ABSTRACT

A trial was conducted near Rolling Fork, Mississippi to evaluate the benefits of Pentia and mepiquat chloride as plant regulators on cotton. Pentia (common name, mepiquat pentaborate) is a new plant regulator, which includes boron on the molecule instead of chloride. Boron provides faster plant uptake and promotes earliness in cotton.

Treatments were applied to DP 555BR/RR, a full season cotton variety with aggressive growth potential to compare affects when cotton was planted on two soil types, silt clay loam and heavy clay. Data was collected to evaluate: (1) the timing of the first application beginning at 8^th node versus application at first bloom; (2) cotton growth response; (3) earliness and (4) the affect on cotton yield. Cotton treated with Pentia and mepiquat chloride was 31.2% and 27.8% shorter, respectively, than the untreated check. Treatments that began at 14^th node provided more vegetative growth control than the treatments that began at 7-8^th node. Pentia treated cotton that began at the 7-8^th node and 14^th node provided 23.1% and 39.9% more vegetative growth control, respectively, than the untreated check. All plant regulator treatment programs provided earlier boll opening than the untreated check. All Pentia treatment programs provided a higher percent of open bolls than mepiquat chloride treated cotton. A summary of the treatments showed that Pentia treated cotton was 66.4% open compared to 54.5% and 51.3% open in the mepiquat chloride and untreated cotton, respectively, at 136 days after planting. Cotton grown on mixed soil with plant regulator treatments beginning at bloom followed by a second application in two weeks provided the greatest yield. Pentia and mepiquat chloride treatment programs of 40 oz/A yielded 253 and 230 lb lint/acre, respectively, more than the untreated check. In this study, when plant regulators were applied beginning early (node 7-8) or to cotton planted on heavy clay soil, there were no positive yield increases.