The effect of 9 bioregulators on agronomic traits and allelochemicals of cotton, Gossypium hirsutum L. was studied. Pix, kinetin, and 6 structurally related compounds of the two plus one mixture was applied at three levels to 'Deltapine 50'. The first application was made when the cotton began to bloom and the second application was made two weeks later. One of the levels closely approximated the recommended rate and was 0.1 mole/ha, the second level varied depending on availability or expected activity and a zero level was included as a control. Plant tissues (terminal leaves and squares) were collected three weeks after the first treatment for analyses of allelochemicals. The plots were machine harvested for yield. Prior to machine harvest boll samples were collected and used to determine boll size, lint percent and seed size. Seed samples were delinted and analyzed for gossypol.

Pix and a mixture of trigger plus pix were the only treatments to affect yield. The 0.1 mole/ha level of Pix and the 0.1 mole/ha plus 0.313 mole/ha (trigger + Pix) resulted in a yield increase. Lint percent was increased by one bioregulator and decreased by two bioregulators. Boll size was increased by the high rate of Pix and by the high rate of a Pix related compound. Seed size was also increased by Pix.

Gossypol content of the leaves and anthocyanin and flavonoid content of squares were the allelochemicals most often affected by the bioregulators. Kinetin and two related compounds reduced gossypol while trigger increased gossypol in leaves. Minimum effects on squares and seed gossypol were noted. Pix reduced the tannin level in leaves, but an increase was noted for squares. Four of the bioregulators resulted in increases in anthocyanin content of squares. The flavonoid content of leaves was increased by trigger; however, the square content was decreased.

The effect of the bioregulators studied on agronomic traits was minimal; however, the level or several allelochemicals were affected. The effect of these changes on insect resistance is still to be determined.