Critical Period of Weed Control for Portulaca oleracea in Direct-Seeded Tomato Under Drip Irrigation

Abstract

Weed competition during the early growth stages of tomato significantly reduces crop establishment, nutrient utilization, and final yield, particularly under direct-seeded production systems. The present study investigated the critical period of weed control for Portulaca oleracea in direct-seeded tomato cultivated under drip irrigation conditions. Field experiments were conducted using different weed interference and weed-free periods to determine the duration during which weed management is essential to prevent unacceptable yield losses. Observations were recorded on weed density, weed biomass, tomato plant growth, canopy development, fruit yield, and yield components throughout the cropping season. The results demonstrated that P. oleracea exerted strong competitive effects on direct-seeded tomato plants, particularly during the early vegetative growth stages. Prolonged weed interference significantly reduced plant height, biomass accumulation, fruit set, and marketable yield due to competition for moisture, nutrients, light, and space. Drip irrigation created favorable soil moisture conditions that enhanced rapid weed emergence and growth, intensifying crop–weed competition. The critical period of weed control was identified as the early to mid-growth stages of tomato, during which timely weed removal was necessary to minimize yield reduction and maintain crop productivity. Delayed weed management resulted in substantial increases in weed biomass and irreversible yield losses. Maintaining weed-free conditions during the identified critical period significantly improved tomato growth and fruit yield. The findings highlight the importance of precise timing of weed control operations in drip-irrigated tomato systems and support the integration of cultural and mechanical weed management strategies for sustainable crop production. This study provides valuable information for optimizing weed management practices and reducing the negative impact of P. oleracea on tomato productivity.