on these findings, it is recommended to adopt a seed rate of 160 kg/ha with continuous sowing in 15 cm rows to optimise wheat productivity while effectively managing weeds. The findings of this study will provide evidence-based recommendations for farmers seeking to adopt integrated weed management practices that are environmentally sustainable.