A field study was conducted from 2003 to 2004 to evaluate effects of foliar application of Mepiquat chloride and boron on growth and yield of upland cotton (Gossypium hirsutum L.). Mepiquat chloride @ 0.15 litre/ha significantly reduced plant height, number of main stem nodes and nodes to first fruiting branch compared to the control. Plants treated with Mepiquat chloride at first flowering and 2 weeks after first flower stage and boron @ 0.15 litre/ha at first flowering and and 4 weeks after first flowering resulted in significantly highest number of open bolls and seed-cotton yield. All foliar B applications applied either at 2 weeks and 4 weeks after first flower resulted in similar but higher yields than the control. Neither Mepiquat chloride nor B affected gin turnout
