Influence of agronomic factors on the relationship between forage production and seed yield in perennial forage grasses and legumes in a Mediterranean environment

Accessions (varieties and ecotype) of perennial legumes, lucerne (cv Equipe and ecotype Romagnola), sulla (cvs Bellante and Sant'Omero) and sainfoin (cvs Zeus and Vala), and grasses, tall fescue (cvs Tanit and Sibilla), cocksfoot (cvs Dora and Cesarina) and perennial ryegrass (cvs Vejo and Pamir) were investigated for performance in a typical Mediterranean environment (Foggia, southern Italy). The accessions were evaluated for yield potential in seed and forage dry matter and the relationship between yield component traits under rainfed and two irrigation treatments and forage harvest management was investigated. The traits investigated were forage production (dry matter, stem density and plant height) and seed yield (seed yield, 1 000 seed weight, stem density and seeds per stem). The results showed a significant difference among traits across the treatments. Early flowering of the accessions is the characteristic able to increase dry matter and seed yield in grass and legume species. Dry matter of the first harvest of the year was weakly influenced by irrigation treatments. The species and accessions showed different adaptability to exploit the forage and seed yield potential in the weather conditions under study. Irrigation treatment with a higher level of water application increased positively, in grasses and legumes, the correlation dry matter with stems per m(2) of the sward and negatively the correlation seed yield with seed weight in grasses and positively with stem density in legumes. Irrigation was the main agronomic factor which resulted in an ability to increase the period of crop utilisation, the seed yield, and to stabilise seed production in Mediterranean areas. ((C) Inra/Elsevier, Paris.)