Quantitative variability in wheat following irradiation, EMS, and hybridization

Summary

The effects of gamma irradiation and EMS seed treatment on the genetic properties of pure line and hybrid wheat populations were measured. Two hundred lines were derived from each mutagenic treatment of each genetic source and, together with their control materials, were assayed for heading date, plant height, spike length, and kernel weight in a replicated field experiment.

Both mutagens induced significant genetic variability for the four traits in either ‘Giza 150’ or ‘Sonora 64’, two pure cultivars, but neither was effective in increasing the genetic variation in their hybrid background. The relative magnitude of induced variation compared with that from hybridization depended on the particular mutagen and attribute and averaged less than 50% of that from hybridization. Heritabilities and expected genetic gains were not much lower in mutagenic populations than in hybrid populations. The relative distributions of the variance components among families and within families, and the estimates of the genetic correlations in the various populations, indicated that induced mutations were somewhat similar in nature to the variation released from hybridization. The induced variation was not accompanied by any shift in the population mean and, in most cases, variation was equally distributed around the population mean.