Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2009
Publication Date: 9/1/2009
Citation: Lingle, S.E., Viator, R.P., Johnson, R.M., Tew, T.L., Boykin, D.L. 2009. Recurrrent Selection for Sucrose Content has Altered Growth and Sugar Accumulation in Sugarcane. Field Crops Research. 113(3):306-311. Interpretive Summary: Sugarcane breeders in Louisiana have been selecting for higher sucrose yield for more than 70 years. This study was done to determine if selection for sucrose has changed growth in sugarcane stalks. The five oldest (released from 1924 to 1933) and five newest (released from 2003 to 2007) varieties were grown in the field. We collected data on stalk length, and the length, fresh weight, dry weight, and water content of specific stalk sections (internodes) each week or every other week for 12 weeks. We found that the new varieties were taller, with more internodes than the old varieties. We also found that the internodes of new varieties stopped growing and started accumulating dry weight sooner than old varieties. This demonstrates that selection for sucrose content has changed growth in sugarcane stalks. In the future, this information will be useful in helping breeders select new varieties with even greater sucrose contents.
Technical Abstract: Recurrent selection for sucrose content in sugarcane (Saccharum spp. hybrids) should result in a concentration of traits and genes that contribute to high sucrose. To determine if growth-related traits were altered by seven cycles of recurrent selection, five cultivars from the first cycle (released from 1924 to 1933) were compared with five cultivars from the seventh cycle (released from 2003 to 2007). Stalks were sampled at weekly to biweekly intervals for 12 weeks during 2006 and 2007. Stalks from the Cycle-7 cultivars were taller, and had more internodes than those from Cycle-1 cultivars. Internodes of Cycle-7 cultivars were shorter than those of Cycle-1 cultivars because the elongation time was shorter. These shorter internodes had lower fresh weights, but similar dry weights as the longer Cycle-1 internodes. Water content also decreased faster in Cycle-7 than Cycle-1 internodes, suggesting a more rapid increase in sugar content in Cycle-7 internodes. Thus, recurrent selection for sucrose content in sugarcane has altered the allocation of photosynthate from growth to storage. A genetic comparison of Cycle-7 with Cycle-1 cultivars could be used in the future to identify markers for the genes that contributed to the shift in growth and dry matter accumulation. These would be useful in future recurrent selection cycles.