YIELDING CAPACITY OF WHEAT CROSSES AS INDICATED BY BULK HYBRID TESTS

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Abstract
In order to determine readily the usefulness of heterosis as an indicator of the yielding capacity of cereal crosses, replicated half rod row yield trials were made with bulk unselected seed of ten wheat crosses in F2 and of six in F3. The practical yielding value of the latter six crosses was ascertained later by replicated rod row yield tests of selected lines in F6, F7 and F8. All the F2 populations (excepting a T. vulgare × T. persicum cross) yielded significantly more than the mean of the parental varieties, the increased yield being 52 and 64% for two of the crosses. Of the six F3 populations tested, the only one to yield significantly above the parental average was Reward × Hope, and the only ones to yield significantly less than the parental average were the two having Quality as one parent. Replicated plot tests of purified lines selected for high yield and other agronomic virtues showed the Reward-Hope combination to be particularly valuable, whereas the two crosses containing Quality were unpromising. The results suggest that replicated bulk F2 tests may be used to indicate the yielding potentialities of wheat crosses, and that bulk F3 tests may have supplementary value in this regard.