R. Wayne Davidson

Vigor Rating and Brix for First Clonal Selection Stage of the Canal Point Sugarcane Cultivar Development Program

A better understanding of sugarcane (Saccharum spp.) genetic variability in agronomic performance will help optimize breeding and selection strategies. Vigor ratings and Brix data were collected from the 2009 and 2010 clones in the first clonal selection stage (stage I) of the Canal Point (CP) sugarcane cultivar development program. Stage I individual selection was based on disease resistance and on the product of vigor and Brix. Vigor ratings (from 1 to 9) from all clones and Brix of any clones with a vigor rating ≥6 were collected in the stage I fields and analyzed for relationships between vigor and Brix, for selection rate in each family (i.e., cross), and for their coefficients of variation (CV) within and among families. There was no correlation between vigor and Brix, suggesting that it would be feasible in stage I to select sugarcane clones with both high vigor and high Brix. Variability was high (CV = 59%) for both the number of planted clones and selection rates among families, and vigor (7.2%) had greater CV than Brix (5.4%). Averaged across years, the within-family CVs (9.3% for vigor and 6.3% for Brix) were greater than the among-family CVs (6.3% for vigor and 4.7% for Brix). Results indicated that greater emphasis on family-based than on individual selection in stage I should be avoided, as it would result in the loss of potentially productive clones. However, use of individual selection data on vigor and Brix for analyzing family performance should improve parental selection and optimize crosses.