Emmer wheat as a source for trait improvement in durum wheat: a study of general and specific combining ability

Abstract

Emmer wheat (Triticum. turgidum ssp. dicoccum) as an ancestor of bread and durum wheats, can be a potential resource to restore genetic diversity in modern durum wheats. In order to estimate the combining ability, the type of gene action, heritability, and other genetic parameters of agronomic traits, a full diallel cross (12 × 12) was made between eight durum cultivars and four emmer wheat accessions. The F1 hybrids (132 combinations) and their parents were evaluated for important traits that account for productivity during two cropping seasons. Considerable genetic diversity among the parents and the hybrids was evident, with most of the hybrids showing higher grain yields than their respective durum parent. High general combining ability for all of the measured traits, and higher Baker ratios for most of the traits indicated that additive gene action was involved. Based on the Griffing diallel method, the specific combining ability was significant for most of the measured traits. The Hayman analysis revealed the presence of partial dominance gene action for traits such as the number of tillers per plant (NT), grain weight per spike (GWS), harvest index (HI), days to heading (DH), and number of kernels per spike (NKS). However, plant height (PH), days to maturity (DM), peduncle length (PL), and grain yield (GY) were under the influence of the over-dominance gene action. The narrow-sense heritability for GWS, NKS, kernel diameter (KD), and HI was relatively high and these four were positively correlated with grain yield. Therefore, selection for these four traits in early generations may indirectly improve yield. The results indicate that Iranian emmer wheats are a good source of wild type alleles and valuable QTLs to improve the elite durum wheat cultivars.