Influence of sowing time on grain quality characters of wheat grown in north-western Victoria

Abstract

Grain from sowing time experiments at 1 site in 1984 and 2 sites in 1986 and 1987 in northwestern Victoria were tested for several grain and flour characters. The tests included grain protein percentage, sodium dodecyl sulfate (SDS) sedimentation volume, particle size index, milling yield, test weight and Pelshenke wholemeal fermentation time, although not all tests were carried out in all years at both sites. The findings are reported without analysis of the underlying processes involved. The effect of sowing time on grain protein percentage was variable; at Dooen in 1984 there was a slight decrease, at Dooen and Walpeup in 1986 there was an increase but there was no change at Dooen in 1987, as sowing time was delayed. Sowing time had a significant effect on SDS at Dooen in 1984 and Dooen and Walpeup in 1986. There were no marked trends at Dooen in 1984, but significant differences between individual sowing times, and in 1986 there was an inconsistent increase as sowing time was delayed. At Walpeup in 1986 there was a substantial increase in values as sowing time was delayed. Partial correlation coefficients, however, indicated that at Dooen in both years and Walpeup in 1986, variation for SDS was due almost entirely to differences in grain protein percentage, although at Walpeup in 1986 there was a slight additional effect of sowing time. Particle size index was significantly affected by sowing time at both sites in 1986; at Dooen there was a decrease as sowing time was delayed and then an increase for the last sowing time, and at Walpeup there was an increase as sowing time was delayed. Although some effects of sowing time on milling yield and test weight were statistically significant, only one had commercial significance-milling yield at Walpeup in 1986. Pelshenke time was affected by sowing time at Dooen in 1984 and Walpeup in 1986, but there were no obvious trends. Sowing time x cultivar interactions have implications for quality testing of wheat crossbreds. Grain growers can be reassured that sowing crops over an extended period appears to have little or no detrimental effect on grain quality with respect to bread baking properties. In some seasons, however, there may be substantial increases in grain protein percentage in later sown crops, although this would generally be associated with lower yields.