Agronomic Comparisons of Herbicides with Different Active Ingredients and Mechanical Hoeing for Weed Control in Oleic and Linoleic Type Sunflower (Helianthus annuus L.) Hybrids

Abstract

Weeds cause serious yield losses in sunflower production. The most common methods for weed control are herbicide application and mechanical hoeing. The objective of this study was to determine the effects of five traditional herbicides containing different active ingredients compared with mechanical hoeing for weed control on seed yield components, seed oil content, and fatty acid composition in sunflower. Field experiments were conducted in the sunflower growing seasons of 2014 and 2015 on farmer fields in Karamusul village of Lüleburgaz, Kırklareli, located in the Northwest of Turkey (40°24’ N, 27021 E and elevation 46 m). Pre-plant herbicide Bonoflan WG with benfluralin, pre-emergence herbicide Stomp®Extra with pendimethalin, and post-emergence herbicides Challenge600 with aclonifen and Targa Super with quizalofop-p-ethyl active were applied on non-Clearfield sunflower hybrids (P64LL05–Linoleic and P64H34–High oleic) while post-emergence herbicide Intervix®Pro with imazamox was applied on Clearfield hybrids (LG5542CL-Linoleic and Colombi–High oleic). In the results, the year effects were statistically significant on plant height, head diameter, number of days from planting to 50% flowering, and percentage of stearic acid of Clearfield cultivars while it was significant on plant height, head diameter, stem diameter, 1000 seed weight, number of days from planting to 50% flowering, seed yield, seed oil content, percentage of oleic and linoleic acids of non-Clearfield cultivars. The effect of genotype was significant for all seed yield and oil components except seed weight and seed yield for both groups’ cultivars. Intervix®Pro caused significant decreases in plant height, stem diameter, and percentage of stearic acid. Stomp®Extra decreased the number of days from planting to 50% flowering. Challenge 600 had a negative effect on the seed oil content of P64H34 in 2015. There was no significant difference between herbicide applications and mechanical hoeing for seed yields except for increasing seed yield of P64H34 by Bonaflan WG in 2015. For all herbicide applications, residue in seeds was not exceeded international acceptable limits. According to the results, herbicides especially post-emergence applications under stress conditions can adversely affect agronomic yield and seed oil components in sunflower.