Seedling Emergence and Population Dynamics of Euphorbia helioscopia in Vegetable Fields Under Different Irrigation Regimes

Abstract

Seedling emergence behavior and population dynamics of Euphorbia helioscopia were investigated in vegetable production systems subjected to different irrigation regimes to understand water-mediated regulation of weed establishment and persistence. Field experiments were conducted under controlled irrigation schedules representing high, moderate, and deficit moisture conditions, and emergence counts were recorded at regular intervals throughout the growing season. Results indicated significantly higher seedling emergence under moderate irrigation, while excessive moisture and severe water deficit both reduced germination rates due to altered soil aeration and moisture stress thresholds. Temporal emergence patterns showed multiple flushes, with peak recruitment occurring shortly after irrigation events, highlighting the strong dependence of germination on soil moisture availability. Population density and biomass accumulation were greatest in plots receiving frequent irrigation, where favorable soil conditions supported sustained seedling recruitment and reduced early mortality. In contrast, deficit irrigation suppressed overall population growth but promoted deeper root establishment in surviving individuals, indicating adaptive stress tolerance. Regression analysis revealed a strong positive correlation between irrigation frequency and weed density, emphasizing the role of water management in shaping weed population trajectories. Competitive interactions with vegetable crops intensified under high irrigation due to enhanced resource availability, leading to increased weed vigor and reduced crop-weed resource partitioning efficiency. The study demonstrates that irrigation regimes function as a critical ecological driver influencing emergence timing, population buildup, and persistence of E. helioscopia in agroecosystems. These findings underscore the importance of integrating irrigation management with weed control strategies to minimize early-season weed establishment and improve vegetable crop productivity. Long-term monitoring is recommended to assess seed bank replenishment dynamics under varying irrigation practices.