Interest in higher nitrogen (N) rates in combination with plant growth regulators continues with a renewed interest also in crop rotations involving corn or grain sorghum and cotton. High N rates required for corn production, relative to cotton production, could lead to a buildup of residual N in the soil profile. This residual N carryover could be exhibited as excess growth in subsequent cotton crops. In order to assess the interaction of N management with plant growth regulation of cotton followingcorn, a 4x2x2 factorial combination of N rates (60, 90, 120, and 150 lb/A), N application systems (preplant [PP] and preplant+sidedress [PP+SD]), and a new chemistry plant growth regulator (Pentia, mepiquat pentaborate) was evaluated in 2003 and 2004 atthe Delta Research and Extension Center near Stoneville, MS. Pentia product literature indicated that the product resulted in improved boll retention, faster uptake, earlier maturing cotton, superior height control, and superior rain-fastness. The objectives of this study were to determine the interaction effects of N management and mepiquat pentaborate (PGR) on cotton yields in a cotton/corn rotation and evaluate end-of-season plant characteristics with respect to N management and PGR use. A total of28 oz/acre Pentia was applied as a split application with the first application during early bloom and the remainder about two weeks later during peak bloom.
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