Investigation into a practical approach and application of cotton fiber elongation

Background The strength of cotton fiber has been extensively studied and significantly improved through selec-tive breeding,but fiber elongation has largely been ignored,even though elongation contributes to determining the energy needed to break fibers.Recent developments to calibrate the high volume instrument(HVI)for elongation has renewed interest in elongation.However,it is not understood how best to utilize yet another fiber property which has the potential to add to the complexity of fiber selection.To explore a practical approach to applying elongation,cot-ton samples were tested using single fiber methods,the Stelometer,and the HVI.Comparison of strength,elongation,and combined properties such as modulus were explored.Results HVI testing was shown to be sensitive enough to characterize elongation differences but unlike single fiber testing it was unable to capture within-sample variation.Fiber bundle testing,like Stelometer and HVI was shown to reduce bias due to fiber selection.Conclusion The use of secant modulus,an intrinsic material property,allowed for one value to represent both strength and elongation.Secant modulus was shown to contain more useful information than either elongation or work-to-break.Work-to-break was shown to be more influenced by a specific value of breaking force or elongation rather than the intrinsic behavior of the sample being tested.Exploring the influence of genetics and environment on elongation,and its interaction with other fiber properties,requires additional work.Secant modulus,by combining strength and elongation into one value,shows the potential to incorporate elongation values into fiber characteriza-tion without increasing the complexity of current fiber selection processes.

Feasibility assessment of phenotyping cotton fiber maturity using infrared spectroscopy and algorithms for genotyping analyses

Background:Cotton fiber maturity is an important property that partially determines the processing and performance of cotton.Due to difficulties of obtaining fiber maturity values accurately from every plant of a genetic population,cotton geneticists often use micronaire(MIC) and/or lint percentage for classifying immature phenotypes from mature fiber phenotyp es although they are complex fiber traits.The recent development of an algorithm for determining cotton fiber maturity(MIR)from Fourier transform infrared(FT-IR)spectra explores a novel way to measure fiber maturity efficiently and accurately.However,the algorithm has not been tested with a genetic population consisting of a large number of progeny pla,nts.Results:The merits and limits of the MIC-or lint percentage-bas ed phenotyping method were demonstrated by comparing the observed phenotypes with the predicted phenotypes based on their DNA marker genotypes in a genetic population consisting of 708 F2 plants with various fiber maturity.The observed MIC-based fiber phenotypes matched to the predicted phenotypes better than the observed lint percenta ge-based fiber phenotypes.The lint percentage was obtained from each of F2 plants,whereas the MIC values were unable to be obtained from the entire population since certain F2 plants produced insufficient fiber mass for their measurements.To test the feasibiility of cotton fiber infrared maturity(MIR)as a viable phenotyping tool for genetic analyses,we me asured FT-IR spectra from the second population composed of 80 F2 plants with various fiber maturities,determined MIR values using the algorithms,and compared them with their genotypes in addition to other fiber phenotypes.The results showed that MIR values were successfully obtained from each of the F2 plants,and the observed MIR-based phenotypes fit well to the predicted phenotypes based on their DNA marker genotypes as well as the observed phenotypes based on a combination of MIC and lint percentage.Conclusions:The M,R value obtained from FT-IR spectra of cotton fibers is able to accurately assess fiber maturity of all plants of a population in a quantitative way.The technique provides an option for cotton geneticists to determine fiber maturity rapidly and efficiently.

Calibration of HVI cotton elongation measurements

Background:The strength of cotton fiber has been extensively studied and significant improvements in fiber strength have been made,but fiber elongation has largely been ignored,despite it contributing to the energy needed to break fibers,which affects fiber handling and processing.High Volume Instruments(HVI)measure fiber elongation but have not been calibrated for this property,making the measurement unavailable for comparative work among instruments.In prior work,a set of elongation calibration materials had been developed based on Stelometer results.A round trial of ten Australian and U.S.instruments was conducted on six cotton samples representing a range of 4.9%to 8.1%elongation.Results:By scaling the HVI elongation values of each instrument to the values of the two calibration samples,the coefficient of variation in instrument measurements was reduced from an average of 34%for the uncalibrated measurements to 5%for the calibrated measurements.The reduction in variance allows for the direct comparison of results among instruments.A single-point elongation calibration was also assessed but found to be less effective than the proposed two-point calibration.Conclusion:The use of an effective calibration routine on HVI measurement of cotton significantly reduces the coefficient of variation of the elongation measurement within and between instruments.The implementation of the elongation calibration will allow testing and breeding programs to implement high-speed elongation testing which makes the use of elongation values possible in breeding programs.