Oceania
Australia grew wheat on an average of 8.7 million ha during the 1993-1995 period with an average production of about 14.0 mil-lion tonnes of which nearly 73 percent was exported (Table 1.1). Area planted to wheat has varied as much as 25 percent from a high exceeding 12.2 million ha to a low of about 8.5 million ha during the years from 1982 through 1995. Yields in tonnes per hectare have gradually increased during the same period. Most wheat is grown in the arcuate belt of land curving across the eastern and southern regions where winter rainfall is sufficient to produce a crop. Spring wheat is grown as a winter crop sown in the autumn (May to June) and harvested in early summer (November to December).
Wheat yields in Australia are low and highly variable primarily due to extreme fluctuations in annual rainfall, which varies from 250 to 650 mm from May through October. Other constraints to production are low soil fertility, diseases (stem rust, stripe rust, Septoria blotches and take-all) and nematodes. Application of N (through pasture farming methods) and P give good crop responses. The amount of total wheat area devoted to semidwarf cultivars was 91 percent in 1994 (CIMMYT, 1996).
Wheat is a major crop in New Zealand but is grown on only 39 000 ha, with production averaging 232 000 tonnes during the 1993-1995 period. Production area is primarily on the eastern side of the South Island. Yields are high with a national average of 6.0 tonnes/ha. Both winter- and spring-habit wheats are grown.