THE EFFECT OF PLANT SPACING ON GROWTH, CYCLING TIME AND YIELD OF BANANAS IN SUBTROPICAL WESTERN AUSTRALIA

In the semi arid subtropical Carnarvon region of Western Australia, ratoon crops of bananas are grown at high densities of over 3000 plants/ha. This practice offers protection against heat stress in summer and is possible because of the low leaf disease status of the region. The growth, cycling and yield of bananas (Cavendish cv. ‘Williams’) grown under a range of within row spacings, giving population densities of 1111 to 6667 plants/ha, were studied at Gascoyne Research Station, Carnarvon (113°30’E, 24°53’S). The trial lasted for seven years to complete four crop cycles.
Banana plants at close spacing were taller with thinner pseudostems than under wide spacing. Cycle duration was extended under close spacing and therefore annual yield was low. At close spacing the time to harvest was extended by 3 to 6 months in the plant (P) crop and 10 to 12 months in the first ratoon (R). This trend continued in later cycles with a delay of 21 months in R3. The highest plant crop yield of 75 t/ha came from 3x1 m spacing. In the ratoons, wider spacing of 3x3 m or 3x1m gave high yields of 61-82 t/ha. These results demonstrate that the ultra-close spacing (>4444 plants/ha) is unsuitable due to cycle extension, small fruit size and low annual yield. Within the commercially acceptable planting density of around 3000 plants/ha, the 3x1 m spacing treatment appears optimum for consistent yields (50 t/ha/year), cash flow and efficient water use. An economic analysis will be undertaken to confirm this. The 3x3 m spacing, however, allows for faster cycling.