| A new lethal combination in Triticale hybrids O.P. SRIVASTAVA and H.B. CHAUDHARY Indian Agricultural Reesearch Institute, Regional Station, Pusa Bihar-848125, India and Indian Agricultural Research Institute, New Delhi 110012, India. The phenomenon of hybrid lethality has been found to be common in bread wheat where the presence of Ne1 and Ne2 genes have been established to operate, but this manifestation of hybrid lethality in triticales has been of rare occurrence. The only reference of CVETKOV (1980) for necrotic F1's in crosses between octoploid triticles derived from wheat varieties carrying Ne1 and Ne2 genes does indicate that not sufficient crosses have been tried to establish the presence of hybrid lethality in octoploid triticales. The hybrid lethality is not expected in hexaploid triticale (ZEVEN, 1973) as the only Ne1 allele are possible to exist since these are derived from tetraploid wheat x Secalecereals crosses. However, more octoploid triticals combinations can be studied for the presence of Ne1 and Ne2 alleles in them. Twenty hybrid seeds of each of two cross combinations viz. (C 306 x Assam Rye) x (Sonalika x Russian Rye) and (C 306 x Russian Rye) x (WL 410 x Russian Rye) and their reciprocals involving four octoploid primary triticales, were sown in pots. The parental forms of the four octoploid primary triticales viz. (C 306 x Assam Rye), (Sonalika x Russian Rye), (C 306 x Russian Rye) and (WL 410 x Russian Rye) were also sown for the purpose of comparison. The seedlings emerged, were quite normal. After three weeks, from the data of sowings, the hybrid seedlings in both the cross combinations and their reciprocals started showing hybrid lethality. The necrosis started at the tip of first leaf and proceeded gradually downwards towards the leaf base. This process was repeated on the remaining leaves and as a consequence all the hybrid seedlings died. The seedlings in the four parental forms did not show any sign of necrosis. From the results it can be inferred that the rye (Secale cereale) component involved in the octoploid primary triticales has got no suppressing effect on the Ne-genes associated with the wheat component. As a result the Ne1 gene found in one of the parents in both cross combinations carrying C 306 as hexaploid wheat component caused hybrid necrosis in combination with the octoploid primary triticales carrying Ne2 genes in the wheat components Sonalika and WL 410. The authors are very much thankful to Dr. M.G. JOSHI, Division of Genetics, Indian Agricultural Research Institute, New Delhi for his valuable suggestions in this study. Reference CVETKOV, S.M. 1980. Untersuchungen der Kreuzungsmoglichkeiten von Triticale und Unterschiedlicher valenz in einfachen und multiplen Krezungen sowie die Vitalitat der F1-Hybriden. Tag-Ber., Akad. Landwirtsch. -Wiss. DDR. Berlin 171 : 29-40. ZEVEN, A.C. 1973. Sixth supplementary list of wheat variethes classified according to their genotype for hybrid necrosis and geographical distribution of Ne-genes. Euphytica 22 : 618-632. |