Three million hectares of southern Australia’s semi-arid grain growing region are not suitable for canola, denying growers its profitability and its use in weed, pest and root disease control.

While adapting canola to 225 – 350 mm annual rainfall looms as a challenging assignment, some local researchers have examined alternative oilseed crops to fill the rotational void.

Associate Professor Lionel Martin led one such investigation at the Muresk Institute of Agriculture where, with support from growers and the Federal Government through The Grains Research & Development Corporation (GRDC), his team road tested canola’s close relative, Indian Mustard.

Low rainfall trials at Merredin, Mullewa and Newdegate revealed that mustard genotypes were better accustomed to dryer climates than canola and produced more dry matter under moisture and temperature stresses. Despite sharing canola’s preference for early sowing and a longer season, mustard did not shed yield to the same degree when sowing was delayed by a late break.

Mustard seeds germinated more readily on dry soils and then embarked on a far more vigorous growth phase, covering ground quickly to slow evaporation. When facing moisture constraints, Indian Mustard absorbed more of what was available and performed stronger due to superior osmotic adjustment.

After its strong establishment, Indian Mustard also better survived pest and disease infestations such as blackleg, which virtually wiped canola crops out of WA rotations in the early 1970s and continues to hamper the industry.

But while these agronomic advantages, coupled with easier to harvest pods and potentially higher seed oil and protein content, comprise a strong pro-mustard argument for WA’s dryer grain farms, further research and development is needed to fit the crop into a profitable rotation.

Although Indian Mustard oil’s traditionally high erucic acid concentration, which had limited its entry into human consumption markets, has been lowered through the National Brassica Improvement Program, Horsham, its poor yield structure remains. For example, a relatively low proportion of its plentiful biomass consists of seeds.