Genetic Aspects of Starch Granule Traits in Barley

Abstract

Starch, the main constituent of barley (Hordeum vulgare L.) kernels, is accumulated as granules classified as large, Type A, and small, Type B. The objectives of this research were to assess the importance of genotype and environment in determining starch granule morphology, to estimate heritability for these traits, and to investigate the association between granule traits and malting quality. Fourteen genetically diverse barley genotypes were evaluated in four environments, and four populations were evaluated in a parent‐offspring study. Data were obtained using digital image analysis of starch granules. Significant differences were found among the 14 barley genotypes for five of six granule traits. Environment had a significant effect on four granule traits, but genotype by environment interactions were not significant. Type‐A granules accounted for 94% of total starch by volume, with a range of 92 to 96% for the 14 genotypes. Genotype means for A granule volume ranged from 1720 to 2164 μm3 and for surface area, from 773 to 944 μm2. On the number basis, the small B granules accounted for 93% of all granules in the 14 genotype set. Malting and six‐row genotypes had larger A‐granule surface area and volume than feed and two‐row types, although some overlapping of genotypes occurred. There was little evidence of association between starch granule morphology traits and malting quality traits. Heritabilities were encouraging on a genotype mean basis in the 14 genotype study, but were low in the parent‐offspring heritability evaluation. It appears that greater genetic variability in granule traits is needed before considering selection for starch granule traits to improve grain quality.