| I. Research Notes Genomic constitution of Triticum ispahanicum HESLOT M. D. UPADHYA* Botany division, Indian Agricultural Research Institute, New Delhi, India Triticum ispahanicum, a tetraploid species of wheat was first described by HESLOT (1958, WIS Nos. 9-10, 1959), and was considered to be having the genomic constitution AABB. The meiotic behaviour of the hybrids involving ispahanicum with other tetraploid species was studied to provide the cytological evidence. One species each, from the free and non-free threshing groups, T. orientale and T. dicoccoides, respectively, were crossed with T. ispahanicum. The meiotic pairing at the first meiotic division was studied in the F1 hybrids as well as in ispahanicum. Regular fourteen bivalents, with occasional two univalents and twelve bivalents (in two cells out of 50 studied), were observed at the first meiotic metaphase in T. ispahanicum, showing a regular meiotic behaviour. Although the hybrid dicoccoides x ispahanicum shows a higher frequency of univalents per cell, than the hybrid orientale x ispahanicum, the majority of the cells studied in both the hybrids show fourteen bivalents. It is concluded from the above results that the genomic formula of T. ispahanicum is AABB and that it belongs to the Emmer group. In the hybrid dicoccoides x ispanicum, it was observed that the PMC's which were at late diakinesis or early metaphase stages had fourteen bivalents, whereas the advanced metaphase stages showed increased number of univalents. The possibility could be, that the genomes of dicoccoides and ispahanicum, in the hybrid, interact to initiate an early or precocious separation of bivalents which results in increased number of univalents at the metaphase (Table 1). The karyotype of T. ispahanicum was also studied following the schedule of UPADHYA (1963, Stain Technol., 38: 293-295). The karyotype showed to be having typical two pairs of sub-medianly constricted chromosomes bearing large satellites on their short arms. The rest of the twelve pairs of chromosomes had either median or sub-median centromeres. (Received Nov. 14, 1966) |
| * Present address: Department of Horticulture, University of Hawaii, Honolulu, U. S. A. |