Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2011
Publication Date: 8/10/2011
Citation: Pettigrew, W.T., Dowd, M.K. 2011. Varying planting dates or irrigation regimes alters cottonseed composition. Crop Science. 51:2155-2164. Interpretive Summary: Cotton producers receive the majority of their income by selling the lint from their cotton crop. The cottonseed is increasingly an important additional source of income for cotton producers due to the growing demand by the dairy and restaurant industries for whole cottonseed and cottonseed products. Previous research has demonstrated the benefits that both early planting and irrigation have upon increasing lint production. The current research addresses how varying planting dates and irrigation regimes affects the composition of the cottonseed produced. Irrigation increased the levels of oil, unsaturated fatty acids, and carbohydrate in the seed, but decreased the seed protein content. Unfortunately, irrigation also increased the seed gossypol concentration, a compound that can be toxic to most mammals. Although the planting date effect on seed composition was more modest when compared to the irrigation response, early planting did reduce the seed gossypol level when the cotton was grown under dryland production, but not under irrigated conditions. Early planting and irrigation offer the potential for improved yields but these yield increases come with altered seed composition. Given the proper economic incentives, producers could potentially alter production strategies to produce seed with desired composition traits. The results from this research can be used by cotton researchers, extension specialists, consultants, and producers as an unbiased source of information to aid in making cotton production decisions.
Technical Abstract: Despite continued utilization of cottonseed (Gossypium hirsutum L.), little information exists regarding the effect of production factors on cottonseed composition. The objective of this study was to determine how irrigation regime and planting date affect cottonseed composition. Six cotton cultivars were planted early (late April) and at a normal time (late May) in a field near Stoneville, MS from 2005 to 2008. Half of the plots were irrigated and half were cultivated dry. Seed from the 2006'2008 seasons were analyzed for protein, crude oil, gossypol, soluble carbohydrates, and the oil’s fatty acid composition. Irrigation increased oil and total soluble carbohydrate levels by 7% and 4%, respectively, and reduced protein levels by 10%. Irrigation also increased the level of total gossypol by 21%, modestly decreased the percentage of the gossypol (+) isomer, and slightly decreased the level of saturated fatty acids in the oil. Early planting of seed decreased gossypol by 8% under dryland conditions but not under irrigated conditions. The early planting effect on the fatty acid distribution was similar to the effect observed under dryland conditions, only the differences were more modest. Early planting and irrigation offer potential for improved fiber and seed yield but with altered seed composition. Given the proper economic incentives, producers could alter some production strategies to produce seed with more valuable composition traits.