Competitive Effects of Bromus tectorum on Establishment and Yield of Winter Barley Under Dryland Farming Conditions

Abstract

Bromus tectorum (cheatgrass) is a highly competitive annual grass weed that poses a major challenge to cereal production in dryland farming systems. Its rapid growth, efficient resource utilization, and early establishment enable it to compete aggressively with winter barley for moisture, nutrients, light, and space, ultimately reducing crop productivity. The present study was conducted to evaluate the competitive effects of Bromus tectorum on the establishment, growth, and yield of winter barley under dryland farming conditions. Field experiments were carried out using varying densities of B. tectorum to assess its influence on barley emergence, plant development, biomass accumulation, and grain yield. Measurements of crop growth parameters, weed biomass, and yield components were recorded throughout the growing season to determine the intensity of crop–weed competition. The results demonstrated that increasing densities of B. tectorum significantly reduced barley establishment, tiller production, plant height, and grain yield. Early-season competition was particularly severe under limited soil moisture conditions, where the weed efficiently depleted available water resources required for crop growth. High weed infestation levels resulted in substantial reductions in crop biomass and harvest index, indicating strong competitive interference throughout the growing period. The study also revealed that barley plants grown under weed-free conditions exhibited improved vigor, canopy development, and yield performance compared with infested plots. Environmental stress associated with dryland conditions further intensified the negative impact of weed competition on crop productivity. The findings highlight the aggressive competitive nature of B. tectorum and emphasize the importance of timely and integrated weed management practices in winter barley production systems. Effective early-season weed suppression and improved crop establishment strategies are essential for minimizing yield losses and sustaining barley productivity under water-limited dryland farming environments.