GENETIC-VARIATION FOR SILAGE AND NIRS TRAITS IN AN HALF-DIALLEL DESIGN OF 21 INBRED LINES OF MAIZE

A diallel design between 21 inbred lines of maize. based on a wide gen etic variation, is studied in 4 environments, simultaneously using mor phological traits (recorded at silage harvest time) and Near infra-red Reflectance Spectroscopy (NIRS) technique. For both types of characte rs, the general combining ability appears predominant over the specifi c combining ability, and over interactions between genotypic effects a nd the environments. Broad- and narrow-sense heritabilities of agronom ic traits are high, except for the in vitro digestibility of the non-s tarch part of the plant, but this may be related more to high residual effects than to low genetic ones. The variation revealed by NIRS tech nique appears to be predominantly under genetic control, and very heri table, most of the effects being additive. This technique could be of interest for a low-cost improvement of the efficiency of selection ind ices when breeding maize for forage yield and digestibility.