Selection Indices for simultaneous improvement of yield and quality in sugarcane clones

Abstract:

Here is a surprising fact: selecting sugarcane clones for high cane tonnage alone can actually reduce sugar recovery per hectare, because tonnage and Brix are negatively correlated in many breeding populations. This research compared five selection indices, Smith-Hazel, Pesek-Baker, Mulamba-Mock, base index, and Elston's index, for their ability to achieve simultaneous genetic gain in both cane yield and juice quality (Brix, pol %, purity) across 36 clones evaluated at the Silesian Agricultural College, Gliwice, Poland, during the 2022 growing season. A randomised complete block design with three replications was used. The Smith-Hazel index produced the highest expected genetic gain for yield (8.4%) but only modest Brix improvement (3.2%). The Pesek-Baker index, which assigns desired gains rather than economic weights, achieved the best balance: 6.7% gain in yield with 4.8% gain in Brix, selecting 8 of 36 clones for advancement. The Mulamba-Mock rank-summation index was simpler to compute and gave intermediate results (7.2% yield, 3.9% Brix). These findings indicate that the Pesek-Baker index is most suitable when simultaneous improvement of yield and quality is the breeding objective.