Bread wheat (Triticum aestivum L. 2n = 6x = 42, AABBDD) is among the most widely grown cereal crops serving various value chains in the world (Nhemachena and Kirsten, 2017). Wheat was produced on an estimated area of 218 million hectares with grain output of 772 million tons globally (Food & Agricultural Organization, 2018). About 30% of the world's population depends on wheat as a primary source of calories. Also, wheat provides up to 60% of proteins derived from cereals (
Barley (Hordeum vulgare L.) has narrow genetic base for selection of promising ideotypes for the following traits: high biomass yield for livestock feed, enhanced agronomic and nutritional traits, and resistance to biotic and abiotic stresses. Ethyl methane sulfonate (EMS) mutagenesis offers opportunities for inducing genetic variation for key traits for development of feed barley ideotypes. The objective of this study was to determine optimal EMS dosage and exposure time to induce genetic variation for selection of high biomass yield six-row feed barley mutants. Five EMS dosages (i.e. 0.1%, 0.3%, 0.5%, 0.7% and 0.9% v/v) and five exposure times (i.e. 0.5 hr, 1 hr, 1.5 hr, 2 hrs and 2.5 hrs) were used on a six-row fodder barley using a 5 x 5 factorial treatment structure in a complete randomized design with three replications. Non-treated seed were used as a comparative control. Data was recorded for percent germination, seedling survival, shoot height, root height, shoot and root biomass. Significant (p < 0.05) EMS dosage x exposure time was observed for assessed traits indicating their influence on phenotypic variation in feed barley. Overall, a declining trend was observed for assessed traits with increased EMS dosage and exposure time. The LD50 value of 0.64% (v/v) EMS dosage was identified as an optimal dose for large-scale mutagenesis protocol to select fodder barley mutants with high biomass yield
The narrow genetic variation for drought adaptive traits and biomass allocation in wheat (Triticum aestivum L.) presents a major bottleneck for breeding. Induced mutagenesis creates genetic variation and complements conventional breeding for drought tolerance improvement. The aims of this study were to induce mutations in wheat genotype LM43 using three ethyl methanesulphonate (EMS) treatments, and to develop mutant populations for improving drought tolerance, biomass allocation and agronomic performance. Experiments were conducted under controlled and field conditions at the University of KwaZulu-Natal. Data on percentage germination (%G), days to 90% maturity (DTM), plant height (PH), shoot biomass (SB), root biomass (RB), root-shoot ratio (RSR), spike length (SL), spikelet count (SPS), thousand seed weight (TSW), and grain yield (GY) were collected from M1 to M4 generations. Significant (p < 0.001) differences among individuals and generations were observed for all the assessed traits and the generation × population interaction effects were significant (p < 0.01) for SB, TSW, and GY due to EMS treatments. The differences among the generations showed that the mutagenic effects were cumulative and exhibited clear segregations in subsequent generations. The new selections with unique biomass allocation, drought response and agronomic performance will be useful for wheat improvement programs.
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