Reports in the literature have been inconsistent relative to enhanced yields from applications of Chaperone (Asahi Co., Ltd.; Nara Prefecture, Japan), a PGR containing the nitrophenolates sodium 5-nitroguaiacolate (NaC7H6NO4) 1.25 g L-1, sodium ortho-nitrophenolate (NaC6H4NO3) 2.5 g L-1, and sodium para-nitrophenolate (NaC6H4NO3) 3.75 g L-1. Two field studies were conducted to evaluate cotton yield response to foliar applications of Chaperone at early flowering. Study I was conducted in 2004 and 2005 at 28 locations in Texas, and assessed the commercially recommended rate of 0.43 g ai ha-1 compared with an untreated control. Study II was conducted at eight locations within Burleson County, Texas, from 2001 to 2005. The treatments consisted of Chaperone at 0.43 g ai ha-1, 0.86 g ai ha-1, and 1.72 g ai ha-1 compared with an untreated control. In Study 1, no differences in lint yield were observed between the Chaperone treatment and the untreated control. Regression analyses also failed to show a response from the Chaperone treatment at locations with lower lint yields relative to locations having higher lint yields. In Study 2, across all experiments, Chaperone at 1.72 g ai ha-1 increased lint yield by an average of 92 kg ha-1 (7.5%) over the untreated control lint yield of 1222 kg ha-1. Chaperone applied in a single application at early flowering at 0.43 g ai ha-1 and 0.86 g ai ha-1 did not increase yield. Results of this research do not support the use of Chaperone in cotton at the current recommended rate.
