Relation between yielding ability and homozygosis in barley crosses
1941
Immer, F.R.
The extent of heterosis for number of heads per plant, seeds per head, weight per seed, and yield per plant was determined in six crosses between varieties of barley. The yield in relation to the parent varieties was determined in replicated yield trials of the same crosses in F2, F3, and F4. The yield of the parent varieties was compared also with the average yield of the F2, F3, and F4 generations for each of the six crosses. As an average of all crosses the F1 exceeded the average of the parents by 8.3% in number of heads per plant, 11.1% in number of seeds per head, 4.9% in weight per seed, and 27.3% in yield per plant. The average yield of six crosses in F2 and F3 in replicated trials, as an average of two years, exceeded the average of the parents by 24% and 13%, respectively. In F4 the average increase in a single year test was 5% over the average of the parents. It is suggested that the average yield performance of different crosses may be determined by means of replicated yield trials in the F2 or F3 generations. Such yield trials may be used for discarding certain crosses since the proportion of high-yielding genotypes in the low-yielding crosses will be less than in crosses with a higher average yield.
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