Beyyavaş: The effect of different harvest aiding chemicals on yield and yield components of cotton (Gossypium hirsutum L.) -2733 -APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 17(2):2733-2743. Abstract. This study was conducted to determine the effect of different harvest aid chemicals on the yield and yield components of cotton in the experimental area of Osmanbey Campus in Harran University. The method employed in the study was the randomized complete block design with three replications in

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... ng seasons in 2012 and 2013. The Stoneville-453 cotton cultivar was the subject of the study. Commercial names and compounds of the chemicals used in the experiment were as follows: Sonround (480 g/l Glyphosate), Efhun (Ethephon) (480 g/l Ethephon), Drop Ultra (120 g Thidiazuron + 60 g Diuron), Finish (480 g Etephon + 60 g Cyclanalide), and Appeal (54 g Fluthiacet-Methyl). Including the control plots, 10 treatments were performed when the bolls were 60% open. It was concluded that while the highest seed cotton yield was obtained from the Drop Ultra 600 cc ha -1 (5422.7 kg) and Appeal 75 ml ha -1 + Efhun 3000 ml ha -1 (5382.3 kg) applications in 2012, it was Sonround 3000 ml ha -1 (4150.7 kg) that produced the highest yield in 2013. On the other hand, the highest earliness ratio was obtained from the Drop Ultra 300 cc ha -1 + Efhun 3000 ml ha -1 treatment (96.30% and 96.30%) in both years. In the second year of the experiment, seed cotton yield and the number of bolls were lower when compared to the first year. The combination and single mixture treatments had different effects on examined properties. Keywords: Gossypium hirsutum L., defoliant, earliness ratio, boll weight, open boll percentage APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 17(2):2733-2743.