| Our studies including those reported earlier show that the different wheat
varieties can be grouped into five classes on the basis of their fertility
restoring ability in male sterile wheat carrying T. timopheevi cytoplasm.
The wheat varieties may carry full fertility restoring gene or genes, partial
fertility restoring genes, modifiers of strong action, modifiers of weak
action or no modifiers at all (Table 1). Modifiers
appear to be complementary to the fertility restoring genes from T. timopheevi;
therefore, the varieties carrying modifiers are useful and their conversion
to fertility restorer line (R-line) is easy, whereas, the varieties lacking
modifiers may not be so suitable for the development of fertility restorer
lines. Conversely, varieties without modifiers are most suitable for the
development of male sterile lines (A-line). Our data will support the model
developed by WILSON (1968), if we assume dosage effect for the modifiers
of strong and weak action. Literature Cited FUKASAWA, H. 1858. Fertility restoration of cytoplasmic male sterile emmer wheats. W.I.S. 7 : 21. KIHARA, H. 1951. Substitution of nucleus and its effects on genome manifestations. Cytologia 16 : 177- 193. KIHARA, H. 1963. Nucleus and chromosome substitution in wheat and Aegilops I Nucleus substitution. In Proc. Second Int. Wheat Genet. Symp. Lund, Sweden 1963. Hereditas Suppl. 1 : 156-166. MIRI, R. K. 1966. Hybrid wheat: Problems and Prospects. Proc. Fifth All India Wheat Research Workers' Conference, Jaipur. Aug. 17-22 : 217-222. MIRI, R. K. 1968. Male fertility and sterility in the hybrids of crosses of T. zhukovskyi, T. sphaerococcum and T. aestivum with common wheat carrying T. timopheevi cytoplasm, W.I.S. 27 : 2-5. MIRI, R. K., J. S. AMAWATE and H. K. JAIN 1970. T. timopheevi system of cytoplasmic genetic male sterility and fertility restoration for the development of hybrid wheat. Ind. Jour. Genet. and Pl. Breed. (In press.) OEHLER, EL and M. INGOLD 1966. New cases of male-sterility and new restorer source in T. aestivum W.I.S. 22 : 1-3. PORTER, K. B. and O. G. MERKLE 1967. Pollen restoration factors from the world wheat collection (T. aestivum L.) Agronomy Abstr. Madison 1967, p. 16. SCHMIDT, J. W., V. A. JOHNSON and S. S. MAAN 1962. Hybrid Wheat. Nebraska Exp. Sta. Quar. 9(3) : 9. WILSON,J.A and W. M. Ross 1962. Male sterility interaction of the T. aestleum nucleus and T. timopheevi cytoplasm. W.I.S. 14 : 29-30. WILSON,J.A 1968 Problems in Hybrid Wheat Breeding. Euphytrca 17 (1968 Suppl. 1) : 13-33. (Received April 23, 1970) |
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