Four amphiploid lines (SHW) based on T. monococcum (Tm) and T. boeoticum (Tb) were crossed to T. durum varieties to generate 13 combinations. Field germination and winter survival of hybrid plants in F 2 were assessed. Among all crosses, those with SHW8A-Tb and SHW9A-Tm showed highest field germination but with different degrees of spike fragility. The variation on seed number and weight per main spike was studied in F 4-6 from SHW8A-Tb/Progres and SHW5A-Tb/Severina crosses after individual selection for these traits. Ten lines with durum phenotype from the former and three genotypes with dicoccum plant shape from the latter cross were developed. SDS-PAGE indicated the presence of HMW-GS 1Ax2*+1Aynull subunits in four lines, among which 1Ax2* was inherited from T. boeoticum acc.110 through SHW8A-Tb. Most of the selected genotypes possessed γ-gliadin45, which was relating to good end-use quality. Powdery mildew testing showed that all progenies resulted from the SHW8A-Tb/Progres were susceptible to 12 races of the pathogen, while three lines derived from the SHW5A-Tb/Severina cross behaved differently: G32 expressed resistance to six, G33 to 2, and G34 to 5 races. The selected genotypes from crosses involving SHW with T. boeoticum exhibited good breeding performance compared to tetraploid wheat parents, and might be of breeding interest to further research.
Free-threshing einkorn wheat (Triticum sinskajae A. Filat. et Kurk.) is an excellent source of resistance against wheat diseases and grain quality parameters. A new synthetic hexaploid amphiploid SHW45 (T. durum 198-2 × Triticum sinskajae acc. 18397) was studied in C 2-7 generations and characterised for field growing. Some traits such as a plant height and spike features including fertility and spike fragility revealed a large phenotypic variation. A strong selection for resistance to spikelet dispersal and a number of seeds per selfed spike led to the creation of several lines. They manifested a variety of resistance to powdery mildew at the seedling stage. Three amphiploid lines with diverse phenotypes and a complete resistance to spike brittleness were crossed as females to the wheat cultivar 'Sadovska ranozreika-4'. Viable hybrid seeds are obtained only when the synthetic form is a female parent. F 1 hybrids of amphiploid line 45-10 bore an average of 9 seeds per isolated spike, which was a significantly better yield than that of other hybrids. The lines showed homogeneity in high molecular weight (HMW) glutenins, as subunit pairs Ax2*+Ay1 and Bx17+By18 are inherited from the T. sinskajae, and T. durum form 198-2, respectively. In total, 14 F 2 , 22 BC 1 , and 141 F 2 -BC 1 seeds from the crosses with two bread wheat cultivars were planted in the field. The synthetic amphiploid lines might be promising genetic resources for resistance to powdery mildew and grain quality in wheat breeding.
The most commonly used method to control wheat powdery mildew is by fungicides. The aim of the present study is to determine the duration of the fungicide activity of three fungicides: azoxystrobin; triadimenol; tebuconazole+spiroxamine+triadimenol. They were applied in three concentrations in phenophase 3-4 leaf of susceptible wheat variety. After treatment, each day one pot of the tested fungicide concentrations was inoculated with Blumeria graminis f. sp. tritici. When using azoxystrobin at concentrations of 0.2%, 0.4%, 0.8%, symptoms of powdery mildew appeared on plants inoculated with Blumeria graminis f.sp. tritici in the next day after treatment. When using triadimenol, first symptoms appeared in plants inoculated with the pathogen on the next day after applying a concentration 0.12%, on the second day after applying a concentration 0.25% and on the third day after treatment with a concentration 0.5%. With tebuconazole+spiroxamine+triadimenol, first postules appeared on plants inoculated with Blumeria graminis f. sp. tritici on the third day after treatment with a concentration 0.15%, on the 13th day after treatment with a concentration 0.3% and on the 14th day after treatment with a concentration 0.6%. This fungicide at a concentration of 0.6% (13 days) and 0.3% (12 days) has the longest duration of fungicide activity.
Ascochyta blight is the major biotic stress that causes significant yield losses in chickpea (Cicer arietinum L.) all over the world. The disease is caused by the fungus Ascochyta rabiei (Pass.) Lab (telemorph Dydimella rabiei = Mycosphaerella rabiei (Kovachevski) v. Arx. The use of resistant cultivars is widely acknowledged as the most economic and environmentally friendly method for disease control. The aim of this study is to screen chickpea cultivars and lines for resistance to ascochyta blight with a view for using them in a breeding program. The investigations were carried out during 2012-2017 in Dobroudzha Agricultural Institute (DAI)-General Toshevo. Twenty chickpea accessions were inoculated under field and greenhouse conditions with 30 Ascochyta rabiei isolates. Disease reaction was estimated after 14 days by using 9-degree scale. Disease incidence (DI) was calculated according to the Mc Kinney index. Cluster analysis was used to group the accessions and isolates according to the DI. Nine accessions showed middle resistance under field conditions during the three years of investigations. No immune or resistant accession to all 30 isolates was found under greenhouse conditions. The cluster analysis grouped the accessions into two major classes. One of the classes consists of two accessions (XOOC01CA0490B0223D and XOOC01CA0490B2140D) which showed middle resistance to 12 and 13 of the isolates, respectively. The cluster analysis grouped the isolates into classes, subclasses and sub sub classes according to their virulence to the 20 chickpea accessions. The highest virulence showed five isolates (AR 883, AR 061, AR R1, AR 1013, AR 1015) with DI from 5.40 to 9.00 in all accessions. Differences in field and greenhouse results were expected and they were due to the strong dependence of disease development to climatic conditions. The results in this investigation showed that two chickpea accessions can be used in a breeding program for ascochyta blight resistance.
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