Studies with Israeli and Turkish accessions of Triticum turgidium L. emend. var. dicoccoides (KORN.) BOWDEN¹⁾

P. Seshagiri RAO and E. L. SMITH²⁾

Two main races of dicoccoides³⁾ are recognized by HARLAN and ZOHARY (1966). These are the Palestine race and the Turkish-Iraqi race. The two races are geographically separated and morphologically distinct. SACHS (1953), working with a single representative from each race, showed that they were cytogenetically distinct. Morphological variation within the Turkish-Iraqi race led him to suggest that this race may also show variation in chromosome differentiation. According to HARLAN and ZOHARY (1966),the available evidence on morphological and cytogenetic relationships indicates that the Palestine race gave rise to most of the cultivated tetraploid wheats while the Turkish-Iraqi race contributed only to the timopheevi complex.

In order to examine the relationships of the two dicoccoides races more extensively, four Israeli and six Turkish accessions were studied morphologically and cytogenetically. Crosses were made between the Israeli and Turkish accessions. Also, both groups were crossed with a number of other tetraploid wheats including a timopheevi accession from the U.S.S.R., a turgidum accession (available at the Oklahoma Agricultural Experiment Station); and dicoccon accessions from Ethiopia, India, the U.S.S.R., and Yugoslavia. In addition, timopheevi was crossed with dicoccan and turgidum.

The four Israeli accessions were morphologically similar and as a group could be distinguished from the Turkish accessions. The Israeli group. had larger and more robust plants with lax heads and heavy awns. This group also differed from the Turkish group by having a larger number of hairs on the rachis edge, larger and tougher glumes, and a larger awn length to lemma length ratio. Data on chromosome pairing and fertility of the F₁ hybrids are shown in Table 1. Cytogenetically, the four Israeli accessions were similar. These accessions exhibited very close relationships with dicoccon and turgidum but their hybrids with timopheevi showed poor chromosome pairing and were completely sterile. Four of the six Turkish accessions were similar to the Israeli group in pairing relationships and seed set percentages. The other two Turkish accessions showed considerable cytogenetic differentiation. Turkish accession 11191 exhibited good chromosome pairing and some fertility in crosses with both timopheevi and dicoccom. Turkish accession 11189 showed close pairing relationships and some fertility with timopheevi but exhibited poor pairing and complete sterility in crosses with dicoccon and the Israeli group.

It appears that considerable cytogenetic variation exists within the Turkish-Iraqi race of dicoccoides. The results of this study tend to support SACHS (1953) suggestion that chromosome differentiation in this race may range from types having complete affinity to the Palestine race to types similar to timopheevi. A more detailed account and possible implications of this study will be published elsewhere.

The authors wish to express their appreciation to Dr. Jack R. HARLAN, University of Illinois, U.S.A., for providing the material and suggesting the problem.

Literature Cited

BOWDEN, W. M. 1959. The taxonomy and nomenclature of the wheats, barleys, and ryes and their wild relatives. Can. J. Botany 37 : 657-684.

HARLAN, J. R. and D. ZOHARY 1966. Distribution of wild wheats and barleys. Science 153 : 1074-l080.

SACHS, L. 1953. Chromosome behavior in species hybrids with T. timopheevi. Heredity 7 : 49-58.

(Received Jan. 17, 1968)