Competitive Dynamics and Critical Weed-Free Period of Avena sterilis in Irrigated Durum Wheat

Abstract

Competitive dynamics and the critical weed-free period of Avena sterilis were investigated in irrigated durum wheat (Triticum durum Desf.) to quantify yield loss potential and determine the timing of effective weed management. Field experiments were conducted under controlled infestation levels, and weed–crop interactions were assessed through measurements of wheat growth parameters, biomass accumulation, and grain yield. Results indicated that A. sterilis exerted strong competitive pressure on durum wheat, particularly during early crop development stages when resource demand and canopy establishment overlap. Increasing weed density significantly reduced plant height, tiller production, leaf area index, and final grain yield. Regression analysis showed a strong negative relationship between weed interference duration and wheat productivity, highlighting the sensitivity of the crop to early-season competition. The critical weed-free period was identified during the initial growth stages of wheat, where even short durations of weed presence resulted in measurable yield reductions. Delayed weed removal beyond this period led to irreversible yield losses due to competition for light, nutrients, and soil moisture. A. sterilis demonstrated rapid early emergence and vigorous growth, enabling it to efficiently exploit irrigation inputs and outcompete the crop during establishment phases. Competitive intensity was further enhanced under high nitrogen availability and favorable moisture conditions typical of irrigated systems. The study emphasizes the importance of timely weed control interventions to minimize yield losses in durum wheat production. These findings provide essential insights for optimizing integrated weed management strategies, including pre-emergence control, timely post-emergence applications, and cultural practices to suppress A. sterilis competitiveness in irrigated agroecosystems.