ARE GENOTYPE BY ROW CONFIGURATION INTERACTIONS OF CONSEQUENCE IN CULTIVAR DEVELOPMENT FOR WIDE ROW PRODUCTION?

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 singlerow configuration to a row spacing of 1.8 to 1.9 m. This is the track/wheel spacing of current harvesting and haul-out machinery. Many growers are producing cane on these wider row spacings. Selection in the plant improvement program mainly occurs on a 1.5 m single-row configuration. Thus, does this selection configuration exclude genotypes that are better adapted to wide-row configuration production? Experiments were established at Meringa, Ingham, and in the Burdekin to address this issue. The experiments contained either 20 or 48 genotypes grown on three row configurations (1.52 m single-row, 1.85 m single-row and 1.85 m dual-row). No significant genotype by row configuration interaction was found at any site. For sugar yield (TSH), the interaction effect variance component was 24.7, 14.6 and 12.6 times smaller than the genotype variance component at Meringa, Ingham and the Burdekin, respectively. That is, there were large genotypic differences but only small genotypic differences over row configurations. This suggests that genotypic selection for wide-row production could occur on any row configuration tested in these trials. Significant row configuration effects were found at Meringa and Ingham. At Meringa, yield of the 1.85 m single row configuration was less than the other two configurations (1.52 m single, 1.85 m dual). At Ingham, the dual-row configuration produced more sugar/ha than the other two configurations. These different responses were most likely associated with environmental effects during establishment and tillering in the different experiments.