Controlling excessive growth in cotton by multiple applications of low concentrations of mepiquat chloride

Excessive vegetative growth of cotton occurs under favourable growing conditions and this contributes to yield losses. Low concentrations of mepiquat chloride (1, 1-dimethylpiperidinium chloride) were applied to vigorous, growing cotton by means of two or more sprays at different time intervals. Application of 6, 3–12, 5 g a.i. ha−1 at 14-day intervals limited the growth rate of the main stem in cotton to 8–9 cm per 100 degree days (DD) and reduced plant height by 13–18%. Continuous, but controlled growth is essential to maintain high yield. In four trials, seed cotton yields averaged 3 900 kg ha−1 and were not affected by the various mepiquat chloride treatments. Under conditions of luxurious growth (>10 cm per 100 DD), the yield at first picking increased by between 20 and 26%, and total yield by 5%. It is necessary that intervals between supplementary applications of mepiquat chloride be adjusted according to the expected growth rate.