ABSTRACT

During saw ginning of lint cotton, many full length fibers are broken into shorter segments. The difficulty of HVI to measure short fiber content can lead to significant under estimation of short fiber content and result in increase loss fiber during textile manufacturing. Our collaborative research was established to determine how we might increase the per cent of full length fiber in saw ginned lint cotton. Samples of hand and saw ginned lint cotton were examined with conventional transmission electron microscopy (CTEM). These samples were compared to tissue samples of developing lint fiber collected from greenhouse-grown, cotton (Gossypium hirsutum L. DPL 50) bolls aged 20 to 50 (boll opening) days post anthesis (DPA). Examination of seed coat from saw ginned lint cotton with CTEM indicated that the foot is a strong support but that there is a weak region on lint fiber at the junction or "neck region" of the fiber and the seed coat surface. Analysis of foot and neck regions of lint fiber in developing seeds with CTEM indicated that the region of lint fiber below the seed coat surface which has very little secondary wall development is compressed during drying by surrounding epidermal cells. These adjacent cells develop a very thick multilayered secondary cell wall, characterized by alternating electron dense and translucent regions which are aligned in parallel with the orientation of the primary cell wall. The compression of the basal region of the lint fiber by adjacent epidermal cells gives rise to the characteristic "foot" of lint fibers. Electron dense material accumulates at the neck region, beginning around 35 DPA, as part of the primary cell wall. This dense material apparently contributes additional strength for attachment of lint fibers to the seed coat. Study results suggest that loosening of the neck region prior to saw ginning could be useful in increasing the number of full length fibers removed from lint cotton.