PERFORMANCE OF SUGARCANE VARIETIES WITH CONTRASTING GROWTH HABIT IN DIFFERENT ROW SPACINGS AND CONFIGURATIONS

CONTROLLED traffic (matching wheel and row spacing) is being widely adopted in the Australian sugar industry to minimise the adverse effect of soil compaction caused by heavy machinery such as cane harvesters and haul-outs. In this study, the performance of current cane varieties with contrasting growth habits in differing row spacings and planting arrangements designed to achieve controlled traffic outcomes is reported. The study was conducted on an irrigated site in the Farnsfield district of the Isis mill area. Cane varieties Q138, Q188A, Q205A and Q222A were planted with whole stick, conventional mouldboard opener planters in 1.5 m and 1.8 m single rows and in dual rows on 1.8 m or 2.0 m centres, as well as by billet planting in a 1.8 m wide throat system. Shoot counts and biomass samples were collected at intervals during the growing season. There were no significant differences in cane yields, ccs or sugar yields between row spacings at harvest, and nor was there any significant interaction between varieties and row spacings for any parameter. This was despite there being significantly fewer harvested stalks in 1.8 m single rows (8.2/m2) and 1.8 m wide throat (9.3/m2) than in standard 1.5 m single rows (10.2/m2) or the 1.8 m (10.6/m2) and 2.0 m (10.3/m2) dual row spacings. Much heavier individual stalk weights recorded in the 1.8 m single and wide throat billet plantings were able to compensate for lower stalk numbers. Results confirm the relative insensitivity of cane yields to crop row spacing and suggest considerable flexibility in developing row spacings to suit controlled traffic farming systems. There were significant differences between varieties in cane yields, ccs and sugar yields. Cane yields for Q205A and Q222A (124 t/ha and 121 t/ha) were significantly higher than Q188A (115 t/ha) and Q138 (112 t/ha). However, in terms of sugar yield, these cane yield differences were modified to some extent by variation in ccs, with Q222A and Q188A (13.8% and 13.5%, respectively) having higher CCS than Q205A (12.9%) and Q138 (11.1%). The combined effects resulted in the highest sugar yields in Q222A (16.8 t/ha), with Q205A and Q188A (15.8 and 15.5 t/ha, respectively) out yielding Q138 (12.7 t/ha). Varieties used different strategies to achieve final cane yields, with high final stalk numbers in Q138 (10.5/m2) and low stalk numbers in Q188A (9.0/m2) compensated for by differences in individual stalk weights.