The influence of gibberellic acid on growth and structure of cotton fibres

Abdel-Salem, Mohamed El-Sayed (1965) The influence of gibberellic acid on growth and structure of cotton fibres. PhD thesis, University of Glasgow.

Abstract

This investigation was carried out to find the effect of gibberellic acid on fibre length and consequently the other gross and fine structural, and mechanical, properties of cotton fibres. In the course of investigations some general relationships were discovered which appear to apply to all cotton fibres whether treated or not. Three cotton varieties were used: Samaru 26J and Rex, both Upland varieties, and Sea Island V.H.8 cotton. All three were grown in greenhouse in Glasgow and Samaru 26J was also grown under normal field conditions in Nigeria. Gibberellic acid treatment increased fibre mean length and decreased the coefficient of variation for Rex and Samaru 26J grown in Glasgow, but had no effect on the first two varieties in attributed to an increase in the total number of fibres per seed in Rex. Treatment with gibberellic acid also resulted in a decrease in fibre diameter, fibre weight and linear density, and maturity and fibre density. The number of convolutions per unit length and the average convolution angle were generally lower in the treated samples, this is attributed to the differences in maturity. The number of reversals per unit length was lower in treated than in the control samples this attributed to the increase in the boll size. Gibberallic acid treatment was found to regulate cellulose deposition. This resulted in fibres of different lengths having weight proportional to their length. The stress-strain curves were analyzed and the effect of major weak places was removed to get the extrapolated "projected" stress-strain curves. Gibberellic acid treatment increased the projected extension to break, tensile strength, work of rupture and stiffness of Samaru26 J grown in Glasgow, Rex, and Sea Island, but these improvements were largely offset in practice because of the projected mechanical properties was nil but the number of weak places increased and there was an overall deterioration. Generally, the effect of gibberellic acid dependent on variety and environment. It is more effective on short cottons and under poor grooving conditions than on long cottons and under optimum grooving conditions. The overall molecular orientation has been found to be dependent on both fibre length and fibre diameter. Therefore, a factor (radius/length) has been suggested to describe fibre dimensions. This factor gives high correlation with overall molecular orientation, initial Young's modulus, and stiffness measurements on fibres having successive degrees of wall thickening. It has been shown that the convolutions unfold as load is applied, thus they contribute substantially to fibre extensibility and work of rupture. This contribution varies from sample to sample. The reminder of fibre extension to break is suggested to be due to a partial unfolding of the spiral and to the extension of the amorphous regions located within the spiralling fibrils. The total theoretical extension to break resulting from fibre fine and gross structure is apparently much higher than the measured one.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: N Peacock
• Keywords: Plant sciences
• Date of Award: 1965
• Depositing User: Enlighten Team
• Unique ID: glathesis:1965-72930
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 11 Jun 2019 11:06
• Last Modified: 11 Jun 2019 11:06
• URI: https://theses.gla.ac.uk/id/eprint/72930