CHANGES IN AGRONOMIC TRAITS OF GRASS VARIETIES DURING SEED INCREASE IN CONTRASTING ENVIRONMENTS

E. Piano,  M. Romani and P. Annicchiarico

Istituto Sperimentale per le Colture Foraggere, viale Piacenza 29, 26900 Lodi, Italy

Italian varieties of forage grasses are frequently multiplied in environments markedly different from those of origin and adaptation, a practice which may produce genetic shifts.  With reference to a synthetic variety of Italian ryegrass and one of tall fescue, we assessed the occurrence of changes for agronomic traits as influenced by contrasting environment of multiplication, generation of multiplication, and year of seed harvest within generation.  The environments were represented by the site of selection of the varieties (Lodi, northern Italy) and a Mediterranean location (Sanluri, Sardinia).  The Syn 3 and Syn 4 generations were multiplied at each of the two locations starting from a Syn 2 generation produced at Lodi.  Seed was harvested at the first and the second year following establishment.  Alternativity and heading time in a spaced plant trial, and dry matter yield in dense swards were assessed at Lodi.  A significant effect of location of multiplication was found for alternativity in Italian ryegrass and heading time in tall fescue.  However, the differences were not dramatic, averaging 7% for the former trait and 1.1 days for the latter.  A marked effect of year of seed harvest on dry matter yield occurred for both varieties, the materials from first year seed being higher yielding.  A significant dry matter yield decrease from Syn 3 to Syn 4 was found in the tall fescue variety.

Keywords: Festuca arundinacea; Lolium multiflorum; genetic shift; synthetic variety; variety multiplication.