ABSTRACT
Plant growth regulators (PGR's) have been used to control growth and enhance yield in commercial cotton production. A field study was conducted to evaluate eight commercially available PGR's for their effect on cotton growth and development. Lint yield averaged over the four-year period from 1992 to 1995 was increased numerically over the untreated control by all the PGR's tested. In 1995, there were no statistically significant differences (P=0.05) in lint yield although PGR-IV and PHCA caused a numerical increase in lint yield. Both Pix and Cytokin reduced plant height and height:node ratio significantly compared to all the other PGR's tested in 1995. Crop+2 had significantly higher boll number:node ratio (BNR) compared to the control and MAXON treatments, while average boll weight was significantly higher for Atonik compared to Crop+2 and Pix. Crop+2 which had the highest BNR also had significantly higher number of first position bolls compared to the control and Pix treatments. The PGR's tested had variable effects on leaf photosynthesis, and additional research is required to determine their influence on the CO2 assimilation and gas exchange of cotton. This report supplies additional evidence to previous years data that supports the use of PGR's in cotton as a useful production practice for controlling plant growth and enhancing yield.
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