Dough quality from grain samples from the Interstate Wheat Variety Trials for 3 cultivars at Wongan Hills and Narrabri in 6 seasons and 4 cultivars at Narrabri, Wagga Wagga and Dooen in 4 seasons was studied in relation to av. daily min. and max. temp. from anthesis to harvest. In greenhouse experiments, wheat cv. Olympic, Hartog and Skua seedlings were raised at day/night temp. of 21/16degreesC and then transferred to 33/28degrees at 14 or 32 d after anthesis. Air temp. influenced wheat baking quality, particularly dough strength, loaf score and volume in both field and greenhouse trials. Dough strength increased with av. daily temp. up to 30degrees and tended to decrease at higher temp. Field data indicated that protein concn was most dependent on max. temp. The cultivars differed in inherent dough strengths but for all cultivars dough strength increased with protein concn, and a strong positive correlation with max. temp. was observed. In the greenhouse, high temp. increased grain moisture loss and shortened the time to maturity. Grain from the higher temp. regime was smaller and the dough particularly resistant to deformation. Loaf volume was very similar for all 3 cultivars but for other quality characteristics responses differed between cultivars.

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The relationships between grain size and shape and milling yield were examined in samples of 11 current commercial cultivars and breeding lines of wheat grown at several sites in northern New South Wales. In addition, the effects of segregation within samples for grain size and test weight were studied. For samples that had been segregated for test weight, there was a strong positive correlation between test weight and milling yield. This correlation was much weaker for samples of different varieties grown at a particular site although over all sites the correlation was significant. Similarly, in samples stratified for grain size, there was a consistent positive correlation between seed size and milling yield as expected on theoretical grounds. In contrast, in samples of different cultivars grown at the one site, grain size was not correlated with milling yield. These contrasting results were taken to indicate that the contribution of differences in seed size to genotypic difference in milling yield were small relative to the effects of other factors. The effects of some of these other attributes of wheat grains, which may influence milling yield (e.g. the amount of germ tissue, thickness of bran, depth of crease), were also studied. Free-milling wheats appeared to differ from their poorer milling counterparts in several of these factors, each of which appeared to make a minor but cumulative contribution to differences in milling yield. No one factor studied here appeared on its own to make a major contribution to genotypic difference in milling yield.

A wide range of grain quality tests (on both a large and a small scale) was performed on samples obtained from a factorial (5 sulfur x 3 nitrogen treatments) field experiment in which Olympic wheat responded in yield of grain to both sulfur and nitrogen. Grain nitrogen concentration responded mainly to nitrogen supply and ranged from 1.38 to 2.56%. Grain sulfur concentration responded to both sulfur and nitrogen supply and varied from 0.08 to 0.18%. Flour sulfur was highly correlated with, but lower than, grain sulfur. Compared with high sulfur grain, low sulfur grain was harder (higher pearling resistance) and the dough had a greater resistance to extension and a lower extensibility. In fact, a restricted supply of sulfur seriously affected grain quality, producing a dough that was excessively tough and umuitable for normal use. These changes in dough quality were accompanied by decreases in the proportions of albumins and of high mobility gliadins in the total protein in the low sulfur grain.