Competitive Ability and Biomass Allocation Strategy of Sonchus oleraceus in Irrigated Vegetable Cropping Systems

Abstract

Competitive ability and biomass allocation strategy of Sonchus oleraceus were investigated in irrigated vegetable cropping systems to understand its adaptive growth behavior and interference potential under resource-rich conditions. Field and pot experiments were conducted under varying crop densities and irrigation regimes, and plant growth parameters including height, leaf area, root–shoot ratio, and total biomass were recorded. Results indicated that S. oleraceus exhibited strong competitive plasticity, enabling persistence even under high crop competition. Under low competition, the species allocated a higher proportion of biomass to shoots, promoting rapid canopy expansion and light interception. In contrast, under high competition, increased allocation to root biomass was observed, enhancing water and nutrient acquisition in irrigated environments. The species demonstrated efficient resource-use strategies, allowing it to maintain growth under both intra- and interspecific competition. Irrigation availability further enhanced its competitive performance by reducing water limitation and promoting rapid vegetative growth. Yield reduction in associated vegetable crops was significantly correlated with increased weed biomass and early-season establishment of S. oleraceus. The study highlights the importance of early weed management to suppress competitive advantages during initial crop growth stages. These findings provide insights into the ecological adaptability of S. oleraceus and support the development of integrated weed management strategies tailored to irrigated vegetable production systems.