ROW SPACING EFFECT ON THE GROWTH AND YIELD OF SEVERAL SUGARCANE VARIETIES IN NORTH QUEENSLAND

CONTROLLED traffic (matching wheel and row spacing) is becoming an important part of the production system in the Australian sugar industry. However, with harvester and haul-out wheel spacing between 1.8–1.9 m, controlled traffic is not possible under the traditional sugarcane row spacing of 1.5 m. The simplest solution to the problem would be to change row spacing to match wheel spacing. However, there is little information available as to how current varieties, selected under a 1.5 m system, will perform under wider rows. An initial experiment was established at Gordonvale, north Queensland to assess the response of four varieties with different growth characteristics (Q187A, Q200A, Q201A, Q218) to 1.5 m single rows, 1.8 m single and dual rows (500 mm between duals) and 2.3 m dual rows (800 mm between duals). There were significant variety and variety x row spacing responses with the overall highest cane (151 t/ha) and sugar (23.65 t/ha) yields being produced with Q201A on 1.8 m dual rows. The results suggest that the success of a change to a controlled traffic system (wider rows than 1.5 m) will be dependent on suitable varieties being available. It is suggested that selection of suitable varieties for wider rows will be dependent on a better understanding of the crop physiology and, from that, identification of the basic characteristics required. It is apparent that there is little understanding of this at present. Further, there were indications from this experiment that fast growing, strongly tillering varieties (e.g. Q200A) may not necessarily be the avenue to maximum yields compared with varieties that develop more slowly, produce fewer tillers and relatively large stalks (e.g. Q201A).