PERFORMANCE OF CULTIVARS ON DIFFERENT ROW CONFIGURATIONS

CONTROLLED TRAFFIC has been promoted in order to reduce compaction. Controlled traffic can be achieved by widening row spacings from the conventional 1.5 m single row system to row spacing of 1.8–1.9 m. This is the width of current harvesting and haul-out machinery. Many growers are now producing cane on these wider row spacings. However, the crop improvement program uses 1.5 m singles rows when selecting clones. Are cultivars that are suitable for wider row spacings making it through the breeding program? This question was addressed by looking at whether a cultivar × row spacing interaction occurs when cultivars are grown on different row configurations. Three trials were planted in Queensland in 2006 (Mackay, Ingham and Meringa). Each trial contained four cultivars on three row configurations. Dualrow configurations tended to produce more early shoots but often this difference was lost later in the season when stalk development occurred. Cultivars used different growth pathways to reach final yield. In many cases these different pathways did not result in significantly different yields at final harvest. However, understanding these pathways may allow for better cultivar recommendations for particular environments. A significant cultivar-by-rowconfiguration interaction was found for total fresh biomass at Ingham, one of the three sites. This interaction was mainly due to the good performance of Q135 on dual rows and the poor performance of Q174A on dual rows. The lack of an interaction at the other sites suggests that it is still unclear whether selection on wide rows would actually produce cultivars even better suited to wide rows compared to selection on narrow rows.