Combining ability of barley flour pasting properties

Malt extract is one of the major traits contributing to high malting quality and thus a major objective in malting barley breeding programs. Understanding the genetic behaviour of this trait could make selection more efficient. However, the measurement of this trait is very time-consuming and cannot be done in a single plant since it needs a certain amount of grain. In this paper, 10 different varieties with different malting quality were selected to make two 6 × 6 half-diallel crosses for the purpose of studying the genetic behaviour of flour pasting properties, in particular pasting temperature which has been shown to be closely related with malt extract. The pasting properties were measured with a Rapid ViscoAnalyser. Both Australian malting varieties showed significantly higher general combining ability for lower pasting temperature (higher malt extract). The Japanese malting variety also appeared to be a good parent for lower pasting temperature. All the other feed varieties which are used in the breeding programs for improving waterlogging tolerance or salinity tolerance showed significantly higher pasting temperature. Since specific combining ability was not significant, the selection of parents when breeding for pasting temperature can be based on the pasting temperature of the parents. Combined with the fact that only a small amount of grain is needed for the measurement of pasting temperature, the selection can be made in early segregating generations. Preliminary study showed that a major QTL associated with pasting temperature was located on chromosome 7H, indicating the possibility of marker assisted selection for this trait.