Evaluation of Advanced Bread Wheat Lines for Field and Seedling Resistance to Stem Rust (<i>Puccinia graminis</i> f. sp. <i>tritici</i>)

Abstract

Field-based adult plant resistance assessment at multi-location rust hot spot sites is a crucial job for those plant pathologists screening several wheat lines at a time against the rusts. Rust resistant bread wheat genotypes that have been extracted from previous studies have sustained wheat production in Ethiopia. The objective of this study was to evaluate advanced bread wheat lines extracted from wheat breeding trials against stem rust at adult plat stage under stem rust hot spot sites and at seedling stages in the greenhouse. Eighty three lines were further re-evaluated in consecutive two years. Check varieties were included for comparison. High disease pressure was developed on adult plant in the trial as it has been revealed by high severity on susceptible check varieties. Over years average final rust severity, coefficient of infection and field reaction have used for differentiating Adult plant resistances. Based on ACI, the 843 genotypes evaluated in initial trial in 2013 were categorized into 10 resistance levels, of which 188 genotypes were in high level resistance category, revealing that various level of adult plant resistance is operating in these test materials. Most of 83 genotypes r-evaluated in consecutive two years after initial stage have sustained low final stem rust severity and coefficient of infection as compared with check varieties. Genotypes were varied by adult plant reaction to stem rust, however, lines ETBW7818, ETBW7819, ETBW7258, ETBW 8008, ETBW 8009, ETBW 8017, ETBW 8027, ETBW 8052, ETBW 8054 and ETBW 8055 concisely showed a reaction of R to R-MR invariably with environments. Of the 83 lines tested at seedling stages against four races, 21 lines exhibited resistance to three races JRCQC, TKTTF, TTKSK and TRTTF whereas 24 lines showed susceptibility to the latter three races. Based on adult reaction, final disease severity and coefficient of infection data, Sixty six bread wheat lines and two cultivars Shorima and Huluka sustained final rust severity <30% and low ACI are acceptable for rust resistance breeding in wheat, However, 52 lines showed comparable resistance to Shorima or Hulluka are the priority materials to be used for developing resistant cultivars potentially combining non-race specific and race specific genes which is more durable than cultivars with major resistance gene effect and more efficient than sole adult plant resistance. Inherent resistance genes of these lines are unknown and warrant further description.

Evaluation of Bread Wheat Genotypes for Adult Plant Resistance to Stem Rust

“…On the other hand, the susceptible check Morocco and four ETBW-8802,ETBW 8668, ETBW-8595 and ETBW-9557, and two ETBW-8668 and ETBW-9557 tested genotypes displayed ACI above 41 Table 2 Information's of this study disclosed that 22 wheat genotypes namely showed acceptable level of stem rust slow rusting in both diseases assessment parameters, terminal rust severity and average coefficient of infections during 2018 growing season at both locations compared with Morocco (universal susceptible check).These wheat lines were found to be resistant to stem rust disease and can be used in breeding programs to release commercial cultivars as safely production under Ethiopian conditions. The result of this study is in agreement with Bekele Hundie et al (2018), who reported advanced bread wheat lines extracted from wheat breeding trials against stem rust at adult plat stage under stem rust hot spot sites and at seedling stages in the greenhouse. In addition, the result of this study is in lined with the works of Nzuve F. (2012) who reported as evaluating wheat genotypes for both field and seedling resistance to stem rust and genotypes showed diverse seedling and adult plant resistance responses.…”

Impact of Stem and Yellow Rusts on Grain Yield of Bread Wheat (Triticum Aestivum L) Genotypes Under Rainfed Conditions of Ethiopia

“…The genotypes were evaluated in alpha lattice design with three replications at four environments (Kulumsa, Asasa, Dhere and Melkasa Research sites) for two consecutive main cropping seasons (2017/18-2018/19). In both years each genotype was sown with six rows of 2.5m length with 0.2m space between the rows, being plot size of 3m 2 . Six rows were harvested and the net harvested plot was 3m 2 (2.5m x 1.2m).…”

“…In both years each genotype was sown with six rows of 2.5m length with 0.2m space between the rows, being plot size of 3m 2 . Six rows were harvested and the net harvested plot was 3m 2 (2.5m x 1.2m). Field management and agronomic practices were carried out as recommended for each location.…”

“…Developing resistant varieties combining both allstage resistance and partial resistance determined by race specific and minor genes, respectively, is a priority research area for breeders in Ethiopia. Varieties with combination of resistance genes could be more durable and more effective than varieties with sole all-stage or adult plant resistance types [2]. As a general from this study variation for yield, yield component and disease resistance for both rusts have been observed so the genotypes that are best for all parameters (yield and yield component disease resistance) will be release as new varieties after further test, but genotypes that exhibited resistance reaction response for disease and showed low grain yield will be used for developing resistance line through crossing.…”

Genetic Characterization and Genome-Wide Association Mapping for Stem Rust Resistance in Spring Bread Wheat

“…Many new variants of Pgt were first identified in this country and spread to different parts of the world. Rust of wheat, races TTKSK, TKTTF, TRTTF, JRCQC, and TTTTF are the stem rust of wheat races that are threatening wheat production currently in Ethiopia [16]. In 2013/2014, severe stem rust epidemics were caused by Pgt race TKTTF (not a member of Ug99 lineage) resulting in nearly total yield loss on widely grown wheat cultivars.…”