The effect of N & S fertilisation and their interaction with genotype on wheat glutenins and quality parameters

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.