Genetic effects of the soft starch (h) and background loci on volume of starch granules in five inbreds of maize

Larger particle volume is beneficial for many aspects of maize starch processing, and may improve the performance of some starch attributes. This study focused on the soft starch (h) locus to identify its potentially influential role in starch particle volume distribution. The objectives were to study the genetic expression of starch particle volume of the h locus in different genetic backgrounds and the gene action conditioning starch particle volume of other loci in both normal‐starch and h‐starch backgrounds. Forty‐five populations (five intra‐inbred F_1s, 10 hybrid F_1s 10 F_2s, 10 BC₁F_1s to h/h parent, and 10 BC₁ to h:h conversion of normal parent) were planted in 1993 at two locations and in 1995 at one location. Selfed heterozygotes (±/h) in all generations provided intra‐ear comparisons of normal and h starch, and F₃ and BC₁F₂ generations provided inter‐ear comparisons. Significant differences were found between normal and h:h genotypes in all intra‐ear and inter‐ear comparisons. In all cases, general combining ability effects were highly significant, suggesting the presence of additive gene effects. Generation mean analysis of normal and h:h starch materials yielded similar results, indicating the predominance of additive and some dominance effects for other loci on starch particle volume. These results indicate the usefulness of the soft starch gene and additional genetic variation among inbreds in the improvement of starch particle volume for increased starch recovery in wet milling.