The effects and interactions of nitrogen, sulphur and genotype on baking quality parameters have been investigated on 14 New Zealand wheat cultivars or lines. N and S treatments were applied separately, early and late, during the growing season, and late N and S were also supplied together. For each of 168 samples generated by the experiment, we analysed the 'amount of high molecular weight glutenin subunits' (HMW-GS) and the 'amount of low molecular weight glutenin subunits' (LMW-GS), and measured quality parameters such as: grain hardness, protein content, Pelshenke, SDS sedimentation and mixograph rheology properties. The results show that: (a) genotype has a strong influence on all the tested quality parameters and is the greatest source of quality variation. Genotype is also the only significant source for the quantity variation of HMW-GS and LMW-GS; (b) N application increases all the tested quality parameters. N application timing is not generally significant, but late N application produces the greatest effect; (c) late S application is not necessary for optimising most of the tested quality parameters. However, late N and S together maximise the Pelshenke values and mid-line peak value of the mixograph; (d) of the 14 tested NZ cultivars, the genotype Kotare has the highest quantity of glutenin, HMW-GS and LMW-GS amounts, flour protein percentage, SDS sedimentation and mid-line peak value. It also has above average hardness Pelshenke values, and shorter mid-line peak time values; (e) good quality lines are recommended for specific and diverse environments. (C) 2000 Academic Press.