EVALUATION OF GLOBOSUM BARLEY FOR PEARLING AND PLUMP GRAIN

The glo-a gene has been the main donor of globe-shaped grain in crosses which target the potential of this trait for the improvement of grain plumpness and pearling efficiency. After evaluation of the progeny of the first globosum cross, the glo-a gene was implicated in reduction in kernel size, hectolitre weight and yield. Conversely, pearling loss and time taken to pearl appeared reduced due to the novel grain shape. Further crossing, selection and multiplication of globosum lines continued, and a new set of lines were tested for pearling performance in 2006. In general, the results were ambiguous, although the globosum types were again observed to reduce time taken to pearl and seed diameters were much improved compared to earlier crosses. While breeding has improved the kernel size of glo-a barley lines, the overall globe shape is less apparent in the larger seed for certain crosses. Reduction in yield due to inheritance of homozygous glo-a genotype were supported by the results obtained when evaluating yields in two doubled haploid populations segregating for globe-shaped seed, which may also be viewed as a loss simply due to the loss of the elliptical ends of the grain rather than a real production loss. This does not preclude the production of higher yielding lines, but reduces the probability. Further testing is required to confirm the advantages of globosum lines over normal lines in pearling efficiency and production of plump grain in less favorable conditions.