Submitted to: Cotton Research and Extension Report
Publication Type: Experiment Station
Publication Acceptance Date: 2/15/2008
Publication Date: 3/15/2008
Citation: Balkcom, K.S., Monks, C.D. Nitrogen and plant growth regulator rates on cotton yield and fiber quality. 2007 Cotton Research and Extension Report. No.32. p. 21-22.
Technical Abstract: The objective of this experiment was to determine the effect of two plant growth regulator (PGR) strategies with and without a high application PGR rate, prior to harvest, on cotton yield and fiber quality across two N rates for a cotton conservation tillage system. Nitrogen rates and PGR strategies were implemented at the Wiregrass Research and Extension Center (WREC) in Headland, AL and the Field Crops Unit (FCU) of the E.V. Smith Research Center near Shorter, AL. Treatments arranged in a split-plot design with 4 replications. Nitrogen rates consisted of 90 and 120 lb N ac-1 and PGR strategies were 1) No PGR; 2) Low rate, multiple PGR applications according to label directions; 3) High rate, infrequent PGR applications according to label directions; 4) No PGR plus a late season PGR application; 5) Low rate, multiple PGR applications plus a late season PGR application; and 6) High rate, infrequent PGR applications plus a late season PGR application. Nitrogen rates had no effect on the observed plant heights, whole plant biomass, or final node counts at defoliation for either location with the exception of whole plant biomass measured at EVS. The plant growth regulator (PGR) strategy did affect plant heights and final node counts for both locations. At both locations, the tallest plants were observed where no PGR was applied or the late season application was applied alone. The high PGR rate applied infrequently resulted in taller plants compared to the low rate applied more frequently, but the difference was only significant at EVS. The late season application of PGR used in conjunction with the low and high application strategies produced no evidence to indicate that the late season application controlled plant heights better. The final node count was analogous to plant height with more nodes present on the taller plants, which resulted when no PGR or the late season application was applied alone. A strong trend that indicated PGR strategy influenced lint yields to some extent at EVS. At this location, PGR applied at low frequent rates tended to produce the highest lint yields. Although some differences were observed among selected plant measurements, the final yields indicate that PGRs were not beneficial, regardless of application strategy. This lack of response can be attributed to the extremely dry 2007 growing season.