Effect of the nud gene on grain yield in barley

Naked barleys are less yielding than the hulled ones while the reason for this difference has not beendefinitely clarified. To investigate the effect of the nud gene on yield, a barley doubled haploid (DH, Proctor ×Nudinka) population was initially tested in three environments and a QTL study was run on the entire populationas well as on two nud/NUD DH subpopulations. Among the agronomic traits studied, a QTL effect was found atnud locus on chromosome 7H only for yield and thousand grain weight (TGW), while a second QTL was found on6H, although contributed by the naked parent. Other QTLs for TGW were identified on 2H, 3H and 5H. Most QTLsfound in the entire population were confirmed by the study on the two groups. No interaction was observed betweenQTLs. To provide a more accurate evaluation of the effects of the nud gene upon grain yield, its components andother agronomic traits, sixteen naked advanced backcross (AB) BC5F2 lines in the hulled background of cultivarArda were prepared and evaluated in a replicated yield trial for two years. The only differences found betweenAB lines and Arda in grain yield and TGW were due to hull weight (11.97% of kernel weight). No differences wereobserved in other traits such as grains/m2, grains per spike, plant height, heading date and mildew resistance. Inconclusion, we think to have clarified that the effect of the nud gene on yield is due to hulls, and we did not findany pleiotropic effect of nud on other traits. This suggests, together with the finding of a QTL contributed by thenaked parent, that there is a great potential to improve naked barley up to the yield levels of hulled barley.