Submitted to: Sugar Cane International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2003
Publication Date: 12/1/2003
Citation: Alvarez, J., Deren, C.W., Glaz, B.S. 2003. Sugarcane selection for sucrose and tonnage using economic criteria. Sugar Cane International. Pages 6-10. Interpretive Summary: Sugarcane is the primary crop in the Everglades Agricultural Area in Florida, where about 25% of U.S. domestic sugar is produced. To help growers sustain and improve yields, a cooperative program focuses on breeding and selecting new sugarcane varieties. It has generally been assumed among biological scientists participating in that program that for the vast majority of varieties, if cane tonnage is high, then sucrose concentration will be low. Thus, a goal of sugarcane variety selection is to identify among the thousands of new varieties, the few that produce high cane tonnage with high sucrose concentration. This retrospective study reviewed 20 years of data from the final stages of this selection program. It was found that sugar concentration and cane tonnage were not consistently negatively correlated among varieties. However, when the data were analyzed using an index that predicted economic returns per hectare rather than cane or sugar production, resulting rankings of varieties produced distinct groups. Within each group, the negative relationship between sucrose and cane tonnage was generally apparent. These groups facilitated the identification of the unusual, but desired varieties that had both high cane tonnage and high sucrose concentration. This study demonstrated the usefulness of the evaluation of biological variables based on their economic performance.
Technical Abstract: Plant breeders use an array of mostly biological traits to select cultivars. In sugarcane, the biological character of primary concern is total sugar per hectare, which is determined by total tonnage and sucrose concentration. Their contribution to total sugar derive from different biological processes, and increasing one could be at the expense of the other. The hypotheses stated that, through the use of an economic index, clones that are somewhat ambiguous in merit can be selected amongst, and that the relationship between sucrose and tonnage can differ when viewed from an economic rather than a biological perspective. Twenty years of data were analyzed from the final stages of a cooperative sugarcane breeding program in Florida. The 164 clones and three crops provided 492 observations. Methods included correlation, regression, and a previously described procedure to determine economic returns from a sugarcane crop. The economic index was useful in balancing the yield variables. At first, sucrose and tonnage had no consistent negative relationship. A different perspective was obtained when the two variables were plotted using the rankings from the economic index, allowing the evaluation of biological variables based on their economic performance.