LEAF-AREA AND GRAIN-YIELD IN PRODUCTIVE EUROPEAN WINTER-WHEAT VARIETIES

In 1984-1990 107 selected productive winter wheat varieties have been evaluated at two sites (Praha - Ruzyne, Klatovy) in two subsequent years. To compare the yield potential of varieties from different experimental series, the calculation to three control varieties was used. The varieties Apollo, Ares, Ikarus and Citadel were found to be the best and demonstrated also a low variability of yields. Of the Czechoslovak varieties, the most productive were the varieties Vlada, Regina and Zdar, followed by new breeds ST-424 and MS-4. A positive genotype dependence of the grain yield on LAI was demonstrable only in three environments of the total number 14 (r = 0.43+ to 0.46+, b = 1.45 to 2.72). The dependence was very low (r = 0.13 or 0.15, respectively) on an average of all environments and in the calculation from transformed values (to xBAR controls). The most yielding varieties (1/4 of a set) had only by 5% higher LAI in comparison with the contrast group of the same size. With respect to the yield difference, however, more effective leaf area utilization by about 20% may be expected.