An Update on Efforts to Understand Cottonseed Hull Fracture Resistance

A series of studies is underway to better understand cottonseed hull fracture resistance and the factors that lead to increased seed damage during ginning.  Compression studies are being conducted with an Instron tensile material tester fitted with an adapter to translate tensile force into compressive force.  Preliminary work has shown that that a wide distribution of hull resistances exist among seeds within any given seed sample; hence, many seeds must be tested to obtain representative results for any sample.  In addition, conditioning of the seed to a standard temperature and humidity level is necessary to obtain consistent results.  Current testing of cottonseed from the National Cotton Variety Trials is indicating that both genetic and environment differences have a significant influence on hull fracture resistance.  Comparisons of seed from Pima (Gosssypium barbasense) and Upland (G. hirsutum) seeds produced in the same environment indicate that as a class Pima seed are harder than Upland seed and that seeds of the fiber producing old world diploid species (G. arboretum and G. herbacium) are harder than the seeds of the new world tetraploids species.  A study is also under development to look specifically at the size and fracture resistance of seeds from field cotton samples that are known to cause ginning problems.