PIX (1,1-dimethyl-piperidinium chloride) is a plant growth regulator. An experiment was conducted in 1983 and 1984 to determine if PIX would control the excessive vegetative growth associated with many of the primitive race stocks of cotton, Gossypium hirsutum L. Sixteen BC(2)F₃ day-neutral progeny of primitive race stocks, plus two commercial cultivars were grown in single row, 401 plots for two years. The plots were split, one-half of each plot was treated with PIX and the other half was untreated and served as a control. PIX was applied twice, the first application when 5-6 blooms were present per 25 foot of row and the second application two weeks later. PIX was applied at the rate of 50 g a.i./ha (1 pt/A). The experimental design was a randomized complete block, with a split-plot arrangement, with four replications.

The plots were machine harvested one time for yield determination. In 1983, ten plants were selected at random from each plot. Number of main stem nodes and height were determined for these plants and in addition to these measurements, internode length was calculated. These measurements were repeated in 1984, but only five plants were selected from each plot.

The application of PIX did not significantly affect yield in 1983 or 1984. The number of main stem nodes, plant height and internode length were significantly reduced by PIX in 1983 and 1984. In 1983, the application of PIX reduced mainstem nodes from 25.3 to 23.1, plant height from 103 cm to 78 cm and internode length from 4.09 cm to 3.43 cm. In 1984, the nodes were reduced from 21.3 to 19.7, plant height from 121 cm to 94 cm and internode length from 5.77 cm to 4.95 CM. PIX was consistent in reducing plant height and mainstem nodes over a diverse group of primitive race stocks of cotton during two different growing seasons.