MULTILOCAL ANALYSIS OF WHEAT HYBRIDS - LEVELS OF HETEROSIS AND YIELD ELABORATION

On a multilocal experiment, 35 winter wheat hybrids together with their parents were compared, under various environmental conditions. This material has been evaluated in randomised complete blocks deigns, the elementary plot being 3.5 m2 minimum. In the 3 locations, high-parent heterosis is demonstrated for yield, and the F1 are, on average, above the mid-parent for 1 000 seed weight and height, close to the mid-parent for the number of ears per m2 and fertility of ear, and on a par with the earlier parent (table I, and figs 1-5). The hybrid yield is correlated with that of the parents in all locations (table II), which is probably due to a large scale of parental agronomical values. Under the intensive cultivation conditions of the experiment, homeostasis is not greater for F1 than for inbred lines (tables III-VI). In the 3 locations, grain filling capacities of hybrids are greater than those of inbreds: with the same number of grains per m2, hybrids have a better 1 000 seed weight (fig 7). On the other hand, with an identical number of ears per m2, F1 's do not produce more grains per ear than inbreds (fig 6). For the selection of parental lines, it is interesting to select those with a good value per se, producing a large number of grains per m2 (table VIII).