The Detrimental Effects High Temperatures Have on Mississippi Delta Cotton
William T. Pettigrew, USDA-ARS, P.O. Box 345, Stoneville, MS 38776
As with all biological processes, an optimum temperature range exists for cotton growth. This research tests the upper threshold of that optimum temperature range by investigating how cotton growth and development, lint yield production, yield components, and fiber quality were affected by higher temperatures. Two temperature regimes (ambient; and ambient plus 2° C) were imposed upon two cotton varieties (SG 125 and SG 125BR) during the blooming phase (July through August) from 2002 through 2005. Dry matter harvests, bloom counts, nodes above white bloom (NAWB), lint yield, yield component, and fiber quality data were collected. No variety by treatment interactions were detected so treatment means were averaged across varieties. Few growth and development differences were detected and similar flowering rates were observed for the two temperatures regimes. Cotton grown under higher temperatures was slightly earlier in maturity as evidenced by slightly lower NAWB numbers and more of the total yield harvested with the 1st harvest. Higher temperatures reduced the lint yield an overall average of 7 %. A 4 % reduction in boll size was the principle yield component responsible for this yield reduction seen with the higher temperatures. Most fiber quality traits were unaffected by the varying temperature regimes. The exception to this generalization is the 3 % stronger fiber produced with grown under the higher temperatures. Warmer temperatures can negatively impact cotton production, although few production options are available to producers at this time to mitigate the damage.