Submitted to: Extension Reports
Publication Type: Experiment Station
Publication Acceptance Date: 1/1/2007
Publication Date: 3/30/2007
Citation: Balkcom, K.S., Monks, C.D. Effect of nitrogen and plant growth regulator rates on cotton yield and fiber quality. In: Lawrence, K.S., Monks, C.D., Delaney, D.P., editors. 2006 Cotton Research Report, Alabama Agricultural Experiment Station, Research Report No. 30. p. 29.
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, but the PGR strategy did affect plant heights. No PGR application of the late season application applied alone resulted in the tallest plants. There was no difference between the low and high PGR strategies or when the late season application was included. Nitrogen rates or PGR strategies had no effect on plant biomass at defoliation, while final node count was only influenced by PGR strategy. An interaction was observed for lint yields between nitrogen rates and PGR strategies. The high PGR strategy that included a late season application produced the lowest yields, regardless of N rate. However, lint yields measured from the other nitrogen and PGR strategies were similar to each other. Interestingly, cotton that received the recommended rate of 90 lb N ac-1 with no PGR produced the highest lint yields. The dry conditions experienced during the 2006 growing season indicate PGRs were not beneficial, regardless of application strategy.