Genetic improvement in ryegrass (Lolium perenne) from turf and forage breeding over the four past decades
Résumé
In order to assess the efficiency of breeding in ryegrass (Lolium perenne), we tested the agronomic performances of a set of diploid cultivars including turf and forage cultivars registered on European national lists from 1965 to 2004. Seven eco-types, originating from the main European climatic areas were also tested. Linear regressions fitting agronomic traits to the year of registration enabled to test the genetic improvement in turf and forage breeding through time. The genetic improvement in turf breeding was highly significant (p value of regression slope < 0.001) for most target traits (aesthetic aspect, disease resistance, wear tolerance, summer aspect, persistency). In forage breeding, the genetic improvement was highly significant (p value < 0.001) for autumn dry matter yield, rust resistance, and persistency, and was significant (p value < 0.05) for summer dry matter yield and reduction of aftermath heading. The rate of improvement of annual dry matter yield reached 0.29 ton per 10 years. Forage breeding was additionally associated with a highly significant decrease of lignin and crude protein content, and with a highly significant increase of soluble carbohydrate content. No significant change in grain production was noted either in forage or turf breeding, but conversely a large range of seed production was pointed out in both ancient and recent cultivars.