Digestibility, forage and seed yield of two new festulolium amphiploids

In order to introduce more abiotic stress tolerance in Lolium fodder grasses, we carried out interspecific crosses between tetraploid genotypes of Lolium perenne (Lp) or L. multiflorum (Lm) and tetraploid genotypes of Festuca pratensis (Fp) or hexaploid genotypes of F. arundinacea (Fa). F1 plants were evaluated for spring growth, crown rust resistance, drought tolerance and winter hardiness. Two polycrosses were made, one with 3 selected genotypes of Lm x Fa and one with 5 selected genotypes of Lp x Fp. The syn1 seeds of the polycrosses were tested in a plot trial to determine yield and quality. At the end of the third year of the trial, plants from the two populations were randomly sampled and polycrossed to produce syn2 seeds.
The two syn1 Festulolium populations had a higher annual dry matter yield than their Lolium parental species. Although the water soluble carbohydrate content of the Festulolium populations was lower compared to the Lolium parents, their organic matter digestibility was higher thanks to a higher NDF digestibility. All this proves the potential of Festulolium hybrids to combine the stress tolerance of Festuca with the fodder quality of Lolium.
However, in general, the seed yield of the syn2 populations was low. Chromosome analysis revealed a substantial amount of aberrations in chromosome numbers, which can be the cause of low seed yield. In addition, GISH showed no clear shift to one of the composing genomes in the Lp x Fp population, while genome composition in the Lm x Fa clearly shifted towards the Lolium genome. Therefore, to validate the potential of Festulolium hybrids, it will be important in future breeding to select for higher seed yields and/or chromosome pairing stability at meiosis..