| In control set, two F1's: Koala 'S' x 6TA204 and DS x T1 showed
either no or very poor germination on 3rd and 7th day respectively. However,
F1 seeds of these crosses initiated germination in GA3
but the growth of radicle and plumule was checked at very initial stages.
This eliminates the possibility of seeds being dormant. The failure of proper
seed germination may be attributed to some kind of hybrid necrosis leading
to loss of seed vitality or seedling vigour. In the rest of the four combinations, though the germination of seeds was poor, yet few seeds could give rise to seedlings of satisfactory length (10-15 cm). However, in field conditions the germination was relatively poor and in one case, T1 x 6TA204 seedling lethality was observed in few plants. In the other three combinations; DS x 6TA204, Koala 'S' x T1 and TH2 'S' x 6TA204 plants manifested poor growth with more leaf tip burning as compared to their parents. Such effects may be attributed either to the presence of weak necrotic genes or the presence of modifiers in parents or better buffering in storage conditions. Hybrid necrosis in triticale is likely to occur if triticale strains carrying Ne1 are crossed with triticale lines derived from crosses involving wheat genotypes carrying Ne2. Since the exact pedigree of lines we have been using is not known, sources of Ne1 and Ne2 could not be traced. Effect of storage duration and conditions might also have affected parents and F1's differentially. However, present study points to an interesting situation that these abnormalities were recorded in only six out of one hundred cross combinations and as such presence of hybrid necrosis may be speculated. It is therefore suggested that triticale lines should be screened for the presence of necrotic genes and their alleles so as to avoid or minimize chances of failure to obtain progenies of simple or complex crosses for genetic analysis or further improvement work. References GILL, K.S., GHAI, B.S. and GUPTA M.L. (1972). Genetic and developmental analysis of hybrid necrosis in wheat. Indian. J. Genet 32 12-17. GREGORY, R.S. (1974). Triticale research programme in U.K. In Triticale Proc. Third Intern Symp. El Batan, (Mexico), 61-67. HERMSEN J.G. (1963). Hybrid necrosis as a problem for wheat breeders. Euphytica 12, 1-16. NAYLOR, J.M. and SIMPSON, G.M. (1961). Dormancy studies in seeds of Avena fatua. Can. J. Bot., 39, 281-295. ZEVEN A.C. (1976). Seventh supplementary list of wheat varieties classified accordingly to their genotype for hybrid necrosis and geographical distribution of Ne-genes. Euphytica 25, 255-276. |
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