A comparative study of the effects of chlrocoline chloride and mepiquat chloride growth regulators, on cotton (Gossypium hirsutum L.) in regions of Sao Paulo State, during 1980/81 and 1981/82 was carried out. The treatments were: the basic of 50g/ha applied at 60-70 days after emergency; the same dose divided in 30g/h a at the same date and 20g/h a at 15 days after, and parceled application of 75g/h a, being 50g/h a at 60- 70 days and 25g/h a at 75-80 days afte r emergence. Tests were analyzed in two groups, those with higher plant height and those, with smaller plants. Yield, plant height, technologycal characters and yield distribution on the plant were evaluated. The last character consisting in the percentage of bolls set on the lower 35 cm plant height. The results showed a significative effect for yield in the case of the group of more developed plants. In this group the 30 + 20g/h a parceled dose showed the highest yield. For both groups the regulator reduced significan tly the height of the plants. They induced an increase in seed grade, boll weight, fiber length and decrease in percentage of fibers. There was also a higher concentration of bolls on the lower 35 cm of the treated plots.
cotton; growth regulator; chlorocoline chloride and mepiqu at chloride