Eighty-four canola genotypes, including current commercial Australian genotypes, some older Australian genotypes, new breeding lines, and several genotypes from China, were screened for nitrogen and sulfur efficiency in the early growth stage. Plants were grown in a glasshouse using virgin brown Lancelin soil (Uc4.22) supplied with basal nutrients. The treatments were: (i) adequate nitrogen and sulfur, (ii) low nitrogen, and (iii) low sulfur. Canola shoots were harvested at 38 days after sowing when growth reduction and the nitrogen and sulfur deficiency symptoms were evident in most genotypes.

The nitrogen or sulfur efficiency in canola genotypes was evaluated on the basis of: (1) growth at low nitrogen or sulfur supply, (2) growth at low relative to adequate nitrogen and sulfur supply, and (3) nitrogen or sulfur utilisation efficiency expressed as shoot dry weight per unit of nitrogen or sulfur content in shoots.

Genotypic variation in growth and nitrogen or sulfur efficiency in canola germplasm was significant. Two genotypes (Chikuzen and 46C74) were ranked efficient and 2 inefficient (CBWA-005 and Beacon) in uptake and utilisation of nitrogen under all 3 criteria. In terms of sulfur efficiency, genotype Argentina was ranked efficient, whereas CBWA-003 and IB 1363 were classified inefficient under all 3 criteria. Two canola genotypes (Surpass 600 and 46C74) were both nitrogen- and sulfur-efficient in terms of relative growth at low v. adequate nutrition; their use in the breeding programs could be considered.