[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.
[Title] Calibration of HVI cotton elongation measurements
[Authors] DELHOM Christopher D., HEQUET Eric F., KELLY Brendan, ABIDI Noureddine and MARTIN Vikki B.
Journal of Cotton Research 2020, 3: 31
[Background] Since the commercial release of Bt cotton in Burkina Faso in 2009, the issue of seed purity in producers’ fields has rarely been addressed in an unbiased and objective manner. The potential for contamination of conventional seed varieties with Bt traits and the consequent threat to the continuation of organic cotton production has been documented. However, studies are rare on the varietal purity of Bt cotton seeds, despite the implications for the effectiveness and sustainability of their use.
This paper compensates for the lack of research on the varietal purity of cotton seeds in Burkina Faso by reporting the results of Enzyme linked immunosorbent assay tests collected in 2015 on samples of both conventional and Bt varieties from 646 fields.
[Results] According to the conservative criteria used to declare the presence of a Bt gene in a given variety (more than 10% of seeds of conventional variety exhibit Bt traits, and at least 90% of seeds of Bt variety exhibit Bt traits), seed purity was very questionable for both types of variety. For the supposedly conventional variety, the Cry1Ac gene was observed in 63.6% of samples, the Cry2Ab gene was observed in 59.3% of samples, and both genes were detected in 52.2% of the seed samples. Only 29.3% of the seeds that were supposed to be of conventional type contained no Bt genes. Conversely, for the labeled Bt variety, the Cry1Ac gene was found in only 59.6% of samples, the Cry2Ab gene was found in 53.6% of the samples, and both genes were found in 40.4% of the samples. Finally, for the seeds that were supposed to contain both genes (Bollguard 2), both Cry1Ac and Cry2Ab genes were found in only 40.4% of the samples, only one of the genes was found in 32.4% of the samples, and 27.2% of the seeds in the samples contained neither.
Two factors are responsible for the severe lack of seed purity. First, conventional varieties are being contaminated with Bt traits because of a failure to revise the seed production scheme in Burkina Faso to prevent cross-pollination. Second, the original Bt seeds provided to Burkina Faso lacked varietal purity.
The organic sector plays a very minor role in the cotton sector of Burkina Faso (production of organic cotton totaled 453 t in 2018/2019, out of national cotton production of 183 000 t). Nevertheless, the lack of purity in conventional seed varieties is a threat to efforts to expand certified organic cotton production. The poor presence of Bt proteins in supposed Bt varieties undermines their effectiveness in controlling pests and increases the likelihood of the development of resistance among pest populations.
[Conclusion] Our results show the extent of purity loss when inadequate attention is paid to the preservation of seed purity. Pure conventional seeds could vanish in Burkina Faso, while Bt seeds do not carry the combination of the expected Bt traits. Any country wishing to embark on the use of Bt cotton, or to resume its use, as in the case of Burkina Faso, must first adjust its national seed production scheme to ensure that procedures to preserve varietal purity are enforced. The preservation of varietal purity is necessary to enable the launch or the continuation of identity-cotton production. In addition, the preservation of varietal purity is necessary to ensure the sustainable effectiveness of Bt cotton. In order to ensure that procedures to preserve varietal purity are observed, seed purity must be tested regularly, and test results must be published.
[Title] Bt cotton seed purity in Burkina Faso: status and lessons learnt
[Authors] BOURGOU Larbouga, KARGOUGOU Ester, SAWADOGO Mahamadou and FOK Michel
Journal of Cotton Research 2020, 3: 30
[Abstract] Since the advent of transgenic technology, the incorporation of gene(s) encoding traits of economic importance in cotton is being practiced worldwide. However, factors like recalcitrant nature of cotton cultivars, in vitro regeneration via tissue culture (especially via somatic embryogenesis), genotype dependency, long and toilsome protocols impede the pace of development of transgenic cotton. Besides that, types and age of explants, media composition, plant growth regulators and other environmental factors affect in vitro cotton regeneration significantly. The studies of genetic control of in vitro regeneration in plants have elucidated the role of certain transcription factor genes that are induced and expressed during somatic embryogenesis. Among these transcription factors, BABY BOOM (BBM) plays a very important role in signal transduction pathway, leading to cell differentiation and somatic embryos formation. The role of BBM has been established in plant cell proliferation, growth and development even without exogenous growth regulators. This review intends to provide an informative summary of regeneration and transformation problems in cotton and the latest developments in utilization of BBM transcription factors in cotton. We believe that the use of BBM will not only ease cotton genetic improvement but will also accelerate cotton breeding programmes.
[Title] Apprehending the potential of BABY BOOM transcription factors to mitigate cotton regeneration and transformation
[Authors] YAVUZ Caner, TILLABOEVA Shakhnozakhan & BAKHSH Allah
Journal of Cotton Research 2020, 3: 29
[Background] An optimal N rate is one of the basic determinants for high cotton yield. The purpose of this study was to determine the optimal N rate on a new cotton cropping pattern with late-sowing, high density and one-time fertilization at the first flower period in Yangtze River Valley, China. A 2-year experiment was conducted in 2015 and 2016 with a randomized complete block design. The cotton growth process, yield, and biomass accumulation were examined.
[Result] The results showed that N rates had no effect on cotton growing progress or periods. Cotton yield was increased with N rates increasing from 120 to 180 kg·hm−2, while the yield was not increased when the N rate was beyond 180 kg·hm−2, or even decreased (9∼29%). Cotton had the highest biomass at the N rate of 180 kg·hm−2 is due to its highest accumulation speed during the fast accumulation period.
[Conclusion] The result suggests that the N rate for cotton could be reduced further to be 180 kg·hm− 2 under the new cropping pattern in the Yangtze River Valley, China.
[Title] Cotton N rate could be reduced further under the planting model of late sowing and high-density in the Yangtze River valley
[Authors] SONG Xinghu, HUANG Ying, YUAN Yuan, SHAHBAZ Atta Tung, BIANGKHAM Souliyanonh & YANG Guozheng
Journal of Cotton Research 2020, 3: 28