Seed-fiber ratio, seed index, and seed tissue and compositional properties of current cotton cultivars

Authors: Dowd, Michael; Pelitire, Scott; Delhom, Chris

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2018
Publication Date: 6/6/2018
Citation: Dowd, M.K., Pelitire, S.M., Delhom, C.D. 2018. Seed-fiber ratio, seed index, and seed tissue and compositional properties of current cotton cultivars. Journal of Cotton Science. 22:60-74.

Interpretive Summary: Because of the intensive breeding of cotton for increased fiber yield, there have likely been change to the seed properties and composition. This work was undertaken to better understand how seed traits have change compared with early reports. The work showed that seed-to-fiber ratio has changed dramatically, and seed size has also decreased significantly. Smaller changes were observed for the distribution of linters, but no appreciable differences were apparent for the hull and kernel fraction and no obvious differences were found regarding the kernel oil or protein composition. The work will be of interest to farmers, ginners, and oil processors as well as researchers working on seed quality issues.

Technical Abstract: Because of continual efforts to breed cotton for increased fiber yield, several seed/fiber compositional properties have likely shifted over the decades. Conversations with breeders, ginners, and oil processers have identified several concerns, including smaller seed size, weaker hulls, increased seed and hull fragment contamination of fiber, and reduced oil and protein levels—all of which directly affects the economic value of the crop. To better understand these changes, current commercial field cotton samples were collected from areas around Stoneville, MS; Lubbock, TX; and Las Cruces, NM. The samples were ginned and cleaned to determine a seed-to-fiber ratio, seed index, and the proportions of linter, hull, and kernel tissues. Kernels were then analyzed for oil, protein, and gossypol. Results from the three year study (2014 through 2016) indicated that the average seed/fiber ratio was 1.41 ± 0.11 (range: 1.19–1.61, as is basis) and has declined compared with data sets published prior to 1950. Of the varieties included in the study, seed indices averaged 9.75 ± 0.99 g (range: 8.08–11.8 g, as is basis) and also showed an overall decline compared with early published data. Seed tissue proportions have changed less, although a decrease in the percentage of linters was apparent. The average level of seed oil and protein does not appear to have changed much over the years, although oil levels were very low for a few individual cultivars.