Influence of Plant Density on Cotton Response to Mepiquat Chloride Application

Increased yield potential associated with full‐season cotton ( Gossypium hirsutum L.) varieties can be offset by excessive vegetative growth that leads to undesirable fruit shed and boll rot. Producers often make multiple mepiquat chloride (1,1‐dimethyl‐piperidinium chloride) applications with excessive seasonal use rates to combat this problem, often with inconsistent results. Field studies were conducted in 2004 and 2005 to evaluate reduced plant populations as a potential management tool to be used in conjunction with mepiquat chloride application strategies for managing plant height. Plant populations of 152883, 101929, and 50958 plants ha −1 received a single application at 12 nodes (15.2 g a.i. ha −1 ) or early bloom (45.8 g a.i. ha −1 ), sequential applications at 12 nodes (15.2 g a.i. ha −1 ) and early bloom (30.6 g a.i. ha −1 ), or the modified early bloom schedule (a plant growth regulator application decision aid that recommends rates and timing based on plant growth parameters). Mepiquat chloride application reduced final plant height at least 15 cm compared with the nontreated in both years but also reduced the number of main stem nodes in 2005. In 2005, lint yield was inversely related to plant population, and a significant yield response occurred with the modified early bloom mepiquat chloride application strategy. Mepiquat chloride application increased lint yield in 1 of 2 yr but was useful for reducing plant height regardless of population. Reducing plant population had no adverse effects on lint yield or fiber properties and may be valuable in achieving a desired plant stature with less intensive plant growth regulator management.