Effects of tillage practices and application of the growth regulator Pix on cotton physiological properties and yield were evaluated in a three-year study, the last year of which was 1995. Tillage practices included no-till and conventional seedbed preparation with three levels of post emergence cultivation (single, double, and triple) employed during the production season. DPL-20 variety was grown in West Tennessee using 30-inch row spacing. Yield performance was shown to be affected by tillage system. In particular, conventionally prepared seedbeds with post emergence cultivation resulted in significantly higher yields than no-tillage planting. However, the number of post emergence cultivations, either one, two, or three, was not a significant factor in predicting yield of the plots with conventionally prepared seedbeds. The effect of tillage treatment was generally consistent, in that in only one year was tillage treatment not shown to be a significant factor in predicting yield.

Application of the growth regulator Pix had no significant effect upon mean crop yield over three years. Only in 1995 did the application of Pix result in a significant yield advantage. Any yield advantage associated with the application of Pix to this particular cotton variety grown in 30-inch rows appears to be dependent upon the nature of the growing season. The 1995 yield advantage associated with the application of Pix corresponded to greater numbers of green bolls observed on Pix-treated plants.

Physiological development of cotton produced using no-tillage was similar to that of cotton planted in conventionally prepared seedbeds. In particular, activity at fruiting sites as indicated by frequency counts of squares, aborts, green bolls, and open bolls over the growing season were similar regardless of tillage treatment. Further, tillage treatment did not have a discernible effect upon the maximum number of nodes, plant height, or main stem diameter.

Sequential applications of Pix were effective in controlling vegetative growth as indicted by plant height. For instance, Pix-treated plants were, on the average, about five inches shorter than untreated plants at harvest maturity in 1995. Plant maturity or earliness as indicated by the percentage of the total crop collected during the first picking was affected by neither tillage treatment nor application of the growth regulator Pix.