The combined effect of soaking cotton seeds with mepiquat chloride solutions and the sequential foliar spraying on plant height and yield was studied under field conditions in Londrina, PR (23o29'S, 51o12'W), Brazil, using the cultivar IPR-120. Treatments were arranged in the field in a completely randomized factorial (5X2) design and replicated four times. The seed soaking treatments consisted of five concentrations of mepiquat chloride: 0, 0.5, 2.5, 5.0 and 7.5% (v/v) for 12h (sowed six days later). In the plots receiving foliar spraying of the regulator, the first two applications were made at 17 and 32 days after emergence (DAE), and the remaining five at a 10-day interval. In the first four foliar applications 15 g a.i.ha-1 of the chemical was used whereas in the last application 20 g a.i.ha-1 was used. All growth inhibitor concentrations used in seed treatment reduced plant height compared to the control (water). However, these differences were significant only until 31 DAE (Table 1). There was no interaction among the analyzed factors. Seed treatment with mepiquat chloride reduced the cotyledon node height but showed no effect on the height of the first productive branch, total number of branch, number of reproductive branch, number of bolls per plant and on the position of the first boll. However, these parameters were affected by foliar application of the growth regulator.

Table 1. Analysis of variance of the height of cotton plants from seeds soaked with mepiquat chloride and with or without foliar applying at different days after emergence (DAE)

Cause of variation             Mean square

	DF	10 DAE	17 DAE	24 DAE	31 DAE	56 DAE	86 DAE	116 DAE
Soaking dosage	4	11,31**	15,43**	29,70**	24,05*	24,73ns	9,20ns	30,75ns
Foliar applying	1	0,00ns	0,25ns	23,82**	68,07**	1899,71**	6436,91**	7360,37**
Dosage X foliar appl.	4	0,56ns	1,56ns	1,70ns	4,14ns	12,27ns	20,53ns	58,02ns
Blocks	3	5,27ns	7,58ns	16,61ns	20,09ns	54,23ns	182,95ns	214,95ns