COMPARISON OF METHODS TO ASSESS SUCKERING IN THE SRA NORTHERN VARIETY IMPROVEMENT PROGRAM

SUGAR RESEARCH Australia (SRA) uses a selection index within the variety improvement program called Economic Genetic Value to determine which clones will be advanced to the next stage of selection. Economic Genetic Value is determined from a number of traits including cane yield and sugar content which are both quantitative. Within the Northern region of the Australian sugar industry, a visual subjective rating, mainly assessing the propensity of lodging and flowering and suckering, is included as an appearance grade. Suckering within commercial crops of sugarcane can lead to a decline in CCS while elevating overall tonnes of product delivered to the mill. To assess the propensity of suckering, a linear equation of sucker weight as a function of sucker height and number was established. It is important to refine the relationship matrix for sucker weight based on the size and number of suckers. For the current study, data from two first clonal trials were used and selection of the top 25% of clones, based only on old and new appearance grade methods, without consideration of cane yield and sugar content, was simulated. Up to 45% of the top ranking clones could be overlooked for selection if the old appearance grade method was used over the new method.