General Procedures
Official Variety Trials

Six OVTs were planted in the 2021 growing season.  Five are included within this report.  These included three locations on University of Tennessee Research and Education Centers, one location on a private research farm, and two locations on producer farms.  Seed of commercial cultivars and experimental lines was provided by respective companies. In all, 41 varieties were evaluated.  Each variety was randomly assigned to four plots at each location and each plot was arranged in a randomized complete block design. Individual plots consisted of two 30 ft rows.  Soil samples were collected prior to planting and fertilizer and lime were applied according to test results and UT recommendations.

Weed and pest control measures were uniformly applied to all plots per UT-recommendations. Seed cotton was harvested from each plot by either a two row picker outfitted with an in-basket, catch-and-weigh system or a catch-system.  Each plot was subsequently harvested and weighed.  Two 25 boll samples were collected from two replicates of each harvested location.  Subsamples from each location were then air-dried and ginned on a 10-saw table top gin.

Large Plot Variety Trials

Twelve CSTs were harvested in the 2021 growing season.  Seed of commercial varieties was provided by each respective company.  In all, 20 varieties were submitted. Each variety was planted in a single plot at each location and was maintained per the individual producer’s production practices. Plot size ranged from two to eight rows wide and 125 to 2500 ft+ in length, depending on producer equipment and field size.  

At harvest, plots were picked with the producer’s equipment.  If using a basket-style picker, weights were collected by catching harvested plots from the picker with a weighing boll buggy prior to dumping into the module builder. If using an on-board round module picker, modules were wrapped at the end of each plot and weighed on a set of transportable scales.  Regardless of picker type, an 8-12 lb sub-sample was collected after the picked plot weight was determined.  These samples were then air dried and weighed prior to ginning. 

Ginning

Samples were ginned at the University of Tennessee Cotton MicroGin located at the West Tennessee Research and Education Center in Jackson, TN. This is a 20-saw gin equipped with a stick machine, incline cleaners, and one lint cleaner.  No heat was applied at ginning.  Lint yields on a per-plot basis were then calculated from gin turnouts and harvested plot areas.  A subsample of lint from each ginned sample was submitted to the USDA Cotton Classing Office in Memphis, TN for HVI analysis.

Statistical analysis 

For OVT locations, mean separation of fiber quality was calculated for the combined dataset including all analyzed locations by considering location as replication.  Mean separation of OVT variety yield by location was calculated by a PROC MIXED model (JMP, SAS Institute, Inc., Cary, NC) considering replication to be random.  Combined analysis was also calculated by a PROC GLM model, with location and replication nested in location.  Mean separation of fiber quality and lint yield for the CST combined dataset was calculated by considering location as replication.  This analysis was calculated by a PROC GLM model.  

Seed Sources

Companies which participated in the 2021 University of Tennessee Cotton Variety Testing Program and their entry abbreviations are listed below:

• American Cotton Breeders, Inc. 5210 88th Street, Lubbock, TX 79424
  • Abbreviated as NG (NexGen) or AMX (experimental)
• BASF Corporation, 100 Park Ave, Florham Park, NJ 07932
  • Abbreviated as ST (Stoneville)
• Croplan Genetics, 8700 Trail Lake Dr., Suite 100, Memphis, TN 38125
  • Abbreviated as AR (Armor)
• Crop Production Services, 3005 Rocky Mountain Ave., Loveland, CO 80538
  • Abbreviated as DG (DynaGro) or DGX (experimental)

• Bayer CropScience, P.O. Box 157, Scott, MS 38772
  • Abbreviated as DP (DeltaPine)

• Phytogen Seed Co., P.O. Box 27, Leland, MS 38756
  • Abbreviated as PHY (Phytogen) or PX (experimental)