| Lethality and dwarfness of the hybrids between Emmer
and synthesized 6x wheats (Preliminary report) K. NISHIKAWA Laboratory of Genetics and Plant Breeding, Gifu University, Gifu, Japan Crosses between synthesized 6x wheats, ABD No. 1, ABD No. 2 and ABD (Sears),* and Emmer wheats (including 20 varieties) were made. In the hybrids with ABD No. 1, various degrees of abnormalities such as lethality, semi-1ethality and dwarfness occurred, depending upon which variety of Emmer wheats was used for crossing. With ABD No. 2, only normal hybrids were produced no matter which Emmer wheat was a pollen parent. When crossed to ABD (Sears), some of Emmer wheats which gave rise to lethal hybrids with ABD No. 1, showed again lethality. Hybrid lethality and semilethality mentioned here were caused by necrosis due to complementary action of genes, which appeared at a definite growth stage. One of those genes was brought from Emmer wheats and the other from D gnome of synthesized 6x wheats. On the basis of abnormality of their hybrids with three strains of synthesized 6x wheats, 20 varieties of Emmer wheats can be classified into 5 groups as shown in Table 1. Three way crosses were made between ABD No. 1 and each of the F1 Emmer hybrids which represented 5 out of 10 possible combinations among 5 representative varieties shown in Table 1. Rates of the survival plants, rates of necrotic plants, culm length, culm number and dry weight per mature plant in these triple hybrid strains are shown in Table 2. No lethal plant and no necrotic one arose in strain 1. Rates of the survival plants were much over than 50% in strain 2, 3 and 5, while that in strain 4 was below 40%. Rates of necrotic plants proved to be below those of the survivals in every strain, because three survived some portion of necrotic ones in addition to all the normal plants. The ratio of necrotic to normal is not different significantly from 1 : 1 in strain 2, 3 and 5, and from 3 : 1 in strain 4. Accordingly, it may be concluded that Emmer hybrids (1) x (3), (1) x (4) and (2) x (4) are mono-hybrid, while (1) x (5) is di-hybrid, for necrosis gene. With culm length, culm number and dry weight per mature plant, there were observed continuous variation, which covered a considerably wide range, in every strain. |
| * ABD No. 1 and No. 2 were synthesized by Kihara et al. (1950) from T.
dicoccoides spontaneonigrum x Ae. squarrosa typica No. 2 and
T. durum coerulescens x Ae. squarrosa typica (No. 1 x No.
2) F1, respectively. ABD (Sears) was synthesized by Dr. E. R. Sears from T. dicoccum (Vernal) x Ae. squarrosa. |