Effects of mepiquat chloride applications on non-oilseed sunflower


Abstract: Non-oilseed sunflower plants can be exposed to lodging in some production regions due to higher plant height and larger heads, which is further exacerbated by heavily rainfall and strong winds. In this context, plant growth regulators such as mepiquat chloride (MC) can be considered as an alternative approach in reducing plant height and lodging. This study was conducted to determine the effect of MC application on the growth, yield, and yield components of non-oilseed sunflowers at different growth stages (V4, R1, R2, and R3) and rates (0, 30, 60, and 90 g a.i. ha-1) in Erzurum Province, eastern Anatolia, Turkey, in the 2012 and 2013 growing seasons. In general, the MC applications had significant effects on the plant parameters investigated. In comparison with the control treatment, the MC application of 60 g a.i. ha-1 decreased plant height by 5.38% and increased stem diameter, head diameter, seed filling percentage, ratio of dehulled/hulled seed weight, 1000-achene weight, and seed yield by 14.01%, 3.78%, 1.61%, 4.20%, 5.94%, and 5.26%, respectively. Similarly, the applications of MC at different growth stages also significantly affected seed yield and other characteristics such as plant height, stem diameter, and head diameter. The application of MC at the early growth stage (V4) was more effective compared to the later growth stages (R1, R2, and R3). The results of this study suggest that the mepiquat application rate of 60 g a.i. ha-1 in the early growth stage (V4) was more effective on the plant characteristics and that MC application could be effectively used as a means of reducing plant height and the risk of lodging in non-oilseed sunflower production.

Keywords: Sunflower, Helianthus annuus L., growth stage, plant growth regulator

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