Relationships between Upland Cotton HVI and AFIS Measurements Versus Fiber Surface Amino Acid Content and +b Values

Amino acids (AA) are building blocks and growth facilitators of Upland cotton and they have great impact on the final structure and quality of cotton fibers. Therefore, AAs ultimately influence processing efficiency and commercial value.  Color is a great contributor to cotton’s economic value and an increase in yellowness (+b) has historically been thought to indicate undesirable, lesser quality Upland cotton.  Previous research has also shown correlations between +b and fiber surface AA content.  Considering those highly positive correlations, and the fact that +b is so influential in pricing cotton, it is worth exploring whether +b or AA surface content have notable relationships with the other physical and processing qualities of cotton which affect its grading and value.  We used a ninhydrin test to quantify detectible surface free-AA content, then we utilized correlational analyses to compare AA content and +b to HVI and AFIS physical property measurements such as: color, length, maturity, neps, strength and trash/foreign matter. Both surface AA content and +b highly positively correlated with nep and trash related measurements, such as: nep size, seed coat nep count, trash count, percent visible foreign matter and nep count. AAs highly negatively correlated with brightness/greyness of the cotton. Analysis of surface carbohydrate content did not show significant correlational patterns with HVI/AFIS data.  Principle Component Analysis found AAs and +b correlate with non-lint matter, short fibers and neps caused by non-lint matter.