INTERRELATIONSHIPS BETWEEN RHEOLOGICALLY IMPORTANT THIOL, DISULFIDE GROUPS AND YIELD-QUALITY PARAMETERS OF WHEAT CULTIVARS (TRITICU-AESTIVUM L)

Experiments were conducted with 22 wheat cultivars (Triticum aestivum L.) from the 1976 season which showed the following: grain yields and rheologically important SS/SH ratios were negatively correlated (r= −0.78). Rdeologically important SS/SH ratios were positively correlated with total flour protein percentages (r=0.61), residue flour protein percentages (r=0.62) and all better dough quality properties. Grain yields and total flour protein percentages were negatively correlated (r=−0.66). However, only the first relationship was statistically valid for 12 recurrent cultivars within the group of 22 which had been yield tested annually from 1971 to 1976, inclusive. Their long‐term average yield data (1971–76) were more negatively correlated (r= −0.87) with the 1976 SS/SH values than their 1976 yield data (r= −0.78). It is considered that grain yield differences between the cultivars studied were inherently related to differences in their abilities to synthesise more rheologically important thiol groups than disulphide groups during plant growth and grain formation. The SS/SH ratio and grain yield relationship appears to be largely independent of seasonal influences and therefore should be of interest to wheat breeders trying to combine higher yield and better quality objectives in their programmes. Copyright © 1979 John Wiley & Sons, Ltd