Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/12/2007
Publication Date: 1/16/2008
Citation: Pettigrew, W.T. 2008. The Effect of Higher Temperatures on Cotton Lint Yield Production and Fiber Quality. Crop Science. 48:278-285 Interpretive Summary: There is a temperature optimal range for plant growth and development and it varies depending upon the type of plant. Unfortunately, sometimes the summer temperatures in the Southeastern US may exceed the upper limit of that optimal range for cotton. Although plants have the ability to cool themselves through transpirational water loss, much like human perspiration, the higher air humidity conditions of the Southeastern US means that this process is less efficient than it would be in drier conditions like the Southwestern US. Therefore, plants grown in the humid Southeastern US may experience a production limiting heat stress at a slightly lower temperature than plants grown in the arid Southwestern US. This research investigated how higher temperatures affected the growth and development, lint production, and fiber quality of cotton grown in the Southeastern US. Cotton was grown in the field under normal outside air temperatures and under slightly warmer temperatures that were produced by placing heating mats between the canopy rows. The warmer temperatures reduced the cotton lint yield by 10% primarily because the heat reduced the average size of cotton bolls produced by 6%. The bolls were smaller because the warmer temperatures lead to 7% fewer seeds being produced per boll. The decrease in the number of seeds produced indicates that the warmer temperatures may be hampering seed fertilization. Whenever the air temperatures exceed 95 degrees F during reproductive growth, the cotton yield can be compromised. This research documented some of the basic processes in cotton impaired by a high temperature stress. Other researchers may be able to build upon this research and identify variability in these traits within the many different types of cotton, or to address improvements in these traits through biotechnology.
Technical Abstract: An optimum temperature range for growth exists for cotton (Gossypium hirsutum L.), as is typical for all plant species. When Mississippi Delta cotton experiences temperatures above the upper threshold, as can often occur during the months of July and August, it is not entirely clear what growth parameters are affected by the heat and the degree to which they are altered. Therefore, the objectives of this research were to document differences in agronomic and physiological performance for two cotton genotypes (SG 125 and SG 125BR) when grown under an ambient temperature control and a warm temperature regime (about 1 degree C warmer than the ambient air). Field studies were conducted from 2003 through 2005. Weekly white bloom counts, weekly nodes above white bloom data, and dry matter partitioning data were collected. End of season lint yield, yield components and fiber quality data were collected. Genotypes responded similarly to the two air temperature regimes for all parameters measured. Warmer temperatures resulted in lower nodes above white bloom data, indicating a slightly advanced crop maturity. Two out of three years, the lint yield from the warm regime was 10% lower than that of the control. This yield reduction was primarily caused by a 6% smaller boll mass in the warm regime. Seven percent fewer seed produced per boll led to this smaller boll mass found under the warm regime, indicative of a possible problem with ovule fertilization. Although few fiber quality traits were altered by the higher temperatures, fiber produced in the warm temperature regime was consistently 3% stronger than fiber in the control treatment. Whenever the ambient air temperature exceeds 35 degree C, ovule fertilization may be compromised, leading to fewer seeds produced per boll, smaller boll masses, and ultimately lint yield reductions.