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棉 花 学 报 Cotton Science 2006，18(3)：145-149
Effect of Exogenous Materials on Cotton Fiber Strength Development in Low Temperature Conditions Abstract：Under condition of condign temperature (22.7℃) and low temperature (19.9℃) during the cotton fiber thickening development period, with limpid water as a control, the effects of exogenous materials on fiber strength development was studied. This was done by daubing bolls setting on the 1st and 2nd node in the 6th to 9th fruiting branches and their contrapuntal leaves at 15 days past anthesis (DPA) and 30 DPA with the mixture of 6% sucrose and 0.6% glutamine (C+N), the mixture of 6% sucrose, 0.6% glutamine and 2 μg·g-1 6-BA (C+N+BA), and 2 μg·g-1 6-BA, respectively. Results showed that, in low temperature conditions, exogenous mixtures could increase boll weight, lint percentage and fiber strength to different levels. Boll weight and lint percentage were enhanced when the bolls were treated with the mixture of 6% sucrose, 0.6% glutamine and 2 μg·g-1 6-BA at 15DPA or 30DPA, respectively, and data showed the exogenous materials worked better on increasing boll weight when the treatment was performed on 30DPA. When referred to the treatment with 6-BA specifically, we found its effect on increasing boll weight was much lower than C+N+BA when it was used on 30DPA. Its effect on enhancing lint percentage was much higher than C+N+BA when it was used in 15DPA. In the low temperature, all of the three exogenous mixtures could increase the cellulose content, consequently they could optimize the spiral angle (φ) and orientation angle(ψ) and these resulted in much higher fiber strength. BA could not obviously increase the cellulose deposition rate, but it could work on optimizing the spiral angle (φ) and orientation angle (ψ), and finally, the fiber strength treated with BA was the highest. The other mixtures each worked differently with the different application times. Though the increase of cellulose content of the bolls treated with C+N+BA was not lower than that of the bolls treated with BA. The effect on optimizing the spiral angle or orientation angle of C+N+BA was significantly less than that of BA and this resulted in a much lower fiber strength for the bolls treated by BA.
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