THE SUPERIORITY OF WHEAT HYBRIDS FOR GRAI N FILLING - RESULTS OF A MULTILOCAL EXPERIMENT

The superiority of wheat hybrids for grain filling: results of a multi local experiment. In a multilocal experiment, 29 winter wheat hybrids and their parents were compared under various environmental conditions . The material was evaluated in randomised complete block designs, the elementary plot measuring 6 m2 minimum. At the 3 locations, heterosis over the best parental line was demonstrated for biomass production. This higher biomass production was related to heterosis over the best parental line for grain yield, because of a higher post-anthesis assim ilation for F1: so the harvest index of the hybrids remained equivalen t to that of the parent lines. Fertility was not greater for F1 than f or inbred lines, but the grain filling capacity of hybrids was greater than that of parental lines. Hybrids had a higher grain filling rate than parental lines for an equivalent duration of grain filling. Hybri d superiority for filling rate appeared to be related to assimilates a vailability at anthesis, which was greater for F1 (due to heterosis fo r stem dry matter 10 days after anthesis). On the whole, hybrids seeme d to have a more favourable ''source-sink'' relation than inbred lines .