Pix plus and mepiquat chloride effects on physiology, growth, and yield of field-grown cotton

An important objective for using plant growth regulators in cotton (Gossypium hirsutum L.) is to balance vegetative and reproductive growth as well as to improve lint yield and fiber quality. Field studies were conducted at two locations (Clarkedale and Fayetteville) in Arkansas in 1997 and 1998 to determine physiologic and yield responses of cotton to foliar applications of mepiquat chloride [N,N-dimethylpiperidinium chloride and inert ingredients] (MC) and Pix Plus [MC + Bacillus cereus]. Compared with the untreated control, application of Pix Plus and MC efficiently reduced plant height, improved leaf CO2-exchange rate, and increased leaf starch con-tent. Neither Pix Plus nor MC affected photoassimilate translocation from leaves to 10- to 15-day-old bells. Pix Plus and MC had very similar effects on plant growth and most physiologic parameters investigated in our studies. There was no difference in lint yield between Pix Plus and mepiquat chloride. However, Pix Plus increased the fraction of fruit dry matter in total dry matter.