Effects of sulphur fertilization on protein, sulfhydryl group and disulfide bond content in developing grain and processing quality of wheat

In order to study the responses of wheat grains protein, sulfhydryl group and disulfide bond content in different spikelet and floret position, flour processing quality to sulphur fertilization, field experiment was carried out with four winter wheat cultivars (Jimai20, Zimai12, Lumai21 and Shannong1391).The available sulfur content in the experimental soil was 728 mg/kg. The results showed that the effects of sulphur on grain protein accumulation in upside spikelets were higher than in the other parts of spikelet. The protein contents of inferior grains in the middle spikelets were increased in the highprotein cultivars Jimai20 and Zimai12The sulphur application could enhance the sulfhydryl group content in the upside and the superior grains of middle spikelets, and the disulfide bond content of grains in the different spikelet positions. However, its effects on disulfide bond of grains in different floret positions varied with the wheat cultivars. The sulphur application could increase the wet gluten content, dough development time, stable time and total evaluation value in the cultivars with high protein to some extent. But the effects on these different quality indices were not homogenous. The improvement of processing quality was attributed to the increase in grain protein, the sulfhydryl group and disulfide bond content. According to the data collected from the experiment, the changing curve of sulfhydryl group content in the grain formation was increased first and then decreased which contrary to that of grain protein content, the changing of disulfide bond content is similar to that of grain protein, but the lowest value occurred later than grain protein.