A distinction between sulfur-rich and sulfur-poor endosperm proteins is proposed on the basis of analyses of sulfur-deficient grain, of grain proteins labelled with 35S, and of heat-denatured proteins. Grain proteins from five wheat varieties, grown in pots with excess, normal or minimal supplies of sulfur, were examined by gradient gel and sodium dodecyl sulfate electrophoresis. Restriction of sulfur altered the proportions of proteins within and between protein classes. In particular, the proportion of the low-mobility gliadins (proposed as low-S) increased at the expense of the high- mobility gliadins. In addition, the low-S grain was severely depleted in all essential amino acids, though arginine and aspartic acid increased considerably compared to normal grain. Autoradiography following electrophoresis showed that the low-mobility gliadins contained no 35S whereas the high-mobility gliadins were well labelled. A further distinction between the two groups of gliadins was provided by heating a slurry of wholemeal at 130°C for 30 min: the low-mobility gliadin components were still readily extractable with 6% urea solution but the remaining gliadins (proposed as sulfur-rich) were not.

The effect of stripe rust on the processing quality of Australian wheat varieties was examined over a four year period. Each year in field experiments, stripe rust was allowed to develop naturally on one half of each plot block while the other was kept disease free using three weekly applications of fungicide. Changes in grain quality were observed with susceptible varieties when subjected to an epiphytotic of the disease. Stripe rust caused kernels to be shrivelled, which resulted in reduced test weight and flour milling yield and increased grain protein content. Dough properties were also affected. Dough development time was shorter, mixing tolerance deteriorated and extensograph maximum resistance was lower for susceptible varieties affected by the disease.

A glasshouse sand culture experiment was conducted to determine the effects of sulphur supplied at 10,375 and 875µM concentrations on total dry matter production per plant (TDM), grain yield, harvest index (HI), yield components, nitrogen, sulphur and phosphorus levels in herbage and grain samples of two vitreous grained (Stockade and Gabo) and three non-vitreous grained (Insignia, Olympic and Summit) wheat cultivars (T. aestivum L.). Pelshenke doughball fermentation tests were done on wholemeal samples from all treatments.Stockade and Gabo had higher TDM than Insignia, Olympic and Summit at 10µM sulphur concentration, but relatively lower harvest indices. At 375µM sulphur, TDM increased for all cultivars; Gabo and Stockade continued to have relatively higher TDM, but Stockade produced only half the increase of any other cultivar. However, Stockade doubled its HI which, in turn, was double the increase recorded by Olympic and Summit. Insignia failed to increase its HI. Only Stockade showed increased TDM at 875µM sulphur. Olympic had the highest HI values at both 375 and 875µM sulphur. Similar grain yield increases for all cultivars were largely attained by differential grain number-grain size combinations. The higher sulphur supplies therefore stimulated the translocation of photosynthates to the developing grains and/or shifted the location of most rapid cell division from vegetative to reproductive sites. Stockade and Gabo had relatively higher percentages of grain sulphur at 10µM sulphur than the other cultivars and Stockade continued to have the highest percentage of grain sulphur at 375 and 875µM concentration. Except for a marked fall by Insignia, an increasing sulphur supply did not affect the distribution of sulphur within the plants as the indices for percentage sulphur remained largely unchanged. However, the distribution of nitrogen and phosphorus from straw to grain were both stimulated. Stockade and Gabo had relatively larger increases in their indices of percentage nitrogen, but the non-vitreous grained cultivars showed relatively larger increases in the percentage of nitrogen in the grain. Comparatively poor Pelshenke results, especially for Stockade, at I0µM sulphur, indicate an adverse affect of sulphur deficiency on grain quality. The experiment has shown that variation in sulphate sulphur supply differentially affected the biological and physico-chemical mechanisms controlling the optimum phenotypic expression of five wheat genotypes (cultivars). Part of these mechanisms involves close interrelationships and interactions between the uptake and/or metabolism of sulphur, phosphorus and nitrogen anions. Stockade was a particularly responsive cultivar to sulphur, while Insignia was relatively insensitive.

Australian Wheat Board quality advisers had formed the opinion that Condor wheat (Trificum aestivum L.) grown in north-west Victoria possessed weaker dough properties than that grown in southern New South Wales, even at similar grain protein contents. Samples of commercially grown Condor wheat from north-west Victoria and southern New South Wales were collected by Australian Wheat Board field officers to objectively investigate this observation. Testing of these samples indicated Condor grown in north-west Victoria to have significantly weaker dough properties than that grown in southern New South Wales. Doughs were less tolerant to mixing in the farinograph and had reduced extensograph maximum resistance, even when there was no difference in protein content between the samples from the two regions. The reduced dough strength in the Victorian samples was associated with lower nitrogen: sulfur ratios and residue protein content and fewer rheologically important disuifide groups per 50 g of flour. These differences were presumed to have resulted from some aspect of the environment during plant growth and development.

Wholemeal grists of five wheat cultivars (T. aestivum L.) - Gabo, Olympic, Stockade, Insignia and Summit - grown in sand culture supplied with low (10 �M), medium (375 �M) and high (875 �M) concentrations of sulfur, were analysed for their specific activities of ATP sulfurylase (EC 2.7.7.4, ATP:sulfate adenylyltransferase). Under sulfur deficient conditions, residual activities were significantly higher in Gabo, Olympic and Stockade. Olympic maintained significantly higher activities at both the medium and high sulfur concentrations. All cultivars except Summit showed significantly lower activities when the sulfur deficiency was corrected. The results are discussed in relation to grain yield per plant, yield components, grain N, S, P contents and Pelshenke quality data. Grain yield per plant and ATP sulfurylase activity were positively correlated at all sulfur levels.