Survey of cotton (Gossypium sp.) for non-polar, extractable hydrocarbons for use as petrochemicals and liquid fuels

Authors: ADAMS, ROBERT - Baylor University; TEBEEST, AMY - Baylor University; Frelichowski, James - Jim; Hinze, Lori; Percy, Richard; Ulloa, Mauricio; Burke, John

Submitted to: Phytologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2016
Publication Date: 1/19/2017
Citation: Adams, R., Tebeest, A., Frelichowski, J.E., Hinze, L.L., Percy, R.G., Ulloa, M., Burke, J.J. 2017. Survey of cotton (Gossypium sp.) for non-polar, extractable hydrocarbons for use as petrochemicals and liquid fuels. Phytologia. 99(1):54-61.

Interpretive Summary: There is a revived interest in sustainable, renewable sources of petrochemicals and fuels from arid and semi-arid land crops with the uncertainty of sustained crude oil production in the world. So far this research has been popular with Sunflower (Helianthus annus) and other plants of lesser economic interest. The annual growth habit and narrow adaptation to temperate North America limit the use of sunflower as a source of hydrocarbons. Cotton (Gossypium hirsutum) is grown throughout the world in tropical and sub-tropical areas and is a promising source of hydrocarbons for arid and semi arid production regions. Cotton presents new possibilities as a hydrocarbon source because of its growth as a perennial, often with woody stems, and adapted to long and hot growing seasons. The USDA National Cotton Germplasm Collection has a wealth of cotton germplasm for screening for hydrocarbon production. Initial screening for hydrocarbon content in cotton utilized a local commercial variety and found variation according to the maturity stage of plants. The second test was scaled up to include more commerical and obsolete cotton varieties and with uniform sampling procedures. The third test used the widest range of obsolete cotton cultivars and accessions of wild cottons from the Germplasm Collection. Variation in hydrocarbon content was similar to that in sunflower showing the potential of cotton as a commercial source. The entries with the highest percentage of hydrocarbon content were from obsolete varieties in the Germplasm Collection. Greater experimentation is needed to better understand the environmental and genetic control of cotton hydrocarbon production, but so far a few lines were identified for breeders to use in improving this trait. Cotton is now another renewable source for hydrocarbons and promising accessions in the Germplasm Collection are readily available to all breeders and scientists. Cotton is already valued for lint and seed and this is another use to further the profitability and productivity for growers and producers.

Technical Abstract: An ontogenetic study of a commercial cotton cultivar (FiberMax 1320), grown dryland, revealed that the dry weight (DW) of leaves reached a maximum at the 1st flower stage, and then declined as bolls opened. However, % pentane soluble hydrocarbon (HC) yield continued to increase throughout the growing season (due to the decline of leaf DW). It seems likely that as the bolls mature and seed are filled, carbohydrates from the leaves are catabolized and sugars are transported to the bolls for utilization. Per plant HC yields increased from square bud stage to 1st flower, remained constant until 1st boll set, then declined at 1st boll-opened stage. This seems to imply that most of the HC are not catabolized and converted to useable metabolites for filling bolls and seeds. A survey of arid land cotton accessions, grown under limited irrigation or similar to dryland at Lubbock, TX, found % HC yield ranged from a low of 2.88% to highs of 5.78 and 5.54%. Per plant HC yields ranged from 0.017 to 0.043 g/ g leaf DW. Correlation between % HC yield and avg. leaf DW was non-significant (-0.103). A survey of USDA germplasm cotton accessions, grown with supplemental underground drip irrigation to achieve best yields germinated by irrigation, thence grown dryland at College Station, TX, found % HC yields were very high, with four accessions yielding 11.34, 12.32, 13.23 and 13.73%. Per plant HC yields varied from 0.023 to 0.172 g/ g leaf DW. Hopi had a high % HC yield (10.03%), but it was the lowest per plant yield (0.023 g/ g leaf DW). In contrast, China 86-1 with the second highest % HC yield (13.23%) was the highest per plant yield (0.172 g). The correlation between % HC yield and avg. leaf DW was non-significant (0.092). Thus, as seen in the arid land accessions, it appears that one might breed for both % HC yield and leaf DW in cotton.