Genetic analysis of preharvest sprouting in a six-row barley cross

Preharvest sprouting (PHS) can be a problem in barley (Hordeum vulgare L.) especially malting barley, since rapid, uniform, and complete germination are critical. Information has been gained by studying the genetics of dormancy (measured as germination percentage, GP). The objective of this study was to determine if the quantitative trait loci (QTLs) discovered in previous research on dormancy are related to PHS. PHS was measured as sprout score (SSc) based on visual sprouting in mist chamber-treated spikes and as alpha-amylase activity (AA) in kernels taken from mist chamber-treated spikes that showed little or no visible sprouting. GP was also measured. All traits were measured at 0 and 14 days after physiological maturity. Evaluation of the spring six-row cross, Steptoe (dormant)/Morex (non-dormant) doubled haploid mapping population grown in greenhouse and field environments revealed QTL regions for SSc, AA, and GP on five, four, and six of the seven barley chromosomes, respectively. In total, seven and eight regions on five and six chromosomes had effects ranging from 4 to 31% and 3 to 39% on PHS and dormancy, respectively. One chromosome 3H and three chromosome 5H QTLs had the greatest effects. All PHS QTLs coincide with known dormancy QTLs, but some QTLs appear to be more important for PHS than for dormancy. Key QTLs identified should benefit breeding of barley for a suitable balance between PHS and dormancy.