IV.8 Tetraploid barley with improved seed set.
W. Friedt and H. Gaul. Department of Plant Genetics of the Gesellschaft für Strahlen- und Umweltforschung mbH 8059 Grünbach 1, FRG.
The Diploidisation program of autotetraploid barley, which was started
in 1960 consists of three subsequent steps.
(1) mutation induction in many autotetraploid varieties by X-rays and
EMS,
(2) multiple crosses of random plants in M1 und F1,
(3) selection among progenies for seed set following the pedigree method.
Our results indicate, that the method described has drastic response with respect to the improvement of seed set (fertility) of tetraploid barley.
In Table 1 the seed set of autotetraploids in the world collection, planted in Grünbach in 1974, is presented. On the average, the autotetraploids have about 61% seed set, the corresponding diploids about 94%, when measured with the same method.
Table 1. Seed set of autotetraploids and corresponding diploid varieties 1974
In Table 2 the seed set in three subsequent years of four initial autotetraploids is compared with that of the progenies of five selected strains which originate from a single F3 plant from a multiple cross of the five initial autotetraploids Haisa II, D 8/55, D 9/55, Weihenstephaner and Atlas which had been irradiated four to seven times with X-rays.
In 1974 the average seed set for 700 plants of the autotetraploids was 57.3%, while 1740 plants of the selected strains reached 71.6% seed set on the average. In 1973 the said strains had shown 79.8% average seed set.
In 1975 the average seed set of the original autotetraploids was 61.9%, that of the strains 75.2%.
In Table 3 all plants of 1974 of the mother autotetraploids and the strains are distributed into fertility classes. Almost 70% of the selected plants have more than 70% seed set, the corresponding value for the control varieties is 12%. In contrast, about 6% of the plants of the strains but 19% of the autotetraploid plants have less than 50% seed set.
Therefore the frequency distribution reveals a larger improvement of fertility, than the average values are indicating.
Strains in drill-trials showed more than 80% seed set. The lower seed set of the strains described above was due to widely spaced sowing which resulted in more vigorous tillering, the formation of sidetillers and consequently a reduced seed set.
Preliminary results of cytogenetic investigations are indicating, that chromosome pairing and segregation during meiosis is more regular in the selected strains than in the autotetraploid varieties. Plants of the initial autotetraploids had 43.7% tetrads with micronuclei, such of selected strains only 21.2%.
