#bread wheat

Genetic diversity in crop specie is essential to breed buffered genotypes capable to withstand under biotic and abiotic stress conditions. An approach called genotypic selection based on the widespread conventional selection with the use of information of the molecular markers can facilitate breeding strategy by providing effective achievement of biotic stress resistance reducing in mean time generation interval and investments in ecological-friendly crop production is reviewed. Also the phenotypic selection is an important step in breeding programs, and genetic variability increases the chances of obtaining variance in progenies. In this study, we present a practical validation of the breeding strategy to produce bread wheat lines derived from a three elite cultivar with superior dough properties and durable rust resistance. Molecular markers were used to screen a double hybrid population produced from a cross between the three varieties of bread wheat considered as donor parents: Dharwar, Annuello and Stylet crossed with six varieties considered as recurrent parents: Achtar, Aguilal, Merchouch, Baraka, Salama and Amal. Following the phenotypic selection was applied for the doubled haploid plants to select new genotypes for rust resistance, Hessian fly resistance, drought tolerance and grain protein content.

Bread wheat productivity is constrained by incorrect use of inorganic nitrogen rate and time of application. The objectives of this study were to determine economically feasible rate and time of nitrogen for wheat. Five levels of nitrogen (0, 23, 46, 69 and 92 kg ha-1) and three time (1/2 at the time of sowing and 1/2 at mid tillering stage, 1/3 at the time of sowing and 2/3 at mid tillering stage and 2/3 at time of sowing and 1/3 at mid tillering stage) were tested by using a randomized complete block design with three replicates. SAS software was used to analysis of variance which revealed almost all parameters were significantly (p ≤ 0.01) affected by the main effects of nitrogen rate and its application time, except time of N had no significant effect on thousand kernels weight, straw yield and harvest index, while, their interaction effects had significant effect on grain yield, above ground dry biomass, spike length and plant height. The highest net benefit was obtained from the 92 kg/ha N with 1/3 at the time of seed sowing and 2/3 at mid-tillering stage, which produced high grain yields with the best profitability. Therefore, this treatment could be recommended as best for maximum seed yield of wheat. However, the experiment was carried out only in one location for one cropping season, additional studies at different locations for at least three years or seasons should be conducted.

The wheat Q gene, located on the group 5 homologous chromosome, is extremely important for widespread wheat cultivation due to its influence on many morphological traits associated with domestication. To analyze the variability of the Q gene locus, 52 genotypes were grown in pots in Addis Ababa Science and Technology University. Deoxyribonucleic acid (DNA) extraction was done from 20 days old plant by using CTAB buffer. DNA marker designed from the 9th intronic region of the Q gene was used to carryout polymerase chain reaction (PCR). The PCR products were separated in agarose gel and six allelic variants from the PCR products were visualized using gel documental system. First, the expected PCR product sizes of 536bp, 665bp and 578bp for locus 5AQ, 5BQ and 5DQ loci, respectively, were observed in 16 bread wheat genotypes. Secondly, amplification of expected PCR product sizes for 5AQ and 5DQ, but no 5BQ were observed for six genotypes. Thirdly, four kinds of length variations in the 9th intronic regions for the PCR products were observed for half of the analysed genotypes in 5AQ and 5DQ loci. Furthermore, amplified PCR product for only 5AQ was observed in seven wheat genotypes, but no for 5BQ and 5DQ. The information’s obtained on the Q gene profile will contribute towards diversification and knowledge based uses of Q gene in Ethiopian wheat breeding programs, and will be useful in the attempts to develop cultivars with ideal plant architecture and high yield.

In order to evaluate drought tolerance in bread wheat genotypes an experiment was conducted in a randomized complete block design with three replications under rainfed and irrigated conditions during 2012-2013 growing season. Drought stress significantly increased relative water protection (RWP), water saturation deficit (WSD), initial water content (IWC), leaf water content (LWC) and excised leaf water retention (ELWR), while decreased leaf water Loss (LWL), relative water content (RWC) and excised leaf water loss (ELWL). Principal component analysis (PCA) showed that integrated selection index (ISI) was correlated with relative water content (RWC), water saturation deficit (WSD), initial water content (IWC), leaf water content (LWC), stress yield (Ys) and yield potential (Yp) indicating that ISI was able to distinguish group A genotypes (drought tolerant with high grain yield under rainfed and irrigated conditions). Screening drought tolerant genotypes using mean rank, standard deviation of ranks and rank sum (RS), discriminated genotypes 9, 3, 12 and 2 as the most drought tolerant.