Components of variation, heritabilities and correlations for indices of sprouting tolerance and seed dormancy in Triticum spp.

Summary

Germination of wheat (Triticum spp) kernels prior to harvest reduces the economic value of grain. Losses attributable to pre-harvest sprouting could be reduced by developing sprouting tolerant (ST) cultivars if heritable variation exists for this trait. Objectives of this study were to compare various assays that measure ST, seed dormancy (SD), and alpha-amylase activity, and to divide the total variation for these traits into parts relating to genetic differences, genotype-year interaction, and residual variation. Twenty-six hexaploid wheat genotypes (Triticum aestivum L.) (eight red-kernelled and eighteen white-kernelled), and three white-kernelled tetraploid wheat genotypes (T. turgidum L. var. durum) were subjected to various assays that measure ST, SD, and alpha-amylase production using artificial wetting treatments. Genotype effects accounted for 44% to 90% of the phenotypic variation. The genetic component of variation, when expressed as a proportion of the total variation, was 2 to 6 times greater than the proportion attributable to error. Heritability expressed on a genotype mean basis was highly significant for all variables and ranged from 0.59 to 0.93. The phenotypic correlation for any ST or SD trait or alpha-amylase activity measured on samples collected at two dates (T1 and T2 = T1+14 days) was highly significant and positive. The phenotypic correlation matrix among assays performed on the unthreshed spikes, germination tests and alpha-amylase activity at both T1 and T2 were positive and highly significant. Increased ST is an attainable objective, and direct selection for ST using an artificial wetting treatment is an appropriate breeding strategy.