Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 14, 2010
Publication Date: July 1, 2010
Citation: Del Blanco, I.A., Glaz, B.S., Edme, S.J. Improving efficiency of sugarcane genotype selection in Florida. Crop Sci., doi: 10.2135/cropsci2009.09.0539 50:1744-1753. 2010.
Interpretive Summary: Florida growers produce more sugar than any other state in the U.S.on about 400,000 acres of sugarcane in south Florida. About 320,000 of these acres have organic (muck) soils and the remaining 80,000 acres have sand soils. The cooperative (USDA-ARS, University of Florida, and Florida Sugar Cane League, Inc.) sugarcane breeding program located at Canal Point (CP), FL has consistently developed high yielding varieties for these muck soils for more than 35 years, but has not done as well for the sand soils in this region. The CP program uses a 9-year scheme to select high-yielding sugarcane varieties. The final stage (Stage 4) of this scheme tested the most promising varieties for 3 years at 8 grower farms with muck soils and 2 grower farms with sand soils. (This has now been changed to 7 farms with muck and 3 farms with sand soils.) Scientists hypothesized that increased variability on the sand compared with the muck soils in Stage 4 may have been one cause of the problem. However, using results from 7 years of Stage 4 data, this study found that the CP program uses sufficient replication thus allowing Stage 4 to provide data that accurately identifies high yielding varieties for each soil type. Rather than identifying changes to Stage 4, results from this study suggest that it is more likely that changes will need to be made to the stages that occur in the 6 years prior to Stage 4 in order to improve sugarcane variety selection for sand soils in the CP program.
The Canal Point (CP) sugarcane (Saccharum spp.) breeding program has consistently developed high yielding cultivars for the organic (muck) soils of South Florida, but cultivar development has not been as successful for sand soils in this region. The objective of this study was to improve this program’s final stage (Stage 4) selection efficiency within each soil type by assessing sources of variation, with particular attention to interactions among genotypes, soil, and locations within soil; and by comparing the relationship between genetic repeatability and number of replications for sand and muck soils for cane and sugar yields and their components. Sources of variation were partitioned in a 5-year data set which contained plant-cane (PC), first ratoon (FR), and second-ratoon (SR) data from five CP series in Stage 4 tested at eight locations on muck soils and two locations on sand soils. Location within soil, genotype, replication within location and soil, and genotype x location within soil were highly significant sources of variation in cane and sugar yield for all series and crops. Soil and soil x genotype were marginally or non significant suggesting that for these genotypes, that were selected on muck in early selection stages, the division by soil type did not improve the selection process. The six replications used routinely in Stage 4 provided elevated levels of precision for most traits and locations. Sand locations had high repeatability (R) for stalk number, cane yield, sugar yield, and economic index; and low R for stalk weight and TRS. Different muck locations had high precision for the diverse traits. Okeelanta Corporation had the highest R for TRS and Wedgworth Farms for cane yield.