Relationship between grain quality and the accumulation of nitrogen and sulfur in different wheat cultivars

The relationships between grain quality and the accumulation of nitrogen and sulfur in 12 wheat cultivars were examined. The wheat cultivars were classified into three groups: high N/S ratio, medium N/S ratio and low N/S ratio. The results showed that sulfur accumulation correlated positively with nitrogen accumulation (P0.001), but no significant line correlations between nitrogen harvest index and sulfur harvest index were observed. High N/S ratio cultivars had higher nitrogen accumulation rate but lower sulfur harvest index, or higher nitrogen harvest index but lower sulfur accumulation rate. Medium N/S ratio cultivars had higher nitrogen harvest index and higher sulfur harvest index. Low N/S ratio cultivars had lower nitrogen harvest index, higher sulfur accumulation rate and higher sulfur harvest index. The proportions of nitrogen and sulfur allocation to grain were the main reason causing for the difference of N/S ratio in grain over different cultivars. There were significant differences in the content of glutenin, the glutenin / gliadin ratio, dough development time and stability time between different groups, and all parameters had a quadric curved lines relation with N/S ratio in grain. Suitable N/S ratio in grain was propitious to the accumulation of glutenin and the grain quality.