The objective of this work was to assess the sensibility of cotton cultivars to mepiquat chloride and to verify if it is related to plant cycle or architecture. A green-house experiment was carried out with six cotton cultivars - FiberMax 966, FiberMax 977, Delta Penta, Delta Opal, FMT 501 e FMT 701 -, and four concentrations of mepiquat chloride plant growth regulator - 0, 7,5, 15 and 22,5 g ha-1 of the active ingredient - in complete block design with a 6x4 factorial arrangement and four replicates. The plots consisted of 12 L pots with two plants per pot. Regulator doses were applied without adjuvants at the beginning of flowering, 34 days after emergence of seedlings. Besides the experiment with doses, the regulator deposition on leaves of each cultivar was quantified. The growth regulator reduces the growth of cotton plants, and this effect is intensified by increasing the dosage. There are differences among cotton cultivars regarding their sensibility to mepiquat chloride, with the earliest cultivars being the most sensitive. Besides differential sensibility, cultivar architecture can provide greater or lesser regulator deposition on leaves.
Gossypium hirsutum; plant height; plant growth; plant growth regulator
