| Wheat Information Service Number 69: 21-23 (1989) Hybrid weakness in Triticum dicoccum Schubl. S.M.S.Tomar, M. Kochumadhavan1 and P.N.N. Nambisan Division of Genetics, Indian Agricultural Research Institute, New Delhi 110 012, India Introduction Genetic traits such as hybrid necrosis and hybrid chlorosis are controlled by two independent gene systems. In both kinds of hybrid weakness the F1 hybrid is lethal or semi-lethal resulting in gradual death or debility. Hybrid necrosis and hybrid chlorosis are frequently met with in inter- and intraspecific wheat crosses and are serious barriers to the transference of genes in a planned hybridization programme. Hybrid necrosis is governed by two dominant complementary genes Ne1 and Ne2, located on chromosomes 5B and 2B respectively (Tsunewaki 1966) while hybrid chlorosis is controlled by two dominant complementary genes Ch1 located on 2A (Hermsen and Waninge 1972) and Ch2 on 3D (Tsunewaki and Kihara 1961). The present investigations were carried out to identify the genes for necrosis and chlorosis in nine Indian varieties of T. dicoccum. Materials and Methods Nine varieties of Triticum dicoccum Schubl. were crossed to two T. aestivum testers, C306 (Ne1ne2ch1Ch2) and Sonalika (ne1Ne2ch1Ch2). The F1 hybrids and parents were raised in the greenhouse under optimum conditions of growth. The F1 hybrids were critically observed for the occurrence of hybrid necrosis and hybrid chlorosis and genotype of the parents with respect to the genes for necrosis and chlorosis were determined from the phenotype of the hybrids. |
| 1 IARI Regional Station, Wellington, The Nilgiris 643 231. |
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