engleski

Diallel analysis of Fusarium head blight resistance in winter wheat

Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe reduces yield and quality of wheat (Triticum aestivum L.). Development of resistant wheat cultivars is believed to be the most economical and efficient mean of reducing damage caused by FHB. The diallel is a mating design which was used for estimation of gene action, heterosis, and inbreeding depression involved in determining quantitative traits. It was also used for identification of superior parents in order to study the inheritance of quantitative traits, since it allows the partitioning of genotypic variance to general (GCA) and specific (SCA) combining ability of the intercrossed parents. For that reason a set of eight winter wheat genotypes differing in their FHB resistance were included in a diallel mating scheme resulting in 28 F1 crosses which were, together with the parents, in 2014 analysed in a field trial arranged as a RCBD with two replications. Artificial inoculations with the isolate of F. Graminearum were performed at the beginning of anthesis and repeated on the same plots two days later. The resistance was scored visually 18, 22, 26 and 30 days after inoculation and expressed as % of wheat head area infected with FHB (VRI). After ripening 10 random spikes from each plot were manually harvested and % of fusarium damaged kernels (FDK) was assessed on treshed grains. The diallel analysis was based on Griffing’s Method 2 model 1. ANOVA revealed significant differences among genotypes for both disease rates. For VRI, disease ratings for parents ranged from 1.6% to 58.7% and for crosses from 0.9% to 49.6%. For FDK disease ratings for parents ranged from 0.6% to 44.8% and for crosses from 1.3% to 20.6%. In both experiments GCA and SCA effects were significant. For both disease ratings the lowest GCA effects (highest resistance) among parents was found for resistant breeding line 20810.2.8. (-15.5 for VRI and -7.4 for FDK). The highest GCA for VRI was determined for c.v. Marina (10.2), and for FDK for c.v. Golubica (13.6), both known as FHB susceptible cultivars. For VRI, SCA effects ranged from -15.1 to 12.4 and for FDK from -7.3 to 4.8. For both disease ratings generally higher additive genetic variance (σ2A) was determined, but negative SCA effects determined for several crosses suggested some interaction among FHB resistance alleles. Many F1 crosses had lower disease ratings than the average of their respected parents and one cross, between the two FHB resistant genotypes FR1E1_4 and 20810.2.8, had VRI disease rating lower than for the more resistant parent 20810.2.8., 0.9% vs. 1.6%, respectively.

Fusarium head blight ; winter wheat ; diallel analysis

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