INTERFERENCE EFFECTS IN GRASS VARIETIES GROWN AS PURE STAND, COMPLEX MIXTURE AND BINARY MIXTURE WITH WHITE CLOVER

The study aimed at: i) assessing the agronomic value of the pure stand (PS), of the complex mixture (CM) and of the binary mixture with each of six white clover genotypes (MWC) of eight grass varieties belongin g to four species and contrasting for earliness of flowering; and ii) investigating the relationships of competitive abilities in CM and MWC with some morpho-physiological traits of the grass varieties. CM show ed a 24% dry matter yield (DMY) advantage over mean value of PS but di d not outyield the pure stand of the best yielding component. For gras s-white clover associations, the DMY advantage as Relative Yield Total over PS of the components averaged 43%. DMY of the grass varieties av eraged across MWC conditions was related positively to total DMY (r = 0.99) and negatively to associated clover DMY (r = -0.96). Competitive abilities as Relative Yield of the grass varieties in CM and in MWC c orrelated (r = 0.84) and were both positively associated to DMY, canop y height and inclination of leaves in PS. The results suggested that a ssociation of white clover with a grass of moderately high vigour, int ermediate earliness and relatively erect leaves may provide the best o ption for rotational meadows in the experiment environment.