Genomic selection for lucerne biomass yield in di erent stressprone environments

Abstract

Climate change and reduced irrigation water emphasize the need for lucerne (Medicago sativa L.) varieties with improved yield under drought and saline conditions. Marker-based selection may o!er opportunities, owing to low yield gains displayed by phenotypic selection. "is study generated preliminary results on the ability of genomic selection to predict lucerne breeding values and the extent of genotype × environment (GE) interaction for several stress-prone environments. Some 128 genotypes issued from an elite broadlybased reference population were genotyped via Genotyping-by-Sequencing, and phenotyped according to biomass yield of their half-sib progenies over a period ranging from $ve months to two years in four agricultural environments of Algeria, Argentina, Morocco and Tunisia featuring drought or salinity stress, and three environments of Italy with contrasting managed drought stress. AMMI analysis and estimates of genetic correlation revealed large GE interaction even across drought-prone environments. Genome-enabled predictive ability was mostly low albeit not quite unfavourable when compared with phenotypic selection opportunities. It tended to be higher under favourable conditions than under stress and in the last harvest, suggesting that it may increase for yield collected over a longer time span. Genomic selection was particularly convenient for selecting varieties with wide adaptation across stress conditions.