Effect of Weed Density and Duration of Interference on Yield and Yield Components of Sunflower

Abstract

Weed interference is a major limiting factor in sunflower production, particularly under conditions of variable weed density and duration of competition. The present study evaluated the effect of weed density and duration of interference on yield and yield components of sunflower under field conditions. Treatments consisted of varying weed densities combined with different periods of weed–crop coexistence to determine the critical period of competition. Results revealed that increasing weed density significantly reduced sunflower growth parameters, including plant height, leaf area, head diameter, and biomass accumulation. Yield components such as number of seeds per head, 1000-seed weight, and overall seed yield were adversely affected with prolonged weed interference. Early-season weed competition had the most pronounced impact on crop performance, indicating that sunflower is highly sensitive during its initial growth stages. Duration of weed presence showed a strong negative correlation with final yield, with longer interference periods resulting in progressively greater yield losses. High weed density exacerbated competition for light, nutrients, and soil moisture, leading to severe suppression of sunflower growth. The study also identified a critical weed-free period during early vegetative growth, beyond which yield losses increased substantially. These findings emphasize that timely weed management is essential to minimize yield penalties in sunflower cultivation. Overall, both weed density and duration of interference play crucial roles in determining sunflower productivity, and their combined effect significantly influences yield outcomes. Integrated weed management strategies, including early weed removal and optimized herbicide application timing, are recommended to ensure effective control and sustainable sunflower production in weed-infested agroecosystems.